Fixed bed column adsorption of Cu (II) onto maize tassel-PVA beads

Abstract

The intention of this study was to explore the efficacy and feasibility for Cu (II) adsorption onto fixed bed column of maize tassel-PVA beads. The effects of flow rate and bed height were explored. The Thomas, Adams and Bohart and Yoon-Nelson models were analysed to evaluate the column adsorption performance. The adsorption rate constant and correlation coefficient associated to each model for column adsorption was calculated. Thomas model indicated that increase in column height and flow rate increased the values of kTh and qo. Thereafter, the value of qo decreased with decreasing bed height. With Adam-Bohart model, the values of kAB increased as the flow rate and the bed height increased and continued to increase with decrease in bed height. However, the value of No first increased with increase in flow rate and bed height, but later decreased with decrease in bed height. This suggests that the overall system kinetics may have been influenced by external mass transfer, particularly in the initial part of adsorption in the column. In the case of Yoon-Nelson model, the rate constant kYN and τ increased with increase in bed height and flow rate. However, decrease in bed height at a flow rate of 2.33 × 10-3 L min-1 resulted in an increase in τ while the values of kYN decreased. The three models gave high values of R2 (0.9694-0.98920), although the Adam-Bohart model values were, on average, the least. Therefore, it can be said that both the Thomas and Yoon-Nelson models describe the behavior of the adsorption of Cu (II) in a fixed-bed column better than Adam-Bohart.