新型非均相电-Fenton技术深度处理焦化废水

Advanced Treatment of Coking Wastewater with a Novel Heterogeneous Electro-Fenton Technology

分别采用高效氧气还原阴极PAQ/GF和形稳性阳极IrO2-RuO2-TiO2/Ti做为阴、阳极,填充非均相催化剂,研究一种阴、阳极同时催化氧化的电化学过程,并应用于焦化废水生化出水深度处理.采用在石墨毡上电聚合蒽醌制备PAQ/GF电极,并用循环伏安进行了表征.结果表明,蒽醌在电极表面具有很好的可逆性,并对电催化还原氧气生成过氧化氢(H2O2)表现很高的电催化活性;隔膜电解槽中PAQ/GF做阴极,在-0.7 V(相对饱和甘汞电极)和pH 6下电解6 h后,H2O2浓度为13.5mmol/L,电流效率>50%.采用浸渍法制备了非均相催化剂Fe-Cu/Y350,通过结晶紫褪色反应和羟自由基探针化合物(对氯苯甲酸)氧化反应验证Fe-Cu/Y350催化H2O2产生了羟基自由基(.OH);使用Fe-Cu/Y350催化次氯酸钠氧化处理焦化废水,COD去除率达到26%,远高于没有催化剂时的11%.利用组装的电催化反应器对焦化废水进行处理,COD去除率达到49.4%,远高于传统的双极氧化过程(29.8%),其中阴极与阳极催化过程对COD去除的贡献率分别为26.0%和23.4%.在优化条件下(初始COD=192 mg/L、I=10 A.m-2、pH 4～5)电解1 h后,焦化废水COD去除率>50%.反应途径可能为:氧气在PAQ/GF电极上高效电催化还原为H2 O2,再经Fe-Cu/Y350催化分解产生.OH,从而将有机污染物氧化分解;氯离子在IrO2-RuO2-TiO2/Ti电极氧化产生Cl2或次氯酸,并在Fe-Cu/Y350催化作用下将有机污染物氧化或有机物在阳极直接氧化降解.

A novel electro-catalytic reactor, with oxygen-reduction cathode （PAQ/GF）, dimensionally stable anode （IrO2-RuO2-TiO2 Ti） and heterogeneous catalysts, is developed for advanced treatment of coking wastewater after biological process, integrating cathodic and anodie simultaneous oxidation processes. A PAQ/GF electrode was synthesized by the electro-polymerization of 2-ethyl anthraquinone on graphite felt, which was characterized with cyclic voltametry measurements; the results indicated that the PAQ/GF electrode showed high reversibility for oxidation-reduction reaction of anthraquinone and catalytic activity for 05 reduction to H202; 13.5 mmol/L H2O2 was obtained after electrolysis for 6 h at -0. 7 V （vs. SCE） and pH 6 with a current efficiency of 50% in a membrane reactor. Fe-Cu/Y350 catalysts, prepared by impregnation method, could catalyze the production of hydroxyl radicals （.OH） from H2O2, which was confirmed both by fading reaction of crystal violet and oxidation of ·OH-probe compound （p-chlorobenzoic acid）; Fe-Cu/Y350 also showed high catalytic-activity for the oxidation of organics by hypoehlorous sodium, because COD removal of coking wastewater reached 26% in the catalytic process while only 11% of COD removal was obtained in the absence of Fe-Cu/Y350. COD removal of eoking wastewater reached 49.4% （26.0% and 23.4% in cathodic system and anodic system, respectively） in the developed electrolytic-reactor, which was higher than that of conventional eathodic-anodic-oxidation process （29. 8% ）. At optimal reaction condition of initial COD = 192mg/L, I = 10A· m^-2and pH 4-5, more than 50% COD were removed after electrolysis for 1 h. The mechanism might be as follows： in cathodic system, H2O2 is generated from reduction of 05 on PAQ/GF cathode, and catalyzed by Fe-Cu/Y350 for production of ~ OH, which causes mineralization and degradation of organic pollutants; in anodic system, C12 and HCIO are generated from Cl- oxidation on IrO2-RuO2-TiO2/Ti anode and the organic pollutants are oxidized by CI2 and HC10 with Fe-Cu/Y350 catalysts or by direct anodic oxidation.