Visible-light-driven photocatalytic degradation of a typical UV filter by a novel composite photocatalyst: DFT calculation, degradation pathway, and toxicity evolution

Benzophenone-1 (BP1), as a typical ultraviolet (UV) filter, has been detected in large quantities in aquatic environments and can pose a threat to human health through bioaccumulation. To efficiently remove BP1 from the water environment, a type-II AgI/Bi2Fe4O9 (AgI/BFO) heterojunction with AgI particles tightly grown on Bi2Fe4O9 nanosheets was fabricated. The resultant AgI/BFO heterojunction extended the light absorption range of AgI and promoted charge transfer, which significantly enhanced the photocatalytic performance in BP1 degradation. As a result, the obtained AgI/BFO heterojunction has a degradation rate constant of 0.159 min−1 for BP1, which was 15.9 times BFO and 4.1 times AgI. Capture experiments proved that superoxide radicals (·O2–) and holes (h+) are the main active species. According to the high-performance liquid chromatography-mass spectrometry (HPLC-MS) results, combined with density functional theory (DFT) calculations C5, C7, and C11 were the main attack sites of active species, proposed ten possible degradation intermediates. These degradation intermediates showed increasingly lower toxicity compared to BP1. This work provides a new idea for the study of photocatalytic technology to degrade BPs pollutants in water.