Quantitative description of the chloride effect on chlorine dioxide generation from the ClO2-HOCl reaction

The generation of chlorine dioxide from the reaction between hypochlorous acid and chlorite with or without an initial chloride addition has been studied under slightly acidic conditions. Chloride (Cl-), one of the products from the reaction, not only changes the reaction stoichiometry, but also alters the rate law. It was found that the formation of chlorine dioxide from the HOCI-ClO₂- system consists of two distinct parts, one is promoted by chloride, the other is independent of chloride. The overall kinetics of the chlorine dioxide generation from the reaction is: This model can very well predict the reaction under the following conditions: $ 273 - 303{\rm K},\left[ {ClO_2^ - } \right] = 0.001 - 0.00267\;{\rm mol}/{\rm L},\left[ {ClO_2^ - } \right]/\left[ {HOCl} \right] = 2,\;{\rm and}\;{\rm pH}\;3.86 - 4.91 $     

缓释型固体二氧化氯的制备及其释放通量的影响因素

近年来二氧化氯生产方法和应用方面的研究已成为化工和环保的热点。本文从开拓二氧化氯的应用市场着眼, 并结合环境友好的理念, 以蔗渣浆羧甲基纤维素接枝丙烯酸制备的高吸水树脂为缓释基材, 琼脂为交联剂, 制成一种新型长效缓释型固体二氧化氯, 并考察了它的影响因素。实验结果表明:酸性活化剂的种类和用量、蔗渣浆纤维基质高吸水树脂的用量、温度、稳定性二氧化氯溶液的浓度是影响固体二氧化氯释放通量的因素, 且柠檬酸是最佳的缓释活化剂, 固体ClO₂及含固体ClO₂的产品应在低温下保存, 制备长效缓释型的产品, 稳定性二氧化氯溶液的浓度不宜超过l%。研究结果表明:新型缓释型固体二氧化氯制备工艺简单, 价格低廉, 使用安全有效;设计不同平均释放通量, 不同有效释放时间的固体二氧化氯产品可以根据使用环境, 添加不同浓度的稳定性二氧化氯溶液、不同数量的缓释基材、控制酸性活化剂的种类和加入量来实现, 对二氧化氯的广泛应用具有一定的理论和实践指导作用。     

Oxidation of phenol in a bioremediation medium using chlorine dioxide

BACKGROUND: High concentrations of phenol in wastewater are difficult to remove by purely biological methods. Chemical oxidation is one way to treat high concentrations of phenol but complete oxidation will make the treatment process uneconomical. For the purpose of integrating chemical and biological treatment, the oxidation of phenol using chlorine dioxide was investigated in a medium suitable for bioremediation. The effects of chlorine dioxide concentration (500 to 2000 mg L^?1), temperature (10 to 40 °C) and pH (3 to 7) on the oxidation of 2000 mg L^?1 of phenol were determined. RESULTS: Chlorine dioxide concentration was found to be the dominant parameter for the removal of phenol in the nutrient rich medium. The optimal concentration of chlorine dioxide to completely oxidize 2000 mg L^?1 of phenol was 2000 mg L^?1. Compared with Fenton's reagent, half as much chlorine dioxide was needed to oxidize 2000 mg L^?1 phenol. The reaction of chlorine dioxide with phenol was very fast and reached equilibrium within 10 min. The main oxidation products were identified as 1,4‐benzoquinone and 2‐chloro‐1,4‐benzoquinone. CONCLUSION: Compared with Fenton's reagent, chlorine dioxide is a superior oxidant for removal of phenol from both pure water and bioremediation medium. Copyright © 2010 Society of Chemical Industry     

稳定性二氧化氯溶液中二氧化氯存在形态的研究

首先通过理论分析,认为二氧化氯（ClO2）在稳定性二氧化氯溶液（简称稳定液）中存在的形态根据所用稳定剂的不同而有区别。通过对几种样品的红外光谱分析、纸色谱分析、酪氨酸显色反应及抗酸缓冲能力的测定,证实在以过碳酸钠为稳定剂的稳定液中,ClO2以亚氯酸根离子（ClO2^-）形式存在,并处在一个由NaHCO3-Ha2CO3组成的缓冲体系中;在以过硼酸钠为稳定剂的稳定液中,ClO2可能是以活性配位化合物的形式存在,并处在由H3BO3-Na2B4O7组成的缓冲体系中。这一结论对稳定性二氧化氯溶液的生产、贮存和应用具有重要的指导作用。     

Ozone and chlorine dioxide: Similar chemistry and measurement issues

The chemical reactions associated with ozone and chlorine dioxide can be complicated and involve numerous intermediates. When ozone is applied, the presence of reactive intermediate species (O₂ ^‐, O₃ ^‐, OH, HO₂, HO₂ ^‐, and H₂O₂) influence the extent of oxidation that takes place and determines the amount and types of by‐products formed. Similarly, when chlorine dioxide is applied the amount of intermediate (Cl₂O₂) formed determines whether chlorine dioxide producing reactions or chlorate ion forming reactions occur. Ozone and chlorine dioxide are excellent agents for inactivating Cryptosporidium and Giardia. Microbiologically, each of the agents are very reactive. In the case of ozone, typically each molecule undergoes a one‐electron change. The mechanism of chlorine dioxide inactivation involves a recycling process whereby chlorine dioxide is reduced to chlorite ion followed by the “regeneration” of chlorine dioxide that continues to react within the cell over and over again. Chlorite ion also has oxidizing power and in some cases, is a biocide. When ozone and chlorine dioxide are used in combination, it is important that the chlorine dioxide application follow the ozone treatment to prevent the formation of unwanted by‐products such as ClO₃ ^‐.     

Synthese und Reaktionsverhalten von N-(3-Chlorbenzo[b]-thiophen-2-carbonyl)imino-Dithiokohlensäure-Derivaten

Synthesis and Reaction Behaviour of N-(3-Chlorobenzo[b]thiophene-2-carbonyl)-imino-dithiocarbonic Derivatives 3-Chlorobenzo[b]thiophene-2-carbonyl-chloride 1 was treated with potassium rhodanide to afford the appropriate acyl isothiocyanate 3 , which adds nucleophilic agents as amines and thioles in good yields. Addition of methanethiole and subsequent alkylation of the dithiocarbamate 7 gives S, S-dimethylimino-dithiocarbonate 8 . 3-Chlorobenzo[b]thiophene-2-carboxamide 2 reacts with carbon disulphide and phenyl isothiocyanate by chlorine substitution and cyclisation to benzo[b]thieno[2, 3-e]thiazines 9, 10 or 11 . The structure of the final products were determined by analytical and spectroscopical dates.     

The kinetics and mechanism of the chloride-chlorate reaction

The kinetics of the reaction have been studied at 25°C. in strong acid solution; the effects of acidity, chloride, chlorate and chlorine are reported. A mechanism is postulated to interpret the peculiar features of this reaction as well as the stoichiometry and some of the kinetics of the parallel reaction The mechanism involves HClO₂ and HOCl as intermediates General rate expressions are derived for the formation of chlorine dioxide and chlorine, and the individual rate constants are calculated. An expression is obtained for the relationship between the ratio of chlorine dioxide to chlorine produced and the ratio of chlorate to chloride.     

Studies on the Reactions of Phenolic and Non-Phenolic Lignin Model Compounds with Chlorine Dioxide

The reaction between chlorine dioxide and four different lignin model compounds (phenolic and non-phenolic, with or without an α-hydroxyl group) are studied. The key difference with previous studies is the effective elimination of hypochlorous acid by sulfamic acid during chlorine dioxide treatment. The elimination of hypochlorous acid, an important intermediate formed during chlorine dioxide bleaching, makes it possible to study the consumption of the lignin model compounds solely as a result of the action of chlorine dioxide.

Based on almost closed mass balances for the substrate and atomic chlorine it is found that the reaction between ClO₂ and lignin model compounds is generally characterized by three independent parallel reactions:

1) demethylation, 2) formation of 2-methoxy-p-quinone and 3) formation of muconic acid monomethyl ester and/or its derivatives. Although, the importance of each reaction depends on the functional groups of the substrate, the demethylation reaction is the most important. It is shown that non-phenolic lignin model compounds do react with ClO₂ when ClO₂ is supplied in large excess. However at conditions representative of industrial ClO₂ application levels, only the phenolic substrates react with chlorine dioxide when both phenolic and non-phenolic lignin model compounds are present. Contrary to the previous model compound studies done without effective elimination of hypochlorous acid, no chloroaromatic material is detected in the present investigation. This supports the view that the reaction intermediate hypochlorous acid (or chlorine) is solely responsible for the formation of chloro organic material during chlorine dioxide bleaching. Reaction mechanisms of the degradation of phenolic and non-phenolic lignin model compounds by CI0₂ are also discussed.     

REACTIONS OF PINOSYLVIN AND PINOSYLVIN DIMETHYL ETHER WITH CHLORINE DIOXIDE

Products from the reaction of pinosylvin 1a and pinosylvin dimethyl ether 1b with chlorine dioxide were characterized. Pinosylvin was more extensively degraded and gave benzoic acid, traces of other monomeric carboxylic acids, 2,6-dichloro- and 2,4,6-trichloropinosylvin 2, (n = 2 and 3), the benzilic acid rearrangement product 3 and the maleic acids 4a and 4b. Pinosylvin dimethyl ether gave similar monomeric products, the dichloroderivative 5, the dichloroepoxide 6 and a small amount of the dichlorohydroxyketone 7.     

二氧化氯催化氧化H酸废水

采用浸渍法制备Ni-Zn/γ-Al₂O₃催化剂,用于二氧化氯催化氧化处理染料中间体H酸废水,研究废水初始pH、二氧化氯加入量、催化剂用量、反应时间和催化剂重复使用等因素对H酸废水TOC去除率的影响。最佳实验条件为：pH为中性偏碱性范围,V(二氧化氯)∶V(废水)＝0.20,Ni-Zn/γ-Al₂O₃催化剂的加入量为20 g·L^－1,反应时间60 min,Ni-Zn/γ-Al₂O₃催化剂能连续使用7次而保持稳定的催化活性,对H酸废水的TOC去除率为75.94%,与单独化学氧化效果相比,TOC去除率提高了191%。     

Lewis acid induced additions to unsaturated fatty compounds IV: Synthesis of cyclopentenones from Friedel- Crafts acylation products of unsaturated fatty compounds with α,β-unsaturated acyl chlorides

The ethylaluminium dichloride induced Friedel- Crafts acylation of unsaturated fatty compounds such as oleic acid ( 1a ), methyl oleate ( 1b ) and 10-undecenoic acid ( 9b ) and furthermore of 1-octene ( 9a ) with α,β-unsaturated acyl chlorides e.g. crotonic acid chloride ( 2a ) and acrylic acid chloride ( 2b ) gave the corresponding allyl vinyl ketones. Nazarov cyclizations of the acylation products 3a/4a, 3b/4b, 10a and 10b afforded the alkyl substituted 2-cyclopentenones 5a/6a, 5b/6b, 11a/12a and 11b/12b . Catalytic hydrogenation of 5b/6b and 11b/12b gave the respective saturated cyclic products 7b/8b and 13b/14b as diastereomeric mixtures.     

氯酸钠法制备二氧化氯还原剂研究进展

对比介绍了氯酸钠法生产二氧化氯常用还原剂的特点;综述了氯酸钠法制备二氧化氯新还原剂（硫化合物、多元醇、有机酸、碳水化合物、尿素和乙二醛）的研究进展;讨论了氯酸钠法制备二氧化氯有机还原剂甲醇和乙二醛的作用机理;指出采用复合还原剂降低生产成本和采用有机还原剂同时制备两种有用产品是氯酸钠法制备二氧化氯还原剂发展趋势。     

稳定态二氧化氯的测定

用常规法测定成品稳定态二氧化氯的杂质，常有干扰。用蒸馏－滴定法，在H2SO4等酸性溶液中，将ClO2蒸出，吸收于KI溶液中，再用Na2S2O3标准溶液滴定析出的碘，可迅速、方便地测定稳定态二氧化氯。该法NaClO3和NaClO2杂质无干扰。同时对蒸馏时酸的选择、蒸馏时间、吸收液酸度与反应所需时间及方法的重现性进行了比较。     

Development of Phenolic Lignin During ClO2 Bleaching of Kraft Pulp

The development of the phenolic lignin content in kraft pulp during ClO₂ bleaching was quantitatively determined by the periodate oxidation method. The effect of hypochlorous acid, an intermediate formed during chlorine dioxide bleaching, was eliminated by addition of sulfamic acid, a scavenger of hypochlorous acid. It was found that the number of free phenolic lignin groups per 100 lignin monomer units decreased from about 29 for unbleached kraft lignin to about 6.5 after 1 minute of ClO₂ bleaching. It was also shown that the in-situ generated hypochlorous acid created phenolic hydroxyl groups during chlorine dioxide bleaching. Since it was found that delignification by chlorine dioxide itself was mostly restricted to free phenolic lignin, these findings were used to explain the effect on delignification of addition order of chlorine and chlorine dioxide during bleaching of kraft pulp.     

稳定性二氧化氯的热稳定性及活化效果研究

对稳定性二氧化氯(ClO2)的热稳定性及酸度对活化效果的影响进行了研究,并与亚氯酸盐(NaClO2)水溶液进行了对比;对稳定性ClO2活化后对细菌和乙肝表面抗原HBsAg的灭活效果进行了研究。结果表明：稳定性ClO2水溶液不同于NaClO2水溶液,其热稳定性好于NaClO2,盐酸的活化效果好于柠檬酸。     

The effect of chloride on the HClO2-HOCl2 reaction in a 4.5 mol/L sulfuric acid solution

The chlorous acid reaction with hypochlorous acid (chlorine) may be responsible for the chlorine dioxide formation in a methanol based chlorine dioxide generation process. In this paper, the reaction between chlorous acid and hypochlorous acid in a 4.5 mol/L sulfuric acid solution was studied. It was found that chlorine dioxide is generated only if chloride is present. The underlying mechanism associated with the effect of chloride on the reaction was discussed.     

二氧化氯的分析方法

二氧化氯是一种理想的消毒杀菌剂,世界卫生组织将其安全性列为Al级,已成为国际上公认的氯系消毒剂更新换代产品。但是,在二氧化氯的制备过程中会产生多种副产物,二氧化氯自身也会发生分解和歧化反应产生Cl2、ClO-、ClO3-、ClO2-等物质,它们会削弱二氧化氯在应用中的优势。因此在制备及使用过程中,需要对ClO2及副产物进行分析测定,本文对现有的分析方法进行讨论。     

粪肠球菌的二氧化氯消毒试验

该文研究了在0．01mol／L磷酸盐缓冲液中,pH、温度、有机物对二氧化氯灭活粪肠球菌效果的影响。结果显示灭活速率随着pH的增加而增加,达到3log所需的Ct值,在pH为9时比pH为6时要少48％。灭活速率随着温度的升高而增大,温度在由8℃提高到35℃时,达到3log所需的G值减少了大约1／3倍。而且温度对二氧化氯灭活粪肠球菌的速率常数的影响符合阿伦尼乌斯定律,其活化能Ea=30396J／mol。投加甘氨酸和腐植酸后,二氧化氯对粪肠球菌的灭活效果明显下降,达到3log去除率所需的G值由1．22mg·min／L分别提高到1．84和3．58mg·min／L,增加了51％和近2倍。     

中国二氧化氯固体制剂的研究与发展

二氧化氯作为一种新型杀菌消毒剂广泛应用于诸多领域,由于其气体性质不稳定难以制成压缩气体,并且溶液易挥发不易浓缩,因此限制了二氧化氯的使用。相对于气态或液态二氧化氯,稳定性二氧化氯溶液虽然使用上相对方便,但由于须经酸活化才能使用,溶液中二氧化氯的含量低,稳定性受pH影响大,从而限制了其进一步推广。介绍了二氧化氯在实际应用中存在的局限性,论述了二氧化氯固体制剂的3种主要类型及其制备技术现状,提出了新一代反应型二氧化氯固体制剂的发展趋势。     

氯产品的生产、市场与发展建议

对氯产品需求的增长拉动了氯碱产能增长,氯产品的健康、稳定发展成为氯碱工业可持续发展的关键。近年来国内氯产品的产能快速增长,但是生产工艺整体水平不高,部分产品的产能趋于过剩,与上下游衔接不紧密,抵御市场风险的能力较弱,整个行业大而不强。针对目前国内外经济形势、氯产品生产现状和存在的问题,提出了我国发展氯产品的主导思路;并针对聚氯乙烯、聚氯乙烯糊树脂、甲烷氯化物、环氧丙烷、环氧氯丙烷、异氰酸酯、氯代芳烃、氯化高聚物、氯乙酸、氯代异氰尿酸、氯化法钛白粉这些主要的氯产品,提出了未来生产与发展中应该关注和须解决的问题。