Browsing by Subject "nanobead"
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Item Immobilization of catalase on chitosan and amino acid-modified chitosan beads(2013) Başak E.; Aydemir T.Bovine liver catalase was covalently immobilized onto amino acid-modified chitosan beads. The beads were characterized with SEM, FTIR, TGA and the effects of immobilization on optimum pH and temperature, thermostability, reusability were evaluated. Immobilized catalase showed the maximal enzyme activity at pH 7.0 at 30°C. The kinetic parameters, Km and Vmax, for immobilized catalase on alanine-chitosan beads and lysine-chitosan beads were estimated to be 25.67 mM, 27 mM and 201.39 μmol H2O 2/min, 197.50 μmol H2O2/min, respectively. The activity of the immobilized catalase on Ala-CB and Lys-CB retained 40% of its high initial activity after 100 times of reuse. © 2013 Informa Healthcare USA, Inc.Item An efficient removal of RB5 from aqueous solution by adsorption onto nano-ZnO/Chitosan composite beads(Elsevier B.V., 2017) Çınar S.; Kaynar Ü.H.; Aydemir T.; Çam Kaynar S.; Ayvacıklı M.In this study, the removal of Reactive Black 5 (RB-5) by nano-ZnO/Chitosan composite beads (nano-ZnO/CT-CB) from aqueous solution was investigated. ZnO nanoparticles were prepared by the via the microwave-assisted combustion technique. And then nano-ZnO/Chitosan composite beads were prepared by polymerization in the presence of nano-ZnO and chitosan. Characterization of composite beads were conducted using SEM, TEM, FTIR, TGA and XRD. Several important parameters influencing the removal of RB 5 such as contact time, pH and temperature were investigated systematically by batch experiments. At optimum conditions of pH 4 and adsorbent concentration of 0.2 g, dye removal efficiency was found 76%. Langmuir, Freundlich and Temkin adsorption models were used to describe adsorption isotherms and constants. The maximum adsorption capacity (qm) by Langmuir isotherm has been found to be 189.44 mg/g. Isotherms have also been used to obtain the thermodynamic parameters such as free energy, enthalpy and entropy of adsorption. The positive value of the enthalpy change (32.7 kJ/mol) indicated that the adsorption is an endothermic process. The obtained results showed that the tested adsorbents are efficient and alternate low-cost adsorbent for removal of dyes from aqueous media. © 2016 Elsevier B.V.Item Modification of chitosan-bead support materials with l-lysine and l-asparagine for Α-amylase immobilization(Springer Verlag, 2018) Yazgan I.; Turner E.G.; Cronmiller L.E.; Tepe M.; Ozturk T.K.; Elibol M.Maltose syrups have got wide-range utilizations in a variety of applications from bakery to drug-development. α-Amylases are among the most widely utilized industrial enzymes due to their high specificity in production of maltose syrup from starch. However, enzymes are not stable in ex vivo conditions towards alteration in pH, temperature, and such other parameters as high salt concentrations and impurities, where immobilization is required to advance the stability of the enzyme with which approach the requirement of isolation of the enzyme from media is eliminated as well. In this study, Termamyl® α-amylase was immobilized on the none-modified chitosan beads (NMCB), l-lysine-modified chitosan beads (LMCB), and l-asparagine-modified chitosan beads (AMCB) to assess effects of the support material on optimum conditions and kinetic parameters of the α-amylase activity in production of maltose from starch. Immobilization on NMCB, LMCB, and AMCB puts a strong influence on optimum pH, optimum temperature, stability, and kinetic parameters of α-amylase. Modification of chitosan beads with l-lysine and l-asparagine dramatically altered the overall immobilization yield, and enzyme’s response to pH and temperature variations and the kinetic parameters. AMCB provided the best immobilization yield (49%), while LMCB only improved the yield by 2% from 22 to 24%. © 2017, Springer-Verlag GmbH Germany, part of Springer Nature.