Carbon Adsorbents from Sugarcane Bagasse Prepared through Hydrothermal Carbonization for Adsorption of Methylene Blue: Effect of Heat Treatment on Adsorption Efficiency

Abstract

A carbon hydrochar material (BG-230) has successfully been prepared by conversion of sugarcane bagasse through low-temperature hydrothermal carbonization (HTC) at 230 °C. BG-230 was subsequently subjected to further thermal treatment at 400 °C for 1 hour under air (BG-230/400). Both resulting materials were characterized using specific surface area analysis (BET), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), elemental analysis (C, H, N, O) and X-ray photoelectron spectroscopy (XPS). The characterization results showed that BG-230 possesses a higher number of acidic-oxygen functionalities than BG-230/400, indicating that the thermal treatment at 400 °C under air removed those functionalities. The adsorption properties were evaluated by the removal of methylene blue (MB) from aqueous solutions. The adsorption capacity of MB was found to be higher for BG-230 (∼100 mg g-1) than that for BG-230/400 (∼25 mg g-1). The investigation into the adsorption performance of both prepared adsorbents suggests that the oxygen functional groups on the prepared carbon materials are responsible for the adsorption mechanism.