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

• Published in: Journal of hazardous materials 2021-06, Vol.412, p.125224, Article 125224
• Main Authors: Liu, Guanhong, Feng, Meiyun, Tayyab, Muhammad, Gong, Jianqiu, Zhang, Meng, Yang, Mingyang, Lin, Kuangfei
• Format: Article
• Language: English
• Subjects: Bimetallic catalyst; Electron transfer; Mechanical reduction; Perfluorooctanoic acid
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2021.125224

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 CNi-Al2O3 structure (AlCNi) 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 AlCNi through a mechanochemical stirring method and 70.43% of fluorine ions was released from PFOA anchored onto the surface of AlCNi. Both thermocatalysis and photocatalysis technologies were incorporated and compared when utilized in tandem with AlCNi to mitigate the PFOA. In addition, peroxymonosulfate (PMS) and sodium sulfite (Na2SO3) 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 AlCNi, even when assisted by elevated temperatures and ultraviolet irradiation. The feasibility of employing AlCNi 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 AlCNi/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 AlCNi, which can be suitable for large-scale sewage treatment applications. [Display omitted] •A bimetallic Al2O3-Ni structure supported on graphite carbon was synthesized and characterized.•98% of PFOA was effectively removed by AlCNi without resorting to any chemical agent.•PFOA was anchored on the surface of AlCNi in a monodentate ligand and then followed by electron attack during degradation.•A small amount of superoxide radicals was present in this system.