Yazar "Kivanc, Mehmet Riza" seçeneğine göre listele

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    Adsorption of Malachite Green from Aqueous Solution Using Hydroxyethyl Starch Hydrogel Improved by Graphene Oxide
    (Springer, 2022) Onder, Alper; Kivanc, Mehmet Riza; Durmus, Secil; Ilgin, Pinar; Ozay, Hava; Özay, Özgür
    This study is the first report of the preparation of hydroxyethyl starch (HES) hydrogels rapidly crosslinked with divinyl sulfone in a single step and single pot. To develop the physical and chemical features of hydrogels, Graphene oxide (GO) nanoparticles were combined with the crosslinked HES. In addition to swelling studies, structural characterization of the samples was conducted with a scanning electron microscope (SEM) and transmission electron microscope (TEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometry (XRD), Brunauer-Emmett-Teller (BET) analysis and thermogravimetric analysis (TGA). For the removal of malachite green model dye by GO-HES, the effects of GO content, solution concentration, temperature, contact duration, dosage and pH on varying adsorption features were researched. Additionally, adsorption isotherms, kinetic and thermodynamic systematics were analyzed. The maximum adsorption capacity of GO-HES composite hydrogel was found to be 89.3 mg/g for Langmuir isotherm. The possible adsorption mechanism of the composite hydrogels for malachite green dye involved electrostatic, hydrogen bonding, and pi-pi interactions. In addition to reasonable cost and simple synthesis method, the prepared composite materials have potential use in wastewater treatment as adsorbents for the removal of dye from aqueous solutions due to efficient adsorption capacity.
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    Öğe
    Removal of anionic dyes from aqueous media by using a novel high positively charged hydrogel with high capacity
    (Taylor & Francis Inc, 2022) Kivanc, Mehmet Riza; Özay, Özgür; Ozay, Hava; Ilgin, Pinar
    Poly((methacryloylamino)propyl trimethylammonium chloride-co-vinylimidazole) (p(MAPTAC-co-VI)) hydrogels were synthesized through free radical polymerization of 3-(methacryloylamino)propyl trimethylammonium chloride (MAPTAC) and 1-vinylimidazole (VI) in aqueous solutions with ammonium persulfate (APS) used as initiator and N,N '-methylenebis(acrylamide) (MBA) as the crosslinking agent. By modifying with HCl, the positive charge density on the hydrogel network structure was increased and quaternized hydrogels (p(MAPTAC-co-VI)-q) were obtained. Traditional swelling and spectrophotometric characterization techniques were used to gain a better understanding of the performance of cationic hydrogels for the removal of anionic dyes. FTIR, SEM, and EDX confirmed the structure of the hydrogel before and after the adsorption process. Later, dye adsorption performance of these p(MAPTAC-co-VI)-q hydrogels was investigated under different adsorption conditions, including initial concentration, temperature, pH values of dye solutions, and adsorption contact time, adsorbent dosage and in real water samples. Various isotherm and kinetic models of dye adsorption by the hydrogel were also studied and the experimental adsorption followed a pseudo-second order model and fitted the Langmuir isotherm well. Thanks to the effective use of existing adsorption sites, high adsorption capacity was achieved for eriochrome black T (EBT) and methyl orange (MO) dyes. The values of q(max) are as follows: 1818.2 mg/g and 1449.3 mg/g, respectively. Thermodynamic parameters indicate that the process was spontaneous and endothermic. P(MAPTAC-co-VI)-q hydrogels can be used as a potential adsorbent for removal of anionic dye molecules, one of the industrial pollutants, from wastewater.
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    Öğe
    The preparation of various shapes and porosities of hydroxyethyl starch/p(HEMA-co-NVP) IPN hydrogels as programmable carrier for drug delivery
    (Taylor & Francis Inc, 2020) Özay, Özgür; Ilgin, Pinar; Ozay, Hava; Gungor, Zeynep; Yilmaz, Betul; Kivanc, Mehmet Riza
    This study used biocompatible and biodegradable hydroxyethyl starch (HES), 2-hydroxyethyl methacrylate (HEMA) and N-vinyle-2-pyrrolidone (NVP) monomers for hydrogel synthesis with the aim of use as a drug carrier system. As a result of the synthesis reactions using the redox polymerization technique, hydrogels were produced in both film and cylindrical form. The morphological characterization and structural characterization of hydrogels were performed using scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR), respectively. In addition, swelling characterizations of hydrogels to be used for drug release in various media were examined. The release properties of sodium diclofenac (NaDc) and trimethoprim (TMP) loaded into hydrogels produced in order to use as drug carrier material for controlled drug release were examined in media with pH = 1.2 and 7. It was determined that the hydrogels performed controlled release according to the type of drug and the pH values of the medium. Drug release mechanisms deviated from Fickian mode according to determined drug release rate constants, diffusion exponent (n) and regression values at different pH values. In addition, antibacterial properties of drug-loaded hydrogels against B. subtilus, S. aureus and E. coli were investigated.