A study on simultaneous removal of SO 2 and NO from flue gas using H 2 O 2 /urea activated by vacuum ultraviolet (VUV) light was carried out in a pilot-scale photochemical spraying tower. The effects of different operational variables on simultaneous removal efficiencies of SO 2 and NO were investigated. The gaseous and liquid removal products were detected by the flue gas analyzer and ion chromatography (IC), respectively. The removal pathways of SO 2 and NO were analyzed. The application prospect of this new method was also preliminarily discussed. Results show that under most of the process conditions tested, SO 2 can attain complete removal. Removal efficiency of NO is enhanced under increasing the VUV irradiation intensity and H 2 O 2 concentration, but it is inhibited by an increase of the flue gas flow and NO concentration. The urea concentration and liquid−gas ratio have a dual influence on NO removal, and its removal efficiency increases first and then decreases. SO 2 concentration has little impact on NO removal. IC results show that SO 4 2− and NO 3 − are the main removal products in solution. • OH derived from VUV activation of H 2 O 2 plays the crucial role in NO removal.

As a product generated from incomplete combustion, soot is harmful to people’s health and the environment. In recent decades, much attention has been paid to the control of soot generation in combustion systems. Efforts to reduce soot emissions depend on a basic understanding of the physical and chemical pathways from fuel to soot particles in flames. At the same time, flame synthesis method has become an alternative method for the preparation of carbon nanomaterials because of its advantages of low cost and mass production. Carbon-based materials can be synthesized within the sooting zones in flames. The research of soot formation mechanism in flames can provide support for the synthesis of carbon nanomaterials. In this paper, the effects of additives, temperature, and fuel type on soot formation characteristics and soot nanostructure in diffusion flames are reviewed. The deficiencies and prospects are put forward for future research.

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BACKGROUND: Emissions of SO 2 and NO from flue gas have caused serious environmental pollution issues. UV/vacuum ultraviolet(VUV)-activated H 2 O 2 advanced oxidation technology is one of the most promising processes to realize the simultaneous removal of SO 2 and NO. From the application perspective, it is necessary to carry out further research in a pilot-scale photochemical reactor with industrial conditions and actual coal-fired flue gas running conditions. RESULTS: Results showed that SO 2 removal efficiency can reach 100% under most experimental conditions. An increase of the VUV irradiation intensity, H 2 O 2 concentration and solution pH can promote NO removal, but the growth rate of that gradually slows down. It is not conducive to NO removal when the flue gas flow and NO concentration increases. Increasing liquid-gas ratio has dual effects on NO removal; NO removal efficiency increases at first, and then decreases sharply. SO 2 concentration has no great impact on removal of NO. Results of ion chromatography (IC) demonstrate that SO 4 2− and NO 3 − are the major removal products of SO 2 and NO. CONCLUSION: The VUV-activated H 2 O 2 advanced oxidation technology is suitable for industrial application. The investment and operating costs of this technology are lower than those of the combined processes NH 3 -SCR and Ca-WFGD.

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