一种新型电化学法处理硝态氮废水的初步研究

通过对Pd-Me双金属催化还原NO 3--N和折点氯化法处理NH 4+-N的相关理论分析,提出了一种基于电化学法的新型NO 3--N废水处理工艺.即利用具有电子空轨的常见金属元素修饰Ti基获得催化阴极,在电场的作用下,将NO 3--N催化还原;通过调整催化元素的配比和电解条件,控制NO 3--N还原产物主要为NH 4+-N;利用阳极氧化Cl-生成高氧化性物质HOCl,将NH 4+-N氧化为无害产物N2-N.结果表明,金属元素Co和Cu修饰Ti基制得阴极可以有效地催化还原模拟废水中的NO 3--N;按前驱物溶液金属元素摩尔比1∶1制得Ti基Co-Cu复合涂层催化阴极,可以将NO 3--N高效催化还原为NH 4+-N;电解体系中引入Cl-后,通过阳极作用可将NO 3--N还原生产的NH 4+-N有效地氧化为N2-N.在100 mg/L NO 3--N模拟废水中添加1 000 mg/L Cl-,设置极板间距6 mm、电流400 mA,电解2.5 h后出水NO 3--N、NO 2--N、NH 4+-N和TN分别为2.9、0.5、1.7和6.0 mg/L.

Preliminary Research on a New Method of NO-3-N Wastewater Treatment Based on Electrochemistry

A new method based on electrochemistry was presented to treat NO3- -N wastewater by analyzing theories of Pd-Me bimetal catalytic reduction of NO3- -N and NH4+ -N break point chlorination process. Presented method mainly includes following characteristics. Firstly, NO3- -N can be catalytically reduced in electric field while Ti substrate cathode was modified by common metallic elements which have empty electronic track. Secondly, NO3- -N reduction product can be controlled mainly is NH4+ -N by adjusting ratio of catalytic elements and electrolysis conditions. Finally, NH4+ -N is oxidized to harmless product N2-N by HOCl which produced from Cl- by anode oxidation process. Experiments were carried out to verified upwards theoretical assumptions. It's indicated that cathode modified by metal elements of Co and Cu can catalytic reduce NO3- -N in simulated wastewater effectively, as well as reduction product mainly was NH4+ -N while the molar ratio of Co and Cu in cathode precursor solution was 1:1. If Cl- was added to electrolysis system, NH4+ -N produced from NO3- -N reduction could be oxidized to N2-N by the anode action. Under the conditions of plate distance of 6mm, electric current of 400 mA and electrolysis time of 2.5 h, the concentration of NO3- -N, NO2- -N, NH4+ -N, and TN of simulated wastewater which initially contain 100 mg/L NO3- -N and 1000 mg/L Cl- decreased to 2.9 mg/L, 0.5 mg/L, 1.7 mg/L and 6.0 mg/L respectively.