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Öğe Catalase adsorption onto cibacron blue F3GA and Fe(III)derivatized poly(hydroxyethyl methacrylate) membranes and application to a continuous system(Elsevier Science Bv, 1997) Arica, MY; Denizli, A; Salih, B; Piskin, E; Hasirci, VPoly(2-hydroxyethyl methacrylate) (poly(HEMA)) membranes were prepared by W-initiated photopolymerization of HEMA in the presence of an initiator (a-a'-azobisisobutyronitrile, AIBN). An affinity dye, i.e. Cibacron Blue F3GA (CB) was incorporated covalently and then complexed with Fe(III) ions. The polyHEMA-CB and polyHEMA-CB-Fe(III) derivatized membranes were used in the adsorption of catalase (CAT). The enzyme-loading capability of the Fe(III)-containing membrane (23.6 mu g/cm(2)) was greater than that of the poly(HEMA)-CB derivatized membrane (17.1 mu g/cm(2)). The adsorption phenomena appeared to follow a typical Langmuir isotherm. The K-m values for both immobilized catalases (poly(HEMA)-CB-CAT (22.4 mM) and poly(HEMA)-CB-Fe(III)-CAT (19.3 mM)) were higher than that of free enzyme (16.5 mM). Optimum operational temperature was 5 degrees C higher than that of the free enzyme and was significantly broader. A similar observation was made for the optimum pH. Operational, thermal and storage stabilities were found to increase with immobilization, especially in the presence of Fe(III). It was observed that enzyme could be repeatedly adsorbed and desorbed without significant loss in adsorption capacity or enzyme activity.Öğe Cibacron Blue F3GA-incorporated macroporous poly(2-hydroxyethyl methacrylate) affinity membranes for heavy metal removal(Elsevier Science Bv, 1997) Denizli, A; Salih, B; Arica, MY; Kesenci, K; Hasirci, V; Piskin, EMacroporous poly(2-hydroxyethyl methacrylate), poly(HEMA), membranes were prepared by UV-initiated photo-polymerization of HEMA in the presence of an initiator (azobisisobutyronitrile, AIBN). An affinity dye, i.e., Cibacron Blue F3GA was then incorporated covalently. These affinity membranes with a swelling ratio of 58%, and carrying 10.67 mmol Cibacron Blue F3GA/m(2) membrane were used in the adsorption/desorption of some selected heavy metal ions [i.e., As(III), Cd(II) and Pb(II)] from aqueous media. Very high adsorption rates were observed and adsorption equilibria were reached in about 30 min. The maximum adsorptions of heavy metal ions onto the dye-incorporated affinity membranes from their single solutions were 12.6 mmol/m(2) for As(III), 61.0 mol/m(2) for Cd(II) and 79.0 mol/m(2) for Pb(II), However, when the heavy metal ions competed (in the case of the adsorption from their mixture) the amounts of adsorption for As(III), Cd(II) and Pb(II) were quite close. Desorption of heavy metal ions was carried out by using 0.1 M HNO3 (pH 1.0). Up to 95% of the adsorbed heavy metal ions were desorbed in 60 min. Repeated adsorption/desorption cycles showed the feasibility of this novel affinity membrane for heavy metal removal.Öğe New metal chelate sorbent for albumin adsorption: Cibacron blue F3GA-Zn(II) attached microporous poly(HEMA) membranes(John Wiley & Sons Inc, 1998) Denizli, A; Salih, B; Senel, S; Arica, MYPoly(2-hydroxyethyl methacrylate) [poly(HEMA)] membranes were prepared by UV-initiated photopolymerization of HEMA in the presence of an initiator (alpha-alpha'-azobis-isobutyronitrile, AIBN). The triazine dye Cibacron Blue F3GA was attached as an affinity ligand to poly(HEMA) membranes, covalently. These affinity membranes with a swelling ratio of 58% and containing 10.7 mmol Cibacron Blue F3GA/m(2) were used in the albumin adsorption studies. After dye-attachment, Zn(TI) ions were chelated within the membranes via attached-dye molecules. Different amounts of Zn(II) ions [650-1440 mg Zn(II)/m(2)] were loaded on the membranes by changing the initial concentration of Zn(II) ions and pH. Bovine serum albumin (BSA) adsorption on these membranes from aqueous solutions containing different amounts of BSA at different pH was investigated in batch reactors. The nonspecific adsorption of BSA on the poly(HEMA) membranes was negligible. Cibacron Blue F3GA attachment significantly increased the BSA adsorption up to 92.1 mg BSA/m(2). Adsorption capacity was further increased when Zn(II) ions were attached (up to 114.8 mg BSA m(2)). More than 90% of the adsorbed BSA was desorbed in 1 h in the desorption medium containing 0.5M NaSCN at pH 8.0 and 0.025M EDTA at pH 4.9. (C) 1998 John Wiley & Sons, Inc.Öğe Novel dye-attached macroporous films for cadmium, zinc and lead sorption: Alkali Blue 6B-attached macroporous poly(2-hydroxyethyl methacrylate)(Elsevier Science Bv, 1998) Denizli, A; Kesenci, K; Arica, MY; Salih, B; Hasirci, V; Piskin, EAlkali Blue GB-attached poly(2-hydroxyethyl methacrylate) (poly(HEMA)) microporous films were investigated as chelate forming sorbents for heavy metal removal. Poly(HEMA) microporous films were prepared by UV-initiated photo-polymerization of HEMA in the presence of an initiator (azobisisobutyronitrile (AIBN)). Alkali Blue 6E was attached covalently. These films with a swelling ratio of 58%, and carrying 14.8 mmol Alkali Blue 6E m(-2) which were then used in the removal of Cd(II), Zn(II) and Pb(II) from aqueous media. Adsorption rates were very high, equilibrium was achieved in about 30 min. The maximum adsorption of heavy metal ions onto the Alkali Blue BE-attached films were 41.4 mmol m(-2) for Cd(II), 52.4 mmol m(-2) for Zn(II), and 64.5 mmol m(-2) for Pb(II). When the heavy metal ions competed during the adsorption from a mixture the adsorption values for Cd(II), Zn(II) and Pb(II) were quite close. Heavy metal ions were desorbed by using 0.1 M HNO3. A significant amount of the adsorbed heavy metal ions (up to 95%) could be desorbed in 30 min. Repeated adsorption/desorption cycles showed the feasibility of these novel dye-attached microporous films for heavy metal removal. (C) 1998 Elsevier Science B.V. All rights reserved.
