Yazar "Cavus, Aynur" seçeneğine göre listele

Listeleniyor 1 - 2 / 2
  • [ X ]
    Öğe
    Preparation of poly(hydroxyethyl methacrylate) cryogels containing L-histidine for insulin recognition
    (Elsevier, 2013) Cavus, Aynur; Baysal, Zubeyde; Alkan, Huseyin
    In the present study, affinity adsorption technique was studied for insulin adsorption. Firstly, insulin-imprinted supermacroporous cryogel was prepared for the insulin adsorption. N-methacryloyl-(L)-histidine methyl ester (MAH) was chosen as the monomer. Insulin was complexed with MAH, and insulin-imprinted p(HEMA MAH) [insulin-(MIP)] cryogel was prepared by free radical polymerization with 2-hydroxyethyl methacrylate (HEMA), N,N,N',N'-tetramethylethylenediamine (TEMED) and ammonium persulfate (APS) in an ice bath. Then, insulin was removed from the cryogel by using 0.1 M glycine-HCl buffer (pH: 3.5). The characterization of the cryogel was carried out by using scanning electron microscopy (SEM) and swelling test. The equilibrium swelling ratios of the cryogels were found to be 8.56 +/- 0.42 g H2O/g polymer for p(HEMA) and 7.20 +/- 0.36 g H2O/g polymer for insulin-p(HEMA MAH). Insulin adsorption experiments were performed under different conditions, such as flow rate, medium pH, initial insulin concentration and ionic strength. It was observed that insulin could be repeatedly adsorbed and desorbed with MIP cryogel without any significant decrease in the adsorption capacity. (C) 2013 Elsevier B.V. All rights reserved.
  • [ X ]
    Öğe
    Removal of methylene blue from aqueous solutions onto Bacillus subtilis: determination of kinetic and equilibrium parameters
    (Desalination Publ, 2013) Ayla, Ayseguel; Cavus, Aynur; Bulut, Yasemin; Baysal, Zubeyde; Aytekin, Cetin
    In the present study, Bacillus subtilis, a Gram-positive bacteria, was used in dried biomass form as biosorbent for removal of methylene blue (MB) from aqueous solutions. Batch adsorption tests were performed at different contact times, temperatures, pH, adsorbent doses, and initial dye concentration. The adsorption isotherms are described by means of the Langmuir and Freundlich isotherms. It was found that the Langmuir equation fit better than the Freundlich equation. Maximum biosorption capacity was found to be 169.49, 178.57, and 181.82mgg(-1) at 298, 308, and 318K, respectively. The adsorption kinetics of MB could be described by the pseudo-second-order reaction model. The activation energy of the biosorption (E-a) was determined as 11.30kJmol(-1) at initial concentration of 50mgL(-1). Free energy of adsorption (G degrees), enthalpy (H degrees), and entropy (S degrees) changes were calculated to predict the nature of adsorption. The estimated values for G degrees were -21.22, -22.02, and -23.01kJmol(-1) at 298, 308, and 318K, respectively. The enthalpy changes and entropy of adsorption were 5.47kJmol(-1) and 89.43Jmol(-1), respectively. The experimental data obtained in the present study indicate that B. subtilis is a suitable and inexpensive adsorbent which can be used for dye removal in wastewater treatment processes.