Reaction of decabrominated diphenyl ether by zerovalent iron nanoparticles.

Polybrominated diphenyl ethers (PBDEs) recognized as a new class of environmental persistent toxic contaminants have been distributed widely in the world. In this study, the synthesized nanoscale zerovalent iron (NZVI) in the laboratory was used to investigate the removal kinetics and mechanisms of decabrominated diphenyl ether (DBDE) at different pH. Within 40 min 90% of DBDE was rapidly removed by NZVI as compared to around 40 d needed for 24-fold weight of microscale ZVI. The removal by NZVI is much faster than that by microscale ZVI due to its high surface area and reactivity. At a different pH, the pseudo-first-order removal rate constants of DBDE linearly increased from 0.016 to 0.024 min(-1) with the decreasing of aqueous initial pH values from 10 to 5. The degradation of DBDE with NZVI is favorable in an acid condition. The debromination pathways of DBDE with NZVI were proposed on the basis of the identified reaction intermediates ranging from nona- to mono-brominated diphenyl ethers (BDEs) for an acid condition and from nona- to penta-BDEs for an alkaline condition. The debromination of PBDEs from para positions is more difficult than that from meta or ortho positions. Adsorption on NZVI also plays a role on the removal of DBDE. These findings can facilitate the treatment and fate prediction of PBDEs with NZVI in the environment.