Enhanced photocatalytic degradation of PFOA and short-chain PFCAs coupled with hydrogen production via olive kernel biomass-based CQDs-doped TiO2 composites

Increased human activity has intensified waste generation, particularly of persistent perfluorinated carboxylic acids (PFCA pollutants), as well as energy demand. Integrating wastewater treatment with green hydrogen production offers a sustainable approach to reducing environmental pollution while generating clean energy. Hydrogen, a key low-carbon fuel, can be produced more efficiently via photocatalysis from hydrogen-rich pollutants than from water splitting alone. This study investigates the visible and UVC-light-driven photo-degradation of PFOA and short-chain PFCAs (C3-C6) using biomass-derived olive kernel carbon quantum dots (OKCQDs) integrated into TiO2 photocatalyst composites. Hydrogen evolution during photodegradation was also evaluated. Chemical, morphological, and optical analyses confirmed the successful synthesis of OKCQDs via hydrothermal methods and their integration with TiO2 using the sol-gel approach. Photocatalytic results revealed significantly enhanced degradation efficiencies with OKCQD/TiO2 (PFOA: 90.1 % under UVC and 80.3 % under visible light; short-chain PFCAs: 37-65 %) compared to pure TiO2 (PFOA: 40.9 % and 23.7 %; C3-C6: 14.6-26.9 %). Concurrent hydrogen generation was observed during pollutant degradation, showing a 5.71-fold increase with OKCQD/TiO2(892 mu mol. g-1. h-1) compared to pure TiO2(156 mu mol. g-1. h-1) after 480 min of PFOA photodegradation under visible light irradiation. To assess practical applicability, PFOA degradation was also tested in real river water and textile wastewater under visible light. Furthermore, intermediate formation, defluorination efficiency, toxicity assays, and catalyst reusability tests were conducted to evaluate the environmental impact and sustainability of the photodegradation process.