Environmental Science Research Institute, Huazhong University of Science and Technology, Wuhan 430074, PR China.
J Hazard Mater. 2010 Apr 15;176(1-3):1101-5. doi: 10.1016/j.jhazmat.2009.11.092. Epub 2009 Nov 24.
We previously reported that microscale Cu/Fe bimetal could be used for the dechlorination of hexachlorobenzene (HCB), a representative polychlorinated persistent organic pollutant (POPs). But slow reduction rate and rather incomplete dechlorination were reached. In this study, HCB dechlorination by nanoscale Fe and Cu/Fe was evaluated. It was found that HCB reduction by nanoscale Fe was rather slow, and the reduction was significantly increased by nanoscale Cu/Fe. Near complete reduction of HCB was obtained by nanoscale Cu/Fe for 48 h treatment. HCB was quickly dechlorinated to PeCB, TeCBs, TCBs and DCBs without selectivity via a stepwise process. The reduction rate and dechlorination extent were much higher compared with microscale Cu/Fe. Lowering pH during reduction showed slightly negative influence on HCB reduction by nanoscale Cu/Fe due to retarded co-precipitation. A catalytic hydrogenation process on Cu surface through iron oxide film was suggested for the increased HCB reduction by Cu coating on nanoscale Fe. This study proved that using a much cheaper bimetallic iron of nanoscale Cu/Fe than nanoscale Pd/Fe could also achieve the effective dechlorination of HCB.
我们之前曾报道过，微尺度的铜/铁双金属可用于六氯苯（HCB）的脱氯反应，HCB 是一种典型的多氯代持久性有机污染物（POPs）。但反应速度较慢且脱氯不完全。在这项研究中，我们评估了纳米尺度的铁和铜/铁对 HCB 的脱氯作用。结果表明，纳米尺度的铁对 HCB 的还原作用相当缓慢，而纳米尺度的铜/铁则显著提高了还原作用。经过 48 小时的处理，纳米尺度的铜/铁几乎可以完全还原 HCB。HCB 可通过逐步过程快速脱氯生成五氯苯、六氯苯、三氯苯和二氯苯，无选择性。与微尺度的铜/铁相比，还原速度和脱氯程度都要高得多。还原过程中降低 pH 值会由于共沉淀的减缓而对纳米尺度的铜/铁还原 HCB 产生轻微的负面影响。提出了通过氧化铁膜在铜表面上进行催化加氢的过程，以解释铜涂层对纳米尺度的铁还原 HCB 能力增强的原因。这项研究证明，使用比纳米尺度 Pd/Fe 便宜得多的纳米尺度 Cu/Fe 双金属也可以实现 HCB 的有效脱氯。
