Graft Copolymerization of Crosslinked Polyvinyl Alcohol with Acrylonitrile and Its Amidoxime Modification as a Heavy Metal Ion Adsorbent
Polyvinyl alcohol (PVA) hydrogel was crosslinked with glutaraldehyde. The crosslinked polyvinyl alcohol (CPVA) was grafted with acrylonitrile using cericammonium nitrate as an initiator (CPVA-PAN), and then modified by hydroxylamine hydrochloride (CPVA-AO-PAN). CPVA, CPVA-PAN, and CPVA-AO-PAN were characterized by Fourier Transform Infrared spectroscopy. Cu2+ adsorption by CPVA-AO-PAN reached the equilibrium at contact time of 40 h with a adsorption capacity of 40.7 mg g−1. The effects of initial metal concentration, adsorption time, and pH on adsorption capacity were investigated, respectively. Pseudo-first-order and pseudo-second-order models were employed to evaluate the adsorption kinetics, with the R2 values of 0.9524 and 0.9972, respectively. Langmuir and Freundlich isotherm models were compared, and the Langmuir model shows high goodness-of-fit. The adsorption process was endothermic and spontaneous, as evidenced by the positive ∆H and the negative ∆G.
KeywordsAdsorbent Graft copolymerization Cu2+ removal Polyvinyl alcohol modification
We thank the National Natural Science Foundation of China (51674117, 21706059), the Scientific Research Foundation of Hunan Provincial Education Department (18B354, 16K036,15B101), and the Natural Science Foundation of Hunan Province (2018JJ3211, 2018JJ3206).
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