Integrated activated carbon-nanofiltration for effective amoxicillin removal from water

Amoxicillin (AMX) residues are detected in natural and engineered waters, raising concerns over antimicrobial resistance and ecosystem health. This work aims to evaluate an integrated process coupling adsorption onto an activated carbon (AC) derived from Elaeagnus angustifolia seeds with nanofiltration (NF) for AMX removal from synthetic and real waters. Batch adsorption experiments were performed at 298 K and pH 7.0 using 0.2–1.0 g L⁻¹ AC and contact times up to 180 min, while NF tests were conducted in a cross-flow cell at 6 bar, pH 4–10, AMX concentrations of 20–80 mg L⁻¹, and 298–318 K. The Elaeagnus-derived AC exhibited a high Langmuir capacity (qmax = 190.8 mg g⁻¹), pseudo-second-order kinetics, and spontaneous, exothermic uptake (ΔH° = −52.4 kJ mol⁻¹). At an optimal dose of 0.8 g L⁻¹ and 90 min, AMX removal reached 96% in model water and 92% in dam water, remaining above 85% after three NaOH regeneration cycles. Under the selected conditions, the NF membrane achieved 96–97.5% rejection, yielding final overall removals above 99.5% in both matrices. Compared with AC–NF studies relying on commercial carbons, this work demonstrates the feasibility of a low-cost Elaeagnus-seed-based AC–NF system as a scalable solution for mitigating antibiotic contamination and protecting water resources.