Highly efficient degradation of perfluorooctanoic acid: An integrated photo-electrocatalytic ozonation and mechanism study

Perfluorooctanoic acid (PFOA) is a widely used perfluorinated compound that causes hazards to human health and environment, which is difficult to be removed by biological degradation. In this work, we demonstrate a highly efficient PFOA degradation process integrated from photocatalysis, ozonation and electrocatalysis, with rGO/BiOCl nanocomposites as catalysts. The PFOA removal ratio in 3 h reaches unprecedentedly 95.4%, superior to photocatalytic ozonation (80.5%) and photoelectro-peroxone process (56.1%). The mechanism of the enhanced catalytic activities has been detailedly investigated, which lies in synergistic effects of photo-generated hole (h+) oxidation from photocatalysis and accelerated OH formation from cathodically generated H2O2. Through identifying degradation intermediates, it is revealed that decarboxylation of PFOA is rapidly initiated by strongly oxidative h+, forming unstable perfluoroheptyl radicals that are further transformed into shorter-chain perfluorocarboxylic acids by reacting with OH. This strategy will bring new insights into fields of catalysis and other related areas for environmental pollution abatement.