Sorption kinetics of arsenic on laterite soil in aqueous medium

Abstract

The efficiency of a locally available laterite soil in removing both arsenite and arsenate from aqueous medium by adsorption was evaluated. It was observed that in batch experiment conducted at 0.5 mg/L initial concentration of arsenic, laterite soil could remove up to 98% of arsenite and 95% of arsenate under optimized conditions. The kinetic profiles under various conditions were developed. Both arsenite and arsenate removal followed pseudo—second order reaction kinetic model. Pore and film diffusion coefficients were determined from the half-time equation and film diffusion appeared to be the rate-limiting. This was further supported by multiple interruption tests.

Keywords:

• Arsenic adsorption
• laterite soil
• kinetic model
• diffusion coefficient
• rate-limiting process

Acknowledgments

We are thankful to Prof. B. Biswanathan, IIT, Madras, India, for his kind help in BET analysis and for helpful discussions. This work was supported by the Department of Science and Technology, New Delhi, India.