Presence of antibiotics in aquatic environment has raised public concerns due to potential adverse effects. In this study, we synthesized two different bismuth oxyiodide (BiOI) by hydrolysis (BiOI-H) and solvothermal (BiOI-ST) methods and characterized using FTIR, XRD, FESEM, N2 adsorption–desorption isotherm, DRS and PLS. The results of characterization tests showed that the BiOI-ST sample is a better adsorbent and may be more active in photocatalytic reactions as the result of more surface area, higher light absorption ability lower band-gap energy and PL intensity, than BiOI-H. Tetracycline hydrochloride (TCH) antibiotic was selected to evaluate adsorption and photocatalytic efficiency of BiOI-ST using Response Surface Methodology. The optimum conditions of contact time, TCH initial concentration, BiOI dosage and pH for adsorption and photocatalytic processes were obtained 37.5 min, 2.1 mg/L, 1.5 g/L, 8.5 and 101.5 min, 2 mg/L, 0.68 g/L, respectively. Based on kinetic and isotherm studies, experimental data fitted to pseudo-second order kinetics model and followed the Freundlich and D–R isotherm models. The apparent pseudo-first order rate constant of BiOI-ST was higher than that of BiOI-H. Therefore, BiOI-ST can be used as a promising option to treat low level concentration of TCH in hospital wastewaters.

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