{"title":"Availability of Seawater as A Chloride Source for UV/electro-chlorine Advanced Oxidation Process","authors":"N. Kishimoto, Koki Hara","doi":"10.2965/jwet.21-080","DOIUrl":null,"url":null,"abstract":"This study reports the availability of seawater as an economical chloride (Cl−) source for the UV/ electro-chlorine process from the viewpoints of advanced oxidation performance and unwanted byproduct formation of chlorate ion (ClO3) and bromate ion (BrO3). In the electrochemical oxidant production stage, the oxidant production rate in diluted seawater containing 30 mM Cl− was 21% lower than that in the NaCl solution due to coexisting electrolytes in the seawater. The ClO3 formation during electrolysis was successfully inhibited under acidic conditions and BrO3 formation was not detected in the diluted seawater. However, ClO3 and BrO3 were steadily formed in the undiluted seawater electrolysis, even when the initial pH value was set to 3. The oxidant utilization efficiency for 1,4-dioxane removal during UV irradiation was not deteriorated in the diluted seawater but decreased under basic conditions due to the radical scavenging effect of electrochemically produced free bromine and free chlorine. As a result, the formation of BrO3 and ClO3 was enhanced under basic conditions, whereas BrO3 formation was completely inhibited at an initial pH ≤ 5. Consequently, the diluted seawater was thought to be available as a Cl− source for the UV/electro-chlorine process if an acidic condition was maintained throughout the operation.","PeriodicalId":17480,"journal":{"name":"Journal of Water and Environment Technology","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2021-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Water and Environment Technology","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.2965/jwet.21-080","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"Environmental Science","Score":null,"Total":0}
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Abstract
This study reports the availability of seawater as an economical chloride (Cl−) source for the UV/ electro-chlorine process from the viewpoints of advanced oxidation performance and unwanted byproduct formation of chlorate ion (ClO3) and bromate ion (BrO3). In the electrochemical oxidant production stage, the oxidant production rate in diluted seawater containing 30 mM Cl− was 21% lower than that in the NaCl solution due to coexisting electrolytes in the seawater. The ClO3 formation during electrolysis was successfully inhibited under acidic conditions and BrO3 formation was not detected in the diluted seawater. However, ClO3 and BrO3 were steadily formed in the undiluted seawater electrolysis, even when the initial pH value was set to 3. The oxidant utilization efficiency for 1,4-dioxane removal during UV irradiation was not deteriorated in the diluted seawater but decreased under basic conditions due to the radical scavenging effect of electrochemically produced free bromine and free chlorine. As a result, the formation of BrO3 and ClO3 was enhanced under basic conditions, whereas BrO3 formation was completely inhibited at an initial pH ≤ 5. Consequently, the diluted seawater was thought to be available as a Cl− source for the UV/electro-chlorine process if an acidic condition was maintained throughout the operation.
本研究从高级氧化性能和氯酸盐离子(ClO3)和溴酸盐离子(BrO3)的有害副产物形成的角度报道了海水作为UV/电氯工艺经济氯化物(Cl−)源的可行性。在电化学氧化剂生成阶段，由于海水中电解质共存，在含有30 mM Cl−的稀释海水中，氧化剂的生成速率比在NaCl溶液中低21%。在酸性条件下，电解过程中ClO3的生成被成功抑制，而在稀释后的海水中没有检测到BrO3的生成。而在未稀释的海水电解过程中，即使初始pH值为3,ClO3和BrO3也能稳定生成。在稀释后的海水中，由于电化学产生的游离溴和游离氯对自由基的清除作用，紫外线照射去除1,4-二恶烷的氧化剂利用效率没有下降，但在碱性条件下则有所下降。结果表明，碱性条件下促进了BrO3和ClO3的生成，而初始pH≤5时则完全抑制了BrO3的生成。因此，如果在整个操作过程中保持酸性条件，则认为稀释后的海水可作为UV/电氯工艺的Cl -源。
期刊介绍：
The Journal of Water and Environment Technology is an Open Access, fully peer-reviewed international journal for all aspects of the science, technology and management of water and the environment. The journal’s articles are clearly placed in a broader context to be relevant and interesting to our global audience of researchers, engineers, water technologists, and policy makers. JWET is the official journal of the Japan Society on Water Environment (JSWE) published in English, and welcomes submissions that take basic, applied or modeling approaches to the interesting issues facing the field. Topics can include, but are not limited to: water environment, soil and groundwater, drinking water, biological treatment, physicochemical treatment, sludge and solid waste, toxicity, public health and risk assessment, test and analytical methods, environmental education and other issues. JWET also welcomes seminal studies that help lay the foundations for future research in the field. JWET is committed to an ethical, fair and rapid peer-review process. It is published six times per year. It has two article types: Original Articles and Review Articles.
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