Direct and efficient reduction of perfluorooctanoic acid using bimetallic catalyst supported on carbon.

A variety of metal elements have exhibited strong reductive and dehalogenative capabilities for the removal of persistent organic pollutants, owing to electron transfer or electron-hole activation through various methods. Herein, a bimetallic C-AlO structure (AlC) was successfully synthesized to simultaneously function as sorbent and catalyst in the reduction of perfluoroalkyl carboxylic acids (PFOA) polluted wastewater. Using a reaction period of 3 h, 98% of PFOA was removed by AlC through a mechanochemical stirring method and 70.43% of fluorine ions was released from PFOA anchored onto the surface of AlC. Both thermocatalysis and photocatalysis technologies were incorporated and compared when utilized in tandem with AlC to mitigate the PFOA. In addition, peroxymonosulfate (PMS) and sodium sulfite (NaSO) were also integrated into experiments, separately, as a strong oxidant and reductant to improve the degradation effect of PFOA. However, the degradation efficiency of both were lower than that of AlC, even when assisted by elevated temperatures and ultraviolet irradiation. The feasibility of employing AlC for PFOA degradation was further investigated at various temperature and pH conditions. The data obtained from HPLC-MS/MS, TOC, and IC with multiple characterizations of AlC/PFOA, proposed the predominant degradation pathways comprising adsorption, defluorination-hydroxylation, and decarboxylation. This study provides a valuable remediation method without utilizing chemical agents and special activation for PFOA by AlC, which can be suitable for large-scale sewage treatment applications.