Antibiotic mitigation of aqueous systems using untapped potential of unsorted garden waste-derived biochar: performance evaluation and mechanistic insights
摘要
The unchecked consumption of antibiotics leads to the persistence of their active form residues in the environment, perpetuating the cycle of exposure, selection and re-infection, which ultimately exacerbates the environmental antimicrobial resistance (AMR). This work aims to provide a direct comparison of different heterogeneous and underutilised biomass as antibiotic adsorbents. This study investigates the adsorption of the antibiotic, specifically Ciprofloxacin (CIP), by biochars produced from two underutilised biomass sources—unsorted Garden waste (GW) and Cashew nut shells (CNS)-at different temperatures (500–700 °C) and residence times (1–2 h). Based on initial adsorption screening and thermogravimetry, GW biochar, produced at 700 °C with a 2-h residence time (GW700 °C/2 h), was selected as the most suitable. A detailed analysis of this biochar was carried out: TGA confirmed the thermal stability; proximate analysis confirmed a high fixed carbon content; BET analysis (59.11 m2 g 1), FTIR, and XRD indicated the presence of relevant functional groups, and FE-SEM displayed a porous surface morphology, all of which substantiate the adsorption performance. Furthermore, optimum sorption conditions were determined through batch studies, and 50 mg GW700 °C/2 h biochar was found to remove 85.4% of 5 mg L−1 CIP in 285 min at a neutral pH. Kinetic and isotherm data confirmed multilayer chemisorption with a maximum sorption capacity of 6.19 mg g−1. This is the first report exploring unsorted GW biochar as a sustainable solution for antibiotic mitigation, which, in future, can be scaled up to be part of the wastewater treatment systems.