Reductive degradation of 2,2′,4,4′-tretrabromodiphenyl ether with PAC-Pd/Fe nanoparticles: Effects of Pd loading, initial pH and HA, and degradation pathway

Abstract

As a typical congener of Polybrominated diphenyl ethers (PBDEs), 2,2′,4,4′-tetrabromodiphenyl ether (BDE47) has attracted more and more attention due to its high biological toxicity and environmental abundance. In this study, a novel polyanionic cellulose stabilized Pd/Fe (PAC-Pd/Fe) nanoparticle was successfully synthesized for BDE47 degradation under ambient condition. Batch experiments showed that BDE47 degradation followed pseudo first-order kinetic model. Pd loading played a crucial role as it affected the formation of activated hydrogen species H∗ and accelerated electron transfer. At Pd loading of 0.3 wt%, nearly 100% BDE47 was degraded completely within 10 min by 0.4 g L−1PAC-Pd/Fe nanoparticles. When compared with strong acidic (pH 3) and alkaline (pH 9 and 11) conditions, weak acidic condition (pH 5) was more favorable for BDE47 degradation, with nearly 100% BDE47 was removed within 7.5 min. In the presence of HA inhibited the degradation of BDE47, and the degradation efficiencies within 15 min decreased from 100%, 88.6%, 79.5% to 73.1% as HA concentration increased from 0, 10, 40 to 70 mg L−1. The degradation of BDE47 by PAC-Pd/Fe nanoparticles was a reductive debromination process, and a stepwise debromination from n-Br to (n-1)-Br BDEs was the dominant reaction, in which the para-Br was more susceptible to remove than ortho-Br. This study suggests PAC-Pd/Fe nanoparticle can be utilized as a promising remediation technology for PBDEs contaminated wastewater.