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Adsorption of Cd 2+ and Zn 2+ on Carboxylated Polyvinyl Alcohol
Author(s) -
Lu Mang
Publication year - 2020
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.202001569
Subject(s) - adsorption , polyvinyl alcohol , chemistry , nuclear chemistry , methanol , langmuir adsorption model , acrylic acid , vinyl alcohol , enthalpy , fourier transform infrared spectroscopy , inorganic chemistry , metal ions in aqueous solution , metal , polymer chemistry , copolymer , organic chemistry , chemical engineering , physics , quantum mechanics , engineering , polymer
In this study, vinyl acetate (VAc) and acrylic acid (AA) was first copolymerized in methanol to prepare the copolymer of poly(VAc‐co‐AA). Then poly(VAc‐co‐AA) was modified through alcoholysis reaction to obtain a carboxyl modified polyvinyl alcohol (carboxyl modified PVA). The carboxyl modified polyvinyl alcohol was first used for the adsorption of heavy metal ions. The structure of the carboxyl modified polyvinyl alcohol was characterized by Fourier transform infrared spectroscopy (FT‐IR), X‐ray Diffraction (XRD). The effect of pH, contact time and metal ion concentration on the adsorption were investigated. The optimum pH value was found out to be 6 for Zn 2+ and 7 for Cd 2+ , respectively. The adsorption capacity of Cd 2+ and Zn 2+ increased rapidly in the first 36 h contact time and then leveled off. The adsorption capacity of Cd 2+ and Zn 2+ increased gradually with equilibrium concentration C e up to 150 mg/L in the solution. The adsorption process obeyed the pseudo second‐order kinetics and Langmuir adsorption model. The highest metal uptake for Cd 2+ and Zn 2+ were 52.41 and 49.98 mg/g, respectively. In all adsorption processes, the enthalpy change (ΔH) and free energy change (ΔG) were negative, implying that the adsorption process was exothermic and spontaneous.