Catalytic ZnO-Modified Ceramic Membrane for Persulfate Activation: An Integrated System for Efficient Tetracycline Hydrochloride Removal

Tetracycline hydrochloride (TC HCl) is a persistent antibiotic contaminant that is insufficiently removed by conventional wastewater treatment, requiring efficient polishing technologies. In this study, a ZnO-modified ceramic ultrafiltration membrane (ZnO@CM) was developed and coupled with sodium persulfate (NaPS) for TC HCl removal in a membrane-assisted advanced oxidation system. ZnO was synthesized by co-precipitation and immobilized onto an Al2O3 ceramic membrane through dip coating. The membrane had an average pore size of 0.1 μm, a pure water flux of 96 L m−2 h−1 at 2 bar, and a pressure-normalized flux of 48 L m−2 h−1 bar−1. Process performance was optimized using a Taguchi L9 design by varying pH (4–9), NaPS dose (0.2–0.6 mM), contact time (15–45 min), and initial TC HCl concentration (2–10 mg L−1). Under optimal conditions, the ZnO@CM/NaPS system achieved 90.14% apparent TC HCl removal, exceeding the uncoated CM/NaPS system (57.9%). ANOVA identified pH and oxidant dose as dominant controlling factors, emphasizing reaction chemistry and oxidant availability. Radical-quenching experiments suggested oxidative pathway involvement within the catalytic membrane process under tested laboratory conditions; however, removal was measured by UV–vis absorbance at 350 nm and should be interpreted as apparent TC HCl removal rather than confirmed mineralization.