Effects of ferric ion on the photo-treatment of nonionic surfactant Brij35 washing waste containing 2,2′,4,4′-tetrabromodiphenyl ether

The effects of ferric iron on the photo-treatment of simulated BDE-47 (2,2′,4,4′- tetrabromodiphenyl ether)-Brij35 (Polyoxyethylene lauryl ether) washing waste were studied to evaluate the influences of ferric iron on BDE-47 removal and Brij35 recovery. The results show that Fe 3+ accelerated BDE-47 degradation at lower concentrations (<0.5 mM) but attenuated it at higher concentrations (0.5–5 mM) and that Brij35 loss was increased with increasing Fe 3+ . These results likely are caused by changes in the rate of •OH production due to the ferric ion, association of Fe 3+ and electron transfer from Brij35, and light attenuation at high concentration. The BDE-47 and Brij35 had different degradation rates at different pH values and at different dissolved oxygen concentrations. The BDE-47 products were identified by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). The results indicated that BDE-47 transformed into mainly lower-brominated products, a few bromodibenzofurans, some rearrangement products, and some hydroxylated polybrominated diphenyl ethers . A series of Brij35 oxidization products were detected by ultra-performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS), including hydroxylation products, carboxylation products, and some hydrophilic chain-breaking products. Brij35 was mainly oxidized by Fe 3+ and/or reactive oxygen species (ROS) with the final products of CO 2 and H 2 O. The iron ions apparently cycled from ferric to ferrous ions in the micelles such that the Fe 3+ -Brij35 complex dominated the main redox reaction, leading to both BDE-47 and Brij35 degradation. It appears that in any applied soil washing system, the ferric ions in the washing waste need to be removed because of the adverse effects on BDE-47 removal and eluate reuse.