Introduction: The presence of antibiotic residues in the aquatic environment is a likely contributor to the current increase in antibiotic resistance, posing a significant threat to global health. This study investigated the use of a low-cost and sustainable material based on sawdust with the purpose of removing rifampicin residues from water. Methods: The sawdust was pretreated with 2M sulfuric acid and was characterized using Fourier Transform Infrared spectroscopy (FT-IR), a Mastersizer, scanning electron microscopy (SEM), an elemental analyser, and the pH point of zero charge (pH_pzc). The batch adsorption process was conducted using both raw and treated sawdust to determine the effect of contact time, temperature, pH, adsorbent dosage, and the initial concentration of antibiotic dissolved in water. Results and Discussion: The results revealed that the chemical pretreatment of raw sawdust significantly improved its adsorption capacity. The highest removal efficiency of 65% was achieved using an adsorbent dosage of 31.3 g/L. The thermodynamic studies demonstrated that the process was spontaneous and governed by physisorption within the studied temperature range (293.15 K–318.15 K), being more favourable at higher temperatures. The interactions between the functional groups of sawdust and the rifampicin molecules included electrostatic attraction, hydrogen bonding, and π-π interactions. Conclusions: This research highlights the potential of utilizing waste as a valuable and effective adsorbent of residual antibiotics from water, thus contributing to the sustainable practices of solid waste management and water treatment.

Residual antibiotics pollution is one of the main drivers of antibiotic resistance, demanding effective and sustainable technologies for remediation. Adsorption was found to be an effective process for antibiotic contaminant remediation, particularly on surfaces of lignocellulosic materials, which have gained attention as low-cost adsorbents. This study investigated the adsorption mechanisms and the optimisation of rifampicin removal from water using sawdust. Adsorption mechanisms were proposed based on kinetic and isotherms, while response surface methodology (RSM) was employed to optimise and identify the critical operating parameters. The results revealed that the adsorption of rifampicin by both adsorbents could be best described by the pseudo-first-order model, while the experimental results fitted perfectly into the Temkin isotherm model, which suggests that the adsorption of rifampicin on sawdust occurred via multi-interaction on a varying, energetically heterogeneous surface. Optimal conditions resulting in an uptake of 0.71 mg/g were established as follows: initial concentration of 20 mg/L, an adsorbent dosage of 0.5 g per 40 mL, pH 6 and at 250 min. The initial concentration of rifampicin and the adsorbent dosage were found to be the most critical parameters that influenced its uptake. The findings revealed that sawdust is a sustainable and cost-effective material to remove rifampicin from water, with adsorption occurring mainly via physisorption on a varying, energetically heterogeneous surface.