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    Removal of As(V), Cr(III) and Cr(VI) from aqueous environments by poly(acrylonitril-co-acrylamidopropyl-trimethyl ammonium chloride)-based hydrogels
    (Academic Press Ltd- Elsevier Science Ltd, 2015) Dudu, Tuba Ersen; Şahiner, Mehtap; Alpaslan, Duygu; Demirci, Şahin; Aktas, Nahit
    Cationic poly(Acrylonitril-co-Acrylamidopropyl-trimethyl Ammonium Chloride) (p(AN-co-APTMACl)) hydrogels in bulk were synthesized by using acrylonitrile (AN) and 3-acrylamidopropyl-trimethyl ammonium chloride (APTMACl) as monomers. The prepared hydrogels were exposed to amidoximation reaction to replace hydrophobic nitrile groups with hydrophilic amidoxime groups that have metal ion binding ability. Those replacements were increased the hydrogels absorption capacity for As(V) and Cr(VI). Langmuir and Freundlich isotherms equations were utilized to obtain the best-fitted isotherm model for the absorption of the ions at different metal ion concentrations. The absorption data of As(V) ion were fitted well to Freundlich isotherm while those of Cr(VI) and Cr(III) ions were fitted well to Langmuir isotherm. The maximum absorption of poly(3-acrylamidopropyl-trimethyl ammonium chloride (p(APTMACl)) and amid-p(AN-co-APTMACl) macro gels were 22.39 mg and 21.83 mg for As(V), and 30.65 mg and 18.16 mg for Cr(VI) ion per unit gram dried gel, respectively. Kinetically, the absorption behaviors of Cr(III) and Cr(VI) ions were fitted well to a pseudo 2nd-order kinetic model and those of As(V) ions were fitted well to a pseudo 1st order kinetic model. (C) 2015 Published by Elsevier Ltd.
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    Öğe
    Synthesis and preparation of responsive poly(Dimethyl acrylamide/gelatin and pomegranate extract) as a novel food packaging material
    (Elsevier, 2020) Alpaslan, Duygu; Dudu, Tuba Ersen; Şahiner, Nurettin; Aktasa, Nahit
    In this study a novel and smart multi-functional hydrogel (MFH) was synthesized from N, N dimethyl acrylamide (DMAAm), gelatin, citric acid (CA) and pomegranate extract (PE) for instant and easy monitoring of the color change in MFH due to changes in medium conditions such as pH and temperature. MFH was utilized as food packaging material, equipped with the developed properties. MFH was synthesized with a redox polymerization technique in film form on petri dishes. Mechanical and water resistance properties of MFH were improved by CA and N, N, methylenebisacrylamide, while PE was used to gain antimicrobial, antioxidant and anthocyanin properties. Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric Analyzer (TGA), Liquid Chromatography-Mass Spectroscopy (LC-MS/MS) and Scanning Electron Microscopy (SEM) instruments were utilized for characterization of MPH. FTIR revealed the existence of bonding interactions between the functional group of PE and gelatin, carbonyl groups of DMAAm and carboxylic acid groups of CA. TGA results indicate that MFH was stable up to 400 degrees C. Then the response of total antioxidant and anthocyanin activities leading to the color change in MFH were studied at different pH values. The color change in MFH was monitored even at very small pH changes in the medium. Moreover, antimicrobial activity and stability of MFH were investigated when it was tested in harsh environments and against Escherichia colt, Bacillus subtilis and Staphylococcus aureus on real samples of whole pasteurized milk and cheese for a 7-day period. It exhibited remarkable antimicrobial activity with pasteurized whole milk and cheese. It was concluded that MFH is a very good candidate to be used as biodegradable food packaging material.