Response Surface Methodology‐Optimised Removal of Antibiotics in Water Using SDS‐Modified Rice Husk‐ZnO Composites

ABSTRACT The persistence of pharmaceutical residues in aquatic environments presents a significant challenge for water treatment, necessitating the development of efficient and low‐cost removal strategies. In this study, a chemically modified rice husk‐based composite incorporating zinc oxide and treated with orthophosphoric acid and an anionic surfactant was evaluated as an adsorbent for the removal of metronidazole and tetracycline from aqueous solution. The adsorption process was systematically optimised using response surface methodology based on a Box–Behnken experimental design, considering the effects of solution pH, adsorbent dosage and initial contaminant concentration. Under optimised conditions, the modified composite achieved a maximum removal efficiency of 99.1% for metronidazole at alkaline pH with low contaminant concentration and moderate adsorbent dosage, significantly outperforming the unmodified composite.