射频放电诱导还原水中六价铬
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摘要
采用射频放电等离子体对水中六价铬(Cr(Ⅵ))进行还原研究,用高速相机观察了放电过程中等离子体宏观形貌的变化,用光谱仪检测了放电产生的自由基种类,并考察了入射功率、初始pH,Cr(Ⅵ)初始浓度以及羟基自由基(·OH)清除剂对Cr(Ⅵ)还原的影响。结果表明:等离子体形貌在宏观上呈现周期性变化;放电产生了·OH和氢原子(·H)。降低溶液的pH,增加放电的入射功率以及加入·OH清除剂均有利于Cr(Ⅵ)的还原;·H和次级产物过氧化氢(H_2O_2)是Cr(Ⅵ)还原的主要活性物质;射频放电的能量效率高于光催化,与辉光放电和电晕放电相近。利用射频放电还原水中Cr(Ⅵ)是一种高效、简易的水处理技术。
In this study, the radio frequency discharge(RFD) plasma was used to reduce the hexavalent chromium(Cr(Ⅵ)) in wastewater. The macroscopic morphology of the plasma was observed with a high speed camera and the free radicals generated during the discharge were analyzed with an emission spectrometer. The effects of input power, initial pH, initial concentration and hydroxyl radical(·OH) scavenger on Cr(Ⅵ) reduction were examined. The results showed that a periodic macroscopic change occurred on the plasma, ·OH and atomic hydrogen(·H) were formed by the discharge. These two active radicals could lead to pH decrease and input power increase. The ·OH scavenger addition was beneficial to Cr(Ⅵ) reduction. The formed ·H and hydrogen peroxide were the main active species for Cr(Ⅵ) reduction. At the initial pH 2.0, Cr(Ⅵ) removal could reach 99.52% with 30 min discharge treatment. The energy efficiency of RFD is higher than that of photocatalysis, and is comparable to those of glow discharge or corona discharge. The results of Cr(Ⅵ) reduction by RFD indicate it is a high efficient and easy operational wastewater treatment technology, could provide a theoretical basis for Cr(Ⅵ) wastewater treatment.
In this study, the radio frequency discharge(RFD) plasma was used to reduce the hexavalent chromium(Cr(Ⅵ)) in wastewater. The macroscopic morphology of the plasma was observed with a high speed camera and the free radicals generated during the discharge were analyzed with an emission spectrometer. The effects of input power, initial pH, initial concentration and hydroxyl radical(·OH) scavenger on Cr(Ⅵ) reduction were examined. The results showed that a periodic macroscopic change occurred on the plasma, ·OH and atomic hydrogen(·H) were formed by the discharge. These two active radicals could lead to pH decrease and input power increase. The ·OH scavenger addition was beneficial to Cr(Ⅵ) reduction. The formed ·H and hydrogen peroxide were the main active species for Cr(Ⅵ) reduction. At the initial pH 2.0, Cr(Ⅵ) removal could reach 99.52% with 30 min discharge treatment. The energy efficiency of RFD is higher than that of photocatalysis, and is comparable to those of glow discharge or corona discharge. The results of Cr(Ⅵ) reduction by RFD indicate it is a high efficient and easy operational wastewater treatment technology, could provide a theoretical basis for Cr(Ⅵ) wastewater treatment.
引文
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[22]BUXTON G V,DJOUIDER F.Use of the dichromate solution as a dosimeter for high dose and high dose rate[J].Radiation Physics&Chemistry,1996,48(48):799-804.
[23]高青松.隔膜气-液放电等离子体降解水中有机污染物的研究[D].大连:大连海事大学,2017.
[24]邵学俊,董平安,魏益海.无机化学[M].武汉:武汉大学出版社,2003.
[25]司学芝,刘捷,展海军.无机化学[M].北京:化学工业出版社,2009.
[26]何法信.谈谈重铬酸钾与过氧化氢的反应[J].化学通报,1989(5):54-57.
[27]KALECINSSKI J.Radiation reduction of Cr,Mo and W isopolymetalates in aqueous system[J].Journal of Radioanalytical&Nuclear Chemistry,1998,232(1/2):87-90.
[28]JUANG B,GUO J,WANG Z,et al.A green approach towards simultaneous remediations of chromium(Ⅵ)and arsenic(Ⅲ)in aqueous solution[J].Chemical Engineering Journal,2015,262(22):1144-1151.
[29]BUXTON G V,GREENSTOCK C L,HELAN P,et al.Critical review of rate constants for reactions of hydrated electrons,hydrogen atoms and hydroxyl radicals(?OH/?O-)in aqueous solution[J].Journal of Physical&Chemical Reference Data,2009,17(2):513-886.
[30]WANG L,WANG J,ZHANG S,et al.Decomposition and debromination of monobromoacetic acid by radio frequency discharge in an aqueous solution[J].Plasma Chemistry&Plasma Processing,2017,37(6):1-12.
[31]WANG X,JIN X,ZHOU M,et al.Reduction of Cr(Ⅵ)in aqueous solution with DC diaphragm glow discharge[J].Electrochimica Acta,2013,112(12):692-697.
[32]TESTA J J,GRELA M A,LITTER M I.Heterogeneous photocatalytic reduction of chromium(Ⅵ)over TiO2particles in the presence of oxalate:Involvement of Cr(Ⅴ)species[J].Environmental Science&Technology,2004,38(5):1589-1594.
[2]古国榜,李朴.无机化学[M].4版.北京:化学工业出版社,2015.
[3]RAJAPAKSHA A U,ALAM M S,NING C,et al.Removal of hexavalent chromium in aqueous solution using biochar:Chemical and spectroscopic investigations[J].Science of the Total Environment,2018,625:1567-1573.
[4]郭峰.含铬(Ⅵ)废水无害化处理技术研究进展[J].中国资源综合利用,2017,35(8):62-65.
[5]王谦,李延,孙平,等.含铬废水处理技术及研究进展[J].环境科学与技术,2013,36(S2):150-156.
[6]范力,张建强,程新,等.离子交换法及吸附法处理含铬废水的研究进展[J].水处理技术,2009,35(1):30-33.
[7]周栋,高娜,高乐.工业含铬废水处理技术研究进展[J].中国冶金,2017,27(1):2-6.
[8]张昊,谭欣,赵林.废水中重金属离子的光催化还原研究进展[J].天津理工大学学报,2004,20(3):28-32.
[9]KE Z,HUANG Q,ZHANG H,et al.Reduction and removal of aqueous Cr(Ⅵ)by glow discharge plasma at the gas-solution interface[J].Environmental Science&Technology,2011,45(18):7841-7847.
[10]王瑾瑜,孙亚兵,缪虹,等.电晕放电等离子体同时去除水中Cr(Ⅵ)和苯酚的实验研究[J].环境科学学报,2012,32(10):2415-2421.
[11]李承献,邵洪源.含铬废水净化研究进展[J].明胶科学与技术,2015,35(2):55-62.
[12]朱小梅,孙冰,赵娜,等.高压脉冲电絮凝处理含六价铬废水[J].河北大学学报(自然科学版),2010,30(5):538-542.
[13]巩建英.辉光放电等离子体技术处理难降解有机污染物及机理研究[D].上海:上海交通大学,2008.
[14]李天鸣,闫光绪,郭绍辉.低温等离子体放电技术应用研究进展[J].石化技术,2007,14(2):59-63.
[15]刘超越.液相射频放电等离子体降解水中三氯甲烷和腐殖酸的研究[D].大连:大连海事大学,2017.
[16]JI L,ZOU S,SHEN M,et al.Radio frequency underwater discharge operation and its application to congo red degradation[J].Plasma Science and Technology,2012,14(2):111-117.
[17]王蕾.辉光放电等离子体降解水中有机污染物与还原六价铬的研究[D].杭州:浙江大学,2008.
[18]CHANDANA L,SUBRAHMANVA C.Non-thermal discharge plasma promoted redox transformation of arsenic(Ⅲ)and chromium(Ⅵ)in an aqueous medium[J].Chemical Engineering Journal,2017,329:211-219.
[19]ZHANG C,SUN Y,YU Z,et al.Simultaneous removal of Cr(Ⅵ)and acid orange 7 from water solution by dielectric barrier discharge plasma[J].Chemosphere,2017,191:527-536.
[20]赵晓彤,孙冰,朱小梅,等.微波液相放电等离子体发射光谱研究[J].光谱学与光谱分析,2017,37(12):3855-3858.
[21]WANG L,JIANG X.Plasma-induced reduction of chromium(Ⅵ)in an aqueous solution[J].Environmental Science&Technology,2008,42(22):8492-8497.
[22]BUXTON G V,DJOUIDER F.Use of the dichromate solution as a dosimeter for high dose and high dose rate[J].Radiation Physics&Chemistry,1996,48(48):799-804.
[23]高青松.隔膜气-液放电等离子体降解水中有机污染物的研究[D].大连:大连海事大学,2017.
[24]邵学俊,董平安,魏益海.无机化学[M].武汉:武汉大学出版社,2003.
[25]司学芝,刘捷,展海军.无机化学[M].北京:化学工业出版社,2009.
[26]何法信.谈谈重铬酸钾与过氧化氢的反应[J].化学通报,1989(5):54-57.
[27]KALECINSSKI J.Radiation reduction of Cr,Mo and W isopolymetalates in aqueous system[J].Journal of Radioanalytical&Nuclear Chemistry,1998,232(1/2):87-90.
[28]JUANG B,GUO J,WANG Z,et al.A green approach towards simultaneous remediations of chromium(Ⅵ)and arsenic(Ⅲ)in aqueous solution[J].Chemical Engineering Journal,2015,262(22):1144-1151.
[29]BUXTON G V,GREENSTOCK C L,HELAN P,et al.Critical review of rate constants for reactions of hydrated electrons,hydrogen atoms and hydroxyl radicals(?OH/?O-)in aqueous solution[J].Journal of Physical&Chemical Reference Data,2009,17(2):513-886.
[30]WANG L,WANG J,ZHANG S,et al.Decomposition and debromination of monobromoacetic acid by radio frequency discharge in an aqueous solution[J].Plasma Chemistry&Plasma Processing,2017,37(6):1-12.
[31]WANG X,JIN X,ZHOU M,et al.Reduction of Cr(Ⅵ)in aqueous solution with DC diaphragm glow discharge[J].Electrochimica Acta,2013,112(12):692-697.
[32]TESTA J J,GRELA M A,LITTER M I.Heterogeneous photocatalytic reduction of chromium(Ⅵ)over TiO2particles in the presence of oxalate:Involvement of Cr(Ⅴ)species[J].Environmental Science&Technology,2004,38(5):1589-1594.