Modified poly(4-vinylpyridine) coated silica gel. Fast kinetics of diffusion-controlled sorption of Chromium(VI)

A new sorbent has been prepared by coating alkyl quaternized poly(4-vinylpyridine) (PVP) on the high surface area of silica gel. The resulting granular sorbent was used to remove Cr(VI) from water. Batch experiments mere conducted to determine the kinetics and sorption rate. The research demonstrated that the modified PVP coated silica gel (referred to as coated gel) could successfully remove chromium(VI) from solution and that the sorbent provided fast kinetics. A finite-bath diffusion-control model with changing bulk concentration was derived analytically for application to the coated gel sorption of Cr(VI). This model fitted the experimental data well. The sorption kinetics on modified PVP coated gel was found to be diffusion-controlled with a value of 5.8 x 10(-7) cm(2)/s for the product of the distribution coefficient and the effective diffusivity in the sorption of Cr(VI) on the coated silica gel.