Preparation and utilization of anaerobic granular sludge-based biochar for the adsorption of methylene blue from aqueous solutions

In this study, a novel anaerobic granular sludge-based biochar (AGS-BC) was synthesized and utilized to remove methylene blue (MB) from aqueous solutions. The AGS-BC was characterized by scanning electron microscope (SEM), zeta potential, Brunauer-Emmett-Teller (BET) surface area, Boehm's titration, Fourier transform infrared spectroscopy (FTIR) analysis and X-ray photoelectron spectroscopy (XPS). Adsorption results were analyzed by the adjustment of various experimental parameters, including contact time, adsorbent dosage and pH values. In addition, the adsorption mechanism was investigated by adsorption isotherms, adsorption kinetic and adsorption thermodynamics. It was found that MB adsorption by AGS-BC fitted well the Langmuir isotherm model and pseudo-second order kinetics model. Based on the values of activation parameters including Gibbs free energy (Delta G(0) -9.20 to -11.10 kJ/mol), enthalpy (Delta H-0, 19.95 kJ/mol) and entropy (Delta S-0, 0.095 kJ/mol . K), we concluded that the adsorption process of MB onto AGS-BC was endothermic and spontaneous in nature. The result of this study could provide strong evidence of the potential of AGS-BC for removing MB from aqueous solutions. (C) 2014 Elsevier B.V. All rights reserved.