Thermal treated sugarcane bagasse for acetylsalicylic acid removal: dynamic and equilibrium studies, cycles of reuse and mechanisms

Sugarcane bagasse, an abundant residue from ethanol and sugar industry, was used in its natural form (SB) and carbonised (CS) as adsorbent for removing acetylsalicylic acid from aqueous solutions. The surface area, porosity, functional groups and surface charges of the adsorbents were characterised by Brunauer-Emmett-Teller and Barret-Joyner-Halenda methods, Fourier transform infrared spectroscopy and point of zero charge. Analysis indicated that C- and O-containing functional groups may be involved in the adsorption process. Batch experiments were also performed to evaluate the effects of pH, temperature and time on the sorption. The materials exhibited high adsorption efficiency at low pH. Results revealed that the pseudo-first-order kinetic model and pseudo-second-order provided the best fitting to the experimental data for biosorbent SB and biochar CS, respectively. Liu isotherm model describes the adsorption equilibrium for biochar suggesting that the carbonised surface had a heterogeneous nature with Q(max) of 32.73 mg g(-1) at 298 K. Besides, intraparticle diffusion model suggests that adsorption of ASA onto activated carbon was controlled by multiple steps. This study demonstrated that carbonised sugarcane bagasse is a potential adsorbent for removing acetylsalicylic acid from aqueous solutions.