Grant-in-Aid for Scientific Research (B)
Environmental dynamic analysis
|Research Institution||OSAKA PREFECTURE UNIVERSITY|
竹中 規訓 大阪府立大, 工学部, 助手 (70236488)
BANDOW Hiroshi OSAKA PREFECTURE UNIVERSITY,COLLEGE OF ENGINEERING,ASSOCIATE PROFESSOR, 工学部, 助教授 (80124353)
|Project Fiscal Year
1997 – 1998
Completed(Fiscal Year 1998)
|Budget Amount *help
¥10,400,000 (Direct Cost : ¥10,400,000)
Fiscal Year 1998 : ¥3,000,000 (Direct Cost : ¥3,000,000)
Fiscal Year 1997 : ¥7,400,000 (Direct Cost : ¥7,400,000)
|Keywords||Freezing / Frost / Dew / Freezing concentration / Evaporation of water / nuclei of ice crystal / Atmospheric photochemistry / Cloud chemistry / 凍結 / 霜 / 露 / 凍結濃縮 / 水の蒸発 / 氷晶核 / 大気光化学 / 雲化学|
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).
1) 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.