无机阴离子对纳米铁铜去除硝酸盐的影响

Effect of Inorganic Anions on Nitrate Reduction by Nano-Fe/Cu Particles

材料应用于地下水中污染修复是近年来的研究热点之一,然而地下水中含有许多共存阴离子,对纳米材料去除硝酸盐的影响较大。本文通过化学还原制备了负载率为5%的纳米铁铜复合材料,探究了纳米铁铜对硝酸盐的催化还原机制,并分析了地下水中常见阴离子(Cl^-,SO_4^(2-),HCO_3^-,PO_4^(3-))对纳米铁铜去除硝酸盐的影响。结果表明,纳米铁铜颗粒的平均粒径为35nm,对硝酸盐的去除过程属于分步进行,亚硝酸盐为中间产物;纳米铁铜足量时,硝酸盐被彻底还原,产物只有氨氮;纳米铁铜不足量时,硝酸盐部分还原,产物为氨氮和亚硝酸盐。纳米铁铜对硝酸盐的去除反应具有伪一级反应动力学特性。Cl^-对硝酸盐的催化还原过程影响不明显,而SO_4^(2-),HCO_3^-,PO_4^(3-)等离子明显抑制了硝酸盐的催化还原过程,且抑制强度随着各离子的浓度增大而增强,其中PO_4^(3-)的抑制作用最强,当PO_4^(3-)浓度为3mmoL·L^(-1)时,纳米铁铜对硝酸盐的去除率仅有10%。

Nano bimetallic materials for removal of nitrate in groundwater is one of the research hotspots in recent years.However,there are many coexisting anions in groundwater,which greatly influence the removal of nitrate by nanomaterials.In this paper,nano-Fe/Cu with a load rate of 5%was prepared by chemical reduction.The mechanism of catalytic reduction of nano-Fe/Cu on nitrate was investigated,and the effects of common anions(Cl-,SO 2-4,HCO-3,PO 3-4)on nitrate removal by nano-Fe/Cu were analyzed.The results show thatthe average particle size of nano-Fe/Cu is 35 nm,and the removal process of nitrate is carried out step by step,with nitrite asan intermediate product.When the amount of nano-Fe/Cu is sufficient,the nitrate is completely reduced and the product has only ammonia nitrogen;when the amountof nano-Fe/Cu is insufficient,the nitrate is partiallyreduced and the product is ammonia nitrogen and nitrite.The reduction of nitrate by nano-Fe/Cushows a kinetic characteristic of pseudo-first-order reaction kinetics.Cl-had no obvious effect on the catalytic reduction of nitrate,while theSO 2-4,HCO-3 and PO 3-4significantly inhibited the catalytic reduction of nitrate,and intensity of inhibition increases with the concentration of each ion.The inhibitory effect of PO 3-4 was the strongest.When the concentration of PO 3-4 was 3 mmol·L-1,the removal rate of nitrate by nano-Fe/Cu was only 10%.