Effect of temperature on sorption of metals by silica-supported 2-(aminomethyl)pyridine. Part II: Sorption dynamics

Abstract

The effect of temperature has been studied on metal-binding rates and dynamic column separation behavior of an adsorbent containing 2-(aminomethyl)pyridine groups supported on silica–polyamine composite. Binding kinetics of H 2SO 4 as well as copper and nickel sulfates has been measured by batch experiments at temperatures between 25 and 90 °C using synthetic sulfate solutions. The data were correlated with the non-ideal adsorption (NICA) model and a diffusion model of porous particles. The estimated model parameters were utilized in a dynamic column model to calculate the break-through curves obtained with the synthetic metal sulfate solutions and a concentrated ZnSO 4 process solution. The adsorption rate of sulfuric acid and metal sulfates is controlled by pore diffusion and increasing temperature markedly increases the sorption rate. The experimental batch uptake curves can be well correlated with the proposed diffusion model and with constant diffusion coefficients. The estimated activation energies of pore diffusion are about 9 and 20 kJ/mol for the acid and the metals, respectively. In column separation, increasing temperature substantially improves copper removal from the ZnSO 4 process solution. The improvement is predominantly due to enhanced intra-particle mass transport. The effect is further amplified by marked decrease in viscosity of the feed solution.