ARTICLE pubs.acs.org/IECR
Effects of Reaction Conditions on Elemental Mercury Oxidation in Simulated Flue Gas by DC Nonthermal Plasma Meiyan Wang, Tianle Zhu,* Hongjing Luo, Hong Wang, and Weiyi Fan School of Chemistry and Environment, Beihang University, Beijing, 100191, China ABSTRACT: The effects of discharge polarity, discharge electrode configuration, O2/CO2 ratio, and water vapor on the elemental mercury (Hg0) oxidation in simulated flue gas were investigated in a wire-cylinder plasma reactor energized by DC power. The Hg0 oxidation efficiency increases with the increase of specific energy density (SED). Compared with the glow corona discharge energized by negative DC high voltage, the streamer corona discharge induced by positive DC high voltage exhibits a much higher Hg0 oxidation efficiency under identical SED. The discharge electrode configuration significantly influences the energy density in the plasma reactor, but hardly affects Hg0 oxidation for a fixed SED. The increase of O2/CO2 ratio in simulated flue gas obviously enhances Hg0 oxidation. However, with the addition of H2O, Hg0 oxidation is remarkably restrained due to the decrease of O3 formation.
1. INTRODUCTION The emission of mercury has attracted wide attention due to its high toxicity, bioaccumulation, and potential threat to environment and human health. Coal combustion has been considered to be the primary anthropogenic source of mercury in atmosphere. Based on the estimation of Wang et al., mercury emission to the atmosphere from coal combustion in China was 213.8 tons in 1995, and the value rose to 256 tons in 2003.1,2 The elevated mercury contamination leads to huge environmental and economic costs. Hence, developing technologies to reduce the mercury emission is extremely urgent. In the coal-fired flue gas, mercury compounds may be emitted in the forms of elemental mercury (Hg0), oxidized mercury (Hg2þ), and particle-associated mercury (Hgp). Streets et al. estimated that 56% of the Hg in China was released as Hg0, 32% as Hg2þ, and 12% as Hgp.3 Most Hg2þ and Hgp species can be effectively removed by the conventional air pollution control systems such as electrostatic precipitator (ESP), fabric filters, and wet flue-gas desulphurization (WFGD); however, Hg0 is difficult to remove because of its high vapor pressure and low water solubility.4 It is well-known that the WFGD system can remove nearly 90% of the Hg2þ but essentially none of the Hg0.5 Injection of powder activated carbon (PAC) impregnated with certain chemicals (i.e., sulfur, chlorine and iodine species) has been widely studied for the control of mercury emissions.6,7 However, some crucial drawbacks constrain the application of mercury adsorption technology in coal-fired flue gas purification, which includes high cost, high carbon-to-mercury ratio, and working temperature limitation. As an effective alternative, the preoxidation of Hg0 to Hg2þ appears to be a promising approach for the removal of Hg0 by using the existing air pollution control devices. Considerable studies have been conducted regarding gaseous or aqueous oxidation of Hg0, including nonthermal plasma (NTP) oxidation, electron beam (EB) radiation, and chemical oxidation with the oxidative species such as ozone, chlorine, and bromine.814 However, the radiation hazard associated with electron beam and the instability of injected oxidants constrain the practical applications of EB and chemical methods. r 2011 American Chemical Society
NTP has been studied for several decades and is recognized as a potential process for the oxidation of NOx, SO2, volatile organic compounds (VOCs) and trace elements in the flue gas.1519 Active oxygen species such as O, OH, HO2, and O3 generated by high voltage discharge can effectively oxidize Hg0 to Hg2þ. However, the performance of the NTP process could be significantly affected by the discharge conditions and flue gas compositions. For practical applications, the influence of reaction conditions on Hg0 oxidation by NTP should be considered. Many researchers have investigated the effects of gas temperature, residence time, O2/CO2/H2O concentration, and coexistence of other pollutants such as NO and SO2 on Hg0 oxidation in dielectric barrier discharge (DBD) and pulsed corona discharge reactor.2023 Liang et al. have compared the Hg0 removal performance of wire-plate ESP energized by DC and pulse power supplies.24 DC wire-cylinder reactor is more promising for practical applications because of the low cost of DC power supply and the ability to remove aerosol and gaseous pollutants simultaneously. However, the effects of discharge conditions and gas compositions on Hg0 oxidation by DC corona discharge have not been extensively represented in literature. In the present study, the effects of reaction conditions, including discharge polarity, discharge electrode configuration, O2/CO2 ratio, and water vapor on the Hg0 oxidation in simulated flue gas were investigated using a wire-cylinder plasma reactor energized by DC power.
2. EXPERIMENTAL SECTION 2.1. Experimental Apparatus. A schematic diagram of the experimental system is shown in Figure 1a. It consists of a wirecylinder plasma reactor with the positive or negative DC high Received: January 19, 2011 Accepted: April 7, 2011 Revised: March 24, 2011 Published: April 07, 2011 5914
dx.doi.org/10.1021/ie200130m | Ind. Eng. Chem. Res. 2011, 50, 5914–5919
Industrial & Engineering Chemistry Research
ARTICLE
Figure 1. Schematic diagram of the experimental setup (a) and discharge electrodes (b).
voltage power supply (25 kV/5 mA), a gas feeding system, and a set of analytical instruments. A stainless steel cylinder with the inner diameter of 42 mm was used as ground electrode, while a stainless steel rod through which the discharge tooth slices with the outer diameter of 10 mm and thickness of 1 mm were equidistantly linked as discharge electrode. The discharge gap between two electrodes was 16 mm. Four discharge points were evenly distributed on each tooth slice, as shown in Figure 1a. Figure 1b shows the discharge electrode configurations used in this study, where N, I, and L denote the tooth slice number, space interval, and discharge zone length, respectively. Twenty-eight discharge tooth slices linked at space intervals of 10 mm (configuration E) served as the high voltage electrode except for the discharge electrode configuration-effect experiments. As shown in configurations A, B, and C, 15 discharge tooth slices linked at space intervals of 5, 10, and 20 mm were used to investigate the effects of discharge zone length, corresponding to the discharge zone lengths of 90, 165, and 315 mm, respectively. For investigating the effects of tooth slice number, the discharge zone length was kept relatively constant at around 165 mm by linking 8, 15, or 28 discharge tooth slices at space intervals of 20, 10, and 5 mm (configurations D, B, and E), respectively. 2.2. Experimental Procedures. The simulated flue gas was prepared using air, N2, CO2, and so on. A set of mass flow controllers (MFC) were used to adjust the flow rates of dry gases. Water vapor was introduced to the gas mixture by passing the air through a temperature-controlled bubble tower containing water. Gaseous Hg0 was added to the gas mixture from a mercury vapor generator with a mercury permeation tube (VICI Metronics, Inc. USA), which was immersed in a temperature-controlled oil bath.
All the experiments were conducted at atmospheric pressure and room temperature (298 K). The simulated flue gas with a total flow rate of 6 L/min consisted of 6% O2, 12% CO2, 3% H2O, and 110 μg/m3 Hg0 using N2 as balance gas, except for the experiments to evaluate the effects of O2/CO2 ratio and water vapor. Ozone and mercury were sampled at the outlet of plasma reactor and then analyzed by indigo disulfonate spectrophotometry and dithizone spectrophotometry, respectively. Oxidized mercury was absorbed by 0.5 mol/L sulfuric acid solution and elemental mercury by a mixed solution of 0.1 mol/L potassium permanganate and 10% v/v sulfuric acid. The Hg0 oxidation efficiency is defined as ηð%Þ ¼
Coff Con Coff
ð1Þ
where Con and Coff are the concentrations of Hg0 (μg/m3) measured at the outlet of plasma reactor with or without high voltage discharge. Since the specific energy density (SED, the power deposited into 1 L of reaction gas, J/L) directly reflects the energy consumption, all the experimental results were compared on the basis of SED, which is calculated as follows: SED ¼
input ectrical power 60UI ¼ gas flow rate Q
ð2Þ
where U is the applied voltage (kV) measured with a high voltage probe (Tektronix P6139A) and a digital phosphor oscilloscope (Tektronix DPO3012), I is the discharge current (mA) calculated 5915
dx.doi.org/10.1021/ie200130m |Ind. Eng. Chem. Res. 2011, 50, 5914–5919
Industrial & Engineering Chemistry Research
Figure 2. Effects of discharge polarity on discharge characteristics (a) and Hg0 oxidation, outlet O3 concentration (b).
Figure 3. Images of positive DC discharge (a) and negative DC discharge (b) (applied voltage: (13.5 kV).
by measuring the voltage across a resistor connected between the reactor and the ground, and Q is the flow rate of the reaction gas (L/min).
3. RESULTS AND DISCUSSION 3.1. Effects of Discharge Polarity. Effects of discharge polarity (positive and negative DC) on the SED, discharge current, Hg0 oxidation, and O3 formation were investigated. As shown in Figure 2a, the corona on-set voltage for positive DC is higher than that for negative DC, being 12.7 and 9.8 kV, respectively. However, the maximum available voltage and SED to maintain a stable discharge for negative DC are obviously higher than those for positive DC, which are 18.6 kV and 894 J/L for negative DC, as compared with 14.5 kV and 188 J/L for positive DC. Figure 2b shows that the outlet O3 concentration and Hg0 oxidation efficiency increase with the increase of SED for both polarities and are significantly higher for positive DC than those for negative DC under a fixed SED, which indicates that the energy consumption by applying positive DC is much lower than that by applying negative DC. This may arise from the relatively higher chemical activity of positive corona discharge plasma as compared to the negative one. In fact, the images of positive and
ARTICLE
Figure 4. Effects of discharge zone length on discharge characteristics (a) and Hg0 oxidation, outlet O3 concentration (b). Discharge electrode configuration: (A) N = 15, I = 5 mm, L = 90 mm; (B) N = 15, I = 10 mm, L = 165 mm; (C) N = 15, I = 20 mm, L = 315 mm.
negative DC discharge (Figure 3) show a brilliant and uniform streamer corona across the entire interelectrode space for positive DC discharge with an applied voltage of 13.5 kV; on the contrary, the glow corona can be observed only in the vicinity of discharge tooth tine for negative DC discharge with the same applied voltage. The streamer corona discharge exhibits higher chemical activity than glow corona discharge due to a relatively larger ionized region.25 An optical spectrum measurement by Jani et al. also indicated that the average electron-energy induced by positive discharge is obviously higher than that by negative discharge for the same energy consumption.26 In a positive streamer discharge, the strong electric-field intensity in the streamer head induces high-energy electrons (412 eV), which enhance the dissociation of O2 and H2O. Consequently, the formation of active species, including O, OH, HO2 radicals and O3, enhances the Hg0 oxidation. The following reactions are supposed to occur in the plasma reactor:27 O3 þ Hg f HgO þ O2
ð3Þ
O þ Hg f HgO
ð4Þ
OH þ Hg f HgOH
ð5Þ
HgOH þ X f XHgOH
ðX ¼ OH, HO2 , NO, NO2 Þ ð6Þ
All above facts show that the positive DC discharge exhibits a much higher Hg0 oxidation potential than the negative DC discharge under relatively low energy consumption. Hence, the positive DC discharge was adopted in the subsequent experiments. 3.2. Effects of Discharge Electrode Configurations. 3.2.1. Discharge Zone Length. Figure 4 indicates the effects of discharge zone length (90, 165, and 315 mm) on the discharge characteristics, 5916
dx.doi.org/10.1021/ie200130m |Ind. Eng. Chem. Res. 2011, 50, 5914–5919
Industrial & Engineering Chemistry Research
ARTICLE
Figure 5. Effects of tooth slice number on discharge characteristics (a) and Hg0 oxidation, outlet O3 concentration (b). Discharge electrode configuration: (D) N = 8, I = 20 mm, L = 165 mm; (B) N = 15, I = 10 mm, L = 168 mm; (E) N = 28, I = 5 mm, L = 168 mm.
Figure 6. Effects of O2/CO2 ratio on discharge characteristics (a) and Hg0 oxidation, outlet O3 concentration (b).
Hg0 oxidation, and O3 formation, when the discharge tooth slice number was fixed at 15. As seen from Figure 4a, the maximum available voltage decreases with the increase of discharge zone length, while SED increases with increasing the discharge zone length under the same applied voltage. For an applied voltage of 14 kV, the SED is 90, 112, and 155 J/L for the discharge zone lengths of 90, 165, and 315 mm, respectively. In addition, the maximum SED is insensitive to the discharge zone length, which is maintained at about 160 J/L. Figure 4b shows that O3 concentration linearly increases with the increase of SED and is almost the same for a fixed SED regardless of the discharge zone lengths. On the other hand, Hg0 oxidation efficiency significantly increases as SED increases to about 80 J/L, and thereafter levels off with higher SED. For identical SED, Hg0 oxidation is enhanced by increasing the discharge zone length from 90 mm to 165 mm and then keeps relatively constant with the discharge zone length further increasing to 315 mm. Therefore, a discharge zone length of 165 mm may be adequate for sufficient reactions between Hg0 and the active species induced by discharge. Considering the reduction of reactor volume as cobenefit with satisfactory Hg0 oxidation efficiency, the discharge zone length of 165 mm, corresponding to a residence time of 2.3 s, is adopted in the flowing investigation. 3.2.2. Tooth Slice Number. Figure 5 illustrates the effects of tooth slice number (8, 15, and 28) on the discharge characteristics, Hg0 oxidation, and O3 formation. As shown in Figure 5a, the maximum available voltages are almost the same despite different tooth slice numbers. However, both the SED under a fixed applied voltage and the maximum SED increase as the tooth slice number increases, which may arise from the fact that the discharge current is proportional to the number of discharge points in definite discharge zone. In fact, it was also reported that too many discharge points might lead to
corona shield phenomenon, which decreases the discharge current and O3 formation.28 However, the phenomenon does not occur in this study even with 28 discharge slices. It can be seen from Figure 5b that, the maximum O3 concentration increases with the increase of tooth slices, while the maximum Hg0 oxidation efficiency is basically the same for different tooth slice numbers. In addition, excess SED is insignificant to Hg0 oxidation because an energy density of 80 J/L is adequate for a high Hg0 oxidation efficiency of 90%. 3.3. Effects of O2/CO2 Ratio. O2/CO2 ratio resulting from different excess air coefficients is one of the main factors affecting the Hg0 oxidation, as it influences the species and quantities of active radicals induced by NTP. The relationship between SED/ discharge current and applied voltage, as well as the effects of SED on Hg0 oxidation efficiency and O3 formation were studied with the O2/CO2 ratios of 1/17, 7/29, 1/2, and 4/5, corresponding to the gas mixtures of 110 μg/m3 Hg0 þ 3% H2O þ N2 þ 1%, 3.5%, 6%, or 8% O2 þ17%, 14.5%, 12%, or 10% CO2. Figure 6a indicates that SED increases with the increase of O2/ CO2 ratio for a given applied voltage, which might be attributed to the enhanced ionization by the addition of low-ionizationpotential O2.29 In addition, a higher O2/CO2 ratio results in higher maximum available voltage and SED. The maximum SED is 114, 127, 188, and 204 J/L with O2/CO2 ratios of 1/17, 7/29, 1/2, and 4/5, respectively. As shown in Figure 6b, the outlet O3 concentration and Hg0 oxidation efficiency for the same SED, and the maximum O3 concentration and Hg0 oxidation efficiency increase with the increase of O2/CO2 ratio. This can be explained by the fact that O2 is the main source of O3 and O radical, as shown in reactions 78.30 Although the electron-impact dissociation of CO2 also creates O radicals, as shown in reaction 9, it is negligible since the dissociation rate of CO2 is 45 orders of magnitude lower than 5917
dx.doi.org/10.1021/ie200130m |Ind. Eng. Chem. Res. 2011, 50, 5914–5919
Industrial & Engineering Chemistry Research
ARTICLE
leads to the decomposition of HgOH via reaction 13.33,34 HgOH f Hg þ OH
ð13Þ
In addition, the reaction rate coefficients of reaction 5, 6, and 13 are 9.5 1014, 2.5 1010 cm3 molecule1 s1 and 3.2 103 s1 at 298 K (varied by literatures),27 respectively, indicating that the removal of Hg0 through its reaction with OH and HO2 could be greatly attenuated by HgOH decomposition. Some researchers claim that O3 should be the main contributor and OH usually exerts little or no effect on the Hg0 oxidation.10 However, the rate coefficient of reaction 3 is very small (k298 = 7.5 1019 cm3 molecule1 s1). Hence, the O radical, rather than O3, probably plays a key role in oxidizing Hg into HgO, as shown in reaction 4 (k298 = 6.0 1012 cm3 molecule1 s1).
Figure 7. Effects of water vapor on discharge characteristics (a) and Hg0 oxidation, outlet O3 concentration (b).
that of O2.31 O2 þ e f O þ O þ e O2 þ O þ M f O3 þ M
ðM ¼ O2 , N2 Þ
CO2 þ e f CO þ O þ e
ð7Þ ð8Þ ð9Þ
3.4. Effects of Water Vapor. The water vapor in simulated flue gas affects the discharge and oxidation process. Figure 7 shows the SED-U/I-U characteristics and performances of NTP on Hg0 oxidation and O3 formation without H2O or with 3% H2O. It can be seen from Figure 7 that with 3% H2O, both the SED corresponding to the same applied voltage and the maximum available SED are higher than those without H2O. On the other hand, outlet O3 concentration with 3% H2O is lower than that without H2O under the same SED. This can be ascribed to the consumption of energetic electron, O radicals, and O3 for the formation of OH and HO2 radicals in the presence of H2O, as shown in the following equations:32
e þ H2 O ¼ OH þ H þ e
ð10Þ
O þ H2 O ¼ 2OH
ð11Þ
OH þ O3 ¼ HO2 þ O2
ð12Þ
0
Similar to O3 formation, Hg oxidation is restrained in the presence of water vapor. As mentioned in reactions 5 and 6, Hg0 might react with OH and HO2 to form HgOH. However, the HgOH molecule has a relatively short lifetime (280 μs) at room temperature, since the weak HgOH bond (about 39 kJ/mol)
4. CONCLUSIONS The effects of discharge polarity, discharge electrode configuration, O2/CO2 ratio, and water vapor on Hg0 oxidation in simulated flue gas by DC corona plasma were systematically investigated in this study and the following conclusions were obtained. (1) The Hg0 oxidation efficiency and O3 concentration increases with the increase of SED. (2) A streamer and glow corona discharge can be observed with the positive or negative DC power supply. Energy consumption corresponding to the same Hg0 oxidation efficiency for positive DC is much lower than that for negative DC. (3) For a fixed SED, the Hg0 oxidation efficiency slightly increases and then levels off with increasing discharge zone length, while it is almost the same in spite of different discharge tooth slice number. (4) A higher O2/CO2 ratio (or excess air coefficient) could improve the intensity and stability of discharge. Moreover, for a given SED, the outlet O3 concentration and Hg0 oxidation efficiency are significantly enhanced by increasing the O2/CO2 ratio. (5) The presence of H2O increases the maximum SED, but restrains the Hg0 oxidation due to decrease of O3 concentration. ’ AUTHOR INFORMATION Corresponding Author
*E-mail:
[email protected].
’ ACKNOWLEDGMENT The authors acknowledge the financial support for this work provided by the High-Tech Research and Development Program (863) of China (No. 2007AA06Z313 and No. 2009AA064101) and the National Natural Science Foundation of China (No. 20977003). ’ REFERENCES (1) Wang, Q.; Shen, W.; Ma, Z. Estimation of Mercury Emission from Coal Combustion in China. Environ. Sci. Technol. 2000, 34, 2711. (2) Wang, S. X.; Liu, M.; Jiang, J. K.; Hao, J. M.; Wu, Y.; Streets, D. G. Estimate the Mercury Emissions from Noncoal Sources in China. J. Environ. Sci. China 2006, 27, 2401. 5918
dx.doi.org/10.1021/ie200130m |Ind. Eng. Chem. Res. 2011, 50, 5914–5919
Industrial & Engineering Chemistry Research (3) Streets, D. G.; Hao, J.; Wu, Y.; Jiang, J.; Chan, M.; Tian, H.; Feng, X. Anthropogenic Mercury Emissions in China. Atmos. Environ. 2005, 39, 7789. (4) Scala, F.; Clack, H. L. Mercury Emissions from Coal Combustion: Modeling and Comparison of Hg Capture in a Fabric Filter versus an Electrostatic Precipitator. J. Hazard. Mater. 2008, 152, 616. (5) Pavlish, J. H.; Sondreal, E. A.; Mann, M. D.; Olson, E. S.; Galbreath, K. C.; Laudal, D. L.; Benson, S. A. Status Review of Mercury Control Options for Coal-fired Power Plants. Fuel Process. Technol. 2003, 82, 89. (6) Korpiel, J. A.; Vidic, R. D. Effect of Sulfur Impregnation Method on Activated Carbon Uptake of Gas-Phase Mercury. Environ. Sci. Technol. 1997, 31, 2319. (7) Lee, S. J.; Seo, Y. C.; Jurng, J.; Lee, T. G. Removal of Gas-Phase Elemental Mercury by Iodine-and Chlorine-Impregnated Activated Carbons. Atmos. Environ. 2004, 38, 4887. (8) Hutson, N. D.; Krzyzynska, R.; Srivastava, R. K. Simultaneous Removal of SO2, NOx, and Hg from Coal Flue Gas Using a NaClO2Enhanced Wet Scrubber. Ind. Eng. Chem. Res. 2008, 47, 5825. (9) Agarwal, H.; Stenger, H. G.; Wu, S.; Fan, Z. Effects of H2O, SO2, and NO on Homogeneous Hg Oxidation by Cl2. Energy Fuels 2006, 20, 1068. (10) Byun, Y.; Ko, K. B.; Cho, M.; Namkung, W.; Shin, D. N.; Lee, J. W.; Koh, D. J.; Kim, K. T. Oxidation of Elemental Mercury Using Atmospheric Pressure Nonthermal Plasma. Chemosphere 2008, 72, 652. (11) Ribeiro, M. A.; Sato, I. M.; Duarte, C. L.; Sampa, M. H. O.; Salvador, V. L. R.; Scapin, M. A. Application of the Electron-Beam Treatment for Ca, Si, P, Al, Fe, Cr, Zn, Co, As, Se, Cd and Hg Removal in the Simulated and Actual Industrial Effluents. Radiat. Phys. Chem. 2004, 71, 425. (12) Pal, B.; Ariya, P. A. Studies of Ozone Initiated Reactions of Gaseous Mercury: Kinetics, Product Studies, and Atmospheric Implications. Phys. Chem. Chem. Phys. 2004, 6, 572. (13) Niksa, S.; Padak, B.; Krishnakumar, B.; Naik, C. V. Process Chemistry of Br Addition to Utility Flue Gas for Hg Emissions Control. Energy Fuels 2010, 24, 1020. (14) Yan, N. Q.; Liu, S. H.; Chang, S. G.; Miller, C. Method for the Study of Gaseous Oxidants for the Oxidation of Mercury Gas. Ind. Eng. Chem. Res. 2005, 44, 5567. (15) Mok, Y. S.; Kim, J. H.; Nam, I. S.; Ham, S. W. Removal of NO and Formation of Byproducts in a Positive-Pulsed Corona Discharge Reactor. Ind. Eng. Chem. Res. 2000, 39, 3938. (16) Chang, J. S.; Lawless, P. A.; Yamamoto, T. Corona Discharge Processes. IEEE Trans. Plasma Sci. 1991, 19, 1152. (17) Masuda, S.; Nakao, H. Control of NOx by Positive and Negative Pulsed Corona Discharges. IEEE Trans. Ind. Appl. 1990, 26, 374. (18) Chen, Z.; Mathur, V. K. Nonthermal Plasma for Gaseous Pollution Control. Ind. Eng. Chem. Res. 2002, 41, 2082. (19) Penetrante, B. M.; Schultheis, S. E. Non-Thermal Plasma Techniques for Pollution Control. Part A: Overview, Fundamentals and Supporting Technologies; Springer-Verlag: Berlin, 1993. (20) Chen, Z.; Mannava, D. P.; Mathur, V. K. Mercury Oxidization in Dielectric Barrier Discharge Plasma System. Ind. Eng. Chem. Res. 2006, 45, 6050. (21) Jeong, J.; Jurng, J. Removal of Gaseous Elemental Mercury by Dielectric Barrier Discharge. Chemosphere 2007, 68, 2007. (22) Ko, K. B.; Byun, Y.; Cho, M.; Namkung, W.; Hamilton, I. P.; Shin, D. N.; Koh, D. J.; Kim, K. T. Pulsed Corona Discharge for Oxidation of Gaseous Elemental Mercury. Appl. Phys. Lett. 2008, 92, 251503. (23) Ko, K. B.; Byun, Y.; Cho, M.; Namkung, W.; Shin, D. N.; Koh, D. J.; Kim, K. T. Influence of HCl on Oxidation of Gaseous Elemental Mercury by Dielectric Barrier Discharge Process. Chemosphere 2008, 71, 1674. (24) Liang, X.; Looy, P. C.; Jayaram, S.; Berezin, A. A.; Mozes, M. S.; Chang, J. S. Mercury and Other Trace Elements Removal Characteristics of DC and Pulse-Energized Electrostatic Precipitator. IEEE Trans. Ind. Appl. 2002, 38, 69.
ARTICLE
(25) Gasparik, R.; Ihara, S.; Yamabe, C.; Satoh, S. Effect of CO2 and Water Vapors on NOx Removal Efficiency under Conditions of DC Corona Discharge in Cylindrical Discharge Reactor. Jpn. J. Appl. Phys. 2000, 39, 306. (26) Jani, M. A.; Takaki, K.; Fujiwara, T. Streamer Polarity Dependence of NOx Removal by Dielectric Barrier Discharge with a Multipoint-to-Plane Geometry. J Phys. D: Appl. Phys. 1999, 32, 2560. (27) Calvert, J. G.; Lindberg, S. E. Mechanisms of Mercury Removal by O3 and OH in the Atmosphere. Atmos. Environ. 2005, 39, 3355. (28) Wu, Z. L.; Gao, X.; Luo, Z. Y.; Ni, M. J.; Cen, K. F. Formation of Ozone and NOx during Corona Discharge Radical Shower. J. Chem. Ind. Eng. China 2006, 57, 1214. (29) Dean, J. A., Lange0 s Handbook of Chemistry; McGraw-Hill: New York, 1999. (30) Atkinson, R.; Baulch, D. L.; Cox, R. A.; Crowley, J. N.; Hampson, R. F.; Hynes, R. G.; Jenkin, M. E.; Rossi, M. J.; Troe, J. Evaluated Kinetic and Photochemical Data for Atmospheric Chemistry: Volume I-Gas Phase Reactions of Ox, HOx, NOx, and SOx Species. Atmos. Chem. Phys. 2004, 4, 1461. (31) Li, J.; Sun, W.; Pashaie, B.; Dhali, S. K. Streamer Discharge Simulation in Flue Gas. IEEE Trans. Plasma Sci. 1995, 23, 672. (32) Herron, J. T.; Green, D. S. Chemical Kinetics Database and Predictive Schemes for Nonthermal Humid Air Plasma Chemistry. Part II. Neutral Species Reactions. Plasma Chem. Plasma Process. 2001, 21, 459. (33) Goodsite, M. E.; Plane, J. M. C.; Skov, H. A Theoretical Study of the Oxidation of Hg0 to HgBr2 in the Troposphere. Environ. Sci. Technol. 2004, 38, 1772. (34) Pal, B.; Ariya, P. A. Gas-Phase HO-Initiated Reactions of Elemental Mercury: Kinetics, Product Studies, and Atmospheric Implications. Environ. Sci. Technol. 2004, 38, 5555.
5919
dx.doi.org/10.1021/ie200130m |Ind. Eng. Chem. Res. 2011, 50, 5914–5919
