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Öğe Application of NaOH treated Polyporus versicolor for removal of divalent ions of Group IIB elements from synthetic wastewater(Elsevier Sci Ltd, 2002) Satiroglu, N.; Yalcinkaya, Y.; Denizli, A.; Arica, M.Y.; Bektas, S.; Genç, O.Three different forms of Polyporus versicolor, i.e. alkali-pretreated, heat-inactivated and active, were used for the removal of the divalent ions of Group JIB elements from aquatic systems. The biosorption of Zn(II), Cd(II) and Hg(II) ions on three different forms of P. versicolor was studied in aqueous solutions in the concentration range of 30-700 mg/l. Maximum biosorption capacities of alkali-pretreated, heat-inactivated and active forms of P. versicolor was found as 139.3, 70.8, and 54.1 mg/g for Zn(II); 232.2, 118.2, and 90.0 mg/g for Cd(II) and 290.3 168.9, and 131.4 mg/g for Hg(11), respectively. For the divalent ions of Group 1111 elements, the order of affinity of the biosorbents was found as, NaOH treated > heat-inactivated > active. The order of the amount of metal ions adsorbed, on the other hand, was, Hg(II) > Cd(II) > Zn(II) on a weight base. The electro-negativities and standard electrode potentials of these elements show a definite trend with the biosorption capacity values. Biosorption equilibria were established in about 60 min and the equilibria were well described by Langmuir isotherms. Temperature change between 15 and 45 degreesC did not affect the biosorption capacity. The effect of pH was also investigated and the maximum biosorption of metal ions on the three different forms of P. versicolor were observed at pH 6.0. The reusability experiments and synthetic wastewater studies were carried out with the most effective form; alkali-pretreated P. versicolor. The biosorbent could be regenerated using 10 mM HCl solution, with up to 98% recovery and it could be reused in five biosorption-desorption cycles without any considerable loss in biosorption capacity. The alkali-treated P. versicolor removed 60, 73, and 81% of Zn(II), Cd(II) and Hg(II) ions from synthetic wastewater samples, respectively. (C) 2002 Elsevier Science Ltd. All rights reserved.Öğe Biodegradation of aldicarb in a packed-bed reactor by immobilized Methylosinus(Elsevier Science Inc, 1999) Kök, F.N.; Arica, M.Y.; Halicigil, C.; Alaeddinoglu, G.; Hasirci, V.Carboxymethylcellulose microspheres cross-linked via aluminum ions were used as a support material for immobilization of Methylosinus isolated from soil contaminated with aldicarb. The degradation capacity of immobilized bacteria, different parameters such as substrate concentration (50-800 ppm), flow rate (10-60 ml h(-1)), and continuous contact with reaction medium (flow rate, 20 mi h(-1) and concentration, 100 ppm) that affect aldicarb degradation were investigated in a packed-bed reactor. Increases in the flow rate decreased the conversion of aldicarb into its metabolites. On the other hand, increasing the substrate concentration up to 400 ppm led to an increase in the amount of aldicarb converted (max 16%). Beyond this, the proportion of aldicarb that converted was decreased, reaching approximately 7% at 800 ppm. The apparent kinetic parameters, K-m' and V-max, were determined to be as 310.11 ppm and 2.29 X 10(-2) ppm s(-1), respectively. Operation of the bioreactor in the recycled mode was much more efficient, degrading 50% of the aldicarb in 24 h and 100% in four days. (C) 1999 Elsevier Science Inc.Öğe Biosorption of cadmium from aquatic systems by carboxymethyleellulose and immobilized Trametes versicolor(Elsevier Science Bv, 2002) Yalcinkaya, Y.; Soysal, L.; Denizli, A.; Arica, M.Y.; Bektas, S.; Genc, O.Trametes versicolor basidio spores immobilized onto carboxymethylcellulose were used for the removal of cadmium ions from aqueous solutions. The biosorption of Cd(II) ions on carboxymethylcellulose and both immobilized live and heat-killed fungal mycelia of T. versicolor was studied from aqueous solutions in the concentration range of 30-700 mg/L. The biosorption of Cd(II) ions by the carboxymethylcellulose and both immobilized live and heat-inactivated immobilized preparations increased as the initial concentration of cadmium ions increased in the medium. Maximum biosorption capacity for immobilized live and heat-inactivated fungal mycelia of T. versicolor was found as 124 and 153 mg Cd(II)/g, respectively whereas the amount of Cd(II) ions adsorbed on the plain carboxymethylcellulose beads was 43 mg/g. Biosorption equilibria were established in about I h and the correlation regression coefficients show that the adsorption process can be well defined by Langmuir equation. The temperature change between 15 and 45 degreesC did not affect the biosorption capacity. The effect of pH was also investigated and the maximum adsorption of Cd(II) ions on the carboxymethylcellulose and both live and heat-inactivated immobilized fungal mycelia were observed at pH 6.0. The carboxymethylcellulose-fungus beads could be regenerated using 10 mM HCl, with up to 98% recovery. The biosorbents were used in five biosorption-desorption cycles and no notable loss in the biosorption capacity was observed. 84% and 68% of cadmium ions were removed from synthetic waste water samples for 100 and 200 mg/L initial concentrations, respectively. (C) 2002 Elsevier Science B.V. All rights reserved.Öğe Biosorption of Hg(II) and Cd(II) from aqueous solutions: Comparison of biosorptive capacity of alginate and immobilized live and heat inactivated Phanerochaete chrysosporium(Elsevier Sci Ltd, 2002) Kacar, Y.; Arpa, C.; Tan, S.; Denizli, A.; Genc, O.; Arica, M.Y.Basidiospores of P. chryosporium were immobilized into Ca-alginate beads via entrapment, and the beads incubated for vegetation at 30 degreesC for 5 days. The alginate beads and both entrapped live and heat inactivated fungal mycelia of Phanerochaete chryosporium were used for the removal of Hg(II) and Cd(II) ions from aqueous solution in the concentrations range of 30-500 mg l (-1). The biosorption of Hg(II) and Cd(II) ions by the biosorbents increased as the initial concentration of Hg(II) and Cd(11) ions increased in the medium. A biosorption equilibrium was established in about 1 h and the adsorbed heavy metal ions did not change further with time. The effect of pH was also investigated and the maximum biosorption of Hg(11) and Cd(II) ions on all the tested biosorbents were obtained between pH 5.0 and 6.0. Temperature over the range 15-45 degreesC had no significant effect on the biosorption capacity. The equilibrium was well described by Langmuir and Freundlich biosorption isotherms. The alginate-fungus beads could be regenerated using 10 mM HCl, up to 97% recovery. The biosorbents were reused in three biosorption-desorption cycles with negligible decrease in biosorption capacity. (C) 2002 Elsevier Science Ltd. All rights reserved.Öğe Biosorption of mercury by carboxymethylcellulose and immobilized Phanerochaete chrysosporium(Elsevier Science Bv, 2002) Saglam, A.; Yalcinkaya, Y.; Denizli, A.; Arica, M.Y.; Genc, O.; Bektas, S.Phanerochaete chrysosporium basidiospores immobilized onto carboxymethylcellulose were used for the removal of mercury ions from aqueous solutions. The biosorption of Hg(II) ions onto carboxymethylcellulose and both immobilized live and heat-inactivated fungal mycelia of Phanerochaete chrysosporium was studied using aqueous solutions in the concentration range 30-700 mg l(-1). The biosorption of Hg(II) ions by the carboxymethylcellulose and both live and heat-inactivated immobilized preparations increased as the initial concentration of mercury ions increased in the medium. Maximum biosorption capacity for immobilized live and heat-inactivated fungal mycelia of Phanerochaete chrysosporium was found to be 83.10 and 102.15 mg Hg(II) g(-1), respectively, whereas the amount of Hg(II) ions adsorbed onto the plain carboxymethylcellulose beads was 39.42 mg g(-1). Biosorption equilibria were established in approximately 1 h and the correlation regression coefficients show that the adsorption process can be well defined by a Langmuir equation. Temperature changes between 15 and 45 C did not affect the biosorption capacity. The effect of pH was also investigated and the maximum adsorption of Hg(II) ions onto the carboxymethylcellulose and both live and heat-inactivated immobilized fungal mycelia was observed at pH 6.0. The carboxymethylcellulose-fungus beads could be regenerated using 10 mM HCl, with up to 95% recovery. The biosorbents were used in three biosorption-desorption cycles and no significant loss in the biosorption capacity was observed. (C)2002 Elsevier Science B.V All rights reserved.Öğe Ca-alginate as a support for Pb(II) and Zn(II) biosorption with immobilized Phanerochaete chrysosporium(Elsevier Sci Ltd, 2003) Arica, M.Y.; Arpa, C.; Ergene, A.; Bayramoglu, G.; Genç, O.The basidio spores of Phanerochaete chryosporium were immobilized in alginate gel beads, and the immobilized spore containing alginate beads were incubated for the growth of fungus. The biosorption of Pb2+ and Zn2+ ions on alginate beads and both immobilized live and heat inactivated fungus was studied from artificial waste waters in the concentrations range of 30-600 mg 1(-1). The surface charge density of the biosorbents varied with the pH of the medium and the maximum biosorption of heavy metal ions on the biosorbents was obtained between pH 5.0 and 6.0. The biosorption of Pb2+ and Zn2+ on the biosorbents increased as the initial concentration of Pb2+ and Zn2+ ions increased in the medium. Biosorption equilibrium was established about 1 h, the adsorbed heavy metal ions did not significantly change further with time. The maximum biosorption capacity (q(m)) of alginate beads and both immobilized live and heat inactivated fungus were 230, 282 and 355 mg for Pb2+ and 30, 37 and 48 mg for Zn per gram of dry biosorbents, respectively. The experimental biosorption equilibrium data for Pb2+, and Zn2+ ions were in good agreement with those calculated by Langmuir model. The affinity order of heavy metal ions was Pb2+ > Zn2+, (C) 2003 Elsevier Science Ltd. All rights reserved.Öğe Comparative biosorption of mercuric ions from aquatic systems by immobilized live and heat-inactivated Trametes versicolor and Pleurotus sajur-caju(Elsevier Sci Ltd, 2003) Arica, M.Y.; Arpa, C.; Kaya, B.; Bektas, S.; Denizli, A.; Genc, O.Trametes versicolor and Pleurotus sajur-caju mycelia immobilized in Ca-alginate beads were used for the removal of mercuric ions from aqueous solutions. The sorption of Hg(II) ions by alginate beads and both immobilized live and heat-killed fungal mycelia of T versicolor and P. sajur-caju was studied in the concentration range of 0.150-3.00 mmol dm(-3). The biosorption of Hg(II) increased as the initial concentration of Hg(II) ions increased in the medium. Maximum biosorption capacities for plain alginate beads were 0.144+/-0.005 mmol Hg(II)/g; for immobilized live and heat-killed fungal mycelia of T versicolor were 0.171+/-0.007 mmol Hg(II)/g and 0.383+/-0.012 mmol Hg(II)/g respectively; whereas for live and heat-killed P. sajur-caju, the values were 0.450+/-0.014 mmol Hg(II)/g and 0.660+/-0.019 mmol Hg(II)/g respectively. Biosorption equilibrium was established in about 1 h and the equilibrium adsorption was well described by Langmuir and Freundlich adsorption isotherms. Between 15 and 45 degreesC the biosorption capacity was not affected and maximum adsorption was observed between pH 4.0 and 6.0. The alginate-fungus beads could be regenerated using 10 mmol dm(-3) HCl solution, with up to 97% recovery. The biosorbents were reused in five biosorption-desorption cycles without a significant loss in biosorption capacity. Heat-killed T versicolor and P. sajur-caju removed 73% and 81% of the Hg(II) ions, respectively, from synthetic wastewater samples. (C) 2003 Elsevier Science Ltd. All rights reserved.Öğe Comparison of the heavy metal biosorption capacity of active, heat-inactivated and NaOH-treated phanerochaete chrysosporium biosorbents(Wiley, 2004) Gurisik, E.; Arica, M.Y.; Bektas, S.; Genç, O.Three different kinds of Phanerochaete chrysosporium (NaOH-treated, heat-inactivated and active) biosorbent were used for the removal of Cd(II) and Hg(II) ions from aquatic systems. The biosorption of Cd(II) and Hg(II) ions on three different forms of Phanerochaete chrysosporium was studied in aqueous solutions in the concentration range of 50-700 mg/ L. Maximum biosorption capacities of NaOH-treated, heat-inactivated and active Phanerochaete chrysosporium biomass were found to be 148.37 mg/g, 78.68 mg/g and 68.56 mg/g for Cd(II) as well as 224.67 mg/g, 122.37 mg/g and 88.26 mg/g for Hg(II), respectively. For Cd(II) and Hg(II) ions, the order of affinity of the biosorbents was arranged as NaOH-treated > heat-in activated > active. The order of the amount of metal ions adsorbed was established as Hg(II) > Cd(II) on a weight basis, and as Cd(II) > Hg(II) on a molar basis. Biosorption equilibriums were established in about 60 min. The effect of the pH was also investigated, and maximum rates of biosorption of metal ions on the three different forms of Phanerochaete chrysosportum were observed at pH 6.0. The reusability experiments and synthetic wastewater studies were carried out with the most effective form, i.e., the NaOH-treated Phanerochaete chrysosporium biomass. It was observed that the biosorbent could be regenerated using 10 mM HCl solution, with a recovery of up to 98%, and it could be reused in five biosorption-desorption cycles without any considerable loss in biosorption capacity. The alkali-treated Phanerochaete chrysosporium removed 73% of Cd(II) and 81% of Hg(II) ions from synthetic wastewater.Öğe Congo Red attached monosize poly(HEMA-co-MMA) microspheres for use in reversible enzyme immobilisation(Elsevier Science Sa, 2002) Yavuz, H.; Bayramoğlu, G.; Kaçar, Y.; Denizli, A.; Arica, M.Y.Monosize and non-porous poly(2-hydroxyethylmethacrylate-co-methylmethacrylate) (poly(HEMA-co-MMA)), microspheres were prepared by dispersion polymerisation of HEMA and MMA in an ethanol-water medium in the presence of an initiator (alpha,alpha'-azobisisobutyronitrile, AIBN). An affinity dye, i.e. Congo Red (CR) was attached covalently and then Fe3+ ions were incorporated. The poly(HEMA-co-MMA)-CR attached and poly(HEMA-co-MMA)-CR-Fe3+ incorporated microspheres were used in the immobilisation of glucose oxidase (GOD) via adsorption. The adsorption capacities of these microspheres were determined by varying the concentration of GOD in the adsorption medium. GOD adsorption capacities of the Fe3+ incorporated microspheres (165 mg g(-1)) was greater than that of the dye-attached microspheres (126 mg g(-1)). The non-specific adsorption of the GOD on the poly(HEMA-co-MMA) microspheres was negligible. The K values for both immobilised poly(HEMA-co-MMA)-CR-GOD (7.2) and poly(HEMA-co-MMA)-CR-Fe3+-GOD (6.8) were higher than that of the free enzyme (6.6 mM). Optimum reaction pH was 5.0 for free and 7.0 for both immobilised preparations. Optimum reaction temperature of the adsorbed enzymes was 10degreesC higher than that of the free enzyme and was significantly broader. After 10 successive uses the retained activity of the adsorbed enzyme was 93%. It was observed that enzyme could be repeatedly adsorbed and desorbed on the CR attached poly(HEMA-co-MMA) microspheres without significant loss in adsorption capacity or enzyme activity. (C) 2002 Elsevier Science B.V. All rights reserved.Öğe Covalent immobilization of lipase onto hydrophobic group incorporated poly(2-hydroxyethyl methacrylate) based hydrophilic membrane matrix(Elsevier Sci Ltd, 2002) Bayramoğlu, G.; Kacar, Y.; Denizli, A.; Arica, M.Y.In this study, a hydrophobic group containing monomer, 2-methacrylamidophenyalanine (MAPA) was prepared by using methacrylochloride and phenylalanine. Then, poly(2-hydroxyethyl methacrylate-co-methacrylamido-phenlyalanine) (pHEMA-MAPA) membranes were prepared by UV-initiated photopolymerization of HEMA and MAPA in the presence of an initiator alpha-alpha'-azobisisobutyronitrile (AIBN). The lipase was immobilized onto these membranes by covalent bonding through carbodiimide activation. The amount of enzyme loading on the membranes was increased as the MAPA ratio increased in the membrane structure. Immobilization improved the pH stability of the enzyme as well as its temperature stability. Thermal stability was found to increase with immobilization and at 60 degreesC the thermal stability constants were 1.1 x 10(-1) min for free enzyme and 1.2 x 10(-2) min for the immobilized enzyme. The immobilized enzyme activity was found to be quite stable in repeated experiments. (C) 2002 Elsevier Science Ltd. All rights reserved.Öğe DNA adsorption on a poly-L-lysine-immobilized poly(2-hydroxyethyl methacrylate) membrane(Wiley, 2003) Senel, S.; Bayramoglu, G.; Arica, M.Y.The DNA adsorption properties of poly-L-lysine-immobilized poly(2-hydroxyethyl methacrylate) (pHEMA) membrane were investigated. The pHEMA membrane was prepared by UV-initiated photopolymerization and activated with epichlorohydrin. Poly-L-lysine was then immobilized on the activated pHEMA membrane by covalent bonding, via a direct chemical reaction between the amino group of poly-L-lysine and the epoxy group of pHEMA. The poly-L-lysine content of the membrane was determined as 1537 mg m(-2). The poly-L-lysine-immobilized membrane was utilized as an adsorbent in DNA adsorption experiments. The maximum adsorption of DNA on the poly-L-lysine-immobilized pHEMA membrane was observed at 4 degreesC from phosphate-buffered salt solution (pH 7.4, 0.1 M; NaCl 0.5 M) containing different amounts of DNA. The non-specific adsorption of DNA on the plain pHEMA membrane was low (about 263 mg m(-2)). Higher DNA adsorption values (up to 5849 mg m(-2)) were obtained in which the poly-L-lysine-immobilized pHEMA membrane was used. (C) 2003 Society of Chemical Industry.Öğe Dye-ligand immobilized IPNs membrane for removal heavy metal ions(Wiley-V C H Verlag Gmbh, 2003) Bayramoğlu, G.; Yalçın, E.; Genç, O.; Arica, M.Y.We have developed a novel approach to obtain high metal sorption capacity utilizing a membrane containing chitosan and an immobilized reactive dye (i.e. Reactive Yellow-2). The composite membrane was characterized by SEM, FTIR, swelling test, and elemental analysis. The membrane has uniform small pores distribution and the pore dimensions are between 5 and 10 pm, and the HEMA:chitosan ratio was 50:1. The reactive dye immobilized composite membrane was used in the removal of heavy metal ions [i.e., Pb(II), Hg(II) and Cd(II)] from aqueous medium containing different amounts of these ions (5-600 mg 1(-1)) and at different pH values (2.0-7.0). The maximum adsorption capacities of heavy metal ions onto the composite membrane under non-competitive conditions were 64.3 mmol m(-2) for Pb(II), 52.7 mmol m(-2) for Hg(II), 39.6 mmol m(-2) for Cd(II) and the affinity order was Pb(II) > Hg(II)>Cd(II).Öğe Immobilization of a thermostable α-amylase onto reactive membranes: kinetics characterization and application to continuous starch hydrolysis(Elsevier Sci Ltd, 2004) Bayramoğlu, G.; Yilmaz, M.; Arica, M.Y.Epoxy groups containing porous membranes were prepared by UV-initiated photopolymerisation of hydroxyethylmethacrylate (HEMA) and glycidyl methacrylate (GMA). Epoxy supports could provide multipoint covalent attachment of enzymes, therefore, to stabilize their three-dimensional structure. alpha-Amylase was immobilized onto the poly(HEMA-GMA-1-3) membranes by means of the amide linkage formation between the amino groups of alpha-amylase and the epoxy groups of the support. The alpha-amylase immobilization capacity of the membranes was increased as the GMA ratio increased in the membrane structure. The retained activity of the immobilized alpha-amylase was 76% with poly(HEMA-GMA-2) membrane. The decrease in activity of the immobilized a-amylase could be considered to be due to reduced conformational flexibility of the immobilized alpha-amylase molecules for binding its large substrate, starch, as a result of the covalent immobilization. The immobilized alpha-amylase has more resistance to temperature inactivation than that of the free form. The optimum pH value of alpha-amylase was not affected by the immobilization reaction, but the pH profile was broadened for the immobilized enzyme. Kinetic parameters were determined for immobilized alpha-amylase as well as for the free enzyme. The values of the Michaelis constant K-m of alpha-amylase, were significantly larger (ca. 2.3 times) upon immobilization, indicating decreased affinity of the enzyme for its substrate, whereas V-max was smaller for immobilized a-amylase. In a 120 h continuous operation at 35 degreesC only 4% of immobilized alpha-amylase activity was lost. The operational inactivation rate constant (k(opi)) of the immobilized a-amylase with 2% starch was 8.06x 10(-6) min(-1). (C) 2003 Elsevier Ltd. All rights reserved.Öğe Immobilization of catalase via adsorption onto L-histidine grafted functional pHEMA based membrane(Elsevier Science Bv, 2001) Akgöl, S.; Kacar, Y.; Özkara, S.; Yavuz, H.; Denizli, A.; Arica, M.Y.Poly(2-hydroxyethylmethacrylate) (pHEMA) based flat sheet membrane was prepared by UV-initiated photopolymerization technique. The membrane was then grafted with L-histidine. Catalase immobilization onto the membrane from aqueous solutions containing different amounts of catalase at different pH was investigated in a batch system. The maximum catalase immobilization capacity of the pHEMA-histidine membrane was 86 mug cm(-2). The activity yield was decreased with the increase of the enzyme loading. It was observed that there was a significant change between V-max value of the free catalase and V-max value of the adsorbed catalase on the pHEMA-histidine membrane. The K-m value of the immobilized enzyme was higher 1.5 times than that of the free enzyme. Optimum operational temperature was 5 degreesC higher than that of the free enzyme and was significantly broader. It was observed that enzyme could be repeatedly adsorbed and desorbed without loss of adsorption capacity or enzyme activity. (C) 2001 Elsevier Science B.V. All rights reserved.Öğe Membrane with incorporated hydrophobic ligand for hydrophobic interaction with proteins: application to lipase adsorption(Wiley, 2002) Bayramoglu, G.; Denizli, A.; Arica, M.Y.In this study, phenylalanine as a hydrophobic ligand was covalently attached on a comonomer, methacryloyl chloride. Then, poly(2-hydroxyethyl methacrylate-co-methacrylamido-phenylalanine), poly(HEMA/MAPA), membranes were prepared by UV-initiated photopolymerization of 2-hydroxyethyl methacrylate and methacrylamido-phenylalanine. The lipase adsorption of these poly(HEMA/MAPA) membranes was determined by changing the hydrophobic ligand density, pH, temperature and concentration of lipase in the adsorption medium. The lipase adsorption capacity of the membranes increased as the ligand density on the membrane surface increased. The nonspecific adsorption of lipase on the poly(2-hydroxyethyl methacrylate) membranes was negligible (12 mug cm(-2) of membrane). The adsorption phenomena appeared to follow a typical Langmuir isotherm. The maximum adsorption capacity (Q(m)) of the poly(HEMA/MAPA-5) membrane for lipase was 215 mug cm(-2) of membrane. The equilibrium constant (k(d)) value was 1.43mg ml(-1). The lipase could repeatedly be adsorbed and desorbed on the affinity membrane without any significant loss in the adsorption capacity of the membrane. (C) 2002 Society of Chemical Industry.Öğe A novel pH sensitive porous membrane carrier for various biomedical applications based on pHEMA/chitosan: Preparation and its drug release characteristics(Wiley-V C H Verlag Gmbh, 2003) Bayramoğlu, G.; Arica, M.Y.The synthetic hydrogels based on pHEMA have been widely studied and used in biomedical fields. Numerous techniques exist for entrapment of drugs or proteins in the hydrogels. The suitable biomaterials for biomedical applications include poly(hydroxyethyl methacrylate), (pHEMA), and chitosan. In this work, a novel pH sensitive interpenetrating polymer networks (IPNs) were prepared in the membrane form by using 2-hydroxyethyl-methacrylate monomer (HEMA) and chitosan via UV initiated photo-polymerization in the presence of an initiator (i.e., alpha-alpha'-azo-isobutyronitrile; AIBN). UV-free-radical polymerization techniques are often used to synthesize hydrogels for controlled release applications. A series of HEMA and chitosan IPNs hydrogels were prepared and the equilibrium swelling studies were conducted to investigate swelling behaviors of the membrane according to the pH of the swelling medium. The swelling properties of the membrane were changed with the medium pH. The equilibrium water uptake is reached in about 60 min. The pHEMA/chitosan membrane thickness and density was measured to be 600 gm and 1.26 g cm(-3), respectively. Antibiotic release experiments were also performed with amoxicillin loaded pHEMA/chitosan membrane in physiological saline solution. The IPNs membrane loaded with 100mg antibiotic (i.e., amoxicillin) g hydrogel released around 80 % of the amoxicillin in 10 h at pH 7.4. The presented well-characterized novel pHEMA/chitosan membrane is a potential candidate for transdermal antibiotic carrier or a support in bioseparation.Öğe Preparation and characterisation of surfaces properties of poly(hydroxyethylmethacrylate-co-methacrylolyamido-histidine) membranes: application for purification of human immunoglobulin G(Elsevier, 2004) Arica, M.Y.; Yalcin, E.; Bayramoglu, G.In this study, an affinity membrane containing L-histidine as an amino acid ligand was used in separation and purification of human immunoglobulin G (HIgG) from solution and human serum. The polarities and the surface free energies of the affinity membranes were determined by contact angle measurements. HIgG adsorption and purification onto the affinity membranes from aqueous solution and human serum were investigated in a batch and a continuous system. Effect of different system parameters such as ligand density, adsorbent dosage, pH, temperature, ionic strength and HIgG initial concentration on HIgG adsorption were investigated. The maximum adsorption capacity of p(HEMA-MAAH-4) membranes for HIgG was 13.06 mg ml(-1). The reversible HIgG adsorption on the affinity membrane obeyed both the Langmuir and Freundlich isotherm models. The adsorption data was analysed using the first- and second-order kinetic model and the experimental data was well described by the first-order equations. In the continuous system, the purity of the eluted HIgG, as determined by HPLC, was 93% with recovery 58% for p(HEMA-MAAH-4) membrane. The affinity membranes are stable when subjected to sanitization with sodium hydroxide after repeated adsorption-elution cycles. (C) 2004 Elsevier B.V. All rights reserved.Öğe Procion Brown MX-5BR attached and Lewis metals ion-immobilized poly(hydroxyethyl methacrylate)/chitosan IPNs membranes: Their lysozyme adsorption equilibria and kinetics characterization(Pergamon-Elsevier Science Ltd, 2002) Bayramoğlu, G.; Kaya, B.; Arica, M.Y.Interpenetration networks (IPNs) in membrane form were synthesized from 2-hydroxyethyl methacrylate (HEMA) and chitosan (pHEMA/chitosan) via UV-initiated photo-polymerization in the presence of an initiator alpha, alpha'-azoisobutyronitrile. Procion Brown MX-5BR (PB MX-5BR) was covalently attached onto IPNs membrane as a metal chelating dye-ligand. Two different Lewis metal ions (Fe(III) or Cu(II)) were immobilized onto the dye-ligand for utilization in the immobilized metal affinity chromatography (IMAC). The binding characteristics of a model protein (lysozyme) to IMAC adsorbents and selectivity of immobilized metal ions (Fe(III) and Cu(II)) to the lysozyme have been investigated from aqueous solution using the dye-ligand-attached IPNs membrane as a control system. The experimental data was analysed using the two adsorption kinetic models the pseudo-first-order and pseudo-second order to determine the best-fit equation for the adsorption of lysozyme onto dye-ligand and IMAC adsorbents. The second-order equation for the adsorption of lysozyme on the dye-ligand, dye-ligand-Fe(III) and dye-ligand-Cu(II) membrane systems is the most appropriate equation to predict the adsorption capacity for all the tested adsorbents. The reversible lysozyme adsorption on the dye-ligand and IMAC adsorbents obeyed the Temkin isotherm. The lysozyme adsorption capacities of the dye-ligand, dye-ligand-Fe(III) and dye-ligand-Cu(II) immobilized IPNs membranes were 79.1, 147.4, and 128.2 mg ml(-1), respectively. The adsorption of the lysozyme on the pHEMA/chitosan membrane plain was about 8.3 mg ml(-1). (C) 2002 Elsevier Science Ltd. All rights reserved.Öğe Procion Green H-4G immobilized on a new IPN hydrogel membrane composed of poly(2-hydroxyethylmethacrylate)/chitosan: preparation and its application to the adsorption of lysozyme(Elsevier Science Bv, 2002) Bayramoğlu, G.; Arica, M.Y.The adsorption of lysozyme has been investigated on the Procion Green H-4G immobilized novel poly(2-hydroxyethyl methacrylate)/chitosan) (pHEMA/chitosan; IPN) porous hydrogel membrane. The IPN membranes were prepared by UV initiated photo-polymerization using 2-HEMA and chitosan. The IPN membrane reached an equilibrium swelling within about 60 min. The water content of the dye immobilized membrane was 50 +/- 2% and the amount of immobilized Procion Green H-4G on the membrane was 0.678 mumol ml(-1). The rates of adsorption of lysozyme on pHEMA/chitosan and pHEMA/chitosan-dye immobilized membranes were measured in a stirred cell, The adsorption capacities of these membranes were determined by changing pH and the concentration of lysozyme in the adsorption medium. The adsorption phenomena appeared to follow a typical Langmuir isotherm. Lysozyme adsorption capacity of the pHEMA/chitosan and pHEMA/chitosan-dye immobilized membranes were 0.18 and 14.06 mg ml(-1), respectively. The maximum lysozyme adsorption capacity (q(m)) of the pHEMA-chitosan-dye immobilized membranes was 20.28 mg ml(-1) and the dissociation constant (K-d) value was found to be 1.01 mg ml(-1) lysozyme. The experimental data were also analysed using first order Van't Hoff equation for lysozyme-adsorbent interactions, the change in entropy and Gibbs energy of binding were determined at different temperatures and the enthalpy of the system was calculated as 2.5 kcal mol(-1). All of the adsorbed lysozyme were desorbed in 60 min in the desorption medium containing 1.0 M KSNC at pH 8.0. (C) 2002 Elsevier Science B.V. All rights reserved.Öğe Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) composite membranes for heavy metal removal(Elsevier Science Bv, 2003) Genç, O.; Soysal, L.; Bayramoglu, G.; Arica, M.Y.; Bektas, S.The effective removal of toxic heavy metals from environmental samples still remains a major topic of present research. Metal-chelating membranes are very promising materials as adsorbents when compared with conventional beads because they are not compressible, and they eliminate internal diffusion limitations. The purpose of this study was to evaluate the performance of a novel adsorbent, Procion Green H-4G immobilized poly(hydroxyethylmethacrylate (HEMA)/chitosan) composite membranes, for the removal of three toxic heavy metal ions, namely, Cd(II), Pb(II) and Hg(II) from aquatic systems. The Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) composite membranes were characterized by elemental analysis, scanning electron microscopy and Fourier transform infrared (FTIR) spectroscopy. The immobilized amount of the Procion Green H-4G was calculated as 0.018 +/- 0.003 mumol/cm(2) from the nitrogen and sulphur stoichiometry. The adsorption capacity of Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) composite membranes for selected heavy metal ions from aqueous media containing different amounts of these ions (30-400 mg/l) and at different pH values (2.0-6.0) was investigated. The amount of Cd(II), Pb(II) and Hg(II) adsorbed onto the membranes measured at equilibrium, increased with time during the first 45 min and then remained unchanged toward the equilibrium adsorption. The maximum amounts of heavy metal ions adsorbed were 43.60 +/- 1.74, 68.81 +/- 2.75 and 48.22 +/- 1.92 mg/g for Cd(II), Pb(II) and Hg(II), respectively. The heavy metal ion adsorption on the pHEMA/chitosan membranes (carrying no dye) were relatively low, 6.31 +/- 0.13 mg/g for Cd(II), 18.73 +/- 0.37 mg/g for Pb(II) and 18.82 +/- 0.38 mg/g for Hg(II). Competitive adsorption of the metal ions was also studied. When the metal ions competed with each other, the adsorbed amounts were 12.74 +/- 0.38 mg Cd(II)/g, 28.80 +/- 0.86 mg Pb(II)/g and 18.41 +/- 0.54 mg Hg(II)/g. Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) membranes can be regenerated by washing with a solution of nitric acid (0.01 M). The percent desorption achieved was as high as 95%. These novel membranes are suitable for repeated use for more than five adsorption/desorption cycles without any considerable loss in adsorption capacity. Adsorption equilibria were well described by Langmuir equation. It can be concluded that Procion Green H-4G immobilized poly(hydroxyethylmethacrylate/chitosan) membranes may effectively be used for the removal of Cd(II), Pb(II) and Hg(II) ions from aqueous solutions. (C) 2002 Elsevier Science B.V. All rights reserved.
