Sorption of Cr(VI) by MgAl-NO3 hydrotalcite in fixed-bed column: Experiments and prediction of breakthrough curves

Abstract

This study describes the sorption of Cr(VI) by MgAl-NO3 hydrotalcite in a fixed-bed column. The sorbent was prepared via coprecipitation method and characterized by XRD, FTIR, BET surface area and pHzpc. The effects of operating parameters such as bed height, flow rate and inlet concentration were investigated in continuous mode. As a result, the exhaustion time increased with the increase of bed height, decrease of flow rate and inlet concentration. A mathematical model based on the constant pattern theory and the Freundlich isotherm was applied to predict the experimental data, and to evaluate the model parameters of the fixed-bed column. The developed model describes well the breakthrough curves at various operating conditions. The calculated volumetric mass transfer coefficient KLa depends directly on these conditions. KLa increased with increasing flow rate and inlet concentration, while remained almost constant with varying bed height.