Assessment of hexavalent chromium biosorption using biodiesel extracted seeds of Jatropha sp., Ricinus sp. and Pongamia sp.

Abstract

Biosorbents from the biomass of Jatropha sp. (JES), Ricinus sp. (RES) and Pongamia sp. (PES) biodiesel extracted seeds were used in natural form for the elimination of hexavalent chromium. The study performed by varying the parameters of biosorbents size, solution pH, biosorbents dosage, metal concentration, contact time and temperature. The equilibrium data were correlated with two parameter isotherm models. Biosorption isotherm modeling showed that the biosorption data better explained by the Langmuir isotherm model with maximum monolayer biosorption capacities of 28.57, 19.60 and 27.77 mg/g for JES, RES and PES, respectively. The applicability of pseudo-second-order kinetics was observed in all the three biosorbents. The results of thermodynamic analysis showed that the biosorption of Cr(VI) ions onto JES, RES and PES was spontaneous in nature. Cr(VI)-loaded biosorbents were evaluated for a recycle studies with 0.1 M NaOH solution. Experiments conducted using Cr(VI) solution along with the coexisting ions demonstrated that the presence of co-ions slightly reduced the biosorption capacities of the JES and RES. Results of current research demonstrated that the JES, RES and PES could be used for the elimination of hexavalent chromium from aqueous system.