Akihisa Sakumoto

Exhaustive degradation of humic acid in water by simultaneous application of radiation and ozone

Abstract The combination effect of ionizing radiation and ozone to degrade humic acid in water was superior to ozone and radiation alone. The humic acid treated by this combination method, followed by chlorination, produced only little trihalomethane and total organic halogen. A chain reaction mechanism was suggested for the oxidation of humic acid.

The degradation of an azo dye in aqueous solutions by high-intensity electron-beam irradiation

Abstract A study of the degradation of Acid Red 265 (azo dye) in aqueous solutions by high-intensity electron- irradiation was carried out in a flow system. For the oxygen-saturated solutions (oxygen bubbled during irradiation), the change of absorption spectra, the degree of decoloration at 542 nm, the reduction in optical density at 230 nm, the change of pH, and the amount of dissolved oxygen were measured as functions of dose under various conditions (dye concentration, dose rate, solution flow rate, and oxygen flow rate). The decoloration scheme in the flow system by electron beam irradiation was similar to that in the batch system by gamma radiation. Oxygen was not necessary for the destruction of the chromophore but was absolutely essential for the destruction of substituted aromatic rings in the dye molecule. For the purpose of the destruction of the skeleton of the Acid Red 265 molecules, it was necessary to keep the concentration of dissolved oxygen above at about 30 ppm (in mass) in the case of the 60 ppm dye solution.

Inhibition of trihalomethane formation in city water by radiation-ozone treatment and rapid composting of radiation disinfected sewage sludge

Abstract Humic acid and Fulvic acid in natural water are precursors of carcinogenic THM which is formed during chlorine disinfection in city water processing. The radiation-oxidation process in the presence of ozone is effective to remove the precursors. The THM formation was reduced more than the decrease in TOC by the combination treatment. This is mainly due to a change in the chemical structure of the oxidation products. A composting of radiation disinfected sludge cake for agricultural reuse could be achieved within 3 days primary fermentation in a sewage plant. The rapid fermentation with use of radiation is effective to scale down of a fermentor of composting plant and the process reduces a health risk from the workers as well as final users.

Effect of 60Coγ-Ray Irradiation on Dilute Aqueous Solution of Phthalate

フタル酸ジメチルの希薄水溶液を酸素あるいは窒素飽和下において60Coγ線で照射し, その分解過程を紫外および赤外吸収スペクトルの変化, 添加物効果ならびにガスクロマトグラフ法による分解生成物の分析結果から検討した。その結果, 以下の諸事実が明らかになった, 分解は主としてOHラジカルのベンゼン環への攻撃によって開始されるが, 水和電子は分解には直接寄与しない。分解のG値は酸素飽和 (2.3) のほうが窒素飽和 (1.6) より高い。酸素飽和の状態で照射した場合, 窒素飽和で困難なペンゼン環の開裂と置換基の脱離反応が容易に起こりメタノールが生成する。フタル酸ジメチルは最終的にシュウ酸あるいはギ酸を経て二酸化炭素にまで完全に分解される。

KINETIC STUDY ON THE RADICAL ADDITION OF SODIUM HYDROGENSULFITE TO ALLYL ALCOHOL

The kinetics of the radical chain reaction of sodium hydrogensulfite with allyl alcohol In aqueous solutions was investigated. The apparent rate constant was found to be 4.69×10−4M·sec−1 at the dose rate of 1.35×1016 eV·g−1·sec−1. The kinetic chain length was estimated to be 345.