Synergistic effect of ball-milled Al micro-scale particles with vitamin B12 on the degradation of 2,2′,4,4′-tetrabromodiphenyl ether in liquid system

Abstract

2,2′,4,4′-Tetrabromodiphenyl ether (BDE47) is known as a recalcitrant bromated organic pollutant with the significant persistence, toxicity, and bioaccumulation. In this study, a synergistic effect of ball-milled Al particles with vitamin B12 on the degradation of BDE47 was found according to the coordinated catalytic reduction process. The micro-scale Al particles prepared by ball milling and vitamin B12 as common pharmaceutical composed a new combination reagent for hydrodebromination with low-cost and high reactivity. The degradation conditions were optimized by the addition of 2.0 g/L BM Al particles and 0.3 mM VB12 using the solvent of methanol/H2O (v:v = 40:60) at pH 4.0. More than 97% of 25 mg/L BDE47 was debrominated into lower-brominated diphenyl ethers in a sequential pattern and finally into diphenyl ethers within a 120-min reaction. UV/Visible spectra showed that vitamin B12 (Co(III)) was reduced to vitamin B12s (Co(II)) by the ball-milled Al particles, which possesses super nucleophilic property to associate the carbon atom on CBr bond and then facilitates the hydrodebromination process of brominated diphenyl ethers. The experimental results can provide basic understanding to identify a reaction process of vitamin B12/vitamin B12s for the enhanced reductive debromination of polybrominated diphenyl ethers by ball-milled Al particles, which would be possibly applied to treat soil washing solvent in the field of soil remediation.