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Biosorption of Reactive Black 5 dye by Penicillium restrictum: The kinetic study

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Biosorption of Reactive Black 5 dye by Penicillium restrictum: The kinetic study
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  This article was srcinally published in a journal published byElsevier, and the attached copy is provided by Elsevier for theauthor’s benefit and for the benefit of the author’s institution, fornon-commercial research and educational use including withoutlimitation use in instruction at your institution, sending it to specificcolleagues that you know, and providing a copy to your institution’sadministrator.All other uses, reproduction and distribution, including withoutlimitation commercial reprints, selling or licensing copies or access,or posting on open internet sites, your personal or institution’swebsite or repository, are prohibited. For exceptions, permissionmay be sought for such use through Elsevier’s permissions site at:http://www.elsevier.com/locate/permissionusematerial     A   u    t    h   o   r    '   s    p   e   r   s   o   n  a    l    c   o   p   y Journal of Hazardous Materials 143 (2007) 335–340 Biosorption of Reactive Black 5 dye by  Penicillium restrictum :The kinetic study Cansu Filik Iscen a , Ismail Kiran b , ∗ , Semra Ilhan a a  Department of Biology, Faculty of Arts and Science, Eski¸sehir Osmangazi University, 26480 Eski¸sehir, Turkey b  Department of Chemistry, Faculty of Arts and Science, Eski¸sehir Osmangazi University, Campus of Me¸selik, 26480 Eski¸sehir, Turkey Received 31 May 2006; received in revised form 11 September 2006; accepted 11 September 2006Available online 15 September 2006 Abstract Biosorption of Reactive Black 5 (RB 5) dye onto dried  Penicillium restrictum  biomass was studied with respect to pH, contact time, biosorbentand dye concentrations. The effect of temperature on the biosorption efficiency was also carried out and the kinetic parameters were determined.Optimum initial pH, equilibrium time and biomass concentration for RB 5 dye were found to be 1.0, 75min and 0.4gdm − 3 at 20 ◦ C, respectively.The maximum biosorption capacities ( q max ) of RB 5 dye onto dried  P. restrictum  biomass were 98.33 and 112.50mg (gbiomass) − 1 at 175mgdm − 3 initial dye concentration at 20 and 50 ◦ C, respectively, and it was 142.04mg (gbiomass) − 1 at 200mgdm − 3 initial dye concentration at 35 ◦ C. Theresults indicate that the biosorption process obeys a pseudo-second-order kinetic model.© 2006 Elsevier B.V. All rights reserved. Keywords: Penicillium restrictum ; Biosorption; Reactive Black 5 1. Introduction Dyesaresyntheticchemicalcompoundshavingcomplexaro-matic structures. They contain different chromophores such asazo groups, which combine with various reactive groups [1].They are classified as acidic, basic, azo, diazo, disperse, metalcomplex and antraquinone-based dyes [2] according to theirstructural varieties and generally considered as a primary con-tributor for the environmental pollution due to their wide use inmany areas especially in textile industry. The major industriesutilizing dye molecules to colour their final products in addi-tion to textiles are dye houses, cosmetics, food, rubber, leather,pharmaceutical,paperandprintingindustries[3].Thehazardouseffects of dyes come from their discharge into receiving waters.Oncetheyarereleased,theynotonlyproducetoxicaminesbythereductive cleavage of azo linkages which causes severe effectson human beings through damaging the vital organs such as thebrain, liver, kidneys, central nervous and reproductive systems[4,5] but also prevent photosynthetic activity in aquatic life byreducing light penetration [6]. Therefore, their removal causes ∗ Corresponding author. Fax: +90 222 2393578.  E-mail address:  ikiran@ogu.edu.tr (I. Kiran). a big environmental concern in industrialized countries in theworld and is subjected to many scientific researches.Commonly used traditional methods to eliminate dyestuffsfrom textile and dye-containing effluents are those of activatedcarbon adsorption, reverse osmosis, oxidation, ultra filtration,flocculation, color irradiation, coagulation, sedimentation andprecipitation [7], but they are ineffective, especially for theremoval of brightly coloured, water-soluble reactive and aciddyes [8]. This is because dyes show resistance to many chemi-cals,oxidizingagentsandlight[9].Theactivatedcarbonadsorp-tion is of choice because of its high adsorption capacity andsurface area as well as having microporous structures [10], butitslargescaleapplicationisrestrictedduetohighoperatingcosts,problem with regeneration and relatively high price [6,11].Biosorptionprocessisattractedgreatattentioninrecentyearsas less costly alternative methods in place of current adsorptionprocesses since they utilize not only plant materials [10] butalso a wide variety of microorganisms in dead, pretreated andimmobilized forms as adsorbing agents [12]. These materialsare cheap to produce and carry wide range of binding sitesfor dye molecules [13]. Therefore they are subjected to manyresearches to be investigated for the removal of various dyesfrom aqueous solutions such as Acid Red 274 [14], Basic Blue41 [11], Rhodamine B [15], Congo Red [16], Methylene Blue 0304-3894/$ – see front matter © 2006 Elsevier B.V. All rights reserved.doi:10.1016/j.jhazmat.2006.09.028     A   u    t    h   o   r    '   s    p   e   r   s   o   n  a    l    c   o   p   y 336  C.F. Iscen et al. / Journal of Hazardous Materials 143 (2007) 335–340 Fig. 1. The chemical structure of Reactive Black 5. [17] and Acid Red 57 [18]. The term “biosorption” refers to the removal of unwanted organic and inorganic species, whichinclude dyes, metals and odor causing substances by microbialbiomass through a combination of active and passive transportmechanisms including ion-exchange and complexation [19,20].Microbial cell surfaces carry various types of functional groupsof amino, carboxylate, phosphate and hydroxyl which areresponsible for the sequestration of hazardous materials fromindustrial effluents [21].Inthisstudy,biosorptionofRB5dye(seeFig.1),commonlyusedintextileindustryforcoloringclothesinTurkey,ontodried Penicillium restrictum  biomass was investigated in a batch sys-tem with variation in the parameters of initial pH, contact time,dye and biosorbent concentration in addition to temperature.The biosorption kinetic was also investigated. To our knowl-edge, this is the first example for  P. restrictum  biomass to beused as a biosorbent material for the removal of dye moleculesfrom aqueous solutions. 2. Material and methods 2.1. Preparation of the biosorbent  The filamentous fungus,  P. restrictum  (wild type), was iso-lated from Industrial Wastewater Treatment Plant in Eskis¸ehir,Turkey. The fungus was stored on potato dextrose agar slantsat 4 ◦ C [22]. A medium for growing  P. restrictum  was preparedby mixing sucrose (20g), bacto peptone (5g), neopeptone (5g),KH 2 PO 4  (1g), NaNO 3  (1g) and MgSO 4 · 7H 2 O (0.5g) in dis-tilledwater(1dm 3 ).ThepHofthegrowthmediumwasadjustedto5.5bytheadditionof1MHClbeforeautoclavingat121 ◦ Cforat least 20min. Erlenmayer flasks containing the above media(0.1dm 3 ) were inoculated with spore suspension (0.001dm 3 )obtained shaking sterile water (0.01dm 3 ) with mature slopesof   P. restrictum  under sterile conditions. Growth was allowedto proceed for 7 days at 25 ◦ C on a rotary shaker operating at120rpm. After the fungal growth, the biomass and the culturemediumwereseparatedbyfilteration.Theresultingbiomasswaswashed several times thoroughly with distilled water, spread onPetri dishes and dried in an oven at 60 ◦ C overnight. They werethen powdered using a mortar and pestle and sieved to selectparticles 150  m for use as a biosorbent. 2.2. Preparation of dye solution The dye used in this study was Reactive Black 5 (RB 5; com-mercial name Sakazol Black B) obtained from BIRBOY textilecompany in Istanbul, Turkey and used without further purifi-cation. The tests solutions containing RB 5 dye were preparedby diluting 1.0gdm − 3 of stock solution which was prepared bydissolving an accurate quantity of dye in distilled water. 2.3. Dye biosorption experiments Laboratory biosorption experiments were performed at dif-ferentbiomassfeeds,initialRB5dyeconcentrationsandvarioustemperatures.Thebatchexperimentswerecarriedoutinabeaker(0.1dm 3 ) at an agitation speed of 200rpm on a magnetic stirrer.Thebiosorptioncapacitywasdeterminedbyusingthefollowingequation taking into the concentration difference of the solutionat the beginning and equilibrium accounts: q e  = [( C i − C e )] xV m (1)where  C  i  and  C  e  are the initial and the equilibrium dye concen-trations (mgdm − 3 ),  V   is the volume of solution (dm 3 ) and  m  isthe amount of biosorbent used (g).Firstly, the effect of the solution pH on the biosorptioncapacity of RB 5 dye onto dried  P .  restrictum  biomass wasexamined by equilibrating the adsorption mixture with driedbiomass (0.02g) and 0.05dm 3 of 150mgdm − 3 RB 5 dye solu-tion, adjusting the pH value between 1 and 10 adding freshlyprepared 0.1M HCl or 0.1M NaOH solutions for 1h. This wasfollowed by the assessment of the effect of equilibrium timevaried between 10 and 120min on the dye biosorption capac-ity of the biosorbent. Then, the binding capacity of biomass wasassessed,varyingtheRB5dyeconcentrationwithintherangeof 100–250mgdm − 3 and adjusting the pH to a value of 1.0 whichis the optimum pH. The effect of biomass concentration on RB5 sorption was also determined using biomass samples rangingfrom0.02to0.2gat0.05dm 3 of150mgdm − 3 RB5dyesolutionand pH of 1.0 for 1h. When the sorption procedure completed,the solutions were centrifuged at 4500rpm for 10min and thesupernatants were then analyzed for residual RB 5 dye con-centrations spectrophotometrically using a spectrophotometer(UV/vis,Cecil4002)at λ max  596.0nm.Thesolutionsconcernedwere diluted to known concentrations to read the values beforemaking the measurements. The optimum pH and biomass con-centration were determined as 1.0 and 0.4gdm − 3 , respectively,and used throughout all biosorption experiments.Finally, several experiments were conducted to study theeffects of temperature on the biosorption process and deducekinetic parameters as follows: a constant biomass of 0.02g wasweighed and mixed with 0.05dm 3 of 150mgdm − 3 RB 5 dyesolutions at various time intervals between 10 and 120min andtemperatures of 20, 35 and 50 ◦ C. The concentration of RB 5dye was determined as described above.     A   u    t    h   o   r    '   s    p   e   r   s   o   n  a    l    c   o   p   y C.F. Iscen et al. / Journal of Hazardous Materials 143 (2007) 335–340  337Fig. 2. Effect of pH for the biosorption of RB 5 dyes onto dried  P. restrictum biomass at 20 ◦ C. 3. Results and discussion 3.1. Effect of pH  The pH is an important parameter for biosorption studiesand affects not only the biosorption capacity, but also the colourand solubility of dye solutions. The maximum biosorptioncapacities of dried  P. restrictum  biomass are plotted againstsolution pH in Fig. 2 using 0.05dm 3 of 150mgdm − 3 initial dyesolution, 0.02g biomass concentration, contact time of 60minat 20 ◦ C. As shown in this figure, the equilibrium biosorptioncapacity of the biosorbent decreased from 78.00 to 65.50mg(gbiomass) − 1 when the solution pH is changed from 1 to2 and a sharp decrease was observed at pH 3, dropping thebiosorption capacity to 20.00mg (gbiomass) − 1 . This trend iscontinued with increasing solution pH from 4 to 8, causingthe equilibrium uptake capacity to drop from 13.35 to 8.00mg(gbiomass) − 1 . The sorption capacity further decreased afterpH 8 and reaches the lowest level of 2.68mg (gbiomass) − 1 biosorption capacity at pH 10. From this study, the optimum pHis determined as 1 at which the maximum biosorption capacityof dried  P. restrictum  biomass for RB 5 dyes was determined as78.00mg (gbiomass) − 1 at 20 ◦ C. This effect is largely relatedto the anionic characters of RB 5 dye. Weak base groups in thebiomasssurfaceareprotonatedandacquireanetpositivechargewith diminishing solution pH. This causes a significantly highelectrostaticattractionbetweenthesurfaceofdried P.restrictum biomassandRB5dyes,resultinginahighbiosorptioncapacity.Lower biosorption capacity of RB 5 observed at basic pHis a result of competition between the excess hydroxyl ionsand the negatively charged dye ions for the biosorption sites[13].In a study describing the removal of RB 5 dye from aqueoussolutions by dried activated sludge, Gulnaz et al. [23] reportedthat the optimum solution pH was 2 at which the adsorptioncapacity of the dried sludge was determined as 116mgg − 1 for20 ◦ C. Fig. 3. The effect of equilibrium time for biosorption of RB 5 dyes onto dried P. restrictum  biomass at temperatures of 20, 35 and 50 ◦ C. 3.2. Effect of contact time Contact time is one of the important parameters for success-ful deployment of the biosorbents for practical application andrapid sorption is among desirable parameters [24]. Fig. 3 indi- cates the RB 5 dye uptake by the biosorbent as a function of contact time at different temperatures of 20, 35 and 50 ◦ C. Anuptakecapacityof56.83mg(gbiomass) − 1 wasobservedwithin10min and then the sorption capacity was increased constantlywith increasing contact time reaching to a maximum point of 95.83mg (gbiomass) − 1 in 75min at 20 ◦ C. Beyond the equilib-riumtime,thereisasteadydecreaseobservedonthebiosorptioncapacity. A similar trend was observed at 35 and 50 ◦ C andthe maximum biosorption capacities were determined as 97.92and 110.00mg (gbiomass) − 1 in 75min, respectively, followedby steady decrease with increasing the contact time. Therefore75min is fixed as the optimum contact time for studies carriedout at 20, 35 and 50 ◦ C. An increase observed on the biosorp-tion capacity with increasing contact time is due to availabilityofbiosorptionsitesonthebiomasssurface.Adecreaseobservedon the biomass capacity after equilibrium time could be relatedto the desorption of dye molecules from the biomass surfacesprobably caused by repulsive forces between dye molecules atadjacent sites on the biomass surfaces [25]. 3.3. Effect of biosorbent concentration on RB 5 dye removal ThebiosorptionofRB5dyeontodried P.restrictum biomasswas measured at seven different biosorbent concentration atpH of 1 and contact time of 75min and 20 ◦ C, using 0.05dm 3 of 150mgdm − 3 dye solution to investigate the effect of biosorbent concentrations. The results of the experiments arepresented in Fig. 4. It is clear from the figure that the biosorbeddye concentration was decreased from 85.92 to 35.98mg(gbiomass) − 1 with increase in biosorbent concentration, from0.4 to 4.0gdm − 3 . The decrease in biosorption capacity withincreasing biosorbent concentration could be explained by not     A   u    t    h   o   r    '   s    p   e   r   s   o   n  a    l    c   o   p   y 338  C.F. Iscen et al. / Journal of Hazardous Materials 143 (2007) 335–340 Fig. 4. Effect of biosorbent concentration for biosorption of RB 5 dyes ontodried  P. restrictum  biomass at 20 ◦ C. only unsaturation of biosorption sites through the adsorptionreaction but also the particle interaction such as aggregationoccurring at high biosorbent concentration and leading todecrease in total surface area [26]. Another reason could be dueto the splitting effect of concentration gradient between dyemolecules and biomass concentration causing a decrease in theamount of dye biosorbed onto unit weight of biomass [27]. 3.4. Effect of initial dye concentration The parameter, initial concentration, provides an importantdriving force to overcome resistances encountered when allmolecules are transferred between the aqueous and solid phases[28]. In this study, the RB 5 dye removal capacity of dried  P.restrictum  biomass was investigated using RB 5 dye solutionsrangedfrom100to250mgdm − 3 atpH1.0and20 ◦ C.Theequi-librium dye uptake capacity value (mg (gbiomass) − 1 ) is giveninFig.5.Theequilibriumloadingcapacityincreasedfrom73.92to 100.46mg (gbiomass) − 1 as the initial dye concentration wasincreased from 100 to 175mgdm − 3 which is the maximum dye Fig. 5. The effect of initial RB 5 dye concentration for biosorption of RB 5 dyesonto dried  P. restrictum  biomass at 20 ◦ C. uptake value at 20 ◦ C. Then the biosorption capacity decreasedto a value of 81.04mg (gbiomass) − 1 as the initial dye con-centration was further increased to 250mgdm − 3 . Therefore175mgdm − 3 dye concentration is determined as the optimuminitialdyeconcentrationat20 ◦ C.Theeffectscouldbeexplainedasfollows:atlowerinitialdyeconcentrations,alldyemoleculescould interact with the binding sites on the biomass surface andhigh sorption rates occur while at high initial dye concentra-tions, binding sites on the biomass surface are saturated and nofurther biosorption occurs. A decrease observed on the biosorp-tion capacity is mainly due to the repulsive forces betweendye molecules at adjacent sites on the cell surface, resultingin removal of some dye molecules from the surface [25]. 3.5. Effect of temperature The temperature has two main effects on the sorption pro-cesses.Increasingtemperatureisknowntoincreasethediffusionrate of the adsorbate molecules within the pores as a result of decreasing solution viscosity and will also modify the equilib-riumcapacityoftheadsorbentforaparticularadsorbate[29].Toinvestigatetheeffectoftemperature,theequilibriumbiosorptioncapacity of RB 5 dye onto dried biomass of   P. restrictum  wasstudied at three constant temperatures of 20, 35 and 50 ◦ C. Anincrease in the temperature from 20 to 35 and to 50 ◦ C led toan increase on the uptake capacity of the biomass for the dyemolecules from 100.46 to 110.88 and 112.50mg (gbiomass) − 1 ,respectively, under optimum condition of pH, biomass con-centration and equilibrium time at an initial concentration of 175mgdm − 3 , respectively. This result indicated that a betterbiosorption of RB 5 dye is actually obtained at higher tempera-tures after the equilibrium time. 3.6. Biosorption kinetic The kinetics studies have carried out to determine the effi-ciency of RB 5 dye biosorption onto dried  P. restrictum  biomassand indicated that the biosorption capacity increases with theinitial dye concentrations in all cases. Various kinetic modelsincluding first-order and pseudo-second-order were tested forthe experimental data to elucidate the biosorption mechanism.The pseudo-second-order kinetic model [30] is expressed as: t q t  = 1 k 2 q 22 + 1 q 2 t   (2)where  q 2  is the biosorbed dye amount at equilibrium (mgg − 1 )for the pseudo-second-order biosorption,  q t   is the amount of RB5 dye biosorbed at time  t   (mgg − 1 ) and  k  2  is the pseudo-second-order kinetic rate constant (gmg − 1 min − 1 ). Values of   k  2  and  q 2 were calculated from the plot of   t   /  q t   against  t   (Fig. 6).Theplotsoflinearformofthepseudo-first-orderandpseudo-second-order were obtained at the temperatures of 20, 35 and50 ◦ C and the kinetic parameters for the biosorption process aregiven in Table 1. The plots of 1/  q t   versus 1/  t   for the first-orderequation are not shown as a figure because the correlation coef-ficients for the pseudo-first-order model are lower than that of 
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