Utilization of Sapindus saponaria (soap nut) bark powder for the removal of Cu(II) ions from aqueous environment

AbstractSapindus saponaria bark powder (SSBP), an agro-waste material was investigated as a biosorbent for the removal and recovery of Cu(II) from aqueous solution. This biosorbent was characterized by infrared spectroscopy, X-ray diffraction, scanning electron microscopy and elemental analysis. The influence of various parameters such as effect of initial pH, contact time, metal ion concentration and sorbent dose on the removal of Cu(II) was investigated using batch process. Langmuir, Freundlich and Dubinin–Radushkevich isotherm models were applied to describe the adsorption isotherms. The Langmuir model fitted the equilibrium data better than the other isotherm models. The maximum adsorption capacity of Cu(II) was calculated from the Langmuir isotherm and found to be 37.09 mg g−1 at pH 5.0. The kinetic studies revealed that the biosorption of Cu(II) onto SSBP followed the pseudo-second-order rate model. Evaluated thermodynamic parameters, ∆G°, ∆H° and ∆S°, showed that the biosorption of Cu(II) onto SSBP...