Efficacy of Daucus carota L. waste biomass for the removal of chromium from aqueous solutions

In the present study the removal of Cr(III) and Cr(VI) using Daucus carota L. (carrot) waste biomass was investigated from aqueous solutions. Biosorption studies were determined as a function of contact time, pH, initial metal ion concentration, biosorbent size and biosorbent dose. Maximum uptake capacity of D.carota L. waste biomass for Cr(III) (86.65 mg/g) and Cr(VI) (88.27 mg/g) was observed at pH 1 and 5 respectively. Optimum biosorbent dose (0.1 g), biosorbent size (0.250 mm), initial concentration (100 mg/L), temperature (30 °C) and contact time (240 min) gave maximum biosorption. The sorption isotherms followed the Langmuir type suggesting monolayer sorption character. A high degree of correlation coefficient was obtained for the second-order kinetic model. To evaluate the effect of pretreatment on Cr(III) and Cr(VI) uptake by D.carota L., the waste biomass was physically as well as chemically pretreated. Maximum Cr(III) and Cr(VI) uptake was observed with acetone and Moringa oleifera extract pretreated D.carota L. waste biomass. The results also demonstrate that chromium uptake capacity of D.carota L. waste biomass was comparatively higher than most of early reported work.