High-quality low-cost activated carbon/chitosan biocomposite for effective removal of nitrate ions from aqueous solution: isotherm and kinetics studies

Nitrate ions, which mainly come from human activities and are present in wastewater, surface water, and groundwater, are of great environmental concern. In the present work, the activated carbon (AC), chitosan (CH), and biocomposite activated carbon/chitosan (AC/CH) were successfully prepared and characterized using BET, SEM, AFM, elemental analysis, FTIR, PXRD, and TGA/DSC. AC and AC/CH, with specific surface areas of 1327 and 799 m(2)/g, respectively, were used to investigate the effect of contact time, initial nitrate ions concentrations, adsorbent dose, and foreign anions on the removal of nitrate ions by batch adsorption mode. The adsorption results showed that the prepared biocomposite (AC/CH) has a positive impact on the nitrate ion removal compared to AC, with an equilibrium time of 20 min, an optimal pH of 3, and an adsorption capacity of 58 mg/g at an initial concentration of 200 mg/L. Isotherm adsorption data reveal that AC and AC/CH best fitted Sips, Freundlich, and Temkin models while the pseudo-first-order kinetic model describes the adsorption process better than other kinetic models, implying that the adsorption process was mainly governed by physisorption. The biocomposite was found to be reusable after up to seven adsorption/desorption cycles. This study reveals that the prepared AC/CH biocomposite could be considered a promising adsorbent for nitrate ions removal.