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

摘要

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 pH (zpc) . 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 K (L) a depends directly on these conditions. K (L) a increased with increasing flow rate and inlet concentration, while remained almost constant with varying bed height.