A fixed bed column study of natural and chemically modified Lagerstroemia speciosa bark for removal of synthetic Cr(VI) ions from aqueous solution

Abstract

The present study evaluates the feasibility of using natural Lagerstroemia speciosa bark (NLSB) and chemically modified Lagerstroemia speciosa bark (CLSB) in removing Cr(VI) from aqueous solution in fixed bed column process. The effect of influent flow rate, bed depth and inlet Cr(VI) ion concentration on the Cr(VI) removal capacity of NLSB and CLSB was investigated. The column exhaustion time increased with increase in bed depth and reverse trend was obtained with increase in flow rate and influent Cr(VI) ion concentration. The Bohart–Adams, Thomas and Yoon–Nelson dynamic models were applied at various studied experimental conditions to predict the breakthrough curve behavior and to determine the characteristics fixed bed column parameters that are very crucial in scale up of the column process for its industrial scale application. Both Thomas and Yoon–Nelson models showed very good agreement with the column data and explained the mechanism of Cr(VI) adsorption by NLSB and CLSB in column process. The high Cr(VI) adsorption capacity and regeneration efficiency of NLSB and CLSB in column suggest its applicability in removal of Cr(VI) present in industrial effluents.

Keywords:

• Adsorption of chromium (VI)
• breakthrough curve
• fixed bed column
• regeneration efficiency

Acknowledgements

The authors are thankful to Department of Botany, Center of Advanced Study, Botany, Institute of Science, Banaras Hindu University and Department of Chemical Engineering, Indian Institute of Technology (Banaras Hindu University), India for providing all the necessary facilities to undertake the present work. Authors are also thankful to UGC for financial support.