Development of a new Cr(VI)-biosorbent from agricultural waste: Adsorption characteristics and the kinetics

Abstract

Agricultural wastes are excellent carbon materials for adsorption of heavy metal ions from toxic industrial wastewaters. Here we report the biosorption potential of a low cost agricultural waste, Pongamia seed shell (PSS), in the removal of toxic hexavalent Cr, from aqueous synthetic solution. The effect of pH, adsorbent dosage and contact time on the removal of Cr(VI) was studied using batch system. The Cr(VI) removal efficiency was highest at pH 2.0 and adsorbent dosage of 10.0 g/L. A maximum monolayer adsorption capacity of 83.3 mg/g at 30 °C was obtained. Freundlich isotherm model (R2 ≥ 0.95) and pseudo-second order kinetic model (R2 ≥ 0.99) fitted well with experimental data among the others. The morphology and surface functional groups of the raw PSS and Cr(VI)-loaded PSS were observed by scanning electron microscopy and Fourier transform infrared spectroscopy, respectively, which confirmed the adsorption and binding of Cr(VI) onto PSS. Experimental and kinetic results suggest PSS as a potential biosorbent of Cr(VI) in industrial wastewaters. This study evaluated the adsorption potential of Pongamia seed shell (PSS) in removing Cr(VI) from aqueous synthetic solution. The optimum pH for adsorption was 2.0. The structural properties and surface functional groups further confirmed the adsorption and binding of Cr(VI) onto PSS. Freundlich isotherm model and pseudo-second-order kinetic model were found to best describe the equilibrium and the adsorption process, respectively. © 2014 The Chemical Society Located in Taipei & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.