Performance and reusability features of solar-driven N-TiO2-PVDF hybrid photocatalytic membrane for sulphamethoxazole degradation

Abstract

Antibiotic overuse combined with increased water demand has had a detrimental effect on the ecosystem, leading to water contamination and scarcity. N-TiO₂-PVDF, or nitrogen-doped titanium dioxide polyvinylidene fluoride membrane, was synthesized and its performance evaluated in order to address the growing problem of antibiotic-induced water contamination. The impact of the initial sulphamethoxazole (SMZ) concentration and solution pH were assessed. Additionally, the N-TiO₂-PVDF's durability and reusability were assessed. At solution pH of 4, the highest SMZ degradation efficiency 81.3 %, and relative flux of 0.78 (552ml/7cmD/hr flux) were achieved. This was attributed to enhancement of surface charges and antifouling capability of N-TiO₂ nanoparticles. The total organic carbon (TOC) removal was 65 % at pH 7. At SMZ concentration of 6 mg/l a degradation was 69.9 % and 0.73 relative flux (518.4ml/7cmD/hr flux). The N-TiO₂-PVDF membrane was recovered and reused repeatedly in five cycles and a minimal drop in performance was observed: notably, a reduction in 10.1 % degradation efficiency, 13.6 % for TOC reduction and 0.29 for relative flux (205ml/7cmD/hr flux). The flux recovery ratios were above 0.97 with a total fouling ratio of 0.316. The performance was dependent on the level of N-TiO₂ inactivation, competition for radicals and amounts of foulants. The study demonstrates that solar photocatalytic N-TiO₂-PVDF membrane are effective, robust and durable. The valuable information gathered can direct the use and scaling up of photocatalytic membranes in the treatment of water and wastewater.