Factors Affecting Chromium(VI) Removal by Modified Poly(4-Vinylpyridine) Coated Silica Gel

A reactive polymer, alkyl quaternized poly(4-vinylpyridine) (PVP) was synthesized and coated on the surface of silica gel to test its ability to remove Cr(VI) from water. Batch experiments were conducted with the coated gel to determine the effect of the Cr(VI) concentrations on the rate of sorption and the influence of other anions on the Cr(VI) adsorption. The concentrations of Cr(VI) had a pronounced effect on the rate of sorption. The adsorption of Cr(VI) was influenced to some extent by other anions. The relative effect in decreasing order for SO2-4, Cl−, and CH3COO− ions on the adsorption of Cr(VI) was SO2-4 > Cl− > CH3COO−. Chromium adsorbed on the coated gel was easily recovered under certain conditions. NaOH was a good desorption reagent for Cr(VI) with a desorption efficiency of up to 90%. The desorption rate was very fast. After desorption, the coated silica gel could be reused.