Highly Efficient Mineralization of Typical PPCPs in Medical Wastewater via P25TiO2 Photocatalysis Under Sunlight Irradiation

Pharmaceuticals and personal care products (PPCPs), as persistent organic pollutants, are widely present in various aquatic environments. Their long-term presence in aquatic environments poses a potential threat to ecosystems and human health. This study established an efficient, green, and cost-effective photocatalytic method using P25 titanium dioxide (P25TiO2) to simultaneously degrade five representative PPCPs (methyl paraben (MeP), carbamazepine (CBZ), bisphenol A (BPA), diclofenac (DFC), and triclosan (TCS), while elucidating the reaction mechanisms. Under sunlight irradiation, degradation rates for all five PPCPs reached 100%, achieving near-complete mineralization with total organic carbon (TOC) removal rates exceeding 95%. This demonstrates the system’s exceptional capability to not only degrade the parent compounds but to thoroughly convert them into benign inorganic substances. We systematically investigated the effects of catalyst concentration, initial pollutant concentration, light intensity, pH, and various common inorganic anions (chloride, sulfate, bicarbonate, phosphate) and humic acid (HA) on the degradation process. Additionally, mechanistic studies indicated that hydroxyl radicals (·OH) are the primary active species in the system. The degradation rate differences among various persistent organic pollutants (DFC > BPA > TCS > CBZ > MeP) primarily stem from variations in the reactivity of different functional groups within their molecular structures toward ·OH. In summary, this study provides a promising and practical solution for treating complex medical wastewater containing five typical PPCPs.