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Phsicochemical Treatment of Hazardous Wastes - Chapter 12

Chùm tia điện tử năng lượng cao Chùm tia điện tử đã được sử dụng thương mại từ những năm 1950. Các ứng dụng sớm liên quan đến các liên kết chéo của bộ phim polyethylene và cách điện dây. Sau đó, quá trình này đã được mở rộng để bao gồm khử trùng các vật tư y tế, cao su lưu hóa, khử trùng nước thải, bảo quản thực phẩm, và nhiều ứng dụng hơn. Trong giải quyết các vấn đề môi trường, quá trình này đã được chứng minh là hiệu quả cho sự hủy diệt của một số. | 12__ High-Energy Electron Beam 12.1 Introduction Electron beams have been in commercial use since the 1950s. Early applications involved the cross-linking of polyethylene film and wire insulation. Later the process was extended to include sterilization of medical supplies rubber vulcanization disinfection of wastewater food preservation and many more applications. In solving environmental problems the process has been shown to be efficient for the destruction of several classes of hazardous organic compounds as well as the inactivation of total coliform and bacteria in sewage sludge Kurucz et al. 1991 . It can be applied to treat wastewater from numerous industries such as the food health pharmaceutical pulp and paper and textile sectors. The groups of compounds from these wastewaters may contain benzene substituted benzenes such as toluene m-xylene and o-xylene phenol halogenated ethenes such as trichloroethylene TCE and tetrachloroethylene PCE halogenated methanes such as trihalom-ethanes THMs carbon tetrachloride and methylene chloride. Table 12.1 shows the removal efficiency of these organic compounds in aqueous solution by high-energy electron beam as a function of solute concentration absorbed dose pH and scavengers in potable water and raw and secondary wastewaters. This innovative treatment process is not only limited to simple toxic organic chemicals but is also applicable to complex mixtures of organic pollutants under varying water quality. 12.2 Chemistry of Aqueous Electrons 12.2.1 Formation of Radical Species The irradiation of pure water with high-energy electrons generated by an accelerator results in the rapid formation of electronically excited states and or free radicals in 10-14 to 10-9 s. These reactive species will react with organic ệè 2004 by CRC Press LLC TABLE 12.1 Summary of Overall Removal Efficiencies for Various Organic Compounds Tested at the Miami Electron Beam Research Facility Compound Removal Required