Optimization of lead removal in exhausting Manilkara zapota based activated carbon: application of response surface methodology

The present study demonstrates the removal of lead ion from aqueous solution by the adsorption process using Manilkara zapota tree wood-based activated carbon (MZTWAC) as an adsorbent. The MZTWAC was characterized using a scanning electron microscope and Fourier transform infrared spectroscopy. XRD analysis was carried on MZTWAC. Batch adsorption studies were designed and performed to evaluate the adsorption property of MZTWAC for the removal of lead from an aqueous solution based on the central composite design with response surface methodology. The experiments were focused on the individual and combined effects of process parameters, namely, lead concentration, pH and adsorbent dose on the uptake of lead from aqueous solution. A quadratic polynomial equation was established between the adsorption capacity of the activated carbon and the parameters influencing the adsorption with a coefficient of determination R2 = 0.9792. The analysis of variance gauged the significance of process parameters and the optimization of process variables was attained by desirability function. There was a noticeable indication of the strong connotation of lead adsorption with Langmuir (R2 = 0.9911) and Freundlich (R2 = 0.8368) isotherm models. The D-R isotherm model indicated that physisorption occurred in the adsorption of lead by MZTWAC. The pseudo-second-order adsorption kinetic model (R2 = 0.9973) perfectly fitted into the present study.