AC-Fe/Ni联合次氯酸钠去除水中硝酸盐氮

Removal of nitrate nitrogen from water by AC-Fe/Ni combining sodium hypochlorite

随着工业、农业的快速发展,硝酸盐氮(NO_(3)^(−)-N)的污染范围不断扩大、污染程度不断加深,因此,有效去除水中的NO_(3)^(−)-N具有重要意义。本研究通过在活性炭上原位负载零价铁和镍,制备了载铁/镍双金属活性炭(ACFe/Ni),并联合次氯酸钠去除水中的NO_(3)^(−)-N。结果表明,AC-Fe/Ni能够快速还原NO_(3)^(−)-N,反应20 min时NO_(3)^(−)-N的去除率为99.29%,比AC-Fe提高40%,且N2选择性提高8%。AC-Fe/Ni在酸性和碱性条件下均能有效还原NO_(3)^(−)-N,但碱性条件更有利于形成N_(2)。减少材料投加量或提高NO_(3)^(−)-N初始质量浓度均会降低NO_(3)^(−)-N的去除率;共存阴离子、阳离子、有机物对NO_(3)^(−)-N的去除无明显影响。NO_(3)^(−)-N的还原过程总铁释出量仅为0.28 mg·L^(−1),总镍浓度低于0.05 mg·L^(−1)。与此同时,次氯酸钠联用能有效去除出水中的NH_(4)^(+)-N,反应60 min时溶液中残余氨氮仅为0.28 mg·L^(−1)。

With the rapid development of industry and agriculture,the scope of nitrate nitrogen(NO_(3)^(−)-N)pollution continues to expand and the pollution degree becomes increasingly severe.Therefore,it is of great significance to effectively remove NO_(3)^(−)-N in water.In this study,iron/nickel bimetallic nanoparticles loaded activated carbon(AC-Fe/Ni)was prepared by a in-situ reduction method.Subsequently,the AC-Fe/Ni was combined with sodium hypochlorite for the NO_(3)^(−)-N removal.The results show that AC-Fe/Ni could quickly reduce NO_(3)^(−)-N.The removal rate of NO_(3)^(−)-N reached 99.29%after 20 min of reaction,which was 40%higher than the AC-Fe,and the N2 selectivity increased by 8%.AC-Fe/Ni could effectively reduce NO_(3)^(−)-N under both acidic and alkaline conditions,but alkaline condition was more conducive to the formation of N_(2).Reducing the AC-Fe/Ni dosage or increasing the initial NO_(3)^(−)-N concentration decreased the removal rate of NO_(3)^(−)-N.Coexist anions,cations and organic matter had no significant effect on the removal of NO_(3)^(−)-N.The total iron released in the solution was only 0.28 mg·L^(−1) during the reduction process of NO_(3)^(−)-N,and the total nickel concentration was less than 0.05 mg·L^(−1).At the same time,the combination of sodium hypochlorite could effectively remove NH_(4)^(+)-N in the effluent,and the residual NH_(4)-N in the solution after 60 min of reaction was only 0.28 mg·L^(−1).