Highly efficient debromination of 4,4'-dibrominated diphenyl ether by organic palygorskite-supported Pd/Fe nanoparticles.

Weizhong Shi,Xiaoju Wen,Zongtang Liu,Jiang Shao,Dandan Wang,Zhenghao Fei,Ziyan Chen,Yi Zhang,Chenggang Gu,Yufeng Sun

doi:10.1007/s11356-021-15997-7

Abstract

Organic palygorskite (OP)-supported Pd/Fe nanoparticles composite (OP-Pd/Fe) was prepared by stepwise reduction method. The removal capacity of 4,4'-dibrominated diphenyl ether (BDE15) by OP-Pd/Fe was compared with other various materials. For better understanding the possible mechanism, the synthesized and reacted OP-Pd/Fe materials were characterized by TEM, SEM, XRD, and XPS, respectively. The effects of major influencing parameters on the degradation of BDE15 were also studied. Benefit from the synergistic effect of the carrier and bimetallic nanoparticles, BDE15 could be completely debrominated into diphenyl ether (DE) under suitable conditions. A two-stage adsorption/debromination removal mechanism was proposed. The degradation of BDE15 with OP-Pd/Fe was mainly stepwise debromination reaction, and hydrogen transfer mode was assumed as the dominated debromination mechanism. The removal process fitted well to the pseudo first-order kinetic equation. The observed rate constants increased with increasing Pd loading and OP-Pd/Fe dosage while decreased with increasing initial BDE15 concentration, the tetrahydrofuran/water ratio, and the initial pH of the solution. The work provides a new approach for the treatment of PBDEs pollution.

Highlights

As a group of nonreactive brominated flame retardant (BFR) chemicals, polybrominated diphenyl ethers (PBDEs) have been widely added to various commercial products in the past decades (Wong et al 2012; Labunska et al 2013)
When using OP as control, the removal efficiency of BDE15 only arrived at 9.3% during 360 min reaction, which was due to the adsorption of the supporting material OP for BDE15
In the reductive debromination stage, the Pd/Fe bimetallic nanoparticles efficiently supported by OP worked as an excellent catalyst for degrading BDE15

Summary

Introduction

As a group of nonreactive brominated flame retardant (BFR) chemicals, polybrominated diphenyl ethers (PBDEs) have been widely added to various commercial products in the past decades (Wong et al 2012; Labunska et al 2013) Because of their high persistence, easy bioaccumulation, and potential toxicity, tetra- to hepta-BDE congeners and deca-BDE have been added to the list of persistent organic pollutants (POPs) under the Stockholm Convention in 2009 and 2019, respectively (Zhu et al 2014; Tan et al 2017; Li et al 2019; Wei et al 2020a; Sarkar and Singh 2021). Effective and feasible reductive methods for removing low brominated PBDEs quickly and completely should be developed

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