Removal of Cr(VI) from aqueous solution using Nirmali seed as biosorbent

Abstract

The removal of Cr(VI) from aqueous solutions was studied using the seeds of the plant species Strychnos potatorum L. The plant is grown in India and is called as Nirmali tree or clearing nut tree. The dried Nirmali seeds were powdered and used as adsorbent for the removal of Cr(VI) from aqueous solution. The zeta potential measurements have indicated negative surface charge similar to that of natural anionic polyelectrolyte. Batch experiments were conducted to study the adsorption of Cr(VI) onto Niramli seed powder. The influence of pH, initial Cr(VI) concentration and the effect of anions on the removal of Cr(VI) was investigated. The removal of Cr(VI) was better in the acidic medium. The influence of anions such as Cl-, NO3and SO4 on Cr(VI) removal was investigated and found that the removal was adversely affected in the presence of NO3and SO4. The results obtained from equilibrium adsorption studies were found to fit in to Langmuir adsorption isotherm and the maximum uptake of Cr(VI) was found to be 59 mg g-1. The rate of removal of Cr(VI) was found to follow the pseudo second order rate equation.