Effects of solution pH on adsorption of chlorophenols by cross‐linked polyvinyl pyrrolidone (PVP XL) polymers

Abstract

AbstractWidely used as insecticides, fungicides, and disinfectants and regarded as having relatively high toxicities, chlorophenols are a group of organic contaminants whose solubility and sorptive properties on different substrates vary greatly with solution pH. In this study, the feasibility and applicability of using cross‐linked polyvinyl pyrrolidone (PVP XL) polymers to adsorb and remove chlorophenols from water under different pH conditions were investigated. The adsorption of chlorophenols on PVP XL was instantaneous and followed a linear sorption isotherm under the tested concentrations from 0.05 to 10 mg L–1, suggesting a partitioning mechanism. The chlorophenol adsorption increased as the degree of chlorination, thus the octanol–water partitioning coefficient, increased. A decrease in contaminant distribution coefficients with an increase in solution pH suggested that the deprotonated species had a weaker affinity for PVP XL surfaces than their protonated counterparts. The free energy of adsorption of 2,3,4,6‐tetrachlorophenol (TeCP) on PVP XL was negative, suggesting a spontaneous adsorption. The negative enthalpy values of TeCP adsorption on PVP XL indicated an exothermic process. The results from this study show that PVP XL could be a viable alternative for the adsorption of chlorinated phenols in aqueous media as a remediation tool. The instantaneous adsorption will make PVP XL a possible choice for ultra filtration to remove chlorophenols from water. © 2010 American Institute of Chemical Engineers Environ Prog, 2011