[en] A study on electron-beam treatment was carried out to find out the effective decomposition conditions of vaporized volatile organic compounds. Air streams containing aromatic and aliphatic compounds were irradiated with electron beams in batch and flow systems. The research showed that chloroethene was readily decomposed through a chain reaction with one of the fragmentation products, Cl radical. A thermal electron and negative oxygen ion were important active species for decomposing carbon tetrachloride. The formation of particles was observed only from the irradiation of aromatics, like benzene, xylene, and chlorobenzene. Dechlorination of chlorobenzene was enhanced in the presence of ammonia

[en] Research on electron beam decomposition of volatile organic compounds (VOCs) in air was carried out to establish an advanced treatment technology for industrial off-gases. Benzene, toluene and o-xylene were selected as aromatic VOCs and dichloro-, trichloro- and tetrachloro-ethylene as chloroethenes. The experimental results showed that G-values of decomposition ranged from 1.0-2.2 in aromatic compounds and 30-60% of decomposed compounds were converted into aerosols. On the other hand, G-values of decomposition of chloroethenes increased with the initial concentration and number of chlorine atoms in a molecule, for example, the G-value at 180 and 1580 ppm of tetrachloroethylene were 22 and 172, respectively. The formation of aerosol was not observed in the decomposition of chloroethenes. An application of low energy electron accelerator for treatment of exhaust gases containing VOCs was also discussed. (author)

[en] A relativistic high-intensity pulsed electron beam generated from a Febetron 706 was strongly self-focused in two pressure regions, i.e., below and above 5 Torr. The dependence of the electron energy spectrum on pressure and path length in He was at first studied by measuring depth-dose distributions in an aluminum-blue cellophane stack. Then, maximum doses of the depth-dose curves in the dosimeter placed on the beam axis at 10.4 cm from the cell window were measured as functions of pressure in He, Ne, Ar, Kr, Xe, H², D², N², O², N²O, CO², SF⁶, CH⁴, C²H², C²H⁴, C²H⁶, C³H⁸, CH³F, CHClF², CCl²F², He + X, Ar + X, and O² + X (X: additive gas). The strong self-focusing at pressure lower than 5 Torr is attributed to space-charge neutralization by positive ions due to escaping of secondary electrons. Therefore, relative total ionization cross sections for beam electrons could be obtained in this region. When the spa ce-charge neutralization time becomes shorter than a rise time of the pulsed beam, secondary electrons are accelerated by a backward electric field E sub(z) induced by the pulsed beam so that the self-focusing declines abruptly due to electron avalanching. The beam is self-focused again gradually with further increasing pressure because of suppression of this avalanching. The avalanching was analyzed self-consistently for He, Ar, H², N², and CH⁴ by a computer simulation in the pressure region between 5 and 300 Torr. The present computational results indicate that the larger cose is given by the longer mean ionization time t sub(i) which depends on E sub(z)/p. The value of t sub(i) increases with increasing pressure in the pressure region of gradually-increasing self-focusing. (J.P.N.)

[en] Intense pulsed electron beams of various types are widely used at present for the researches on the plasma production, radiation chemistry in gas phase, and gas laser. However, the details of gas ionization processes above several Torr by intense pulsed electron beams have been hardly clarified. In this study, a program has been designed which can make a numerical analysis of gas ionization by pulsed electron beams self-consistently including the effects of induced electric field and plasma backward current. The validity and usefulness of this program have been confirmed by its application to Ar. This program is applicable to any gas and to pulsed electron beams of arbitrary characteristics, and useful to clarify the roles of various elementary processes during ionization. (author)

[en] The radiation-induced decomposition of trace amounts of 17 β-estradiol (E2) in water was studied as a function of the dose of ⁶⁰Co γ-rays. The rate constant of the reaction of the OH radicals with E2 was estimated to be 1.6x10¹⁰ mol dm^-3 s^-1 by a comparison with the known rate constant for the reaction with phenol. Both E2 and E2-equivalent concentrations were estimated by LC-MS and ELISA, and decreased with an increase in γ-rays dose. E2 (1.8 nmol dm^-3) in water was degraded almost completely by irradiations up to 10 Gy. The estrogen activity of the same sample solution still remained at a dose of 10 Gy, but decreased at 30 Gy to the lower than the threshold level of contamination to induce some estrogenic effects on the environmental ecology

[en] The effects of the concentration of CO₂ and CH₄ on the radiolysis product yields from a CO-H₂ mixture were studied. The yield of formic acid increased by addition of CO₂, but not by the addition of CH₄. The results were explained by the reaction of CO₂ with ionic intermediates formed from a CO-H₂ mixture by irradiation. (orig.)

[en] The waste water treatment using electron beam is the method of oxidizing and decomposing the polluting substances in water by utilizing the activated species having high chemical reactivity arising in water by irradiation. It is suitable to the treatment of waste water which is difficult to treat by conventional water treatment techniques. It has also sterilizing effect. At present the electron accelerators of 100 kV-5 MV accelerating voltage are on the market, and their technical reliability is high, accordingly they are utilized for many fields including the heightening of heat resistance of electric cables. For water treatment, the accelerators of 1 MV or higher are necessary. The principle and the features of this process are explained. The simplest method of applying electron beam to water treatment is that by simple irradiation only. But in the case of high concentration of polluting substances in water and their complex composition, the simple irradiation requires a large dose, therefore the method of combining with other water treatment techniques for effectively utilizing electron beam has been investigated. The methods of combining with microorganism processing, coagulation and sedimentation, or ozone oxidation are described. The treatment of industrial waste water, sewage and the effluent water from garbage-filled land is explained. (Kako, I.)

[en] Electron beam irradiation is capable of dissolving and removing pollutants, such as sulfur oxides, nitrogen oxides, and organic compounds, by easy production of OH radicals in flue gas and water. This paper deals with current status in the search for techniques for treating flue gas and waste water, using electron beam irradiation. Pilot tests have been conducted during the period 1991-1994 for the treatment of flue gas caused by coal and garbage burning and road tunnels. Firstly, techniques for cleaning flue gas with electron beams are outlined, with special reference to their characteristics and process of research development. Secondly, the application of electron beam irradiation in the treatment of waste water is described in terms of the following: (1) disinfection of sewage, (2) cleaning of water polluted with toxic organic compounds, (3) treatment for eliminating sewage sludge, (4) promotion of sewage sludge sedimentation, (5) disinfection and composting of sewage sludge, and (6) regeneration of activated carbon used for the treatment of waste water. (N.K.)

[en] When ι-butanol in aqueous system was decomposed by simultaneous application of γ-rays and ozone treatment, the addition of the cupric ion (Cu²⁺) drastically improved the efficiency of the removal of organic substances from water. The major reason for the remarkable decrement of total organic substances is the positive catalytic effect of Cu²⁺ on the oxidation of carboxylic acids. (author)

[en] Part of the results was presented on the investigation of treatment of supernatant from sewage sludge by combination of electron beam irradiation and microbiological treatment. Supernatant is electron-beam irradiated after microbiologically treated, and then treated microbiologically again. Based this method, by irradiation of 10 kGy, chemical oxygen demand (COD) in supernatant can be decreased lower than 30 ppm. Moreover, electron-beam irradiation induces remarkable decolorization and deodorization. (author)