共存阴离子对铂电极电解含溴水时溴酸盐生成的影响
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摘要
电化学消毒时,共存离子可能对BrO_3~-副产物生成规律产生影响。以常用Ti/Pt电极作为阳极电解含溴水模拟电化学消毒过程,分别考察不同浓度SO_4~(2-)、Cl~-、HCO_3~-、NO-3对BrO_3~-形成的影响。中性条件下,共存SO_4~(2-)浓度增大,可抑制BrO_3~-的形成; SO_4~(2-)在Pt电极表面产生过氧硫酸盐和过氧化单硫酸盐,占据电极活性位点从而减少Br-被直接或间接氧化的几率。共存Cl~-、HCO_3~-和NO-3浓度增大时,都对BrO_3~-的形成表现出促进作用。Cl~-共存时,电化学体系中的电生HCl O/Cl O-是促进作用的主因; NO-3易在阴极发生还原,减少不分槽电极体系中BrO_3~-的还原几率,促进BrO_3~-生成的同时,还带了NO-2生成的潜在风险。在总离子强度(12.56 mmol/kg)相同的前提下,比较不同共存组分对BrO_3~-生成的影响效应发现,共存NO-3对BrO_3~-生成的促进作用明显强于Cl~-和HCO_3~-; 120 min电解后,含有NO-3的电化学体系内BrO_3~-生成量为含有Cl~-和HCO_3~-条件下的3.21倍和2.69倍。
Coexisting ions may affect the formation of BrO_3~- during electrochemical disinfection. This experiment uses the platinum electrode as anode electrolyzing the bromide-containing water. The effects on BrO_3~- formation with different concentrations of SO2-,Cl~-,HCO_3~- and NO-3 are taken into consideration. Under neutral conditions,the increase of SO_4~(2-) can inhibit the formation of BrO_3~-; the persulfate and peroxide single sulfate generated on the surface of Pt electrode can occupy the active sites and reduce the probability of Br-being directly or indirectly oxidized,which reduces BrO_3~- formation. The coexisting Cl~-,HCO_3~- and NO-3 bringt more BrO_3~- with more concentrations. The HCl O/Cl Oproduced by Cl~-is the main reason for promoting BrO_3~- formation. Reduction reaction of NO-3 is easy to happen to cathode,reducing the reduction probability of BrO_3~- in the system of non-slotted electrode can promote BrO_3~- generation. On the other hand,the potential risk of NO-2 might take place. Under the conditions of same ionic strength( 12. 56 mmol/kg),the results of BrO_3~- generation are compared,the NO-3 promoting efficiency is more obvious than coexisting Cl~-and HCO_3~-. After 120 min electrolysis,BrO_3~- generation with NO-3 is 3.21 times and2.69 times of Cl~-and HCO_3~- conditions,respectively.
Coexisting ions may affect the formation of BrO_3~- during electrochemical disinfection. This experiment uses the platinum electrode as anode electrolyzing the bromide-containing water. The effects on BrO_3~- formation with different concentrations of SO2-,Cl~-,HCO_3~- and NO-3 are taken into consideration. Under neutral conditions,the increase of SO_4~(2-) can inhibit the formation of BrO_3~-; the persulfate and peroxide single sulfate generated on the surface of Pt electrode can occupy the active sites and reduce the probability of Br-being directly or indirectly oxidized,which reduces BrO_3~- formation. The coexisting Cl~-,HCO_3~- and NO-3 bringt more BrO_3~- with more concentrations. The HCl O/Cl Oproduced by Cl~-is the main reason for promoting BrO_3~- formation. Reduction reaction of NO-3 is easy to happen to cathode,reducing the reduction probability of BrO_3~- in the system of non-slotted electrode can promote BrO_3~- generation. On the other hand,the potential risk of NO-2 might take place. Under the conditions of same ionic strength( 12. 56 mmol/kg),the results of BrO_3~- generation are compared,the NO-3 promoting efficiency is more obvious than coexisting Cl~-and HCO_3~-. After 120 min electrolysis,BrO_3~- generation with NO-3 is 3.21 times and2.69 times of Cl~-and HCO_3~- conditions,respectively.
引文
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[16]张冬梅.电化学催化还原去除水中硝酸根的研究[D].山东青岛:青岛科技大学,2013.
[2] Bergmann M E H,Koparal A S,Iourtchouk T. Electrochemical advanced oxidation processes,formation of halogenate and perhalogenate species:a critical review[J]. Critical Reviews in Environmental Science and Technology,2014,44(4):348-390.
[3]姜俐峰.不同阳极电化学消毒过程中溴酸盐的形成[D].太原:太原理工大学,2016.
[4] Kim M K,Zoh K D. Effects of natural water constituents on the photo-decomposition of methylmercury and the role of hydroxyl radical[J].Science of the Total Environment,2013,449(2):95-101.
[5]任学昌,张国珍,朱亚敏,等.水体中常见无机阴离子对Ti O2薄膜光催化还原Cr(Ⅵ)的影响[J].环境化学,2009,28(6):829-832.
[6] Gunten U V,Hoigen J. Bromate formation during ozonization of bromide-containing waters:interaction of ozone and hydroxyl radical reactions[J]. Environmental Science and Technology,1994,28(7):1 234-1 242.
[7] Xie P,Ma J,Liu W,etal. Removal of 2-MIB and geosmin using UV/persulfate:contributions of hydroxyl and sulfate radicals[J]. Water Research,2015,69:223-233.
[8]姜俐峰,张峰,崔建国,等.电解含溴饮用水过程中溴酸盐的形成[J].中国农村水利水电,2017,(1):125-129.
[9] Comninellis C. Electrocatalysis in the electrochemical conversion/combustion of organic pollutants for waste water treatment[J]. Electrochimica Acta,1994,39(11-12):1 857-1 862.
[10] Conway B E,Phillips Y,Qian S Y. Surface electrochemistry and kinetics of anodic bromine formation at platinum[J]. Journal of the Chemical Society Faraday Transactions,1995,91(2):283-293.
[11] Ferro S,Battisti A D. The bromine electrode. Part I:Adsorption phenomena at polycrystalline platinum electrodes[J]. Journal of Applied Electrochemistry,2004,34(10):981-987.
[12] Ferro S,Orsan C,Battisti A D. The bromine electrode. Part II:Reaction kinetics at polycrystalline Pt[J]. Journal of Applied Electrochemistry,2005,35(3):273-278.
[13] Oloman C. Electrochemical processing for the pulp and paper industry[J]. Electrochemical Consultancy,1996.
[14] Borutzky U M,Bergmann M E H,Wenzel J,etal. Pseudomonas inactivation with electrolyzed water poor in chloride ions using BDD electrodes[C]∥Meeting of the International Society of Electrochemistry,2006.
[15]冯玉杰.电化学技术在环境工程中的应用[M].北京:化学工业出版社,2002,(5):76-94.
[16]张冬梅.电化学催化还原去除水中硝酸根的研究[D].山东青岛:青岛科技大学,2013.