摘要
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.
出处
《环境科学》
EI
CAS
CSCD
北大核心
2011年第1期171-178,共8页
Environmental Science
基金
国家高技术研究发展计划(863)项目(2007AA06Z327)
国家自然科学基金项目(20607023)
国家水体污染控制与治理科技重大专项(2008ZX07207-003
2008ZX0708-004)
关键词
焦化废水
电芬顿
高级氧化
深度处理
非均相催化剂
coking wastewater
electro-Fenton
advanced oxidation process
advanced treatment
heterogeneous catalyst