research article a novel biosorbent, water...

Research ArticleA Novel Biosorbent Water-Hyacinth Uptaking MethyleneBlue from Aqueous Solution Kinetics and Equilibrium Studies

Md Nasir Uddin1 Md Tariqul Islam2 and Sreejon Das1

1 Department of Chemical Engineering University of Malaya 50603 Kuala Lumpur Malaysia2 Department of Mechanical Engineering University of Malaya 50603 Kuala Lumpur Malaysia

Correspondence should be addressed to Md Nasir Uddin nasir cep01yahoocom

Received 4 February 2014 Revised 19 March 2014 Accepted 24 March 2014 Published 15 April 2014

Academic Editor Dmitry Murzin

Copyright copy 2014 Md Nasir Uddin et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

The adsorption of MB dye from aqueous solution onto HCl acid treated water-hyacinth (H-WH) was investigated by carried outbatch sorption experiments The effect of process parameters such as pH adsorbent dosage concentrations and contact time andionic strength were studied Adsorption of MB onto H-WH was found highly pH dependent and ionic strength shows negativeimpact on MB removal To predict the biosorption isotherms and to determine the characteristic parameters for process designLangmuir Freundlich Temkin and Halsey isotherms models were utilized to equilibrium data The adsorption kinetics wastested for pseudo-first-order (PFO) pseudo-second-order (PSO) intraparticle diffusion (IPD) and Banghamrsquos kinetic modelsTheLangmuir isothermmodel showed the goodness-of-fit among the tested models for equilibrium adsorption of MB over H-WH andindicated the maximum adsorption capacity as 6330 mgg Higher coefficient of determination (1198772 gt 099) and better agreementbetween the qe (experimental) and 119902

119890(calculated) values predicted that PSO kinetic model showed the goodness-of-fit for kinetic

data along with rate constant 166 times 10minus3 442 times 10minus3 and 357 times 10minus3mg sdot gminus1minminus12 respectively for the studied concentrationrange At the initial stage of adsorption the overall rate of dye uptake was found to be dominated by external mass transfer andafterwards it is controlled by IPD mechanism

1 Introduction

Adsorption is one of the most widely applied techniques forremoval of certain classes of chemical pollutants fromwatersespecially those that are hardly demolished in traditionalwater-treatment plants [1] Amongst the various industrialsectors textile tannery and pharmaceutical industries areemitting significant volume of dyes and pigments intowastewater [2] The adsorption process can be taken as aneffective alternative for the pollutants uptake from wastewater only when the adsorbent is inexpensive and doesnot need an additional pretreatment before its application[3]

The extent of pollutants uptake by aquatic plant has beenextensively tested [4ndash6] Water-hyacinth (WH) an aquaticplant has received considerable attention because of itspotential to remove pollutants when used as a biologicalfiltration system [7] Malik [8] pointed out that the WH

has tremendous survival capability in the presence of toxicpollutants and hence it should be able to be used effectivelyin heavy metals removal process as well as other pollutantsfrom polluted water Many great efforts have demonstratedthat WH can be used to adsorb a cationic dye (methyleneblueMB) [4] phenol [9] cadmium [5] copper [10] uranium(VI) [11] Victoria blue [12] crystal violet [13] and so forthfrom aqueous solution

Low et al [12] have performed the biosorption of basicdyes (MB and Victoria blue) by WH roots at differentoperating conditions including pH sorbent dosage contacttime and initial concentrations They showed that the rateconstant for the sorption of methylene blue is controlledby pseudo-first-order (PFO) model while maximum rateconstant was found 69 times 10

minus2 per min for 100mgL ofinitial methylene blue concentration (IMBC) Finally theypointed out that with increasing IMBC (100ndash500mgL) therate constant for intraparticle diffusion was also increased

Hindawi Publishing CorporationInternational Journal of Chemical EngineeringVolume 2014 Article ID 819536 13 pageshttpdxdoiorg1011552014819536

2 International Journal of Chemical Engineering

(0082ndash1554mggmin12) andWH roots have a great poten-tial as a biosorbent for basic dyes however this is lessso for acidic dyes Soni et al [14] have studied the batchadsorption to remove the MB from an aqueous solutionover WH roots powder at varying operating conditions suchas pH adsorbent dose initial concentration of dye andcontact timeTheyhave reported thatmaximum95 removalof dye was attained at optimum experimental conditionExperimental equilibrium data were best correlated by bothLangmuir and Freundlich isotherms and the maximum dyeuptake was found to be 804mgg The adsorption kineticdata are adequately fitted to the pseudo-second-order (PSO)kinetic model along with higher regression determination(1198772gt 0999) for all ranges of dye concentrations Likewise

Kanawade and Gaikwad [15] described that the uptaking ofMB from aqueous solution by using WH as an adsorbentdepends on its initial concentration and contact time Theyalso noticed that adsorption of MB onto WH follows Lang-muir isotherm model

Kaur et al [13] have used WH as a potential adsorbentto remove dye crystal violet (CV) from aqueous solutionsunder different experimental conditions corroborating thatadsorption increases with increase in contact time adsorbentdose temperature and pH The experimental sorption datashowed the goodness-of-fit with PSO model along withhigher correlation coefficients (1198772 gt 0999) A maximumadsorption capacity of 581mgg was achieved from experi-mental equilibrium data which highly fitted with Langmuirmodel that enables to describe the adsorptive behavior ofthe dye onto WH charcoal Uddin et al [9] have carriedout the adsorption of phenol from aqueous solution by WHash utilizing PFO and PSO models at varying experimen-tal conditions such as contact time phenol concentrationadsorbent dosage and pH They reported that the kineticdata followed closely the PSO model as compared with PFOmodel On the other hand Bhainsa and DrsquoSouza [11] haveconducted the uranium uptake by dried roots of WH andfound that the adsorption was rapid and the WH couldremove 54 of the initial uranium present within 4minof contact time With increasing initial uranium concen-tration the specific metal ion uptake was decreased whileat higher dose of WH the uptake rate was increased andreached a plateau beyond the concentration of 6 gL Theprocess was favored at pH 5-6 and was least influenced bytemperature

In this study the waste WH after treatment with HClacid was used and evaluated as a possible biosorbentfor the removal of a MB from aqueous solution Thepretreatment of WH biomass with HCl acids causes theloss of biomass weight by removing the lignin [16] andincreases the surface area of the WH due to openingof the pore mouth of the WH adsorbent The objectivesof the present study are to determine the kinetic andequilibrium batch adsorption parameters for MB removalfrom aqueous solution and to predict the maximum pos-sible adsorption capacity The feasibility of H-WH useas a potential adsorbent is also studied by using errorfunctions

2 Materials and Methods

21 Adsorbent Preparation Live WH was collected from thelocal pondsThe collectedWHwere cleaned thoroughly withwater for several times to eliminate earthy matter and allthe soil particles followed by boiling in water for 30minLive WH consists of 94-95 water and barely contains 50ndash60 g total solid per kilogram [17] In the present studythe WH was subjected to washing and chemical treatmentwith hydrochloric acid (HCl) to remove lignin and solublecompoundsTheWHwas soaked in 01MHCl for 20min andagain washed with distilled water TheWHwas then dried inthe oven setting temperature in the range of 90ndash100∘C for 8hours The dried WH was ground and the powder was usedas an adsorbent Particle size of the adsorbent samples usedfor the experiments was in the range of 015 times 10minus3 minus 025 times10minus3m

22 Methylene Blue Methylene blue (C16H18N3Cl sdot 3H

2O)

was purchased from Merck and used without further purifi-cation The stock solutions of MB were prepared in distilledwater All MB solutions used in this study were preparedby weighing and dissolving the required amounts of MB indistilled water

23 Adsorption Kinetic Experiments To study the effectof important parameters like pH adsorbent mass initialconcentrations and contact time on the adsorptive removalof MB the kinetic adsorption experiments were carried outThe experimental procedure was as follows (1) several 200 times10minus3 L MB solutions of known concentration amount of the

adsorbent (H-WH) were taken in a 250 times 10minus3 L stopper

plastic conical flask at desired pH (2) The MB solution wasthen agitated using a flash shaker at 500 oscmin constantoscillation rate The temperature was controlled at 27 plusmn

2∘C with neutral pH of 69 (3) Samples were withdrawnat time intervals and were centrifuged and the residualMB concentration in solution was measured immediatelyusing UVVIS spectrophotometer (Shimadzu Model UV-1601) at wavelength 662 nm The amount of dye adsorbedwas determined from the difference in concentration betweensamples withdrawn The stirring was continued until theconcentration of MB was constant To investigate the effectof pH on dye removal was carried over a pH range of 1ndash11The pH of zero point charge (pHpzc) plays an important rolein the adsorption process The pHpzc of WH adsorbent inthe aqueous phase was determined by utilizing the titrationmethod with different system pH values [18] For this pur-pose 50mL of a 01M potassium nitrate solution was takenin a 100mL Erlenmeyer flask A 01 g of adsorbent was addedto the solution and agitated with a magnetic stirrer The pHwas then adjusted by the addition of aqueous solutions ofHClor NaOH (010M) After half an hour contact time the finalpH was calculated and plotted against surface charge of theadsorbent All the experiments were conducted in triplicateand the average values were recorded

24 Batch Equilibrium Studies Thebatch equilibrium studieswere carried out by adding 025 g H-WH adsorbent to

International Journal of Chemical Engineering 3

200 times 10minus3 L MB solutions of different initial concentrations

(50ndash250mgL) in flash shaker and agitating till the equilib-rium was reached and uptake of the dye from the aqueoussolution at equilibrium state was calculated by using thefollowing equation

119902119890=(1198620minus 119862119890) 119881

119882 (1)

where 119902119890(mgMBg H-WH adsorbent) is called adsorption

capacity and defined as the amount of MB adsorbed perunit weight of adsorbent (H-WH) at equilibrium state 119862

0

and 119862119890(mgL) are the liquid-phase concentrations of MB at

initial and equilibrium states respectively The volume of thesolution is119881 (L) and119882 is the mass of dry adsorbent used (g)

25 Batch Kinetic Studies The procedures of kinetic experi-ments were basically identical to those of equilibrium testsThe effect of adsorbent dosage was investigated by contacting200 times 10

minus3 L dye solution of initial concentration of 100mgLwith different H-WH adsorbent dosage (05ndash3 gL) till theequilibriumwas achieved Kinetics of adsorption was studiedby analyzing adsorptive uptake of the dye from the aqueoussolution at different time intervals and the amount of adsorp-tion at time 119905 119902

119905(mgMBgH-WH adsorbent) was calculated

by using the following equation

119902119905=(1198620minus 119862119905) 119881

119882 (2)

where 1198620and 119862

119905(mgL) are the liquid-phase concentrations

of MB at initial and any time respectively The volume of thesolution is119881 (L) and119882 is the mass of dry adsorbent used (g)

26 Fourier Transform Infrared Spectroscopy (FTIR) Fouriertransform infrared spectroscopy of the adsorbent was doneby using an FTIR spectrophotometer (Model FTIR 2000Shimadzu Kyoto Japan) Spectra of the samples wererecorded in the range from 500 to 4000 cmminus1 Approximately3 of dry samples were taken to prepare about 150mg KBrdisks shortly before analysis of the FTIR spectra

27 Effect of Ionic Strength on Adsorption The effect of ionicstrength on the amount of MB adsorbed by H-WH wasperformed over the NaCl concentration range from 0 to018molL MB solutions of 100mgL were agitated with025 gL of H-WH for 4 hours

3 Establishment of Adsorption Models

31 Adsorption Isotherm Models The adsorption isothermindicates how the adsorption molecules distribute betweenthe liquid phase and the solid phase when the adsorptionprocess reaches an equilibrium state Langmuir isotherm [19]refers to homogeneous monolayer adsorption onto a surfacecontaining a finite number of adsorption sites of uniformstrategies of adsorption with no transmigration of adsorbate

in the plane of surface The linear equation in this model isrepresented as follows

119862119890

119902119890

=119862119890

119902max+

1

119902max119870119871 (3)

Equation (3) is known as Langmuir isotherm where 119902119890is

the amount of adsorbate in the adsorbent at equilibrium(mgg) 119862

119890is the equilibrium concentration (mgL) and

119902max and 119870119871 are the Langmuir isotherm constants related toadsorption capacity and rate of adsorption respectively Theabove linearized equation can be fitted to get the maximumcapacity 119902max by plotting a graph of 119862

119890119902119890versus 119862

119890

To determine whether the MB adsorption process byH-WH is favorable or unfavorable for the Langmuir typeadsorption process the isotherm shape can be classified bya term 119877

119871 a dimensionless constant separation factor which

is defined below

119877119871=

1

1 + 1198701198711198620

(4)

where 119877119871is the dimensionless separation factor and 119862

0

is the initial solution concentration (mgL) The parameterindicates the shape of the isotherm accordingly unfavorable(when 119877

119871gt 1) linear (when 119877

119871= 1) favorable (when

0 lt 119877119871gt 1) and irreversible (when 119877

119871= 0) The calculated

119877119871values at different initial MB concentration are plotted to

determine the applicability of Langmuir isothermThe Freundlich isotherm [20] model is derived by assum-

ing a heterogeneous surface of adsorption capacity andadsorption intensity with a nonuniform distribution of heatof adsorptionThe well-known linearized form of Freundlichisotherm can be written as

ln 119902119890= ln119870

119891+1

119899ln119862119890 (5)

where119870119891and 1119899 are Freundlich constants related to adsorp-

tion capacity and adsorption intensity respectivelyThe ln119870119865

is equivalent to ln 119902119890when 119862

119890equals unity However in other

cases when 1119899 = 1 the 119870119865value depends on the units upon

which 119902119890and 119862

119890are expressed The 119870

119891((mgg) (Lg)1119899)

represents the quantity of dye adsorbed onto H-WH forunit equilibrium concentration A value for 1119899 below oneindicates a normal Langmuir isotherm while a value aboveone represents cooperative adsorption [21] The plot of ln 119902

119890

versus ln119862119890gave a straight line and predicts the value for

Freundlich constants parametersTemkin and Pyzhev [22] pointed out that the heat of

adsorption of all the molecules on the adsorbent surfacelayer would decrease linearly with coverage due to adsorbate-adsorbate interactions They pointed out that the heat ofadsorption of all the molecules on the adsorbent surfacelayer would decrease linearly with coverage due to adsorbate-adsorbate interactions The linear form of this isotherm canbe given by

119902119890= 119861119879ln119862119890+ 119861119879ln119870119879 (6)

In (6) 119861119879and 119870

119879are the Temkin isotherm constants The

constant 119861119879is related to the heat of adsorption A plot of 119902

119890


versus ln119862119890enables one to determine the constants 119870

119879and

119861119879The Halsey isotherm model [23] reported the multilayer

adsorption and the fitting of the experimental data to thisequation explains the heteroporous nature of the adsorbentThe Halsey model can be expressed as follows

ln 119902119890=

1

119899119867

ln119870119867minus

1

119899119867

ln119862119890 (7)

According to (7) a plot of ln 119902119890versus ln119862

119890should give

a straight line and the Halsey constants which are usuallydenoted by 119899

119867and119870

119867can be determined from the plot

32 Adsorption Kinetic Models The kinetic behavior of MBremoval by using H-WH was studied to evaluate the rateof adsorbate uptake from aqueous solution which controlsthe mechanism of dye adsorption Several two-parameterkinetic models namely pseudo-first-order (PFO) pseudo-second-order (PSO) and intraparticle diffusion (IPD) areapplied to evaluate the dynamics of the adsorption of MBfrom aqueous solution onto H-WH These models can beexpressed as follows

PFO model [24] is

119902119905= 119902119890(1 minus 119890

minus1198701119905) (8)

PSO model [24] is

119902119905=

1199022

1198901198702119905

1 + 1199021198901198702119905 (9)

IPD model [25] is

119902119905= 119896119882119872

11990512 (10)

All of these models are widely used to determine the kinet-ics of adsorption process and convert the equation into anonlinear form by transforming the kinetics variables Thedifference between experimental data and theoretical datacan be estimated from the curvature plots with regressioncoefficient (1198772) Besides the value of 1198772 the suitability ofkinetic models to narrate the adsorption process was furtheranalyzed by using several statistical equations which read

normalized standard deviation (NSD)

= 100 timesradicsum119873

119894=1[(119902119890exp minus 119902119890cal) 119902119890exp]

2

119873 minus 1

sum of the errors squared (SSE)

=

119873

sum

119894=1

(119902119890exp minus 119902119890cal)

2

Sum of absolute errors (EABS)

=

119873

sum

119894=1

10038161003816100381610038161003816119902119890exp minus 119902119890cal

10038161003816100381610038161003816119894

(11)

After adsorptionBefore adsorption

100

90

80

70

60

504500 4000 3500 3000 2500 2000 1500 1000 500

Tran

smitt

ance

()

(cmminus1)

Figure 1 FTIR analysis before and after adsorption ofMBontoWH

From (11) the number of data points experimental adsorp-tion capacities and calculated adsorption capacities arerepresented by119873 119902

119890exp 119902119890cal respectively

4 Results and Discussions

41 FTIR Analysis WH is a natural fiber which is primarilycomposed of cellulose lignin and wax The FTIR spectrumof WH would therefore contain many bands at the differentabsorption regions The WH FTIR spectrum cannot beaccurately interpreted to identify its functional groups Itcan however be used as one of the tools to differentiate themodified WH Figure 1 shows a very complicated behaviorof WH during the course of adsorption Primarily WHindicates band at 3390 cmminus1 due to stretching frequency ofndashOH A minor shift was noticed for the spectra results fromaromatic ring from 1593 to 1598 cmminus1 This is likely becausethe interaction between carboxylic groups (ndashCOOminus) andMB+ cations would be difficult due to proximity betweenaromatic rings of lignin moieties and MB The adsorptionband for WH in the range between 1312 and 1005 cmminus1 wasshifted which reflects the stretching frequency of CndashO ofmethoxy group (ndashOCH

3) of the aromatic ring of lignin

Through the electrostatic interaction other hydroxyl and car-boxyl groups such as phenolic and aliphatic extractives couldparticipate in sorption of MB Poots et al [26] showed thatcarboxylic and hydroxyl groups were identified as the mostimportant groups for sorption of MB After adsorption it isseen that the trends of CndashO were altered from 1036 cmminus1 to103960 cmminus1 It is obvious from Figure 1 that MB gave strongspectra at 1580 cmminus1 1420 cmminus1 1376 cmminus1 and 65070 cmminus1respectively

42 Effect of pH on Adsorption The interaction between dyemolecule and adsorbent is basically a combined result ofcharges on dye molecules and the surface of the adsorbent[27] Figure 2 shows that pH of the solution has significantlyaffected adsorption of MB on H-WH When the pH of dyesolution was increased from 1835 to 6934 the adsorptioncapacity of MB increased from 887 to 5041mgg At pH


0

12

24

36

48

60

0 4 8 12

Adso

rptio

n ca

paci

ty (m

gg)

pH

Figure 2 Effect of pH on adsorption capacity for MB onto H-WH

012345

0 4 8 12

Surfa

ce ch

arge

(mm

olg

)

pH

minus1

minus2

minus3

minus4

minus5

Figure 3 Determination of pHPZC of H-WH adsorbent

range of 4827 to 6934 the uptake of dye increased veryrapidly from 18 to 5041mgg as shown in Figure 2 The H-WH sorbent achieved its optimum adsorption capacity forMB at pH of 6934 A decrease from 5041 to 2067mgg ofadsorption capacitywas observed in the pH range of 6934ndash11This fact may be explained from the solubilization of organicgroups present on the H-WH sorbent [18]

The adsorption of MB onto adsorbent surface is influ-enced by the surface charge on the sorbent and the initialpH of the solution [28] The pH at the point of zero chargepHpzc value of H-WH was found to be 672 which is veryclose to neutral point (Figure 3) As the pH of the solutionincreases (when pH gt pHpzc) the surface of H-WH mayget negatively charged due to sorption of OHminus and thesorption process is highly favored through electrostatic forceof attraction At pH 6934 surface of H-WH sorbent wasnegatively charged to its maximumnumber Further additionin pH did not increase surface charge intensity as well asadsorption capability [29] On the other hand when pH lt

pHpzc the H-WH surface may get positively charged due toadsorption of the H+ and a force of repulsion occurs betweenthe dye cation and theH-WH sorbent surface At low pH (lt2)sorption was unfavorable probably because of the excess H+ions competing for sorption sites on the adsorbent makingH+-dye+ exchange unattractive Several investigations havereported that MB adsorption usually increases as the pH isincreased [3 30]

0

50

100

150

200

0 01 02 03 04 05

Adso

rptio

n ca

paci

ty (m

gg)

H-WH adsorbent amount (g)

Figure 4 Adsorbent dosage function of adsorption capacity forMBover H-WH at pH of 69 and 27 plusmn 2∘C

43 Effect of Adsorbent Dosage Adsorbent dose is represent-ing an important parameter due to its strong effect on thecapacity of an adsorbent at given initial concentration ofadsorbate Effect of adsorbent dose on removal of MB wasmonitored by varying adsorbent doses from 050 to 30 gmLThe adsorption of dye decreased with the adsorbent dose andthe percentage of dye removal increased (2420ndash9680)withincreasing H-WH adsorbent dosage from 050 to 30 gmL[12] At higher biomass to solute concentration ratio there is avery fast superficial sorption onto the adsorbent surface thatproduces a lower solute concentration in the solution thanwhen biomass to solute concentration ratio is lower This isbecause a fixed mass of biomass can only adsorb a certainamount of dye Therefore the more the adsorbent dosageis the larger the volume of effluent that a fixed mass of H-WH can purify is [31] Figure 4 shows the effect of H-WHadsorbent dosage on adsorption capacity It can be seen thatfrom Figure 4 the adsorption capacity reduced from 18150to 3025mgg when H-WH adsorbent dosage increased from050 to 30 gmL Similar results were reported by Patil et al[32]Many factors can be attributed to this adsorbent concen-tration effect The most important factor is that adsorptionsite remains unsaturated during the adsorption reactionThisdecrease in adsorption capacity with increase in adsorbentmass is mainly attributed by nonsaturation of the adsorptionsites during the adsorption process [33] Thus the amountof dye adsorbed onto unit weight of adsorbent gets reducedcausing a decrease in equilibrium adsorption capacity 119902

119890

(mgg) with increasing adsorbent mass

44 Effect of Initial MB Concentration and Contact TimeFigure 5 shows the effect of initial MB concentration 119862

0

on the kinetics of adsorption of the dye at pH (69) H-WH dosage 025 gL and 27 plusmn 2∘C It can be apparent fromFigure 5 that adsorption capacity increased with increasein MB concentration This indicates that the initial dyeconcentration plays an important role in determining theadsorption capacity of MB on H-WH This may be relatedto the solution state of MB at different concentrations Inthe beginning of the adsorption process the MB is adsorbedon the external surface of H-WH particle which increases


0

10

20

30

40

50

60

70

0 50 100 150 200 250 300 350 400 450 500

Adso

rptio

n ca

paci

ty (m

gg)

Time (min)

50mgL100mgL150mgL

Figure 5 Adsorption kinetics of MB on H-WH for different initialconcentration at pH of 69 and 27 plusmn 2∘C

the local concentration of MB on the surface and leads tothe formation of MB aggregates MB molecules are knownto form dimers and aggregates depending on the conditionsof solution such as pH concentration and presence ofother ions [34 35] MB aggregates can migrate from theexternal surface of H-WH to the internal pores resulting indeaggregation of theMB aggregates and restoringmonomersAt high loading rates of MB it is expected that agglomeratesare predominant in solution while monomers and dimersare virtually absent in the MB-adsorbent complexes on thesolid surface As the MB concentrations increased from 50to 150mgL the experimental adsorption capacity for MBincreased from 33 to 5310mgg It can be inferred fromFigure 5 that the contact time needed to reach equilibriumwith initial concentrationwas less than 2 hoursThe surface ofH-WH contains a large number of active sites andMB uptakecan be related to the active sites on equilibrium time [36] Itis also noticed from Figure 5 that more than 80 of the totalamount of dye uptakewas observable in the initial rapid phaseand thereafter the sorption rate was found to decrease

45 Effect of Ionic Strength The extent of MB adsorptionwas sharply attributed by the concentration and nature ofthe electrolyte ionic species added to the dyebath [37] Theinfluence of common salt (NaCl) on the MB adsorptionrate over H-WH adsorbent is shown in Figure 6 Principallythe adsorption capacity decreases with an increase in ionicstrength if electrostatic forces between the adsorbent surfaceand adsorbate ions are attractive Likewise the adsorptioncapacity increases with an increase in ionic strength if elec-trostatic interaction is repulsive [38 39] As seen in Figure 6the adsorption capacity and removal percentage decreased inthe presence of salt concentration This is likely because ofa competitive effect between MB ions and cations from thesalt for the sites available for the adsorption process whensalt concentration added in the MB solution that is thedegree of adsorbing reduced as salt concentration increased

40

50

60

70

80

90

100

0

10

20

30

40

50

0 003 006 009 012 015 018

Rem

oval

()

Adso

rptio

n ca

paci

ty (m

gg)

Concentration (molL)

NaClRemoval () in presence of NaCl

Figure 6 Effect of ionic strength on MB removal over H-WHadsorbent

0

05

1

15

2

25

0 50 100 150

Ce

Ce

qe

Figure 7 Langmuir isothermmodel forMBadsorption ontoH-WHat pH of 69 and 27 plusmn 2∘C

As seen in Figure 6 the dye sorption and removal percentagewere decreased in the presence of salt concentrations (0 to018molL) The values of adsorption capacity reduced from4682 to 3141mgg while removal percentage reduced from9391 to 851 Moreover the effective concentration of MBand available reaction sites decrease as the ionic strengthincreases therefore a decreasing characteristic in adsorptioncapacity of MB over the adsorbents is highlighted HoweverH-WH adsorbent still has larger removal percentage at016molL of salt concentration and hence it could be usedto efficiently remove MB from aqueous solution with highersalt concentration

46 Adsorption Isotherms Studies Thewell-establishedLang-muir isotherm suggests the presence of monolayer coverageof the adsorbate at the outer surface of the adsorbent oncean adsorbate molecule occupies a site no further adsorptioncan take place at that site The linearized equation (3) canbe fitted to get the maximum capacity 119902max by plotting agraph of 119862

119890119902119890versus 119862

119890as shown in Figure 7 and it is found

to be 6330mgg The isotherm parameters calculated fromthe linear relationship of 119862

119890119902119890versus 119862

119890are represented in


Table 1 Parameters and correlation coefficient of the studiedisotherm models

Model name Evaluated parameters 1198772

Langmuirisotherm 119902max = 6330mgg 119870

119871= 00879 Lmg 09938

Freundlichisotherm 119870

119891= 2122 (mgg) (Lmg)1119899 119899 = 4737 09851

Temkinisotherm 119870

119879= 3823 Lmg 119861

119879= 94401 09873

Halseyisotherm 119870

119867= 551 times 10

minus7 (Lg) 119899119867= minus4737 09851

0

006

012

018

024

0 50 100 150 200 250Co

RL

Figure 8 Separation factor for MB onto H-WH

Table 1 Several factors such as number of sites in the biosor-bent material the accessibility of the sites the chemical stateof the sites (ie availability) and the binding strength canbe affected by the maximum capacity The linear regressioncoefficient (1198772) is good agreement to reach unity (09938)for the studied concentrationsThe applicability of Langmuirisotherm to describe the MB adsorption onto H-WH surfacecan be viable from Figure 8

From Figure 8 it was observed that sorption was foundto be more favorable at higher concentrations Also the valueof 119877119871in the range of 0 to 1 at all initial dye concentrations

confirms the favorable uptake of the MB process Alsohigher 119877

119871values at lower dye concentrations show that the

adsorption is more favorable at lower dye concentrationsAccording to (5) a plot of ln 119902

119890versus ln119862

119890gave a straight

line (Figure 9) and predicts the value for Freundlich constantsparameters The experimental results of (1119899) lt 1 indicatedthat the adsorption isotherms of MB adsorption on H-WHfollowed normal Langmuir models [40] Higher value of 119870

119891

(2122 (mgg) (Lmg)1n) confirms the suitable dye-adsorbentinteraction in the studied concentration range Table 1 givesthe values of parameters and correlation coefficient of theFreundlich equation A lower 1198772 value (09851) of Freundlichequation is indicating that the experimental data correlateswell with Langmuir isotherm which reflects the monolayeradsorption This may be explained from the complex natureof the sorbent material and its varied multiple active sitesas well as irregular pattern of the experimental results In

34

36

38

4

42

2 3 4 5 6ln Ce

ln q e

Figure 9 Freundlich isotherm model for MB adsorption onto H-WH at pH of 69 and 27 plusmn 2∘C

0

25

50

75

2 3 4 5 6

qe

ln Ce

Figure 10 Temkin isothermmodel for MB adsorption onto H-WHat pH of 69 and 27 plusmn 2∘C

addition the higher value (4737) of n is also confirmingthat the interaction between sorbent and solute molecules isexpected to be strong

The experimental equilibrium data for MB adsorptionover H-WH adsorbent calculated from (1) is fitted withTemkin isotherm (6) A plot of 119902

119890versus ln119862

119890should give

a straight line (Figure 10) and enables one to determine theconstants 119870

119879and 119861

119879 These constants are represented in

Table 1 Higher value (94401) of 119861119879indicates the endother-

mic nature of adsorption processThe value of the correlationcoefficient (1198772) confirms that the adsorption of MB dyesonto H-WH adsorbent provides better results than that of theFreundlich isotherm but less than that of Langmuir isothermfor the studied concentration range

The Halsey isotherm model describes the multilayeradsorption and the fitting of the experimental data to thisequation validates the heteroporous nature of the adsorbentAccording to (7) a plot of ln 119902

119890versus ln119862

119890should give

a straight line (Figure 11) and the Halsey constants whichare usually denoted by 119899

119867and 119870

119867can be determined

from the plot The evaluated parameters are representedin Table 1 Evidently the regression coefficient values forHalsey and Freundlich isotherm models are similar (09851)This is indicative that the correlation of the experimentalequilibrium data for MB removal onto H-WH by Halseymodel is in good agreement with Freundlich isothermmodel


Table 2 Adsorption rate constant and coefficient of correlation associated with kinetic models

Model name 1198620(mgL) 119902

119890exp (mgg) 119902119890cal (mgg) Identified parameters 119877

2 NSD SSE EABS

PFO50 3300 2550 119870

1= 00405minminus1 08675 70160 26508 11687

100 4839 2155 1198701= 00760minminus1 08996 49911 40881 12191

150 5310 8131 1198701= 003178minminus1 09073 79788 78205 21378

PSO50 3300 3436 119870

2= 000166 gsdotmgminus1minminus1 09963 22246 26310 13700

100 4839 4926 1198702= 000442 gsdotmgminus1minminus1 09996 32251 40524 12670


IPD50 3300 119896

119882119872= 07140mgsdotgminus1minminus12 09576 55710 70520 28170

100 4839 119896119882119872

= 01506mgsdotgminus1minminus12 08366 27590 27340 69580150 5310 119896


34

36

38

4

42

2 3 4 5 6ln Ce

ln q e

Figure 11 Halsey isotherm model for MB adsorption onto H-WHat pH of 69 and 27 plusmn 2∘C

0

10

20

30

40

50

60

0 100 200 300 400 500Time (min)

q(m

gg)

50mgL100mgL150mgL

Figure 12 The representation of PFO model for MB adsorption onH-WH for different initial concentration at pH of 69 and 27 plusmn 2∘C

47 Adsorption Kinetics Studies The experimental kineticdata of MB calculated from (2) were correlated by threekinetic models as stated above The calculated parametersof the kinetic equations (8)ndash(10) with 1198772 values at differentIMBCs are presented in Table 2 It may be observed fromFigure 12 that as IMBC was increased the sorption capacitywas found to be increased The experimentally observed

adsorption capacity enhances from 33 to 5310mgg as theIMBC increases from 50 to 150mgL A possible reason maybe that different IMBCs have different solution phases In theearly stage of the sorption process MB generates aggregatesThis is because the local concentration of MB onto the H-WH surface enhanced due to MB uptake was found to beon the external surface of H-WH adsorbent Additionallyit is known that aggregates and dimers are generated fromMB molecules but the formation environment depends onprocess variables such as pH the presence of other ionsand concentration [34 35] Moreover the migration of MBaggregates from the outer surface of the H-WH adsorbent tointerior pores leads to the disaggregation of MB aggregatesand release of monomers It is anticipated that the H-WHadsorbent surface was virtually free of both monomers anddimers while agglomerates seem to dominate the dye solutionwhen high concentration loading of MB was tested

By analyzing the 1198772 values it may be seen from Table 2that the PFO kineticmodel was not appropriate for accuratelydescribing the adsorption of MB onto H-WH It can alsobe observed from Figure 12 that the adsorption data did notshow good fit by PFO equation (8) for all IMBCs This isindicative of the fact that all studied concentrations deflectfrom theory from the initial stage of adsorption As the IMBCincreases the difference between experimentally obtainedvalues for adsorption capacity and calculated values fromPFO model was increased in a way that the experimentallyobtained values are higher than the calculated value It is alsoconfirmed from Table 2 that for all studied concentrationsthe PFO model shows a poor fit to the experimental databecause the difference between experimental and calculatedadsorptions is much higher

The experimental kinetic data of MB were furthervalidated by using PSO model of (9) In comparison toFigure 12 Figure 13 showed that the PSO model fits theexperimental data better for the whole period of adsorp-tion It is also proved from Table 2 that the PSO modelbetter represented the adsorption kinetics and there is goodagreement between experimental and calculated adsorptioncapacity values In comparison to PFO the PSOmodel showsless NSD (values from 22246 to 52038) SSE (values from26310 to 41585) and EABS (values from 13700 to 13942)values for all studied concentrations It is meant to that thecalculated value obtained from PSO model are closer to


Table 3 Adsorption kinetic behavior in the PSO model and equilibrium approaching factor (119877119908)

119877119908value Type of kinetic curve Approaching equilibrium level

119877119908= 1 Linear Not approaching equilibrium

1 gt 119877119908gt 01 Slightly curved Approaching equilibrium

01 gt 119877119908gt 001 Largely curved Well approaching equilibrium

119877119908lt 001 Pseudorectangular Drastically approaching equilibrium

0

10

20

30

40

50

60

0 100 200 300 400 500Time (min)

q(m

gg)

50mgL100mgL150mgL

Figure 13 The representation of PSO model for MB adsorption onH-WH for different initial concentration at pH of 69 and 27 plusmn 2∘C

the experimental results than the calculated value obtainedfrom PFO model

It may be observed from Table 2 that the PSO reactionrate model adequately explains the kinetics of MB dyeadsorption with a high correlation coefficient for all rangesof dye concentrations studied Comparing the 1198772 values foreach studied concentration it is observed from Table 2 thatthe PSO model provides the best fit with higher 1198772 values(09963 to 09992) in comparison to the PFO model (1198772values from 08675 to 09073) This result suggests that asthe initial MB concentration increases (50ndash150mgL) thesorption capacity responds positively As IMBC increasesfrom 50 to 100mgL the PSO rate constant 119870

2 increases

from 166 times 10minus3 to 442 times 10minus3 g sdotmgminus1minminus1 however with

further increase in IMBC to 150mgL the1198702shows opposite

trends and decreases to 357 times 10minus1g sdotmgminus1minminus1 A possiblereason may be that different initial MB concentrations havedifferent solution phases In the early stage of the sorptionprocess MB generates aggregates This is because the localconcentration ofMB onto theH-WH surface is enhanced dueto the contaminant uptake occurring on the external surfacesof the adsorbent The higher 1198772 values indicate that chemicalreaction is the rate controlling step throughout the sorptionprocess

For a PSO type adsorption process it is necessary toinvestigate the kinetic curversquos characteristics by means of anapproaching equilibrium factor value in order to determine

0

02

04

06

08

1

0 02 04 06 08 1

Qt

T

Rw = 005

Rw = 0076

Rw = 0092

Figure 14 Characteristic curves of PSO kinetic model

whether the MB adsorption by H-WH approaches equilib-rium or not The approaching equilibrium factor can bewritten as displayed in the following equations [41]

1198702119902119890119905ref =

119877119908minus 1

119877119908

119876119905=

119879

119877119908(1 minus 119879) + 119879

(12)

where 119879 = 119905119905ref 119877119908 is known as an approaching equilibriumfactor 119905ref is the longest operating time in an adsorptionsystem and 119876

119905is a dimensionless factor respectively A plot

of119876119905versus119879 should give a curvature for three values of119877

119908as

shown in Figure 14 The approaching equilibrium values forthe PSO kinetic model are in Table 3

The curvature of the adsorption curve decreases as 119877119908

increases It may be clearly noticed from Figure 14 thatthe curvature of the adsorption process increases when119877119908= 005 while it decreases at a higher value of 119877

119908(ie

0092) This may be attributed to the fact that the removalof MB from aqueous solution requires larger amounts ofthe H-WH adsorbent [41] It may be also apparent fromFigure 14 that the characteristic adsorption curve approachespseudoequilibrium in the range 01 gt 119877

119908gt 001 and

this finding is consistent with the literature [42 43] Therelationship between the operating time for the adsorption ofMB by H-WH and the extent of its adsorption is representedby this characteristic curve Such results are very importantfor effective engineering design under practical scenarios


0

10

20

30

40

50

60

0 6 12 18 24

50mgL100mgL150mgL

q(m

gg)

t05 (min05 )

Figure 15 Representation of IPD kinetic model for MB adsorptiononH-WHfor different initial concentration at pHof 69 and 27plusmn2∘C

Intraparticle diffusion (IPD) equation was used to studydiffusion mechanism Broadly speaking the initial adsorp-tion usually occurs on the adsorbent surface during batchexperiments Additionally there is a high probability of theadsorbate to diffuse into the interior pores of the adsorbentand hence IPD emerges as the dominant process [44]According to Weber and Morris [44] a plot of solute sorbedagainst the square root of the contact time should yielda straight line passing through the origin when the rate-limiting step is IPD controlled

Thus the 119896WM (mggmin12) value can be obtainedfrom the slope of the plot of q (mgg) versus 11990505 (min12)Theoretically Figure 15 shows the plot of 119902 versus 11990505 formethylene blue onto H-WH particles From Figure 15 it wasobserved that the sorption process tends to be followed bytwo phases The two phases in the intraparticle diffusionplot suggest that the sorption process proceeds by surfacesorption and intraparticle diffusionThe first incisive stage ofthe plot indicates a boundary layer effect while the secondlinear stage is due to intraparticle or pore diffusionThe slopeof the second linear stage of the plot has been defined as theintraparticle diffusion parameter 119896WM (mggmin12) whileintercept is proportional to the boundary layer thickness It isindicative of the fact that the larger the intercept value is thegreater the boundary layer effect is and therefore the greaterthe contribution of the surface sorption to the rate-limitingstep is The calculated intraparticle diffusion coefficient 119896WMvalue was given by 07140 01506 and 01040mgg sdot min12for an IMBC of 50 100 and 150mgL It is also noted that thevalue of the intercept increases from 19827 to 53243 as theIMBC increases from 50 to 150mgLThe 1198772 values (Table 2)for this model were lower compared to PSO model andshow higher deviation between experimental and calculatedvalues (higher NSD SSE and EABS values than those of PSOmodel)

As the double nature of intraparticle diffusion plot con-firms the presence of both film and pore diffusion in orderto predict the actual slow step involved the kinetic data

0

5

10

15

20

25

30

0 100 200 300 400 500Time (min)minus5

50mgL100mgL150mgL

Bt

Figure 16 Representation of Boyd plots for MB adsorption on H-WH for different initial concentration at pH of 69 and 27 plusmn 2∘C

were further analyzed using the Boyd kinetic expressionThiskinetic expression predicts the actual slowest step involvedin the sorption process for different sorbent-sorbate systemsThe linearized Boyd kinetic expression is given by [4]

119861119905= minus04977 minus ln (1 minus 119865) (13)

where 119865 = 119902119905119902119890is the fractional attainment of equilibrium

at time 119905 and 119861119905is a mathematical function of 119865 The 119861

119905

values at different contact times can be calculated using(13) The calculated 119861

119905values were plotted against time 119905

as shown in Figure 16 Figure 16 is used to identify whetherexternal transport or intraparticle transport controls the rateof sorption [4] From Figure 16 it was observed that the plotswere linear but do not pass through the origin confirmingthat for the studied initial dye concentration external masstransport mainly governs the sorption process [4] The cal-culated 119861 values were used to calculate the effective diffusioncoefficient119863

119894(m2s) using the relationship

119861 =1205872119863119894

1199032 (14)

where 119903 represents the radius of the particle calculated bysieve analysis and by assuming spherical particles The 119863

119894

values were found to be 878 times 10minus10 02 times 10minus9 and 20 times10minus10m2s for an IMBCof 50 100 and 150mgL respectively

To correlate the experimental findings evidently sorptiondata were further utilized to identify the slow step occurringin the present adsorption system based on the equationproposed by Aharoni et al [45]

ln ln(1198620

1198620minus 119902119905119898) = ln(

119896119900119898

2303119881) + 120572 ln 119905 (15)

As such linear plot of ln ln(11986201198620minus 119902119905119898) versus ln 119905

(Figure 17) should give the explanation about the diffusionof adsorbate into pores of adsorbents is not the only rate-controlling step [46] The film and pore diffusion both were


0

0 2 4 6 8ln t

minus05

minus1

minus15

minus2

minus25

minus3

minus35

minus4

50mgL100mgL150mgL

ln[ln

(CoC

ominusqtmiddotm

)]

Figure 17 Representation of Banghamrsquos plots for MB adsorption onH-WH for different initial concentration at pH of 69 and 27 plusmn 2∘C

important to different extents in the removal process In(15) 120572 and 119896

119900are Banghamrsquos constants while 120572 is found

to be 02891 02044 and 02457 respectively as the initialmethylene blue concentration increases from 50 to 100mgLIt can be seen that with IMBC the values of 119896

119900increase

from 006816 to 00837 g and with further increase of IMBC119896119900values (0050 g) show opposite trends This statement

supports the decrease in adsorption capacity with increase inadsorbentmass that is mainly attributed from the nonsatura-tion of the adsorption sites of W-HW adsorbents during theadsorption process Therefore Banghamrsquos equation cannotexplain the MB adsorption process onto H-WH adsorbentsufficiently because the linear regression coefficient values(08635 07234 and 06845 resp for studied concentrationof 50 100 and 150mgL) are far away from the unity and thistendency increases with IMBC

5 Conclusions

The present study shows that the HCl acid treated water-hyacinth (H-WH) can be used as an adsorbent for theremoval of MB from its aqueous solutions Upon comparingall the isotherm models the isotherm results predicted bythe Langmuir model coincide with the experimental valueswith a high correlation coefficient The equilibrium datafitted very well in a Langmuir isotherm equation confirmingthe monolayer sorption of MB onto H-WH with a mono-layer sorption capacity of 6330mgg However FreundlichTemkin and Halsey isotherm model equations were usedto express the adsorption phenomenon of MB The kineticsof MB adsorption onto H-WH was examined using PFOPSO IPD and Banghamrsquos kinetic model As is evident fromthe adsorption profiles the PSO equations provide a best fitdescription for the sorption ofMB onto theH-WH adsorbentamongst several kinetic models due to its high correlationcoefficient The adsorption of MB via the H-WH adsorbentmay be controlled by external mass transfer followed by IPD

Nomenclature

119902119890 Adsorption capacity at equilibrium (mgg)

119902119905 Adsorption capacity at time 119905 (mgg)

119877119908 Approaching equilibrium factor

120572 and 119896119900 Banghamrsquos constants

119862119905 Concentration of solution at time 119905 (mgL)

119899119866 Cooperative binding constant

119876119905 Dimensionless factor

119877119871 Dimensionless separation factor

119863119894 Effective diffusion coefficient (m2s)

119862119890 EquilibriumMB concentration (mgL)

119870119891 Freundlich constants related to adsorption

capacity (mgg) sdot (Lg)1119899119899 Freundlich constants related to adsorption

intensity119870119866 Generalized isotherm constants (mgL)

119899119867 Halsey isotherm constant

119870119867 Halsey isotherm constant (Lg)

H-WH Hydrochloric acid treated WH1198620 Initial MB concentration (mgL)

IPD Intraparticle diffusion coefficient119896119882119872

IPD rate constant (mg sdot gminus1 sdotminminus12)119870119871 Langmuir isotherm constants (Lmg)

119882 Mass of dry adsorbent (g)119861119905 Mathematical function of 119865 = 119902

119905119902119890

119902max Maximum adsorption capacity (mgg)MB Methylene blueNSD Normalized standard deviation119873 Number of data points1198701 PFO rate constant (minminus1)

pHPzc pH at the point of zero chargePFO Pseudo-first-order kinetic modelPSO Pseudo-second-order kinetic model1198702 PSO rate constant (g sdotmgminus1 sdotminminus1)

1198772 Regression coefficient

EABS Sum of absolute errorsSSE Sum of the errors squared119861119879 Temkin constant related to heat of

adsorption119870119879 Temkin isotherm constants (Lmg)

119881 Volume of solution (L)WH Water-hyacinth

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] M S Kini M Saidutta and V R Murty ldquoStudies on biosorp-tion of methylene blue from aqueous solutions by powderedpalm tree flower (Borassus flabellifer)rdquo International Journal ofChemical Engineering vol 2014 Article ID 306519 13 pages2014

[2] J K Nduka ldquoApplication of chemically modified and unmod-ified waste biological sorbents in treatment of wastewaterrdquo


International Journal of Chemical Engineering vol 2012 ArticleID 751240 7 pages 2012

[3] P Janos ldquoSorption of basic dyes onto iron humaterdquoEnvironmen-tal Science and Technology vol 37 no 24 pp 5792ndash5798 2003

[4] M I El-Khaiary ldquoKinetics and mechanism of adsorption ofmethylene blue from aqueous solution by nitric-acid treatedwater-hyacinthrdquo Journal of Hazardous Materials vol 147 no 1-2 pp 28ndash36 2007

[5] S H Hasan M Talat and S Rai ldquoSorption of cadmium andzinc from aqueous solutions by water hyacinth (Eichchorniacrassipes)rdquo Bioresource Technology vol 98 no 4 pp 918ndash9282007

[6] B Wolverton R McDonald and J Gordon ldquoWater hyacinthsand alligator weeds for final filtration of sewagerdquo NASATechni-cal Memorandum TM-X72724 NASA Washington DC USA1976

[7] M Ibrahim R Mahani O Osman and T Scheytt ldquoEffectof physical and chemical treatments on the electrical andstructural properties of water hyacinthrdquoThe Open SpectroscopyJournal vol 4 pp 32ndash40 2010

[8] A Malik ldquoEnvironmental challenge vis a vis opportunity thecase of water hyacinthrdquo Environment International vol 33 no1 pp 122ndash138 2007

[9] M Uddin M Islam and M Abedin ldquoAdsorption of phenolfrom aqueous solution by water hyacinth ashrdquo ARPN Journalof Engineering and Applied Sciences vol 2 no 2 pp 11ndash17 2007

[10] R Gandhimathi S Ramesh V Arun and P NidheeshldquoBiosorption of Cu(II) and Zn(II) ions from aqueous solutionby water hyacinth (Eichhornia crassipes)rdquo International Journalof Environment and Waste Management vol 11 no 4 pp 365ndash386 2013

[11] K C Bhainsa and S F DrsquoSouza ldquoUranium(VI) biosorption bydried roots of Eichhornia crassipes (water hyacinth)rdquo Journal ofEnvironmental Science andHealth A vol 36 no 9 pp 1621ndash16312001

[12] K S Low C K Lee and K K Tan ldquoBiosorption of basic dyesby water hyacinth rootsrdquo Bioresource Technology vol 52 no 1pp 79ndash83 1995

[13] S Kaur S Rani and R K Mahajan ldquoAdsorptive removalof dye crystal violet onto low-cost carbon produced fromEichhornia plant kinetic equilibrium and thermodynamicstudiesrdquo Desalination and Water Treatment 2013

[14] M Soni A K Sharma J K Srivastava and J S Yadav ldquoAdsorp-tive removal of methylene blue dye from an aqueous solutionusing water hyacinth root powder as a low cost adsorbentrdquoInternational Journal of Chemical Sciences and Applications vol3 no 3 pp 338ndash345 2012

[15] S M Kanawade and R Gaikwad ldquoRemoval of methylene bluefrom effluent by using activated carbon and water hyacinth asadsorbentrdquo International Journal of Chemical Engineering andApplications vol 2 pp 317ndash319 2011

[16] M Idrees A Adnan S Sheikh et al ldquoOptimization of diluteacid pretreatment of water hyacinth biomass for enzymatichydrolysis and ethanol productionrdquo EXCLI Journal vol 12 pp30ndash40 2013

[17] P S Ganesh E V Ramasamy S Gajalakshmi and S A AbbasildquoExtraction of volatile fatty acids (VFAs) from water hyacinthusing inexpensive contraptions and the use of the VFAs as feedsupplement in conventional biogas digesters with concomitantfinal disposal of water hyacinth as vermicompostrdquo BiochemicalEngineering Journal vol 27 no 1 pp 17ndash23 2005

[18] E Kiefer L Sigg and P Schosseler ldquoChemical and spec-troscopic characterization of algae surfacesrdquo EnvironmentalScience amp Technology vol 31 no 3 pp 759ndash764 1997

[19] I Langmuir ldquoThe constitution and fundamental properties ofsolids and liquids Part I Solidsrdquo The Journal of the AmericanChemical Society vol 38 no 2 pp 2221ndash2295 1916

[20] H Freundlich ldquoOver the adsorption in solutionrdquo Journal ofPhysical Chemistry vol 57 pp 385ndash470 1906

[21] K Fytianos E Voudrias and E Kokkalis ldquoSorption-desorptionbehaviour of 24-dichlorophenol bymarine sedimentsrdquoChemo-sphere vol 40 no 1 pp 3ndash6 2000

[22] M I Temkin and Pyzhev ldquoKinetics of ammonia synthesis onpromoted iron catalystsrdquo Acta Physiochimica URSS vol 12 pp327ndash356 1940

[23] G Halsey ldquoPhysical adsorption on non-uniform surfacesrdquoTheJournal of Chemical Physics vol 16 no 10 pp 931ndash937 1948

[24] FKargi and SOzmihci ldquoBiosorption performance of powderedactivated sludge for removal of different dyestuffsrdquo Enzyme andMicrobial Technology vol 35 no 2-3 pp 267ndash271 2004

[25] Y S Ho and G McKay ldquoSorption of dye from aqueous solutionby peatrdquo Chemical Engineering Journal vol 70 no 2 pp 115ndash124 1998

[26] V J P Poots G McKay and J J Healy ldquoThe removal of acid dyefrom effluent using natural adsorbents I PeatrdquoWater Researchvol 10 no 12 pp 1061ndash1066 1976

[27] N S Maurya A K Mittal P Cornel and E Rother ldquoBiosorp-tion of dyes using dead macro fungi effect of dye structureionic strength and pHrdquo Bioresource Technology vol 97 no 3pp 512ndash521 2006

[28] X S Wang Y Zhou Y Jiang and C Sun ldquoThe removal of basicdyes from aqueous solutions using agricultural by-productsrdquoJournal of Hazardous Materials vol 157 no 2-3 pp 374ndash3852008

[29] P K Malik ldquoUse of activated carbons prepared from sawdustand rice-husk for adsoprtion of acid dyes a case study of acidyellow 36rdquoDyes and Pigments vol 56 no 3 pp 239ndash249 2003

[30] K P Singh D Mohan S Sinha G S Tondon and DGosh ldquoColor removal fromwastewater using low-cost activatedcarbon derived from agricultural wastematerialrdquo Industrial andEngineering Chemistry Research vol 42 no 9 pp 1965ndash19762003

[31] M N Uddin M T Islam M H Chakrabarti and M SIslam ldquoAdsorptive removal of methylene blue from aqueoussolutions by means of HCl treated water hyacinth isothermsand performance studiesrdquo Journal of Purity Utility Reaction ampEnvironment vol 2 no 3 pp 63ndash84 2013

[32] S Patil S Renukdas and N Patel ldquoRemoval of methylene bluea basic dye from aqueous solutions by adsorption using teaktree (Tectona grandis) bark powderrdquo International Journal ofEnvironmental Sciences vol 1 no 5 pp 711ndash726 2011

[33] R Han W Zou Z Zhang J Shi and J Yang ldquoRemoval ofcopper(II) and lead(II) from aqueous solution by manganeseoxide coated sand I Characterization and kinetic studyrdquoJournal ofHazardousMaterials vol 137 no 1 pp 384ndash395 2006

[34] J Bujdak and P Komadel ldquoInteraction of methylene blue withreduced chargemontmorilloniterdquoThe Journal of Physical Chem-istry B vol 101 no 44 pp 9065ndash9068 1997

[35] A P P Cione M G Neumann and F Gessner ldquoTime-dependent spectrophotometric study of the interaction of basicdyes with clays III Mixed dye aggregates on SWy-1 andLaponiterdquo Journal of Colloid and Interface Science vol 198 no1 pp 106ndash112 1998


[36] A M Ben Hamissa F Brouers B Mahjoub and M SeffenldquoAdsorption of textile dyes using agave americana (L) fibresequilibrium and kinetics modellingrdquo Adsorption Science andTechnology vol 25 no 5 pp 311ndash325 2007

[37] Y Ozdemir M Dogan and M Alkan ldquoAdsorption of cationicdyes from aqueous solutions by sepioliterdquo Microporous andMesoporous Materials vol 96 no 1ndash3 pp 419ndash427 2006

[38] G Newcombe and M Drikas ldquoAdsorption of NOM ontoactivated carbon electrostatic and non-electrostatic effectsrdquoCarbon vol 35 no 9 pp 1239ndash1250 1997

[39] G Alberghina R Bianchini M Fichera and S FisichellaldquoDimerization of CibacronBlue F3GAand other dyes influenceof salts and temperaturerdquo Dyes and Pigments vol 46 no 3 pp129ndash137 2000

[40] B E Reed and M R Matsumoto ldquoModeling CD adsorptionin single and binary adsorbent (PAC) systemsrdquo Journal ofEnvironmental Engineering vol 119 no 2 pp 332ndash348 1993

[41] F-C Wu R-L Tseng S-C Huang and R-S Juang ldquoCharac-teristics of pseudo-second-order kinetic model for liquid-phaseadsorption a mini-reviewrdquo Chemical Engineering Journal vol151 no 1ndash3 pp 1ndash9 2009

[42] V C Srivastava M M Swamy I D Mall B Prasad and IM Mishra ldquoAdsorptive removal of phenol by bagasse fly ashand activated carbon equilibrium kinetics and thermodynam-icsrdquo Colloids and Surfaces A Physicochemical and EngineeringAspects vol 272 no 1-2 pp 89ndash104 2006

[43] Z Yaneva and B Koumanova ldquoComparative modelling ofmono- and dinitrophenols sorption on yellow bentonite fromaqueous solutionsrdquo Journal of Colloid and Interface Science vol293 no 2 pp 303ndash311 2006

[44] WWeber and JMorris ldquoKinetics of adsorption on carbon fromsolutionrdquo Journal of Sanitary Engineering Division vol 89 pp31ndash60 1963

[45] CAharoni S Sideman andEHoffer ldquoAdsorption of phosphateions by collodion-coated aluminardquo Journal of Chemical Technol-ogy and Biotechnology vol 29 pp 404ndash412 1979

[46] E Tutem R Apak and C F Unal ldquoAdsorptive removal ofchlorophenols from water by bituminous shalerdquo Water Rese-arch vol 32 no 8 pp 2315ndash2324 1998

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The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

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Navigation and Observation



DistributedSensor Networks



(0082ndash1554mggmin12) andWH roots have a great poten-tial as a biosorbent for basic dyes however this is lessso for acidic dyes Soni et al [14] have studied the batchadsorption to remove the MB from an aqueous solutionover WH roots powder at varying operating conditions suchas pH adsorbent dose initial concentration of dye andcontact timeTheyhave reported thatmaximum95 removalof dye was attained at optimum experimental conditionExperimental equilibrium data were best correlated by bothLangmuir and Freundlich isotherms and the maximum dyeuptake was found to be 804mgg The adsorption kineticdata are adequately fitted to the pseudo-second-order (PSO)kinetic model along with higher regression determination(1198772gt 0999) for all ranges of dye concentrations Likewise

Kanawade and Gaikwad [15] described that the uptaking ofMB from aqueous solution by using WH as an adsorbentdepends on its initial concentration and contact time Theyalso noticed that adsorption of MB onto WH follows Lang-muir isotherm model

Kaur et al [13] have used WH as a potential adsorbentto remove dye crystal violet (CV) from aqueous solutionsunder different experimental conditions corroborating thatadsorption increases with increase in contact time adsorbentdose temperature and pH The experimental sorption datashowed the goodness-of-fit with PSO model along withhigher correlation coefficients (1198772 gt 0999) A maximumadsorption capacity of 581mgg was achieved from experi-mental equilibrium data which highly fitted with Langmuirmodel that enables to describe the adsorptive behavior ofthe dye onto WH charcoal Uddin et al [9] have carriedout the adsorption of phenol from aqueous solution by WHash utilizing PFO and PSO models at varying experimen-tal conditions such as contact time phenol concentrationadsorbent dosage and pH They reported that the kineticdata followed closely the PSO model as compared with PFOmodel On the other hand Bhainsa and DrsquoSouza [11] haveconducted the uranium uptake by dried roots of WH andfound that the adsorption was rapid and the WH couldremove 54 of the initial uranium present within 4minof contact time With increasing initial uranium concen-tration the specific metal ion uptake was decreased whileat higher dose of WH the uptake rate was increased andreached a plateau beyond the concentration of 6 gL Theprocess was favored at pH 5-6 and was least influenced bytemperature

In this study the waste WH after treatment with HClacid was used and evaluated as a possible biosorbentfor the removal of a MB from aqueous solution Thepretreatment of WH biomass with HCl acids causes theloss of biomass weight by removing the lignin [16] andincreases the surface area of the WH due to openingof the pore mouth of the WH adsorbent The objectivesof the present study are to determine the kinetic andequilibrium batch adsorption parameters for MB removalfrom aqueous solution and to predict the maximum pos-sible adsorption capacity The feasibility of H-WH useas a potential adsorbent is also studied by using errorfunctions

2 Materials and Methods

21 Adsorbent Preparation Live WH was collected from thelocal pondsThe collectedWHwere cleaned thoroughly withwater for several times to eliminate earthy matter and allthe soil particles followed by boiling in water for 30minLive WH consists of 94-95 water and barely contains 50ndash60 g total solid per kilogram [17] In the present studythe WH was subjected to washing and chemical treatmentwith hydrochloric acid (HCl) to remove lignin and solublecompoundsTheWHwas soaked in 01MHCl for 20min andagain washed with distilled water TheWHwas then dried inthe oven setting temperature in the range of 90ndash100∘C for 8hours The dried WH was ground and the powder was usedas an adsorbent Particle size of the adsorbent samples usedfor the experiments was in the range of 015 times 10minus3 minus 025 times10minus3m

22 Methylene Blue Methylene blue (C16H18N3Cl sdot 3H

2O)

was purchased from Merck and used without further purifi-cation The stock solutions of MB were prepared in distilledwater All MB solutions used in this study were preparedby weighing and dissolving the required amounts of MB indistilled water

23 Adsorption Kinetic Experiments To study the effectof important parameters like pH adsorbent mass initialconcentrations and contact time on the adsorptive removalof MB the kinetic adsorption experiments were carried outThe experimental procedure was as follows (1) several 200 times10minus3 L MB solutions of known concentration amount of the

adsorbent (H-WH) were taken in a 250 times 10minus3 L stopper

plastic conical flask at desired pH (2) The MB solution wasthen agitated using a flash shaker at 500 oscmin constantoscillation rate The temperature was controlled at 27 plusmn

2∘C with neutral pH of 69 (3) Samples were withdrawnat time intervals and were centrifuged and the residualMB concentration in solution was measured immediatelyusing UVVIS spectrophotometer (Shimadzu Model UV-1601) at wavelength 662 nm The amount of dye adsorbedwas determined from the difference in concentration betweensamples withdrawn The stirring was continued until theconcentration of MB was constant To investigate the effectof pH on dye removal was carried over a pH range of 1ndash11The pH of zero point charge (pHpzc) plays an important rolein the adsorption process The pHpzc of WH adsorbent inthe aqueous phase was determined by utilizing the titrationmethod with different system pH values [18] For this pur-pose 50mL of a 01M potassium nitrate solution was takenin a 100mL Erlenmeyer flask A 01 g of adsorbent was addedto the solution and agitated with a magnetic stirrer The pHwas then adjusted by the addition of aqueous solutions ofHClor NaOH (010M) After half an hour contact time the finalpH was calculated and plotted against surface charge of theadsorbent All the experiments were conducted in triplicateand the average values were recorded

24 Batch Equilibrium Studies Thebatch equilibrium studieswere carried out by adding 025 g H-WH adsorbent to




119902119890=(1198620minus 119862119890) 119881

119882 (1)



0







119902119905=(1198620minus 119862119905) 119881

119882 (2)

where 1198620and 119862








119862119890

119902119890

=119862119890

119902max+

1

119902max119870119871 (3)





119890119902119890versus 119862

119890



is defined below

119877119871=

1

1 + 1198701198711198620

(4)


0


119871gt 1) linear (when 119877







ln 119902119890= ln119870

119891+1

119899ln119862119890 (5)






which 119902119890and 119862


119891((mgg) (Lg)1119899)


119890




119902119890= 119861119879ln119862119890+ 119861119879ln119870119879 (6)

In (6) 119861119879and 119870



119890



119879and



ln 119902119890=

1

119899119867

ln119870119867minus

1

119899119867

ln119862119890 (7)


119890should give


119867and119870



PFO model [24] is

119902119905= 119902119890(1 minus 119890

minus1198701119905) (8)

PSO model [24] is

119902119905=

1199022

1198901198702119905

1 + 1199021198901198702119905 (9)

IPD model [25] is

119902119905= 119896119882119872

11990512 (10)




119894=1[(119902119890exp minus 119902119890cal) 119902119890exp]

2

119873 minus 1


=

119873

sum

119894=1

(119902119890exp minus 119902119890cal)

2


=

119873

sum

119894=1

10038161003816100381610038161003816119902119890exp minus 119902119890cal

10038161003816100381610038161003816119894

(11)


100

90

80

70

60

504500 4000 3500 3000 2500 2000 1500 1000 500

Tran

smitt

ance

()

(cmminus1)










0

12

24

36

48

60

0 4 8 12

Adso

rptio

n ca

paci

ty (m

gg)

pH


012345

0 4 8 12

Surfa

ce ch

arge

(mm

olg

)

pH

minus1

minus2

minus3

minus4

minus5





0

50

100

150

200

0 01 02 03 04 05

Adso

rptio

n ca

paci

ty (m

gg)




119890



0



0

10

20

30

40

50

60

70

0 50 100 150 200 250 300 350 400 450 500

Adso

rptio

n ca

paci

ty (m

gg)

Time (min)

50mgL100mgL150mgL




40

50

60

70

80

90

100

0

10

20

30

40

50

0 003 006 009 012 015 018

Rem

oval

()

Adso

rptio

n ca

paci

ty (m

gg)




0

05

1

15

2

25

0 50 100 150

Ce

Ce

qe




119890119902119890versus 119862



119890119902119890versus 119862






119871= 00879 Lmg 09938


119891= 2122 (mgg) (Lmg)1119899 119899 = 4737 09851


119879= 3823 Lmg 119861

119879= 94401 09873


119867= 551 times 10

minus7 (Lg) 119899119867= minus4737 09851

0

006

012

018

024

0 50 100 150 200 250Co

RL







119890versus ln119862



119891


34

36

38

4

42

2 3 4 5 6ln Ce

ln q e


0

25

50

75

2 3 4 5 6

qe

ln Ce




119890versus ln119862

119890should give


119879and 119861





119890versus ln119862

119890should give


119867and 119870







2 NSD SSE EABS

PFO50 3300 2550 119870

1= 00405minminus1 08675 70160 26508 11687

100 4839 2155 1198701= 00760minminus1 08996 49911 40881 12191

150 5310 8131 1198701= 003178minminus1 09073 79788 78205 21378

PSO50 3300 3436 119870




IPD50 3300 119896


100 4839 119896119882119872



34

36

38

4

42

2 3 4 5 6ln Ce

ln q e


0

10

20

30

40

50

60

0 100 200 300 400 500Time (min)

q(m

gg)

50mgL100mgL150mgL













0

10

20

30

40

50

60

0 100 200 300 400 500Time (min)

q(m

gg)

50mgL100mgL150mgL




2 increases





0

02

04

06

08

1

0 02 04 06 08 1

Qt

T

Rw = 005

Rw = 0076

Rw = 0092



1198702119902119890119905ref =

119877119908minus 1

119877119908

119876119905=

119879

119877119908(1 minus 119879) + 119879

(12)




119908as




119908(ie


119908gt 001 and



0

10

20

30

40

50

60

0 6 12 18 24

50mgL100mgL150mgL

q(m

gg)

t05 (min05 )





0

5

10

15

20

25

30

0 100 200 300 400 500Time (min)minus5

50mgL100mgL150mgL

Bt






119905





119861 =1205872119863119894

1199032 (14)


119894



ln ln(1198620

1198620minus 119902119905119898) = ln(

119896119900119898

2303119881) + 120572 ln 119905 (15)




0

0 2 4 6 8ln t

minus05

minus1

minus15

minus2

minus25

minus3

minus35

minus4

50mgL100mgL150mgL

ln[ln

(CoC

ominusqtmiddotm

)]





119900increase



5 Conclusions


Nomenclature




















119905119902119890









References




















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation












119902119890=(1198620minus 119862119890) 119881

119882 (1)



0







119902119905=(1198620minus 119862119905) 119881

119882 (2)

where 1198620and 119862








119862119890

119902119890

=119862119890

119902max+

1

119902max119870119871 (3)





119890119902119890versus 119862

119890



is defined below

119877119871=

1

1 + 1198701198711198620

(4)


0


119871gt 1) linear (when 119877







ln 119902119890= ln119870

119891+1

119899ln119862119890 (5)






which 119902119890and 119862


119891((mgg) (Lg)1119899)


119890




119902119890= 119861119879ln119862119890+ 119861119879ln119870119879 (6)

In (6) 119861119879and 119870



119890



119879and



ln 119902119890=

1

119899119867

ln119870119867minus

1

119899119867

ln119862119890 (7)


119890should give


119867and119870



PFO model [24] is

119902119905= 119902119890(1 minus 119890

minus1198701119905) (8)

PSO model [24] is

119902119905=

1199022

1198901198702119905

1 + 1199021198901198702119905 (9)

IPD model [25] is

119902119905= 119896119882119872

11990512 (10)




119894=1[(119902119890exp minus 119902119890cal) 119902119890exp]

2

119873 minus 1


=

119873

sum

119894=1

(119902119890exp minus 119902119890cal)

2


=

119873

sum

119894=1

10038161003816100381610038161003816119902119890exp minus 119902119890cal

10038161003816100381610038161003816119894

(11)


100

90

80

70

60

504500 4000 3500 3000 2500 2000 1500 1000 500

Tran

smitt

ance

()

(cmminus1)










0

12

24

36

48

60

0 4 8 12

Adso

rptio

n ca

paci

ty (m

gg)

pH


012345

0 4 8 12

Surfa

ce ch

arge

(mm

olg

)

pH

minus1

minus2

minus3

minus4

minus5





0

50

100

150

200

0 01 02 03 04 05

Adso

rptio

n ca

paci

ty (m

gg)




119890



0



0

10

20

30

40

50

60

70

0 50 100 150 200 250 300 350 400 450 500

Adso

rptio

n ca

paci

ty (m

gg)

Time (min)

50mgL100mgL150mgL




40

50

60

70

80

90

100

0

10

20

30

40

50

0 003 006 009 012 015 018

Rem

oval

()

Adso

rptio

n ca

paci

ty (m

gg)




0

05

1

15

2

25

0 50 100 150

Ce

Ce

qe




119890119902119890versus 119862



119890119902119890versus 119862






119871= 00879 Lmg 09938


119891= 2122 (mgg) (Lmg)1119899 119899 = 4737 09851


119879= 3823 Lmg 119861

119879= 94401 09873


119867= 551 times 10

minus7 (Lg) 119899119867= minus4737 09851

0

006

012

018

024

0 50 100 150 200 250Co

RL







119890versus ln119862



119891


34

36

38

4

42

2 3 4 5 6ln Ce

ln q e


0

25

50

75

2 3 4 5 6

qe

ln Ce




119890versus ln119862

119890should give


119879and 119861





119890versus ln119862

119890should give


119867and 119870







2 NSD SSE EABS

PFO50 3300 2550 119870

1= 00405minminus1 08675 70160 26508 11687

100 4839 2155 1198701= 00760minminus1 08996 49911 40881 12191

150 5310 8131 1198701= 003178minminus1 09073 79788 78205 21378

PSO50 3300 3436 119870




IPD50 3300 119896


100 4839 119896119882119872



34

36

38

4

42

2 3 4 5 6ln Ce

ln q e


0

10

20

30

40

50

60

0 100 200 300 400 500Time (min)

q(m

gg)

50mgL100mgL150mgL













0

10

20

30

40

50

60

0 100 200 300 400 500Time (min)

q(m

gg)

50mgL100mgL150mgL




2 increases





0

02

04

06

08

1

0 02 04 06 08 1

Qt

T

Rw = 005

Rw = 0076

Rw = 0092



1198702119902119890119905ref =

119877119908minus 1

119877119908

119876119905=

119879

119877119908(1 minus 119879) + 119879

(12)




119908as




119908(ie


119908gt 001 and



0

10

20

30

40

50

60

0 6 12 18 24

50mgL100mgL150mgL

q(m

gg)

t05 (min05 )





0

5

10

15

20

25

30

0 100 200 300 400 500Time (min)minus5

50mgL100mgL150mgL

Bt






119905





119861 =1205872119863119894

1199032 (14)


119894



ln ln(1198620

1198620minus 119902119905119898) = ln(

119896119900119898

2303119881) + 120572 ln 119905 (15)




0

0 2 4 6 8ln t

minus05

minus1

minus15

minus2

minus25

minus3

minus35

minus4

50mgL100mgL150mgL

ln[ln

(CoC

ominusqtmiddotm

)]





119900increase



5 Conclusions


Nomenclature




















119905119902119890









References




















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation











119879and



ln 119902119890=

1

119899119867

ln119870119867minus

1

119899119867

ln119862119890 (7)


119890should give


119867and119870



PFO model [24] is

119902119905= 119902119890(1 minus 119890

minus1198701119905) (8)

PSO model [24] is

119902119905=

1199022

1198901198702119905

1 + 1199021198901198702119905 (9)

IPD model [25] is

119902119905= 119896119882119872

11990512 (10)




119894=1[(119902119890exp minus 119902119890cal) 119902119890exp]

2

119873 minus 1


=

119873

sum

119894=1

(119902119890exp minus 119902119890cal)

2


=

119873

sum

119894=1

10038161003816100381610038161003816119902119890exp minus 119902119890cal

10038161003816100381610038161003816119894

(11)


100

90

80

70

60

504500 4000 3500 3000 2500 2000 1500 1000 500

Tran

smitt

ance

()

(cmminus1)










0

12

24

36

48

60

0 4 8 12

Adso

rptio

n ca

paci

ty (m

gg)

pH


012345

0 4 8 12

Surfa

ce ch

arge

(mm

olg

)

pH

minus1

minus2

minus3

minus4

minus5





0

50

100

150

200

0 01 02 03 04 05

Adso

rptio

n ca

paci

ty (m

gg)




119890



0



0

10

20

30

40

50

60

70

0 50 100 150 200 250 300 350 400 450 500

Adso

rptio

n ca

paci

ty (m

gg)

Time (min)

50mgL100mgL150mgL




40

50

60

70

80

90

100

0

10

20

30

40

50

0 003 006 009 012 015 018

Rem

oval

()

Adso

rptio

n ca

paci

ty (m

gg)




0

05

1

15

2

25

0 50 100 150

Ce

Ce

qe




119890119902119890versus 119862



119890119902119890versus 119862






119871= 00879 Lmg 09938


119891= 2122 (mgg) (Lmg)1119899 119899 = 4737 09851


119879= 3823 Lmg 119861

119879= 94401 09873


119867= 551 times 10

minus7 (Lg) 119899119867= minus4737 09851

0

006

012

018

024

0 50 100 150 200 250Co

RL







119890versus ln119862



119891


34

36

38

4

42

2 3 4 5 6ln Ce

ln q e


0

25

50

75

2 3 4 5 6

qe

ln Ce




119890versus ln119862

119890should give


119879and 119861





119890versus ln119862

119890should give


119867and 119870







2 NSD SSE EABS

PFO50 3300 2550 119870

1= 00405minminus1 08675 70160 26508 11687

100 4839 2155 1198701= 00760minminus1 08996 49911 40881 12191

150 5310 8131 1198701= 003178minminus1 09073 79788 78205 21378

PSO50 3300 3436 119870




IPD50 3300 119896


100 4839 119896119882119872



34

36

38

4

42

2 3 4 5 6ln Ce

ln q e


0

10

20

30

40

50

60

0 100 200 300 400 500Time (min)

q(m

gg)

50mgL100mgL150mgL













0

10

20

30

40

50

60

0 100 200 300 400 500Time (min)

q(m

gg)

50mgL100mgL150mgL




2 increases





0

02

04

06

08

1

0 02 04 06 08 1

Qt

T

Rw = 005

Rw = 0076

Rw = 0092



1198702119902119890119905ref =

119877119908minus 1

119877119908

119876119905=

119879

119877119908(1 minus 119879) + 119879

(12)




119908as




119908(ie


119908gt 001 and



0

10

20

30

40

50

60

0 6 12 18 24

50mgL100mgL150mgL

q(m

gg)

t05 (min05 )





0

5

10

15

20

25

30

0 100 200 300 400 500Time (min)minus5

50mgL100mgL150mgL

Bt






119905





119861 =1205872119863119894

1199032 (14)


119894



ln ln(1198620

1198620minus 119902119905119898) = ln(

119896119900119898

2303119881) + 120572 ln 119905 (15)




0

0 2 4 6 8ln t

minus05

minus1

minus15

minus2

minus25

minus3

minus35

minus4

50mgL100mgL150mgL

ln[ln

(CoC

ominusqtmiddotm

)]





119900increase



5 Conclusions


Nomenclature




















119905119902119890









References




















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










0

12

24

36

48

60

0 4 8 12

Adso

rptio

n ca

paci

ty (m

gg)

pH


012345

0 4 8 12

Surfa

ce ch

arge

(mm

olg

)

pH

minus1

minus2

minus3

minus4

minus5





0

50

100

150

200

0 01 02 03 04 05

Adso

rptio

n ca

paci

ty (m

gg)




119890



0



0

10

20

30

40

50

60

70

0 50 100 150 200 250 300 350 400 450 500

Adso

rptio

n ca

paci

ty (m

gg)

Time (min)

50mgL100mgL150mgL




40

50

60

70

80

90

100

0

10

20

30

40

50

0 003 006 009 012 015 018

Rem

oval

()

Adso

rptio

n ca

paci

ty (m

gg)




0

05

1

15

2

25

0 50 100 150

Ce

Ce

qe




119890119902119890versus 119862



119890119902119890versus 119862






119871= 00879 Lmg 09938


119891= 2122 (mgg) (Lmg)1119899 119899 = 4737 09851


119879= 3823 Lmg 119861

119879= 94401 09873


119867= 551 times 10

minus7 (Lg) 119899119867= minus4737 09851

0

006

012

018

024

0 50 100 150 200 250Co

RL







119890versus ln119862



119891


34

36

38

4

42

2 3 4 5 6ln Ce

ln q e


0

25

50

75

2 3 4 5 6

qe

ln Ce




119890versus ln119862

119890should give


119879and 119861





119890versus ln119862

119890should give


119867and 119870







2 NSD SSE EABS

PFO50 3300 2550 119870

1= 00405minminus1 08675 70160 26508 11687

100 4839 2155 1198701= 00760minminus1 08996 49911 40881 12191

150 5310 8131 1198701= 003178minminus1 09073 79788 78205 21378

PSO50 3300 3436 119870




IPD50 3300 119896


100 4839 119896119882119872



34

36

38

4

42

2 3 4 5 6ln Ce

ln q e


0

10

20

30

40

50

60

0 100 200 300 400 500Time (min)

q(m

gg)

50mgL100mgL150mgL













0

10

20

30

40

50

60

0 100 200 300 400 500Time (min)

q(m

gg)

50mgL100mgL150mgL




2 increases





0

02

04

06

08

1

0 02 04 06 08 1

Qt

T

Rw = 005

Rw = 0076

Rw = 0092



1198702119902119890119905ref =

119877119908minus 1

119877119908

119876119905=

119879

119877119908(1 minus 119879) + 119879

(12)




119908as




119908(ie


119908gt 001 and



0

10

20

30

40

50

60

0 6 12 18 24

50mgL100mgL150mgL

q(m

gg)

t05 (min05 )





0

5

10

15

20

25

30

0 100 200 300 400 500Time (min)minus5

50mgL100mgL150mgL

Bt






119905





119861 =1205872119863119894

1199032 (14)


119894



ln ln(1198620

1198620minus 119902119905119898) = ln(

119896119900119898

2303119881) + 120572 ln 119905 (15)




0

0 2 4 6 8ln t

minus05

minus1

minus15

minus2

minus25

minus3

minus35

minus4

50mgL100mgL150mgL

ln[ln

(CoC

ominusqtmiddotm

)]





119900increase



5 Conclusions


Nomenclature




















119905119902119890









References




















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










0

10

20

30

40

50

60

70

0 50 100 150 200 250 300 350 400 450 500

Adso

rptio

n ca

paci

ty (m

gg)

Time (min)

50mgL100mgL150mgL




40

50

60

70

80

90

100

0

10

20

30

40

50

0 003 006 009 012 015 018

Rem

oval

()

Adso

rptio

n ca

paci

ty (m

gg)




0

05

1

15

2

25

0 50 100 150

Ce

Ce

qe




119890119902119890versus 119862



119890119902119890versus 119862






119871= 00879 Lmg 09938


119891= 2122 (mgg) (Lmg)1119899 119899 = 4737 09851


119879= 3823 Lmg 119861

119879= 94401 09873


119867= 551 times 10

minus7 (Lg) 119899119867= minus4737 09851

0

006

012

018

024

0 50 100 150 200 250Co

RL







119890versus ln119862



119891


34

36

38

4

42

2 3 4 5 6ln Ce

ln q e


0

25

50

75

2 3 4 5 6

qe

ln Ce




119890versus ln119862

119890should give


119879and 119861





119890versus ln119862

119890should give


119867and 119870







2 NSD SSE EABS

PFO50 3300 2550 119870

1= 00405minminus1 08675 70160 26508 11687

100 4839 2155 1198701= 00760minminus1 08996 49911 40881 12191

150 5310 8131 1198701= 003178minminus1 09073 79788 78205 21378

PSO50 3300 3436 119870




IPD50 3300 119896


100 4839 119896119882119872



34

36

38

4

42

2 3 4 5 6ln Ce

ln q e


0

10

20

30

40

50

60

0 100 200 300 400 500Time (min)

q(m

gg)

50mgL100mgL150mgL













0

10

20

30

40

50

60

0 100 200 300 400 500Time (min)

q(m

gg)

50mgL100mgL150mgL




2 increases





0

02

04

06

08

1

0 02 04 06 08 1

Qt

T

Rw = 005

Rw = 0076

Rw = 0092



1198702119902119890119905ref =

119877119908minus 1

119877119908

119876119905=

119879

119877119908(1 minus 119879) + 119879

(12)




119908as




119908(ie


119908gt 001 and



0

10

20

30

40

50

60

0 6 12 18 24

50mgL100mgL150mgL

q(m

gg)

t05 (min05 )





0

5

10

15

20

25

30

0 100 200 300 400 500Time (min)minus5

50mgL100mgL150mgL

Bt






119905





119861 =1205872119863119894

1199032 (14)


119894



ln ln(1198620

1198620minus 119902119905119898) = ln(

119896119900119898

2303119881) + 120572 ln 119905 (15)




0

0 2 4 6 8ln t

minus05

minus1

minus15

minus2

minus25

minus3

minus35

minus4

50mgL100mgL150mgL

ln[ln

(CoC

ominusqtmiddotm

)]





119900increase



5 Conclusions


Nomenclature




















119905119902119890









References




















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation













119871= 00879 Lmg 09938


119891= 2122 (mgg) (Lmg)1119899 119899 = 4737 09851


119879= 3823 Lmg 119861

119879= 94401 09873


119867= 551 times 10

minus7 (Lg) 119899119867= minus4737 09851

0

006

012

018

024

0 50 100 150 200 250Co

RL







119890versus ln119862



119891


34

36

38

4

42

2 3 4 5 6ln Ce

ln q e


0

25

50

75

2 3 4 5 6

qe

ln Ce




119890versus ln119862

119890should give


119879and 119861





119890versus ln119862

119890should give


119867and 119870







2 NSD SSE EABS

PFO50 3300 2550 119870

1= 00405minminus1 08675 70160 26508 11687

100 4839 2155 1198701= 00760minminus1 08996 49911 40881 12191

150 5310 8131 1198701= 003178minminus1 09073 79788 78205 21378

PSO50 3300 3436 119870




IPD50 3300 119896


100 4839 119896119882119872



34

36

38

4

42

2 3 4 5 6ln Ce

ln q e


0

10

20

30

40

50

60

0 100 200 300 400 500Time (min)

q(m

gg)

50mgL100mgL150mgL













0

10

20

30

40

50

60

0 100 200 300 400 500Time (min)

q(m

gg)

50mgL100mgL150mgL




2 increases





0

02

04

06

08

1

0 02 04 06 08 1

Qt

T

Rw = 005

Rw = 0076

Rw = 0092



1198702119902119890119905ref =

119877119908minus 1

119877119908

119876119905=

119879

119877119908(1 minus 119879) + 119879

(12)




119908as




119908(ie


119908gt 001 and



0

10

20

30

40

50

60

0 6 12 18 24

50mgL100mgL150mgL

q(m

gg)

t05 (min05 )





0

5

10

15

20

25

30

0 100 200 300 400 500Time (min)minus5

50mgL100mgL150mgL

Bt






119905





119861 =1205872119863119894

1199032 (14)


119894



ln ln(1198620

1198620minus 119902119905119898) = ln(

119896119900119898

2303119881) + 120572 ln 119905 (15)




0

0 2 4 6 8ln t

minus05

minus1

minus15

minus2

minus25

minus3

minus35

minus4

50mgL100mgL150mgL

ln[ln

(CoC

ominusqtmiddotm

)]





119900increase



5 Conclusions


Nomenclature




















119905119902119890









References




















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation













2 NSD SSE EABS

PFO50 3300 2550 119870

1= 00405minminus1 08675 70160 26508 11687

100 4839 2155 1198701= 00760minminus1 08996 49911 40881 12191

150 5310 8131 1198701= 003178minminus1 09073 79788 78205 21378

PSO50 3300 3436 119870




IPD50 3300 119896


100 4839 119896119882119872



34

36

38

4

42

2 3 4 5 6ln Ce

ln q e


0

10

20

30

40

50

60

0 100 200 300 400 500Time (min)

q(m

gg)

50mgL100mgL150mgL













0

10

20

30

40

50

60

0 100 200 300 400 500Time (min)

q(m

gg)

50mgL100mgL150mgL




2 increases





0

02

04

06

08

1

0 02 04 06 08 1

Qt

T

Rw = 005

Rw = 0076

Rw = 0092



1198702119902119890119905ref =

119877119908minus 1

119877119908

119876119905=

119879

119877119908(1 minus 119879) + 119879

(12)




119908as




119908(ie


119908gt 001 and



0

10

20

30

40

50

60

0 6 12 18 24

50mgL100mgL150mgL

q(m

gg)

t05 (min05 )





0

5

10

15

20

25

30

0 100 200 300 400 500Time (min)minus5

50mgL100mgL150mgL

Bt






119905





119861 =1205872119863119894

1199032 (14)


119894



ln ln(1198620

1198620minus 119902119905119898) = ln(

119896119900119898

2303119881) + 120572 ln 119905 (15)




0

0 2 4 6 8ln t

minus05

minus1

minus15

minus2

minus25

minus3

minus35

minus4

50mgL100mgL150mgL

ln[ln

(CoC

ominusqtmiddotm

)]





119900increase



5 Conclusions


Nomenclature




















119905119902119890









References




















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation
















0

10

20

30

40

50

60

0 100 200 300 400 500Time (min)

q(m

gg)

50mgL100mgL150mgL




2 increases





0

02

04

06

08

1

0 02 04 06 08 1

Qt

T

Rw = 005

Rw = 0076

Rw = 0092



1198702119902119890119905ref =

119877119908minus 1

119877119908

119876119905=

119879

119877119908(1 minus 119879) + 119879

(12)




119908as




119908(ie


119908gt 001 and



0

10

20

30

40

50

60

0 6 12 18 24

50mgL100mgL150mgL

q(m

gg)

t05 (min05 )





0

5

10

15

20

25

30

0 100 200 300 400 500Time (min)minus5

50mgL100mgL150mgL

Bt






119905





119861 =1205872119863119894

1199032 (14)


119894



ln ln(1198620

1198620minus 119902119905119898) = ln(

119896119900119898

2303119881) + 120572 ln 119905 (15)




0

0 2 4 6 8ln t

minus05

minus1

minus15

minus2

minus25

minus3

minus35

minus4

50mgL100mgL150mgL

ln[ln

(CoC

ominusqtmiddotm

)]





119900increase



5 Conclusions


Nomenclature




















119905119902119890









References




















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










0

10

20

30

40

50

60

0 6 12 18 24

50mgL100mgL150mgL

q(m

gg)

t05 (min05 )





0

5

10

15

20

25

30

0 100 200 300 400 500Time (min)minus5

50mgL100mgL150mgL

Bt






119905





119861 =1205872119863119894

1199032 (14)


119894



ln ln(1198620

1198620minus 119902119905119898) = ln(

119896119900119898

2303119881) + 120572 ln 119905 (15)




0

0 2 4 6 8ln t

minus05

minus1

minus15

minus2

minus25

minus3

minus35

minus4

50mgL100mgL150mgL

ln[ln

(CoC

ominusqtmiddotm

)]





119900increase



5 Conclusions


Nomenclature




















119905119902119890









References




















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation










0

0 2 4 6 8ln t

minus05

minus1

minus15

minus2

minus25

minus3

minus35

minus4

50mgL100mgL150mgL

ln[ln

(CoC

ominusqtmiddotm

)]





119900increase



5 Conclusions


Nomenclature




















119905119902119890









References




















































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation


























































RoboticsJournal of





Journal of



RotatingMachinery





VLSI Design



Shock and Vibration







Journal of



Volume 2014


SensorsJournal of





Propagation









research article a novel biosorbent, water...

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