可溶性有机质对凹凸棒土负载铁/镍降解黄棕壤中BDE47的影响

摘要

多溴联苯醚(PBDEs)是一类广泛使用的溴代阻燃剂,在大气、水体、土壤、生物体等环境介质中普遍检出,严重威胁环境安全和人体健康.本文以凹凸棒土负载铁/镍材料(A-Fe/Ni)为修复剂,以普遍检出的2,2′,4,4′-四溴联苯醚(BDE47)为模式化合物,开展了可溶性有机质(DOM)存在条件下,A-Fe/Ni对黄棕壤中BDE47的降解动力学过程研究,探讨了DOM对材料降解BDE47的影响机制.结果表明:A-Fe/Ni可高效地降解黄棕壤–甲醇/水体系中的BDE47,降解过程符合假二级动力学方程,BDE47可被降解成一溴~三溴联苯醚和联苯醚.体系中加入3种DOM(胡敏酸、柠檬酸和草酸)后,DOM在Fe/Ni颗粒表面形成钝化层,抑制了降解过程中的传质和电子传递作用,不同程度降低了A-Fe/Ni对黄棕壤–甲醇/水体系中BDE47的降解效率,并影响其降解产物物质的量的组成.实验结果为使用零价纳米铁及零价纳米铁基双金属材料修复污染土壤中PBDEs提供了理论依据和参考.%Polybrominated diphenyl ethers (PBDEs) are efficient brominated flame retardants, which have been used extensively over recent three decades in various industrial and consumer products. PBDEs have been detected frequently in air, water, soil, sediment, and have attracted increasing attention in recent years because of their increasing levels in animal and human tissues, which can potentially pose serious adverse effects to the environmental safety and human health. Attapulgite- supported Fe/Ni bimetallic nanoparticles (A-Fe/Ni) were prepared to degrade the 2,2′,4,4′-tetrabromodiphenyl ether (BDE47) in this study. The effects of different dissolved organic matters (DOM) on the degradation of BDE47 in contaminated yellow brown soil-water/methanol solutions were investigated through debromination tests under anoxic conditions. A-Fe/Ni could degrade BDE47 effectively in contaminated yellow brown soil-methanol/water solutions, and the degradation process could be well described by the pseudo-second-order kinetics. BDE47 could be degraded into mono- to tri-BDEs and diphenyl ether (DE) by A-Fe/Ni. When the three different DOMs (humic acid, citric acid, and oxalic acid) were added in yellow brown soil-water/methanol solutions, the uptake of DOM on the Fe/Ni particles surface could form a mass and electron transfer barrier that retard the contact and reaction between BDE47 and the reactive sites of nanoparticles. The presence of DOM could obviously decrease the BDE47 degradation efficiency and also affect the profile changes of byproducts formation. The experimental results can provide scientific proofs on the PBDEs contaminated soil remediation using nanoscale zerovalent iron and Fe based bimetallic materials.