The biosorption of chromium from an aqueous solution onto erythrina variegate orientalis leaf powder was investigated in batch operations studying the effects of agitation time biosorbent size and dosage, pH and temperature of the aqueous solution and initial concentration of chromium in aqueous solution. The extent of chromium biosorption was increased from 74.2% to 86.4% with decrease in biosorbent size from 150 to 45 µm for a dosage of 30g/L. The biosorption was decreased from 99.1(0.45
mg/g) to 45.5%(1.64 mg/g) with an increase in chromium initial concentration (Co ) from 22.5 to 180mg/L. The extent of biosorption was maximum at pH =3. The experimental data were well explained by Langmuir and Redlich- Peterson isotherm models. The biosorption data followed second order kinetics with a rate constant of 0.078g/mg-min for 50g/L of 45um size biosorbent. The biosorption was exothermic and feasible. The reversible biosorption was tending towards irreversibility.
Keywords : chromium, Biosorption, Erythrina, Thermodynamics
