Facile removal of sulfamethoxazole antibiotic from contaminated water using bagasse-derived pyrolytic biocarbon: Parametric assessment, mechanistic insights and scale-up analysis

The excessive use of antibiotics leads to the presence of unused antibiotics and their byproducts in sewage, ultimately finding their way to contaminate water bodies. These organic pollutants pose significant ecotoxicological risks, necessitating their removal from the wastewater. Sulfamethoxazole (SMX), an emerging aqueous contaminant of antibiotic origin, has been associated with allergic reactions, gastrointestinal, liver, and kidney issues, exacerbating environmental and health concerns. This study focuses on the removal of SMX from wastewater through adsorption using bagasse-based biocarbon. Various adsorption parameters, including contact time, initial solution pH, adsorbate concentration, adsorbent dosage, and temperature were optimized. Experimental studies demonstrated an 89 % SMX removal efficiency at a 50 ppm adsorbate concentration, with a contact time of 150 min and a pH of ∼2. Equilibrium and kinetic studies showed that the Jovanovic isotherm and fractional power kinetic models best represented the SMX adsorption data, both achieving a coefficient of determination (R2) of 0.92. The maximum adsorption capacity of SMX onto biocarbon was observed to be 21.5 mg g−1. Thermodynamic analysis was conducted to determine Gibbs free energy (ΔG°), enthalpy (ΔH°), and entropy (ΔS°). The findings indicated the spontaneity and exothermic nature of the adsorption process, accompanied by a decrease in randomness at the solid-liquid interface during SMX uptake. The adsorption mechanism plausibly involved hydrogen bonding and π-π interactions. The scale up analysis implied the feasibility of large-scale wastewater treatment applications with minimal biocarbon requirements. The results of the study suggest the suitability of bagasse-based biocarbon for effectively removing SMX from contaminated water.