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RADIATION CHEMISTRY AND PHYSICS, RADIATION TECHNOLOGIES 45 was shown that complete decomposition at a concentration of 100 mg/l requires a dose of 3 kGy, and the main products of radiolysis are phenolic compounds and carboxylic acids [19]. In present studies, a yield of MCPA decomposition was compared in different conditions, where MCPA exists in acid or anion form, and where predominate particular, highly reactive products of radiolysis of water, which can react with MCPA. As it can be found from data in Table 1, obtained for an initial MCPA concentration of 100 mg/l at a 1 kGy dose, the effectiveness of decomposition is affected mostly by a kind of reactive species present, and not by the degree of protonation. The largest yield was observed in solutions saturated with nitrogen monoxide, what means that radiolytic decomposition of MCPA is a result of reaction with hydroxyl radicals. The results of experimental data on the decomposition of MCPA and change of concentration of the main degradation product at low doses of radiation of 4-chloro-2-methylphenol (CMP) have been compared for different conditions used in the experiments with model kinetic calculations based on known rate constants of radical reactions. The calculations have been performed with the use of software KINETIC, which was used earlier, e.g. for modeling of a high temperature radiation-induced reduction of nitrogen oxide [20], and for the examination of decomposition mechanism of 1,1-dichloroethylene in humid air under EB irradiation [21]. The results of modeling obtained for processes carried out at different pH values are shown in Fig.1. The computer calculations have been carried out with the use of rate constants for MCPA and OH radical k=6.6x10 9 M –1 s –1 [22]. Similarly to experimental results, also well correlated with them model calculations (Fig.1A), indicate a minor effect of pH of irradiated solutions on yield of MCPA decomposition. No satisfactory correlation, however, has been observed between the experimental data and the results of kinetic modeling for decomposition of products of CMP for radiation doses above 2 kGy (Fig.1B), which means that some other processes take place, and not only those for which rate constants have been taken for modeling. Fig.2. Chromatograms obtained for the sample of wastes from the process of chlorination of MPA in production of MCPA prior to the irradiation (A), after gamma irradiation with a 5 kGy dose (B), and after a 5 kGy dose irradiation in the presence of 39 mM (1.32 g/l) hydrogen peroxide in irradiated solutions (C). Gradient elution with a 2 g/l citric acid solution with 5% acetonitrile and mixed with pure acetonitrile. Peak assignment: 1 – hydroquinone, 2 – catchol, 3 – o-cresol, 4 –MPA, 5 – 4-chlorophenol, 6 – MCPA, 7 – CMP. In investigations of radiolytic decomposition of several different organic pollutants based on reaction with hydroxyl radical, it has been shown that in some cases the effectiveness of decomposition can be improved by the addition of hydrogen peroxide to irradiated solutions. This effect was observed also in this study for irradiation of indus- Fig.3. Comparison of experimental data with kinetic modeling for the yield of degradation of (A) MCPA of initial concentration 0.5 mM in aerated solutions of pH 1.5 and different concentration of hydrogen peroxide added to irradiated solutions, and (B) formation and decomposition of CMP in irradiated solutions of MCPA. Data for irradiation without hydrogen peroxide – experimental (•) and calculated (), data for irradiation in the presence of 1.2 mM hydrogen peroxide – experimental (•) and calculated (◦), data for added 2.4 mM hydrogen peroxide – experimental () and calculated (), data for added 4.8 mM hydrogen peroxide – experimental () and calculated ( ).
46 RADIATION CHEMISTRY AND PHYSICS, RADIATION TECHNOLOGIES trial wastes from production of MCPA (Fig.2). The irradiation of wastes with a 5 kGy dose at an initial MCPA content of 554 mg/l results in the decomposition of 89% MCPA. For irradiation with the same dose, but in the presence of added 39 mM hydrogen peroxide, the observed yield increased to 100%, and also much more effective removal of other organic compound has been found. Figure 3 shows the results of model calculations for processes carried out at pH 1.5 and various levels of hydrogen peroxide in irradiated solutions. A general course of calculated changes of MCPA and CMP concentrations in function of dose magnitude and hydrogen peroxide content is closed to those observed experimentally. The best correlation between the results of calculation and experimental data has been obtained for the largest amount of hydrogen peroxide added to irradiated solution (4.8 mM). As it was shown in our earlier studies on radiolytic decomposition of chlorophenols, such processes, especially when low radiation doses are employed in order to be cost effective, may result, in formation of the products which are more toxic than the initial target compound. In order to examine this aspect in case of radiolysis of MCPA, with the use of bacterial, bioluminescence test Microtox, the toxicity of MCPA and the expected products of its radiolysis at low doses has been determined Table 2. The experimentally evaluated toxicity with a Microtox test for MCPA and considered potential products of its radiolytic degradation, expressed by EC 50 (15 min). (Table 2). Although MCPA exhibits a low toxicity with Microtox, the main product of its radiolysis at low doses CMP shows toxicity about 50 times larger, while hydroquinone and its methyl- and chloro-derivatives show even one order of magni- Fig.4. Chromatograms of the industrial waste samples from MCPA production prior to irradiation (A, B, C) and toxicity changes after gamma irradiation of each waste sample with different doses in aerated solutions of pH 1.5 (E, F, G). A – waste after chlorination of MPA, B – final waste from production line prior to adsorption on activated carbon, C – the same as B after adsorption on activated carbon.
Page 1 and 2: ANNUAL REPORT 2005 50 years in the
Page 3 and 4: CONTENTS GENERAL INFORMATION 9 MANA
Page 5 and 6: DETERMINATION OF CADMIUM, LEAD, COP
Page 7 and 8: NUCLEONIC CONTROL SYSTEMS AND ACCEL
Page 9 and 10: GENERAL INFORMATION 9 GENERAL INFOR
Page 11 and 12: MANAGEMENT OF THE INSTITUTE 11 MANA
Page 13 and 14: MANAGEMENT OF THE INSTITUTE 13 •
Page 15 and 16: SCIENTIFIC STAFF 15 5. Danilczuk Ma
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RADIOBIOLOGY
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100 RADIOBIOLOGY THE ROLE OF LYSOSO
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102 many found the ratio to be high
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104 RADIOBIOLOGY DNA INTER-STRAND C
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106 SIRTUIN INHIBITION INCREASES TH
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108 The possible reason of this eff
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THE INCT PUBLICATIONS IN 2005 163 V
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NUKLEONIKA 169 NUKLEONIKA THE INTER
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NUKLEONIKA 171 7. Influence of time
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INTERVIEWS IN 2005 173 INTERVIEWS I
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CONFERENCES ORGANIZED AND CO-ORGANI
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EDUCATION 209 EDUCATION Ph.D. PROGR
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RESEARCH PROJECTS AND CONTRACTS 211
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RESEARCH PROJECTS AND CONTRACTS IAE
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LIST OF VISITORS TO THE INCT IN 200
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LECTURES AND SEMINARS DELIVERED OUT
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LECTURES AND SEMINARS DELIVERED OUT
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AWARDS IN 2005 221 AWARDS IN 2005 1
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INSTRUMENTAL LABORATORIES AND TECHN
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INDEX OF THE AUTHORS 235 Lisowska H
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