电氧化-电絮凝对柠檬酸-镍的破络机制研究
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摘要
采用基于Ti/RuO_2-IrO_2和Fe电极的电氧化-电絮凝工艺处理柠檬酸-镍(citrate-Ni)的重金属络合废水,探究电解质、pH、电流密度和处理时间对citrate-Ni的影响及破络行为。实验结果表明,采用NaCl为电解质,初始pH值为5,电流密度为100A/m~2,电氧化反应25min,电絮凝反应20min时,Ni和COD的去除率分别可以达到99.6%和75%,出水Ni和COD的浓度均满足《电镀污染物排放标准》(GB 21900-2008)的要求。Citrate-Ni的破络机制为:通过Ti/RuO_2-IrO_2直接氧化和间接氧化产物HOCl的作用,破坏其络合结构,生成C_3H_6O、HCOOH、CH_3COOH、C_3H_6O_3、C_4H_8O_3和C_5H_6O_5等小分子物质,同时释放Ni~(2+);再利用Fe-电絮凝产生的新生态Fe(OH)_2对Ni~(2+)的吸附和混凝沉淀作用将其去除。
An experimental study was carried out focusing on breakdown of citrate-Ni complex in wastewater by using the electrooxidation-electrocoagulation process based on Ti/RuO_2-IrO_2and Fe electrolyte,in which effects of the electrolyte and parameters of initial pH value,current density and electrolytic time on citrate-Ni and its decomplexation behavior were investigated.As a result,high removal rates were achieved(99.6%of Ni,75%of COD_(Cr))under the condition,i.e.,initial pH 5,100A/m~2of current density,25 min of electrochemical oxidation reaction time,and 20 min of electrocoagulation reaction time with the NaCl as the electrolyte;and concentrations of Ni and COD in the wastewater being treated met the requirements of the Emission Standard of Pollutants for Electroplating(GB 21900-2008).In addition,it was also found that the de-complexation mechanism of citrate-Ni related to the complex structure breakdown to small molecules such as C_3H_6O,HCOOH,CH_3COOH,C_3H_6O_3,C_4H_8O_3 and C_5H_6O_5,etc.,through direct oxidation of Ti/RuO_2-IrO_2 and the indirect oxidation product(HOCl),and Ni was finally removed by adsorption and coagulation of the fresh Fe(OH)_2that was produced by Fe-electrocoagulation.
An experimental study was carried out focusing on breakdown of citrate-Ni complex in wastewater by using the electrooxidation-electrocoagulation process based on Ti/RuO_2-IrO_2and Fe electrolyte,in which effects of the electrolyte and parameters of initial pH value,current density and electrolytic time on citrate-Ni and its decomplexation behavior were investigated.As a result,high removal rates were achieved(99.6%of Ni,75%of COD_(Cr))under the condition,i.e.,initial pH 5,100A/m~2of current density,25 min of electrochemical oxidation reaction time,and 20 min of electrocoagulation reaction time with the NaCl as the electrolyte;and concentrations of Ni and COD in the wastewater being treated met the requirements of the Emission Standard of Pollutants for Electroplating(GB 21900-2008).In addition,it was also found that the de-complexation mechanism of citrate-Ni related to the complex structure breakdown to small molecules such as C_3H_6O,HCOOH,CH_3COOH,C_3H_6O_3,C_4H_8O_3 and C_5H_6O_5,etc.,through direct oxidation of Ti/RuO_2-IrO_2 and the indirect oxidation product(HOCl),and Ni was finally removed by adsorption and coagulation of the fresh Fe(OH)_2that was produced by Fe-electrocoagulation.
引文
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[28]代冬梅,徐睿,王玉军,等.电絮凝处理牛仔布印染废水[J].环境工程学报,2014,8(7):2947-2951.Dai Dongmei,Xu Rui,Wang Yujun,et al.Treatment of denim dyeing and printing wastewater by electric flocculation[J].Chinese Journal of Environmental Engineering,2014,8(7):2947-2951.
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[30]Barrera Díaz C,Ure?a Nu?ez E,Campos E,et al.A combined electrochemical-irradiation treatment of highly colored and polluted industrial wastewater[J].Radiation Physics and Chemistry,2003,67(5):657-663.
[2]Li Z,Dong H,Zhang Y,et al.Enhanced removal of Ni(Ⅱ)by nanoscale zero valent iron supported on Na-saturated bentonite[J].Journal of Colloid and Interface Science,2017,497:43-49.
[3]Chaudhary A J,Donaldson J D,Grimes S M,et al.Separation of nickel from cobalt using electrodialysis in the presence of EDTA[J].Journal of Applied Electrochemistry,2000,30(4):439-45.
[4]陈健俊,孙贤波,王英华,等.UV/H2O2协同光降解处理酒石酸镍废水[J].环境工程学报,2016,10(8):4284-4288.Chen Jianjun,Sun Xianbo,Wang Yinghua,et al.Photo-degradation of tartaric nickel wastewater by UV/H2O2process[J].Chinese Journal of Environmental Engineering,2016,10(8):4284-4288.
[5]Xu H Y,Yang Z H,Luo Y L,et al.A novel approach to sustain Fe0-electrocoagulation for Cr(Ⅵ)removal by optimizing chloride ions[J].Separation and Purification Technology,2015,156:200-206.
[6]Xu H Y,Yang Z H,Zeng G M,et al.Investigation of pH evolution with Cr(Ⅵ)removal in electrocoagulation process:proposing a real-time control strategy[J].Chemical Engineering Journal,2014,239:132-140.
[7]Yang Z H,Xu H Y,Zeng G M,et al.The behavior of dissolution/passivation and the transformation of passive films during electrocoagulation:influences of initial pH,Cr(Ⅵ)concentration,and alternating pulsed current[J].Electrochim Acta,2015,153:149-158.
[8]Li G,Zhu W,Chai X,et al.Partial oxidation of polyvinyl alcohol using a commercially available DSA anode[J].Journal of Industrial and Engineering Chemistry,2015,31:55-60.
[9]Gumpu M B,Sethuraman S,Krishnan U M,et al.A review on detection of heavy metal ions in water:an electrochemical approach[J].Sensors Actuators B:Chem,2015,213:515-533.
[10]任学昌,史载锋,孔令仁,等.Ti O2薄膜光催化体系中羟基自由基的水杨酸分子探针法测定[J].环境科学学报,2008,28(4):705-709.Ren Xuechang,Shi Zaifeng,Kong Lingren,et al.Salicylic acid as a molecular probe to determine hydroxyl free radicals in a Ti O2thin films photocatalytic system[J].Acta Scientiae Circumstantiae,2008,28(4):705-709.
[11]Sillanp M,Sorvari J,Sihvonen M L.Low-level determination of EDTA and DTPA in natural waters by gas chromatography[J].Chromatographia,1996,42(9):578-582.
[12]Oviedo C,Contreras D,Freer J,et al.Fe(Ⅲ)-EDTA complex abatement using a catechol driven Fenton reaction combined with a biological treatment[J].Environmental Technology,2004,25(7):801-807.
[13]Wang J,Wang X,Li G,et al.Degradation of EDTA in aqueous solution by using ozonolysis and ozonolysis combined with sonolysis[J].Journal of Hazardous Materials,2010,176(1/2/3):333-338.
[14]Li J,Yang Z H,Xu H Y,et al.Electrochemical treatment of mature landfill leachate using Ti/Ru O2-Ir O2and Al electrode:optimization and mechanism[J].RSC Advances,2016,6(53):47509-47519.
[15]Song P,Yang Z,Zeng G,et al.Electrocoagulation treatment of arsenic in wastewaters:a comprehensive review[J].Chemical Engineering Journal,2017,317:707-725.
[16]卢凯歌,李新宝,吕建波,等.电化学处理黄姜生化尾水研究[J].环境科学学报,2013,33(8):2174-2180.Lu Kaige,Li Xinbao,Lyu Jianbo,et al.Electrochemical treatment of biotreated effluent of turmeric wastewater[J].Acta Scientiae Circumstantiae,2013,33(8):2174-2180.
[17]谭竹,杨朝晖,徐海音,等.铝铁电极联用电絮凝法处理Cu-EDTA络合废水[J].环境工程学报,2014,8(8):3167-3173.Tan Zhu,Yang Zhaohui,Xu Haiyin,et al.Removal of CuEDTA from aqueous solution by electrocoagulation using Al and Fe electrodes[J].Chinese Journal of Environmental Engineering,2014,8(8):3167-3173.
[18]Liu S,Sun H,Sun L,et al.Effects of pH and Cl-concentration on corrosion behavior of the galvanized steel in simulated rust layer solution[J].Corrosion Science,2012,65:520-527.
[19]Keshmirizadeh E,Yousefi S,Rofouei M K.An investigation on the new operational parameter effective in Cr(Ⅵ)removal efficiency:a study on electrocoagulation by alternating pulse current[J].Journal of Hazardous Materials,2011,190(1/2/3):119-124.
[20]Oturan N,Wu J,Zhang H,et al.Electrocatalytic destruction of the antibiotic tetracycline in aqueous medium by electrochemical advanced oxidation processes:effect of electrode materials[J].Applied Catalysis B:Environmental,2013,140/141:92-97.
[21]Kaur P,Kushwaha J P,Sangal V K.Evaluation and disposability study of actual textile wastewater treatment by electro-oxidation method using Ti/Ru O2anode[J].Process Safety and Environmental Protection,2017,111:13-22.
[22]Younis A A,El Sabbah M M B,Holze R.The effect of chloride concentration and pH on pitting corrosion of AA7075aluminum alloy coated with phenyltrimethoxysilane[J].Journal of Solid State Electrochemistry,2012,16(3):1033-1040.
[23]Huang J,Yang Z H,Zeng G M,et al.Influence of composite flocculant of PAC and MBFGA1 on residual aluminum species distribution[J].Chemical Engineering Journal,2012,191(15):269-277.
[24]Iniesta J,Michaud P A,Panizza M,et al.Electrochemical oxidation of phenol at boron-doped diamond electrode[J].Electrochim Acta,2001,46(23):3573-3578.
[25]李国亭,王海荣,李东颖,等.紫外光协助下DSA电极对1,4-苯醌的强化开环作用研究[J].环境科学,2009,30(7):1955-1961.Li Guoting,Wang Hairong,Li Dongying,et al.Enhanced decomposition of 1,4-benzoquinone ring by DSA electrode under ultraviolet irradiation[J].Chinese Journal of Environmental Science,2009,30(7):1955-1961.
[26]Dubrawski K L,Mohseni M.In-situ identification of iron electrocoagulation speciation and application for natural organic matter(NOM)removal[J].Water Research,2013,47(14):5371-5380.
[27]Isa M H,Ezechi E H,Ahmed Z,et al.Boron removal by electrocoagulation and recovery[J].Water Research,2014,51(0):113-123.
[28]代冬梅,徐睿,王玉军,等.电絮凝处理牛仔布印染废水[J].环境工程学报,2014,8(7):2947-2951.Dai Dongmei,Xu Rui,Wang Yujun,et al.Treatment of denim dyeing and printing wastewater by electric flocculation[J].Chinese Journal of Environmental Engineering,2014,8(7):2947-2951.
[29]Mart Nez Huitle C A,Brillas E.Decontamination of wastewaters containing synthetic organic dyes by electrochemical methods:a general review[J].Applied Catalysis B:Environmental,2009,87(3/4):105-145.
[30]Barrera Díaz C,Ure?a Nu?ez E,Campos E,et al.A combined electrochemical-irradiation treatment of highly colored and polluted industrial wastewater[J].Radiation Physics and Chemistry,2003,67(5):657-663.