Sorptive removal of aqueous arsenite and arsenate ions onto a low cost, calcium modified Moringa oleifera wood biochar (CaMBC)

Abstract

Arsenicosis, due to consumption of an elevated amount of arsenic‐containing groundwater is a serious issue related to human health. The ubiquitous nature of arsenic is also a part of agricultural soil solution and its uptake by edible plants imposes a considerable human health risk. A calcium pretreated wood of Moringa oleifera was pyrolyzed and converted into biochar. The resultant biochar was examined for arsenite and arsenate uptake from an aqueous solution. Further, characterization of biochar was performed using Fourier transformed infrared spectroscopy (FT‐IR) and Scanning electron microscope with energy dispersive x‐ray (SEM‐EDAX) analysis. Results suggested the involvement of different functional groups of calcium‐modified biochar in As(III) and As(V) sorption processes. Experimental data of batch sorption revealed that CaMBC could adsorb analyte ions from pH 5.0 to 7.0 with maximum percentage removal, that is, 87.27 and 94.52% at adsorbent concentration 2 g/L. A high loading capacity of prepared adsorbent was found to be 37.22 mg/g for arsenate and 33.44 mg/g for arsenite ions. The sorption occurred due to chemical interaction between functional group and arsenic ions, which existed over the surface of prepared biochar. The spontaneous sorption makes a CaMBC, an ideal candidate for the removal of dissolved arsenite, arsenate ions.