Preparation and characterization of low-cost activated carbon from Moringa oleifera chemically activated using ZnCl2 for the adsorption of bisphenol A

NOVELTY STATEMENTThe novelty of this study is the selection of Moringa oleifera plants as suitable plant species for activated carbon synthesis by adopting appropriate procedures for bisphenol A removal. Although the biowaste-derived activated carbons prepared by different activation methods have been studied before, M. oleifera plants activated carbon prepared via ZnCl2 activation for bisphenol A adsorption was not reported. This study will be a significant endeavor in promoting alternative techniques for BPA removal. Using activated carbon derived from agricultural waste will replace commercial activated carbon which is more economic and environmentally friendly. This study will bring tremendous environmental and economic benefits as well as limit the harmful effect. The use of agricultural by-products such as Moringa oleifera plants is one effort to support the reduction of environmental pollution. Activated carbon produces from agricultural wastes is relatively less expensive and can replace traditional methods such as renewable as well as nonrenewable materials such as petroleum residue and coal. In this study, the removal of bisphenol A from aqueous media was studied using activated carbon produced from M. oleifera pods and peels. A batch adsorption study was carried out by varying the parameters of the adsorption process. A maximum removal percentage of 95.46% was achieved at optimum conditions of 2.5 g L-1 adsorbent dose, pH 7, 60 min contact time and 20 mg L-1 initial concentration of BPA. The BET surface areas of MOP, MOP-AC and MOP-ACZ were found to be 12.60, 4.10 and 45.96 m(2)/g, respectively. The experimental data were analyzed by Langmuir, Freundlich and Temkin adsorption isotherm models. Equilibrium data fitted well with the Langmuir isotherm with a maximum monolayer adsorption capacity of 20.14 mg g(-1). The rates of adsorption were found to conform to the pseudo-second-order kinetics with a good correlation. The results indicate that the M. oleifera activated carbon could be employed as a low-cost alternative to commercial activated carbon in the removal of BPA from water.