Impact of modified chitosan on pore water bioavailability of zinc in contaminated soils

Abstract

The present work examines the utilisation potential of the bio-waste, chitosan for the remediation of soils contaminated with zinc (Zn). The mechanism involved was elucidated via a study of Zn sorption kinetics on pure and modified chitosan beads, the latter containing molybdate and phosphate compounds. The effect of equilibration time on adsorption was explained with reference to chemical sorption and intra-particle diffusion mechanisms. The findings showed that chitosan acts upon freely dissolved zinc in soil pore water. The use of modified chitosan beads resulted in a significant decrease in Zn bioavailability, which may be attributed to a combination of Zn complexation, the sorbent's high surface area and cation exchange capacity (CEC). This study provides an insight into issues associated with zinc contaminated soils and the amelioration of nutrient-deficient soil through modified chitosan amendments. Capsule abstract Modified chitosan has potential to remediate Zn-contaminated soil. The bioavailability of zinc in the pore water of contaminated soils decreased upon the application of chitosan beads.