纳米铁去除水中硝酸盐氮的批试验

Batch experiment on reduction of nitrate in water by nanoscale zero valent iron particles

采用微乳液法制备出粒径约为80 nm,主要成分为α-Fe的纳米铁粒子。纳米铁具有极高的活性,在无氧环境中,室温、中性条件下与初始质量浓度为30、50、80、120 mg/L的NO3--N振荡反应30 m in,即可获得90%以上的脱硝率。零价纳米铁去除硝酸盐氮的一系列批实验结果表明:硝酸盐与纳米铁反应为非一级动力学反应,硝酸盐氮浓度随时间单调减少,氨氮浓度随时间单调升高,而亚硝酸盐氮的浓度在反应过程中出现极大值,由动力学分析可知其具有连续反应的突出特征,并以此对反应路径进行了探讨。提出纳米铁与硝酸盐反应是氧化还原与吸附作用同时存在且主要产物为氨氮的观点。

The nanoscale α-Fe particles with size of about 80 nm was prepared with a microemulsion method. This kind of Fe particles is characterized by high surface energies, removes mostly 30,50,80,120 mg/L of NO3^--N within a reaction period of 30 min under room temperature, neutral, and anaerobic conditions. The nitrate reduction rate is larger than 90%. Experiments show that during the reaction the [ NO3^-] decreases monotonously, the [ NH4 ^＋] increases monotonously, while the concentration of the intermediate species [ NO2^- ] increases firstly, achieving the maximum value and then decreases, implicating the character of the consecutive reaction instead of the first order reaction. It was suggested that the role of nanoscale iron in the denitrification lies in the directly participaing in the redox reaction accompanied by the adsorption of nitrate, and the major product of the reaction is amonium nitrate.