| Some of the radionuclide will deposit on the surface of an online instrument which works in a radioactive environment for a long time and cause harm to the health of people who directly contact with those.There are the following requirements in decontamination to the surface of the instrument equipment: reduce the amount of pollution to the safety standard effectively, ensure that the decontamination dosen't do damage to the online instrument, less waste liquid, easy to dispose the waste liquid, do not cause secondary pollution. Therefore in this paper,the alkyl polyglucoside(APG), alpha-olefin sulfonate(AOS) are used as the basic raw materials,compared with linear alkylbenzene sulfonate(LAS), mixed with the thickening agent such as konjac glucomannan(KGM), carboxymethyl cellulose(CMC), sodium alginate(SA) and the decontamination agents such as citric acid(CA), EDTA, acetic acid,tartaric acid, the foam detergent based on APG is synthesized. The foaming property of foam detergent, foam stability, rheology and decontamination performance of simulated uranium(U(VI)) pollution are studied; X-ray photoelectron spectroscopy(XPS) and fourier transform infrared(FTIR) are applied to analyse the mechanism.TG-FTIR is applied to analyse the thermal decomposition characteristics of the foam detergent and the decomposition product of waste liquid; The engineering decontamination device of foam detergent is studied, decontamination process parameters and defoaming of waste liquid are also researched. The main conclusions are as follows:1. The study on foam properties: Foamability of the single surfactant: AOS > LAS > APG and foamability of the compound surfactant: APG/AOS > APG/LAS. The foam volume of APG + AOS is the highest when APG: AOS is 3:1 and it had a obvious compound synergism. The selection of APG + AOS is conducive to reducing the amount of waste liquid.2. The study on foam stability and rheological properties: Theaddition of KGM, CMC, SA improves the foam stability, reduces the foaming ratio and addition of KGM obviously increases foam stability;The detergent system mainly presents viscous, the behave of the solution like Newtonian fluids in the low shear rate region and there is a shear thinning phenomenon in the high shear rate region.3. The study on synthesis and decontamination of foam detergent:with APG + AOS surfactant as raw materials, citric acid, acetic acid,citric acid and EDTA-2Na as detergent additives, the foam detergent was prepared. The performance of decontamination was studied. The results showed that decontamination performance of citric acid was better. The biggest decontamination rate of ceramic, stainless steel,PVC and PE was respectively 95.43%, 99.1%, 98.11%, 98.43% and the decontamination factor was 21.88, 111.11, 52.91, 63.69 when the adding amount of citric acid was 10 g/L, decontamination time was more than 30 min, temperature was 30 ? and the pollution time of simulated nuclide was 14 days.4. The study on engineering application: Simulated plates and equipment of different materials and robot were put into the simulated pollution box. The engineering application device and technical parameters of foam detergent were studied with using foam gun device.Results showed that the biggest decontamination rate was 96.49% and the decontamination factor was 28.49 when the pressure of air compressor was 0.3 Mpa and cleaning time was 30 min.5. The study on decontamination mechanism and treatment of waste liquid: The decontamination of foam detergent was the result of physical and chemical interactions. The main components of the thermal decomposition products was carbon dioxide. The potassium permanganate oxidation was used to treat with the waste liquid after decontamination. The foam could be completely defoamed when the concentration of potassium permanganate oxidation was 0.4 wt%, the time was 2 h. |
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