Los conflictos escolares

High effectiveness of emulsion grafting in terms of preirradiation dose, monomer concentration, grafting time is attractive for industrial grafting process owing to the reduction of production cost. There was a need for high-performance adsorbent which can remove Ni and Cu ions from strong alkaline solution used in the surface etching process of Si wafer.[9.10].

When the wafer washing-agent was contaminated by Ni and Cu ions at the concentration ofsome mg/kg (ppm), these ions diffused into the Si wafer and caused the creation of pits on the surface of the wafer. The removal of Ni and Cu ions in the wafer-washing agent can maintain the high productivity of Si wafers having fine smoothness of surface without any pits.

Hence, fibrous adsorbent was synthesized in the bench scale of radiation-induce emulsion graft polymerization onto polyethylene nonwoven fabric and subsequent amination for practical application. The reaction condition was optimized using 30 L reaction vessel and nonwoven fabric, 0.3 m width and 18 m long. The resulting fibrous adsorbent was evaluated by 48 % NaOH and KOH contaminated with Ni and Cu ions, respectively. TABLE 9.1 shows that the

99 TABLE 9.1. COMPARISON OF METAL REMOVAL PERFROMANCE USING

FINROUS GRAFT ADSORBENT AND COMMECIALLY AVAILABLE RESIN ADSORBENT .

concentration levels of Ni and Cu ions were reduced to less than 1 µg/kg (ppb) at the flow rate of 10 h^-1 in space velocity.

The life of adsorbent was 30 times higher than that of the commercialized resin. This novel adsorbent was commercialized for the metal removal in Si wafer processing since the ability of adsorption is remarkably higher than that of commercial resin.

Irradiation-grafted nonwoven filter media was successfully commercialized, ^®" which has metal removal function to reduce the concentration of harmful metal ions dissolving in the liquids. Straw type aqua filter was developed for the purification of water at catastrophic emergency. This filter can remove the hazardous metals such as Cs, As, Cd, Pb, Cr, etc. in streaming water.

CONCLUSION 9.4.

Environmental remediation was considered from the viewpoint of radiation processing of polymers. Radiation processing can modify various kinds of polymers. The clean and biodegradable polymers such as poly (lactic acid) and natural polysaccharides need the improvement of heat resistance and gelation property, respectively, when they can be used for practical materials. The radiation processing is a clean tool for modification of the biodegradable polymers for practical applications. This is a direct contribution of radiation processing of clean products. Another contribution is to create the products for environmental remediation in terms of removal hazardous metals in contaminated water. Radiation-induced grafting easily synthesized tailored adsorbent for the removal of targeting toxic metals.

Radiation processing is a superior tool for the development of polymeric materials. Emulsion graft polymerization realizes environmentally friendly process using water instead of organic solvent. It is expected that many environmental problems will be solved by matching of seeds technology of polymer modification with radiation processing and needs of environmental remediation.

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REFERENCES TO CHAPTER 9

[9.1] NAGASAWA, N., KASAI, N., YAGI, T., YOSHII, F., TAMADA, M., “Radiation-induced crosslinking and post-processing of poly(L-lactic acid) composite”, Radiat.

Phy. Chem. 80 (2011) 145–148.

[9.2] FEI, B., WACH. R.A., MITOMO, H., YOSHII, F., KUME, T., “Hydrogel of biodegradable cellulose derivatives. I. Radiation-induced crosslinking of CMC”, J.

Appl. Polym. Sci. 78(2) (2000) 278–283.

[9.3] WACH, R.A., MITOMO, H., YOSHII, F., KUME, T., “Hydrogel of biodegradable cellulose derivatives. II. Effect of some factors on radiation-induced crosslinking of CMC”, J. Appl. Polym. Sci. 81(12) (2001) 3030–3037.

[9.4] YAMASHITA, S., HIROKI, A., TAGUCHI, M., “Radiation-induced change of optical property of hydroxypropyl cellulose hydrogel containing methacrylate compounds: As a basis for development of a new type of radiation dosimeter”, Radiat. Phys. Chem. 101 (2014) 53–58.

[9.5] HIEN, N.Q., RHU, D.V., DUY, N.N., LAN, N.T.K., “Degradation of chitosan in solution by gamma irradiation in the presence of hydrogen peroxide”, Carbohydrate Polymers 87(1) (2012) 935–938.

[9.6] IWANADE, A., KASAI, N., HOSHINA, H., UEKI, Y., SAIKI, S., SEKO, N., “Hybrid grafted ion exchanger for decontamination of radioactive cesium in Fukushima Prefecture and other contaminated areas”, J. Radioanal. Nucl. Chem. 293 (2012) 703–

709.

[9.7] SEKO, N., BANG, L.T., TAMADA, M, “Syntheses of amine-type adsorbents with emulsion graft polymerization of glycidyl methacrylate”, Nucl. Instr. Meth. B 265(1) (2007) 146-149.

[9.8] WADA, Y., TAMADA, M., SEKO, N., MITOMO, H., “Emulsion grafting of vinyl acetate onto preirradiated poly(3-hydroxybutyrate) film”, J. Appl. Polym. Sci. 107(4) (2007) 2289-2294.

[9.9] MOHAMED, N.H., TAMADA, M., UEKI, Y., SEKO, N., “Emulsion graft polymerization of 4-chloromethyl styrene on kenaf fiber by pre-irradiation method”, Radiat. Phys. Chem. 82 (2013) 63–68.

[9.10] TAMADA, M., UEKI, U., SEKO, N., TAKEDA, T., KAWANO, S., “Metal adsorbent for alkaline etching aqua solutions of Si wafer”, Radiat. Phys. Chem. 81 (2012) 971–

974.

101 10. APPLICATION OF MOBILE E-BEAM FOR GREEN ENVIRONMENT

B. HAN, S.M. KIM, W.G. KANG, J.K. KIM EB TECH CO., LTD.

Daejeon, Korea (rep. of)

N.K. KUKSANOV, R.A. SALIMOV Budker Institute of Nuclear Physics

Novosibirsk, Russia Abstract

Due to the necessity of pilot scale test facility for continuous treatment of wastewater and gases on site, a mobile electron beam irradiation system mounted on a trailer has developed in EB TECH Co. Ltd. This mobile electron beam irradiation system is designed for the individual field application with self-shielded structure of steel plate and lead block which will satisfy the required safety figures of ICRP. Shielding of a mobile electron accelerator of 0.7 MeV, 30 mA has been designed and examined by Monte Carlo technique. Based on a 3-D model of electron accelerator shielding which is designed with steel and lead shield, radiation leakage was examined using the MCNP code. Calculations using two different versions (version 4c2 and version 5) of MCNP showed agreements within statistical uncertainties, and the highest leakage expected is 5.5061x10^-01 (1±

0.0454) µSv/h, which is far below the tolerable radiation dose limit of 1mSv/week.

This mobile unit will be used for on-site test of liquid waste and gaseous waste in U.S. by PELE Technology Inc. and EB TECH Co. Ltd. This unit could treat up to 500m³ of liquid waste per day or 10,000 Nm³ of gases per day.

OBJECTIVE OF THE RESEARCH 10.1.

Radiation technologists have been investigating the use of high-energy radiation for treatment of pollutants such as wastewaters, flue gas, and sewage sludge. The major advantage of radiation technology is that the reactive species are generated in-situ during the radiolysis process without addition of any chemicals. The results of practical applications have confirmed that radiation technology can be easily and effectively utilized for treating large quantities of pollutants [10.5–10.7]. Even the advantages of radiation technology on environmental pollution control, there are very few commercial scale plants in operation since the cost for proving this technology by pilot scale test on site.

Thus, the needs for economical ways applying pilot scale are getting more and more the issues in the field. Due to the necessity of pilot scale test facility for continuous treatment of wastewater and gases on the spot, a mobile electron beam irradiation system mounted on a trailer has developed in EB TECH Co. Ltd.

INTRODUCTION 10.2.

The problems of environmental damage and degradation of natural resources are receiving increasing attention throughout the world. The increased population, higher living standards, increased urbanization and enhanced industrial activities of humankind are all leading to degradation of the environment. Increasing urbanization has been accompanied by significant water pollution. Industrial activities to produce heat and electrical energy are responsible for emitting a large number and amount of pollutants, such as fly ash, sulphur oxides (SO2 and SO3), nitrogen oxides (NOX = NO2 + NO) and volatile organic compounds, into the atmosphere.

Electrons interact with gas creating divergent ions and radicals including oxidizing radicals and excited species. These excited species react in a various ways of neutralization reactions and dimerization. Irradiation of flue gas to convert SO2 and NOX into a dry product containing (NH4)2SO4 and NH4NO3 that was usable as a fertilizer. Two larger scale plants were constructed in Indianapolis, USA [10.2] and Karlsruhe, Germany [10.3]. The engineering

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design technology for electric utility applications was established at the pilot plant in Kaweczyn, Poland (2×10⁴ Nm³/h) using two accelerators (5kW, 700keV each) [10.4].

Electron beam processing of wastewater is non-chemical, and uses fast formation of short-lived reactive radicals that can interact with a wide range of pollutants. Such reactive radicals are strong oxidizing or reducing agents that can transform the pollutants in the liquids wastes. The first studies on the radiation treatment of wastes were carried out in the 1950s principally for disinfection. In the 1960s, these studies were extended to the purification of water and wastewater. After some laboratory research on industrial wastewaters and polluted groundwater in 1970s and 1980s, several pilot plants were built for extended research in the 1990s. The first full-scale application was reported for the purification of wastewater at the Voronezh synthetic rubber plant in Russia. Two accelerators (50kW each) were used to convert the non-biodegradable emulsifier, ‘nekal’, present in the wastewater to a non-biodegradable form [10.5].

The installation treats up to 2,000 m³ of effluent per day. A pilot plant of 1,000 m³/d for treating textile-dyeing wastewater has been constructed in Daegu, Korea with 1MeV, 40kW electron accelerator [10.6].

MATERIALS AND METHODS 10.3.