Micro biochar derived from mango leaves and banana peduncle for efficient oxytetracycline removal from aquatic environments

• Mango leaves and banana peduncle, an unexplored agro waste materials, were utilized for oxytetracycline (OTC) remediation. • The yield of micro-biochar is greater than that of nano-biochar, whereas surface area and removal efficiency are higher compared to bulk biochar. • Removal efficiency of MLMB700 and BPMB700 were 88.98 ± 0.85 % and 95.07 ± 0.19 % respectively for 40 ppm OTC at a dose of 3 g/L at equilibrium time. • Adsorption mechanism followed Freundlich isotherm, pseudo-second-order, and intraparticle diffusion models. Antimicrobial resistance (AMR) is a critical global challenge, impacting human health, animal welfare, and environmental stability. The misuse and overuse of antibiotics, such as Oxytetracycline (OTC) in aquaculture and veterinary medicine, significantly contribute to the proliferation of AMR. Due to OTC's low absorption, 70–90 % is excreted, accumulating in aquatic environments. Biochar adsorption is a cost effective remediation strategy, but unmodified biochar often has low adsorption capacity, requiring modifications that can be costly and yield limited quantities. In this study, mango leaves micro biochar prepared at 700 °C (MLMB700) and banana peduncles micro biochar prepared at 700 °C (BPMB700), from readily available and previously underutilized raw materials, was employed for OTC remediation. Micro biochar, with a higher surface area than bulk biochar, offers a cost effective alternative to nano biochar and can be produced in larger quantities. MLMB700 and BPMB700 achieved removal efficiencies of 88.98 ± 0.85 % and 95.07 ± 0.19 %, respectively, for 40 ppm OTC at 3 g/L. Both biochars demonstrated high reusability, maintaining removal efficiencies of 55.85 ± 2.15 % (MLMB700) and 66.25 ± 3.06 % (BPMB700) up to five cycles. Adsorption followed the Freundlich isotherm, pseudo second order, and intraparticle diffusion models. OTC removal increased with temperature. Micro biochar was evaluated in real water matrices to assess its practical applicability for oxytetracycline hydroch (OTC) removal. The removal efficiency ranged from 25.41 ± 1.21 % to 48.47 ± 2.19 % in seawater and 76.63 ± 2.14 % to 84.19 ± 2.16 % in tilapia tank water for MLMB700 and BPMB700, respectively.