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INVESTIGATION OF THE EFFECT OF PHASE TRANSITION OF WATER ON THE TRANSFORMATION OF AIR POLLUTANTS

水相变对空气污染物转化影响的研究

基本信息

批准号：
09480118
负责人：
BANDOW Hiroshi
金额：
$ 6.66万
依托单位：
OSAKA PREFECTURE UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09480118/
关键词：
Freezing Frost Dew Freezing concentration Evaporation of water nuclei of ice crystal Atmospheric photochemistry Cloud chemistry

项目摘要

1997 :1) In dew collection and monitoring, the pH values of dew were relatively high compared with those in rain or fog. High concentration of nitrous acid, ammonium cation and carboxylic acids, such as formic acid and acetic acid, could be observed in dew.2) Nitrous acid could be reduced to molecular nitrogen in the presence of ammonium cation and escaped from aqueous phase during the dryihg process of dew(evaporation of water from dew).19981) The reaction rate of the aqueous phase oxidation of sulfide with hydrogen peroxide was accelerated by freezing of the solution. This sulfide oxidation proceeds consecutively via thiosulafate, trithionate and tetrathionate, and finally produces sulfate. The oxidation of thiosulfate to sulfate could take place even in the frozen solution. On the contrary, trithionate and tetrathionate could not be oxidized to sulfate in frozen solution.2) The pH values were relatively high and the concentrations of nitrous acid, ammonium cation, carboxylic acid were also high in drain water collected from air conditioner.3) The reduction of nitrous acid to molecular nitrogen in dew during the drying process takes place as follows ;a) During the evaporation of water, sulfate ions in dew react with sodium cations and sodium sulfates precipitate in solid state.b) Excess sodium cations (unreacted) react with nitrite anions and then the sodium nitrites precipitate in solid state.c) Finally free nitrite anions(unreacted) react with protons and nitrous acid produced can escape from aqueous phase to gas phase, and molecular nitrogen can be produced from nitrous acid with ammonium in concentrated solution by evaporation of water.4) Relatively high concentration of nitrous acid could be observed in ambient air on cloudy day or at night and also in the indoor air. Now we began to develope the selective and sensitive monitoring system for nitrous acid.

1997:1)在露水的采集和监测中，露水的pH值相对于雨或雾的pH值较高。在露水中可以观察到高浓度的亚硝酸、铵离子和甲酸、乙酸等羧酸。2)在铵离子存在的情况下，亚硝酸可以还原为分子氮，并在露水干燥过程中从水相中逸出。（19981）硫化物与过氧化氢的水相氧化反应速率通过溶液的冷冻而加快。这种硫化物氧化通过硫代磺酸盐、三硫代酸盐和四硫代酸盐依次进行，最终生成硫酸盐。硫代硫酸盐甚至在冷冻溶液中也能氧化成硫酸盐。相反，三硫酸盐和四硫酸盐在冷冻溶液中不能被氧化成硫酸盐。2)空调排水pH值较高，亚硝酸、铵离子、羧酸浓度也较高。3)在干燥过程中，硝酸还原为露水中的分子氮的过程如下；a)在水分蒸发过程中，露水中的硫酸盐离子与钠阳离子反应，硫酸钠以固态沉淀。b)多余的钠离子（未反应的）与亚硝酸盐阴离子反应，亚硝酸钠以固体形式析出。c)最后游离的亚硝酸盐阴离子（未反应的）与质子反应，生成的亚硝酸由水相逸出到气相，亚硝酸与铵盐在浓溶液中蒸发生成分子氮。4)阴天或夜间环境空气中有较高浓度的亚硝酸盐，室内空气中也有较高浓度的亚硝酸盐。现在，我们开始研制选择性灵敏的亚硝酸盐监测系统。