Photodegradation of decabromodiphenyl ethane (DBDPE) adsorbed on silica gel in aqueous solution: Kinetics, products, and theoretical calculations

Abstract Decabromodiphenyl ethane (DBDPE) is a kind of brominated flame retardant and an alternative to decabromodiphenyl ether (BDE-209). Significant photodegradation of DBDPE was found on the surface of silica gel (SG) in aqueous solution under simulated solar irradiation. The removal of DBDPE was enhanced under high pH conditions. The DBDPE degradation rate decreased with the addition of humic acid and an increase in the amount of DBDPE. The favorable stability and reusability of SG were presented for the promotion of DBDPE degradation. According to electron paramagnetic resonance (EPR) analysis, quenching experiments and theoretical calculations, OH can be generated from SG under simulated solar irradiation and was the main radicals for the DBDPE decomposition. Low brominated and hydroxylated DBDPEs (OH-DBDPEs) were identified by liquid chromatography time-of-flight mass spectrometry (LC-TOF-MS) and gas chromatography-mass spectrometry (GC–MS), from which hydrodebromination and hydroxyl substitution were proposed as the major reaction pathways. The photochemical transformation of organic compounds is ubiquitous on a solid surface in the natural environment, and thus, low brominated DBDPEs and OH-DBDPEs can be generated from the DBDPE parent compound. This study can provide reference information for the photochemical transformation of DBDPE adsorbed on a solid surface in natural waters.