| The surface of machine and equipment would be affected by the radioactive pollution when they were performing tasks in the radioactive environment,which could damage the machine equipment, interfere with the control system,even cause radioactive damage to workers to a certain extent. As a result,removal of radioactive contaminant on the surface of the machine without delay was of great significance. The technology of strippable films is a relatively good method for radioactive decontamination on equipment surface, which was attributed to simple operation, no cross contamination and little secondary waste quantity. At present, the main types of strippable films were synthetic polymer materials. There existed the limitation of shortage of resources, secondary pollution and difficult to deal with after decontamination, therefore the most important thing was to find suitable membrane materials. Konjac glucomannan glycan and starch were better choices of the decontamination materials because of theirs abundant sources, renewable and biodegradation properties, even with a large number of active group and a certain amount of film-forming ability. In this paper, the hydrophobic konjac glucomannan acetate(KGMA) and starch grafted styrene(St), butyl acrylate(BA) copolymer were synthetized through esterification and graft modification from konjac glucomannan and starch. As the film-forming principal agent, KGM and starch based decontamination sol were prepared. Their removal properties of the decontamination sol for simulated uranium U(VI) contamination on the surface of ceramic, stainless steel, polyethylene and polyvinyl chloride material were studied systematically through decontamination experiments, and the decontamination mechanism was analysed. We also investigated the feasibility of the combustion process of decontamination film after decontamination. Main content and conclusions were as follows:(1) The removal characteristics of Konjac glucomannan base decontamination material for U(VI) : The influences of the concentration of KGMA, U(VI)pollution time, initial content of U(VI), temperature, humidity and the degree of dust on removal rate of U(VI) on the surface of different materials were studied.The results showed that for the ceramic plate and stainless steel plate, the best decontamination KGMA detergent concentration was 85 g/L, while was 80g/L for polyvinyl chloride(PVC) and polyethylene plate; The impacts of pollution time, initial content and the degree of dust on the decontamination rate were not big. When the pollution time was respectively, 1 d ~14 d, the decontamination efficiency of the detergent for four kinds of pollution plate can reach above 92.5%. When the initial pollution was 7.1~35.7 Bq/cm2, the decontamination rate of KGMA detergent for U(VI) on the surface of four kinds of different materials was around 94.3%. In the presence of dust, removal efficiency of four kinds of plank could reach above 94%. As the humidity rose,the decontamination rate slightly increased. Temperature affected significantly on the decontamination. With the increase of temperature, decontamination rate showed obvious downward trend.The mechanism of removing U(VI) of Konjac glucomannan base decontamination material was analyzed by canning electron microscope(SEM),X-ray spectroscopy(EDX), X-ray photoelectron spectroscopy(XPS). Results showed that U(VI) was loaded on film through physical adhesion,conglutination and chemical absorption interaction during the drying process of decontamination film. Furthermore, the chemical coordination for U(VI) was that U(VI) coordinated O in the decontaminant.The thermal decomposition characteristics and products of the decontamination film were studied by means of thermogravimetric analysis(TG)coupled with Fourier transform infared spectromotry(FTIR). The TG analysis indicated that the loss ratio of the KGMA decontamination film was 96.07% at800°C in air atmosphere. The main gaseous products from thermal decomposition of the decontamination film at high temperature were CO2, CO and H2 O, no other toxic and harmful substances was detected.(2) The removal characteristics of starch based decontamination material for U(VI) : as for starch based detergent sol, 100 g/L was suitable the concentration of the agent for the ceramic plate, while 90 g/L was the best concentration of detergent for stainless steel plate and polyethylene plate. With increasing time of pollution, decontamination efficiency showsed an overall downward trend. When the pollution time was short, the decontamination rateappeared a relatively flat trend, and its change was not obvious. However the decontamination efficiency decreased greatly with a long time of pollution.pollution time was within 10 days, the removal rate of stainless steel and polyethylene plate can reach more than 90.5% in general. With the increase of initial concentration of uranyl nitrate, the removal rate of starch based decontamination sol for uranium contamination on the surface of three types of the material was on the decline as a whole. When the initial pollution of uranyl nitrate was low, removing efficiency was good, while the pollution degree was higher, decontamination efficiency was poor. With the ascension of temperature and decontamination time, the removal efficiency showed a downward trend,and the amplitude of time to reduce was larger. Within 35 ?, the decontamination efficiency was ideal,The mechanism of removing U(VI) of starch based detergent sol was analyzed by canning electron microscope(SEM), X-ray spectroscopy(EDX),X-ray photoelectron spectroscopy(XPS). Results showed that U(VI) was loaded on film through physical adhesion, conglutination and chemical absorption interaction during the drying process of decontamination film. Furthermore, the chemical coordination for U(VI) was that U(VI) coordinated O in the decontaminant.The thermal decomposition characteristics of the decontamination film were studied by means of thermogravimetric analysis(TG) coupled with Fourier transform infared spectromotry(FTIR). The TG analysis indicated that the loss ratio of the decontamination film was 97.83% at 750 ? in air atmosphere. he main gaseous products from thermal decomposition of starch based decontamination film at high temperature were CO2, CO and H2 O, no other toxic and harmful substances was detected.The materials of modified konjac glucomannan and starch exhibited good decontaminantion ability. It could be a potential candidate in the decontaminantion field of U(VI) contamination on the surface of equipment. |
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