Use of coal beneficiation tailings as solid sorbents in the treatment of nitrate-contaminated real wastewater

Abstract

This work evaluates the application efficiency of coal tailings beneficiation as a solid sorbent in the treatment of real wastewater contaminated with nitrate. The solid was characterized by XDR, SEM, FTIR and TGA. Adsorption experiments were performed in batch evaluating the effects of pH, solids concentration and contact time parameters. The kinetics of nitrate adsorption was evaluated using pseudo-first-order and pseudo-second-order models. Equilibrium isotherms for this system were analyzed at three different temperatures (298, 308 and 318 K) by Langmuir, Freundlich and Sips models. The best results from the adsorption experiments were pH 6, contact time of 60 min and 1 g 100 mL−1 of solid. The thermodynamics model that best described the behavior of the process was Sips. By applying these conditions to real wastewater, a nitrate removal of 93% was achieved. This result shows that adsorption using coal beneficiation tailings is technically possible.