Insights into Mechanisms of Novel Engineered Biochar Derived from Neem Chips via Iron Catalyst for the Removal of Methyl Orange from Aqueous Phase

Abstract

Methyl orange (MO) is a toxic dye used in many industrial processes. The removal of MO is considered expensive by the sophisticated treatment methods. Hence, there is a need for the discovery of novel methods for removing MO from polluted water. Therefore, this study was aimed at understanding the scientific insights into the adsorption mechanism of novel engineered biochar derived from neem chips via catalytic conversion with FeCl3 for the MO removal. This is the first report describing the use of novel engineered biochar derived from waste neem chip biomass for the removal of the highly resistant anionic dye “methyl orange” by understanding the insights into the removal mechanism. The biochar was prepared at different temperatures: 200 °C, 400 °C, 600 °C, and 800 °C, with a residence time of 2 h. An adsorptive experiment was planned, under a set of experimental conditions: dosage 1 g/L; pH 6; rpm 150; holding time 72 h, to identify the best biochar. The selected biochar has then been activated by iron catalyst of different concentrations (1%, 3%, 5%, and 7%) at a temperature of 700 °C for 30 min. The adsorptive performance was then checked. The engineered biochar with a high qe value (amount of adsorbate removed by unit weight of engineered biochar) was selected, for the detailed studies; isotherm, kinetics, thermodynamics, and rate-limiting factor analyses were used to understand the adsorptive mechanism of novel engineered biochar synthesized. Moreover, it was also treated with wastewater to check its removal efficiency. Furthermore, point zero charge (pzc) was analyzed to study the functional properties of novel engineered biochar along with XRD analysis. The outcomes revealed that the FeCl3 activation improved the (qe) amount of adsorbate removed by grams of engineered biochar to 63.39 mg/g from 80.30 mg/g and it improved the aromatic carbon network. Moreover, the adsorption nature of novel engineered biochar to MO removal is multilayer. It also obeyed well for the pseudo-second-order kinetics. The adsorption is spontaneous and endothermic. The engineered biochar synthesized performed well to remove impurities from a real industrial wastewater: Removal of total suspended solids was 68% and removal of total solids was 74%. Therefore, the engineered biochar produced by the iron catalytic conversion of neem chips is a novel adsorbent for MO removal from aqueous phase.