小分子有机酸对纳米零价铁还原脱氯4-氯联苯的影响

Impact of low-molecular weight organic acids on dechlorination of 4-ClBP by nanoscale zerovalent iron

选取土壤中大量存在的可溶性有机质(DOM)作为试验对象,研究其对纳米零价铁(NZVI)降解4-氯联苯(4-ClBP)的影响。结果表明:初始pH为4.0时,作为对照体系,反应96 h,NZVI对水相中4-Cl BP的还原脱氯效率为65.0%,去除率为74.0%;而分别添加水杨酸(SA)、单宁酸(TA)和没食子酸(GA)的体系中,NZVI对4-Cl BP的还原脱氯效率分别降至54.0%,61.2%和54.6%,去除率分别降至69.9%,70.8和69.5%。添加SA显著抑制了纳米零价铁对4-Cl BP的还原脱氯效率。在上述4种反应体系中,溶液p H值均呈现先快速升高然后达到平衡的趋势。

Nanoscale zero-valent iron （NZVI） has been used to reduce polyehlorinated biphenyls （PCBs）. Howev- er, the effect of dissolved organic matter （DOM） on the dechlorination of PCBs was not well recognized. This study examined the effect of three low weight molecule organic acids, including salicylic acid （ SA）, tannic acid （TA） and gallic acid （GA）, which are widely present in soil, on the dechlorination and removal efficiency of 4-ClBP by NZVI. After 96 h reaction, the dechlorination efficiency of 4-ClBP by NZVI was 65.0%, and the removal efficiency was 74.0%. The dechlorination and removal efficiency of 4-ClBP were 54. 0% and 69. 9% with SA, 61.2% and 70. 8% with TA, and 54. 6% and 69. 5% with GA, respectively. The addition of SA inhibited the reduction of 4-ClBP by NZVI. And in these four reaction system, pH increased rapidly firstly and then reached equilibrium quickly.