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In this study, a hybrid system combining two different techniques (electron beam and cross flow scrubber) has been developed and applied to control odorous sulfur compounds (hydrogen sulfide, methyl mercaptan, dimethyl sulfide and dimethyl disulfide) in a wastewater treatment facility. Removal efficiencies of sulfur compounds using an electron beam were high in the order of hydrogen sulfide > methyl mercaptan > dimethyl sulfide > dimethyl disulfide when the range of absorbed dose was 5–10 kGy. We also found that the liquid/gas ratio at 4.7 L/m 3 was sufficient to remove residual odorous sulfur compounds and its by-products. Based on these results, a pilot study was carried out. As a result, the removal efficiencies of all target compounds were approximately 100% at 2.5 kGy in the pilot-scale hybrid system. It was also found that the levels of NO 2 and CO formed by electron beam irradiation were lowered down to the ambient level by the hybrid system. [ABSTRACT FROM AUTHOR]

This study was carried out to identify by-products generated during the decomposition of sulfur compounds using electron beam (EB) irradiation. We also estimated the effect of O 3 on the reaction. As a result, ozone was generated during the decomposition reaction of sulfur compounds by EB and enhanced the removal rate of the target compounds. H 2 S was converted into SO 2 and H 2 SO 3 by reacting with OH, HO 2 , and various radicals formed through EB irradiation. SO 2 , (CH 3 ) 2 S, (CH 3 ) 2 S 2 , (CH 3 ) 2 SO 2 , C 3 H 8 S 2 and R–O–SO 2 –O–R′ were by-products generated from the CH 3 SH decomposition process. (CH 3 ) 2 S was converted to SO 2 , (CH 3 ) 2 S 2 , R–O–SO 2 –O–R′, R–SO 3 − and R–SO 3 H. Finally, H 2 SO 3 , CH 3 SH, (CH 3 ) 2 S, CS 2 , R–O–SO 2 –O–R′, R–SO 3 − , R–SO 3 H, and R–O–SO 2 –R′ were detected as by-products of (CH 3 ) 2 S 2 . [ABSTRACT FROM AUTHOR]

Influential factors were investigated to increase decomposition efficiencies of sulfur compounds using an electron beam. Their initial concentrations, different background gases, and relative humidity were of main concern as the factors. Decomposition efficiency of H 2 S by primary electrons was lower than those of CH 3 SH, DMS, and DMDS containing one or two CH 3 groups. The G -values increased as their initial concentrations increased and the adsorbed dose decreased. Removal efficiencies were highest for H 2 S and CH 3 SH in the simultaneous presence of N and O radicals. In contrast, reactions with the O radical were the most effective when DMS and DMDS were irradiated by electron beam under different background gases. Adding water vapor to the reactors resulted in the increase of decomposition efficiency. [ABSTRACT FROM AUTHOR]

This study investigated the decomposition characteristics of acetaldehyde using an electron beam. The removal efficiency (RE) in air, O, N and He atmospheres at 10 kGy were 88, 89, 94 and 35 %, respectively. By varying the initial concentration (C), G-values at 240 ppm (C) were maintained from 6.4 to 7.0 molecules/100 eV, while the G-values at 34 and 60 ppm (C) decreased from 4.5 to 1.1 and from 6.6 to 2.0 molecules/100 eV when the absorbed dose increased from 2.5 to 10 kGy. The RE of acetaldehyde at 96 % relative humidity was approximately 10-15 % higher than that at dry air when the absorbed doses were 5-10 kGy. Increasing the water supply did not provide additional improvement of the RE at 2.5 kGy. CO, CO, O and trace VOC compounds such as CHO, CHO, CH, CH and CH were detected as by-products. [ABSTRACT FROM AUTHOR]

To identify the decomposition characteristics of trimethylamine (TMA) by electron beam (EB), we conducted an experiment based on process parameters, including absorbed dose (2.5-10 kGy), background gas (air, O, N and He), water content (1,200, 14,300, and 27,500 ppm), initial concentration (50, 100, and 200 ppm) and reactor type (batch or continuous flow system). Air background gas showed a maximum TMA removal efficiency of 86 % at 10 kGy and that was the highest efficiency of all background gases. Energy efficiencies were higher when the absorbed dose was lower (e.g., 2.5 kGy). Decomposition efficiencies of all initial TMA concentrations were approximately >90 % at 10 kGy. Removal efficiencies increased up to 30 % as water vapor increased. As a by-product, it is observed that CH radical formed by EB irradiation was converted into CH by reaction with residual TMA, (CH)NH, and H. These results suggest that EB technology can be applied for TMA treatment under low concentration and high flow rate conditions. [ABSTRACT FROM AUTHOR]

This study was carried out to determine the decomposition characteristics of ammonia using an electron beam (EB). Factors influencing these decomposition characteristics such as background gases (air, N, O, and He), initial ammonia concentration (50-150 ppm), relative humidity (0 or 90 %), and absorbed dose (1-15 kGy) were investigated. In the results of removal characteristics by different background gases, the decomposition efficiency of ammonia was lower (approximately 45 % at 5 kGy) when He was used as a background gas compared to the efficiencies when other background gases were selected. Ammonia removal efficiencies, when initial concentrations were 50 and 150 ppm, were 95 and 75 %, respectively, at 15 kGy. Ozone generation by EB irradiation increased from 2.5 kGy and reached a maximum of 45 ppm when 5 kGy of the absorbed dose was irradiated. However, ozone generation started to decrease when the absorbed dose exceeded 5 kGy and decreased to 0.27 ppm at 15 kGy. [ABSTRACT FROM AUTHOR]

Abstract: We applied a hybrid technique to assess the decomposition characteristics of ethylbenzene and toluene that annexed the catalyst technique with existing electron beam (EB) technology. The removal efficiency of ethylbenzene in the EB–catalyst hybrid turned out to be 30% greater than that of EB-only treatment. We concluded that ethylbenzene was decomposed more easily than toluene by EB irradiation. We compared the independent effects of the EB–catalyst hybrid and catalyst-only methods, and observed that the efficiency of the EB–catalyst hybrid demonstrated approximately 6% improvement for decomposing toluene and 20% improvement for decomposing ethylbenzene. The G-values for ethylbenzene increased with initial concentration and reactor type: for example, the G-values by reactor type at 2800ppmC were 7.5–10.9 (EB-only) and 12.9–25.7 (EB–catalyst hybrid). We also observed a significant decrease in by-products as well as in the removal efficiencies associated with the EB–catalyst hybrid technique. [ABSTRACT FROM AUTHOR]

Abstract: This research was conducted to determine the removal characteristics of butane, using an electron beam. Influential factors, such as an initial concentration, background gases (nitrogen, air, and helium), and absorbed doses (kGy) were investigated. The decomposition efficiencies of background gases showed that oxidation caused by radicals formed from gases, such as N2 and O2, had a greater influence on results than oxidation from primary electrons for butane removal. Removal efficiencies were 40% at 2.5kGy and 66% at 10kGy, when the initial concentration of butane was 60ppmC. When the initial concentration was lower, the energy efficiency of butane removal by electron beam was higher. By-products, including CO2, CO, acetaldehyde, and acetone, formed after electron beam irradiation. Concentrations of CO2 and CO tended to increase when absorbed doses increased as butane was decomposed by the electron beam through an advanced oxidation. [ABSTRACT FROM AUTHOR]

Abstract: We enhanced the decomposition and the removal of toluene in gas phase using a combined method that consists of electron beam (EB) irradiation and catalytic oxidation. The catalytic oxidation system comprises oxidizing particles of 0.1wt% Pt or 0.1wt% Pd deposited to supporting materials, which were also used as adsorbents. These adsorbents—supporting materials are Cordierite, Y-zeolite, and γ-alumina. We demonstrated that 100% removal of toluene can be achieved using approximately 9kGy of dose level in the presence of Pt or Pd deposited to 12wt%. The G (-toluene) values were determined to be 0.498 and 0.829μmol/J in the absence and presence of these catalysts with adsorbents, respectively. We have also demonstrated that the presence of the oxidation-catalyst prevents the toluene from undergoing radiolytic polymerization. [Copyright &y& Elsevier]

Abstract: The decomposition of volatile organic compounds (VOCs) using a pilot system of electron beam (EB)–catalyst coupling was investigated. Two aromatic VOCs, toluene (1800ppmC) and o-xylene (1500ppmC), were irradiated with a dose range of 0–10kGy at room temperature. The removal efficiencies for toluene and o-xylene were 92.4% and 94.5%, respectively, under a 10kGy absorbed dose condition, which were higher than the results of 45.7% and 52.3% when EB-only was used, respectively. The CO2 selectivity approached 100% for both toluene and o-xylene using the EB-catalyst coupling system, while the concentrations of O3 formed were 0.02ppm (toluene) and 0.003ppm (o-xylene) at 10kGy. The aerosol concentration was also measured as 43.2μg/m3 (toluene) and 53.4μg/m3 (o-xylene) at 10kGy absorbed dose. [Copyright &y& Elsevier]

This study was carried out to apply the decomposition process of SF 6 using an electron beam to the actual field by optimizing the process. To do this, we selected Inconel 625, which has excellent corrosion resistance and durability, as an optimal reactor film to prevent damage from by-products (Hydrogen fluoride). Among additive gases, H 2 gas was used to enhance the removal efficiency (RE) of SF 6 because it has the greatest contribution to the RE. Additionally, the initial concentrations of SF 6 , the currents, and the flow rates, considered the main optimal factors, were 1%, 15 mA, and 10 L/min, respectively. Based on the above experimental results, the long-term operating test was performed for 3.5 h at 10 L/min and for 8 h at 5 L/min. The removal efficiency of SF 6 was constantly maintained at approximately 80% at a flow rate 10 L/min. On the other hand, when the flow rate was adjusted to 5 L/min, the RE continuously remained at a level of about 90%. [ABSTRACT FROM AUTHOR]