SO2 Removal Efficiency Research Articles

Influence of cathode on the electro-generation of peroxydisulfuric acid oxidant and its application for effective removal of SO2 by room temperature electro-scrubbing process

Peroxydisulfuric acid oxidant (H2S2O8) was electro-generated using boron doped diamond (BDD) anode in an undivided electrolytic cell under the optimized conditions and used for the oxidative removal of gaseous SO2. The influence of the nature of cathode material on the formation yield of H2S2O8 was investigated with Ti, Pt, Zr and DSA electrodes in a flow type electrolytic cell under batch recirculation mode. Among the various cathodes employed Ti exhibited a good performance and the formation yield was nearly doubled (0.19M) compared to the reported value of 0.07M. The optimization of electrode area ratio between the anode and cathode brought out the fact that for nearly 8 times smaller Ti cathode (8.75:1) the achieved yield was ∼65% higher than the 1:1 ratio of anode and cathode. The highest concentration of 6.8% (0.48M) H2S2O8 was seen for 35cm2 BDD anode with 4cm2 Ti at 20°C with the measured redox potential value of +1200mV. The oxidative removal of SO2 in an electro-scrubbing column attached to the online production of peroxydisulfuric acid under the optimized conditions of cell parameters shows that SO2 removal efficiency was nearly 100% for 25 and 50ppm inlet concentrations and 96% for 100ppm at the room temperature of 25°C.

Combined process for removal of SO2, NOx, and particulates to be applied to a 1.6-MWe pulverized coal boiler

In this study, a combined process for the removal of SO2, NOx, and particulates at low temperature was suggested to minimize the scale and maximize the removal efficiency of equipment. Based on the results of the activity test for each process, a combined system could be designed, and its performance was also evaluated. SO2, dust, and NOx removal efficiencies were 94.15, 99.98, and 92.51%, respectively. It is believed that the system suggested in this study will be a very useful and popular system to control the air pollutants from coal boilers.

Simultaneous photocatalytic elimination of gaseous NO and SO2 in a BiOI/Al2O3-padded trickling scrubber under visible light

The simultaneous photocatalytic elimination of NO and SO2 was achieved in a BiOI/Al2O3-padded trickling scrubber under visible light. The BiOI/Al2O3 composites, in which nanostructured BiOI was well dispersed on the surface of Al2O3, were successfully synthesized through solvothermal method. The prepared BiOI/Al2O3 was characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM) and UV–vis diffuse reflectance spectra (DRS). The elimination of NO and SO2 was studied in a BiOI/Al2O3 trickling scrubber. It was found that the removal efficiency of NO and SO2 could reach 100% in photocatalytic BiOI/Al2O3-padded trickling scrubber, demonstrating that the present method performs well for simultaneous denitrification and desulfurization. The high removal efficiency for NO and SO2 was attributed to the enhanced gas absorption of BiOI/Al2O3 composites and the generation of reactive OH under visible-light irradiation in the system. The involvement of OH in oxidizing NO and SO2 was examined by determining the photocurrent of BiOI/Al2O3 and removal rates using different scavengers. Ion chromatography (IC) analysis identified that NO3− and SO42− were main products, and the mass balances analysis for N and S in scrubbing solution indicated that NO and SO2 were completely oxidized to be NO3− and SO42−. Most importantly, this BiOI/Al2O3 wet photocatalytic scrubber retained their simultaneous desulfurization and denitrification efficiencies for long-term repetitive batch runs, indicating the stable photocatalytic process.

Wet removal of sulfur dioxide and nitrogen oxides from simulated flue gas by ca(ClO)2 solution

To study the simultaneous removal of Sulfur Dioxide (SO2) and Nitrogen Oxides (NOx) from simulated flue gas by wet method, a bubbling device containing calcium hypochlorite (Ca(ClO)2) solution was used in the experiments. In the first place, thermodynamic analysis was conducted to determine the depth of reaction process, and the reaction mechanism of desulfurization and denitration was proposed. After that, experimental results exhibited that SO2 could be removed by Ca(ClO)2 solution completely while the removal efficiency of NOx was 41.2%. Moreover, on the basis of high SO2 removal efficiency, the effects of various factors on the removal efficiency of NOx, such as: the height of liquid layer, Ca(ClO)2 concentration, reaction temperature, initial pH value, O2 percent, SO2 concentration, and additives were investigated, respectively. Finally, simultaneous removal of SO2 and NOx under the optimized conditions were investigated, SO2 removal efficiency of 100% and NOx removal efficiency of 85.9% were achieved. The analysis of reaction products indicated that the main anions in the liquid phase were and . © 2015 American Institute of Chemical Engineers Environ Prog, 34: 1586–1595, 2015

Adsorption and oxidation of SO2 in a fixed-bed reactor using activated carbon produced from oxytetracycline bacterial residue and impregnated with copper

The SO2 removal ability (including adsorption and oxidation ability) of activated carbon produced from oxytetracycline bacterial residue and impregnated with copper was investigated. The activated carbon produced from oxytetracycline bacterial residue and modified with copper was characterized by x-ray diffraction, scanning electron microscopy, and energy-dispersive spectroscopy. The effects of the catalysts, SO2 concentration, weight hourly space velocity, and temperature on the SO2 adsorption and oxidation activity were evaluated. Activated carbon produced from oxytetracycline bacterial residue and used as catalyst supports for copper oxide catalysts provided high catalytic activity for the adsorbing and oxidizing of SO2 from flue gases.Implications: To improve the SO2 removal efficiency and reduce costs, the pretreatment of activated carbon or activated carbon-based materials has been widely studied. Oxytetracycline bacterial residue is currently a hazardous waste, which has been investigated in terms of an adduct to active carbon (OBR-AC). Unfortunately, the application of OBR-AC was limited due to the absence of several metals in it, such as Fe and K. The OBR-AC was loaded with copper by immersion method to prepared Cu/OBR-AC, which was used to absorb and oxidize SO2. Cu/OBR-AC exhibited significantly greater catalytic activity than OBR-AC.

Removal of Hg0 and simultaneous removal of Hg0/SO2/NO in flue gas using two Fenton-like reagents in a spray reactor

A novel process on oxidation removal of elemental mercury (Hg0) from flue gas using two Fenton-like reagents in a spray reactor was proposed. The effects of several process parameters such as H2O2 concentration, Fe3+ concentration, Cu2+ concentration, reaction temperature, solution pH, Hg0 inlet concentration, liquid–gas ratio, NO concentration, SO2 concentration on Hg0 removal were investigated. Reaction mechanism of Hg0 removal was investigated. Simultaneous removal of Hg0, NO and SO2 in flue gas was studied preliminarily. A simple economic estimate for simultaneous removal of Hg0, SO2 and NO was also carried out. Increasing H2O2 concentration, Fe3+ concentration, Cu2+ concentration or liquid–gas ratio significantly promotes Hg0 removal. Increasing solution pH, NO concentration or SO2 concentration significantly inhibits Hg0 removal. Hg0 inlet concentration and reaction temperature have a small impact on Hg0 removal. Oxidation of Hg0 by OH plays a leading role for Hg0 removal. The simultaneous removal efficiencies of Hg0, SO2 and NO are up to 100%, 100%, 85.3% and 100%, 100%, 75.3% using Fe3+ and Cu2+ as catalysts, respectively.

Study on Removing SO<sub>2</sub> and NOx Simultaneously in Ships Emissions by Wet Scrubbing Based on Natrium-Alkali Method

The present paper investigates the simultaneous removal and synergistic effect of SO2 and NOx in natrium-alkali solutions in a countercurrent packed column in continuous flow mode. On the basis of high SO2 removal efficiency, the NOx removal efficiencies under different process variables such as natrium-alkali concentration, reaction temperature, initial pH value, SO2 concentration, oxidation degree of NOx and additive were investigated. The reaction mechanism for synergistic effect and simultaneous removal of SO2 and NOx based on the natrium-alkali method were deduced. The removal efficiency of SO2 was about 100%, but the effect mechanism of denitration efficiency was complex. In this paper, the optimal conditions for simultaneous removal of SO2 and NOx were determined. The experimental results showed that the simultaneous desulfurization and denitration was possible, and the removal efficiencies could meet the increasingly stringent emissions regulations of IMO.

Simultaneous removal of SO2 and NOx with ammonia combined with gas-phase oxidation of NO using ozone

A process for simultaneous desulfurization and denitrification was proposed, which was made up of ozone as the oxidizing agent for NO and ammonia solution as absorbent. The results showed that the presence of SO2 and the concentration changes of NO and SO2 have little impact on the oxidation of NO, the oxidation efficiency of NO can achieve over 90% when the molar ratio of O3/NO is 1.0. The presence of NOx had little effects on the absorption of SO2, an appropriate increase of SO2 concentration was favorable to the NOx absorption. The removal efficiency of SO2 and NOx reached 99.34% and 90.01% at pH 10, flow rate 0.95 Nm3/h, n[O3]/n[NO] 1.0, initial SO2 concentration 2000 mg/Nm3, initial NO concentration 200 mg/Nm3, ammonia concentration 0.3%, oxygen content of the simulated flue gas 12%, oxidation reaction temperature 423K and absorption reaction temperature 298K in the experimental system.

SO2Gas Physicochemical Removal through Pulse Streamer Discharge Technique Assisted by Vapor Additive

SO2removal has drawn extensive attentions for air pollution treatment. In this paper, the pulse streamer discharge technique is investigated. Emission spectra diagnosis experimentally indicates that the SO2molecule has been physically dissociated into SO and O radicals by electron collision and can be remediated through further chemical reactions during and after discharge. In order to quantitatively analyze the removal physical chemistry kinetics, a zero-dimensional physicochemical reaction model is established. Without H2O vapor additive, the SO2removal efficiency is leanly low and only 0.296% has been achieved under pulse discharge duration of 0.5 μs. Through increasing the electrical concentration six times, the removal efficiency has been slightly heightened to 1.796% at pulse duration of 3 μs. Contrarily, vapor additive can effectively improve the removal kinetics, and removal efficiency has been remarkably heightened to 13.0195% at pulse duration of 0.5 μs with H2O/SO2initial concentration ratio of 0.1 : 1. OH radicals decomposed from H2O through electron collision are the essential factor to achieve such improvement, which have effectively adjusted the chemical removal process to the favorite directions. The major productions have been transformed from HSO3and HOSO2to H2SO4when vapor ratio increased above 1.27 : 1.

Removal of SO2 over Modified Activated Carbon in Fixed Bed Reactor: I, Effect of Metal Oxide Loadings and Acid Treatment


 The removal of SO2 from simulated gas stream (SO2 + air) in a fixed bed reactor using Modified Activated Carbon (MAC) catalysts was investigated. All the experiments were conducted at atmospheric pressure, initial SO2 concentration of 2500 ppm and bed temperature of 90oC. MAC was prepared by loading a series of nickel and copper oxides 1, 3, 5, 7, and 10 wt% on AC. In some of the experimental runs, the original activated carbon was pretreated with two different concentrations of nitric acid 10 and 45 wt%. The results showed that the SO2 removal efficiency, breakthrough time (τ0.05) and sorption capacity increase with increasing metal oxides loadings up to a value of 7 wt% beyond which the desulfurization performance decreases. The pretreatment of the original AC with HNO3 enhanced the removal efficiency of SO2. The copper supported catalysts showed higher flue gas desulfurization activity as compared to the nickel supported catalysts.

Thermophilic biofilter for SO2 removal: Performance and microbial characteristics

A bench-scale thermophilic biofilter was applied to remove SO2 at 60°C in the present study. The SO2 concentration in the inlet stream ranged from 100mg/m3 to 200mg/m3. An average SO2 removal efficiency of 93.10% was achieved after developing acclimated organisms that can degrade SO2. The thermophilic biofilter effectively reduced SO2, with a maximum elimination capacity of 50.67g/m3/h at a loading rate of 51.44g/m3/h. Removal efficiency of the thermophilic biofilter was largely influenced by the water containing rate of the packing materials. The SO2 transfer in the biofilter included adsorption by the packing materials, dissolution in liquid, and microbial degradation. The main product of SO2 degradation was SO42−. The temporal shifts in the bacterial community that formed in the biofilter were determined through polymerase chain reaction–denaturing gradient gel electrophoresis and DNA sequence analysis. These shifts revealed a correlation between biofilter performance and bacterial community structure.

Simultaneous treatment of NO and SO2 with aqueous NaClO2 solution in a wet scrubber combined with a plasma electrostatic precipitator

NO and SO2 gases that are generally produced in thermal power plants and incinerators were simultaneously removed by using a wet scrubber combined with a plasma electrostatic precipitator. The wet scrubber was used for the absorption and oxidation of NO and SO2, and non-thermal plasma was employed for the electrostatic precipitation of aerosol particles. NO and SO2 gases were absorbed and oxidized by aerosol particles of NaClO2 solution in the wet scrubber. NO and SO2 reacted with the generated NaClO2 aerosol particles, NO2 gas, and aqueous ions such as NO2−, NO3−, HSO3−, and SO42−. The aerosol particles were negatively charged and collected on the surface of grounded anode in the plasma electrostatic precipitator. The NO and SO2 removal efficiencies of the proposed system were 94.4% and 100% for gas concentrations of 500mg/m3 and a total gas flow rate of 60Nm3/h, when the molar flow rate of NaClO2 and the gas–liquid contact time were 50mmol/min and 1.25s, respectively. The total amount and number of aerosol particles in the exhaust gas were reduced to 7.553μg/m3 and 210/cm3 at the maximum plasma input power of 68.8W, which are similar to the values for clean air.

Experimental Study on Desulfurization Enhanced by Additive in Limestone-Gypsum FGD Process

This Paper introduced the research background and technical features of the simulative experiments in the laboratory with the sorbent of lime solution without lime particles. By means of the effects of various influencing factors on SO2 removal efficiency were studied carefully. These parameters include gas flow rate (G), inlet SO2 concentration, liquid-to-gas ratios, the height of the packing and the additive, at the same time menstruating the pH value of the liquid flowing from the tower. To improve desulfurization efficiency of limestone in the wet flue gas desulfurization (WFGD), effect of the hexanedioic acid additive on limestone desulfurization agent were studied. The result shows that this system has advantages of high efficiency, stable, low investment and low circulating cost. The result could give a reference to optimization and will be helpful in selecting desulfurization techniques.

Absorption of SO2 with Ammonia-Based Solution in a Cocurrent Rotating Packed Bed

The emission of SO2 leads to serious environmental problems, which has attracted increasing attention. In this work, a cocurrent rotating packed bed (CO-RPB) with a novel SiC structured packing was employed as a process intensification candidate to upgrade existing desulfurization systems. The effects of rotating speed, gas flow rate, liquid flow rate, SO2 inlet concentration, total salt concentration, and alkalinity on the SO2 removal efficiency were investigated by adopting the ammonia-based solution as the absorbent. The experimental results showed that the SO2 concentration at the RPB outlet can meet the new Chinese emission standard very well. In addition, the gas-side volumetric overall mass transfer coefficient (Kya) was deduced based on the mass balance equation, and its correlation was also proposed. The predicted Kya calculated by the correlation was in good agreement with the experimental data, and the deviation was within the range of ±8%.

Flue Gas Desulfurization by Mechanically and Thermally Activated Sodium Bicarbonate

Abstract This paper presents the results of study on structural parameters (particle size, surface area, pore volume) and the sorption ability of mechanically and thermally activated sodium bicarbonate. The sorption ability of the modified sorbent was evaluated by: partial and overall SO2 removal efficiency, conversion rate, normalized stoichiometric ratio (NSR). Sodium bicarbonate was mechanically activated by various grinding techniques, using three types of mills: fluid bed opposed jet mill, fine impact mill and electromagnetic mill, differing in grinding technology. Grounded sorbent was thermally activated, what caused a significant development of surface area. During the studies of SO2 sorption, a model gas with a temperature of 300°C, of composition: sulfur dioxide at a concentration of 6292 mg/mn 3, oxygen, carbon dioxide and nitrogen as a carrier gas, was used. The best development of surface area and the highest SO2 removal efficiency was obtained for the sorbent treated by electromagnetic grinding, with simultaneous high conversion rate.

Modeling and experimental analysis of packed column for SO2 emission control process

Sulfur dioxide (SO2) emissions from chemical process plants are increasing at an alarming rate. It is necessary to implement the best methodology to reduce the SO2 emissions. This paper presents physical modeling, computational fluid dynamics (CFD) analysis, and experimental analysis of a packed column used for flue gas desulfurization (FGD) process to reduce SO2 emission at a greater extent. The packed column parameters such as liquid/gas (L/G) ratio, diameter, packed height and total height were determined using physical modeling with two–film gas–liquid absorption theory. Simulation model of the packed column is developed by GAMBIT 2.2.30 and analysis is carried out by FLUENT 6.2.16. In CFD analysis, hydrogen peroxide (H2O2) (with different concentrations) was used as an absorbent. CFD simulation result ensures that when H2O2 is used as a reactant, better removal efficiency is obtained. Based on the physical modeling and CFD analysis, a lab scale packed column was developed. Experimental result showed that 95% SO2 removal efficiency is achieved for 0.1M H2O2 as a reactant. Experimental results agreed excellently with the developed CFD model and can be used for designing industrial packed columns.

Experimental Research of Flue Gas Simultaneous Desulfurization and Denitrification with the New Gas-Liquid Medium

The flue gas simultaneous desulfurization and denitrification was studied for its feasibility with the new gas-liquid medium by using Ca(OH)2 as absorbent. The effects on key operating parameters were analyzed. They are pH, inlet temperature of flue gas and inlet concentration of air pollution. When pH is almost 5.5-6, and inlet temperature of flue gas is between 110℃ and 120℃, the results show that the removal efficiency of SO2 and NO are above 85% and 80% using rotating biological technology (RDB), respectively, which can satisfy most requirements of industrial scale applications. Besides, When CSO2 is more than 1500 (mg/m3), with the rising of imported pollutant concentration, desulfurization efficiency continues to increasing and denitrification efficiency was growing slowly.

Study on SO<sub>2</sub>, NO Removal from Flue Gas Using an Aqueous NaClO<sub>2 </sub>Solution with Oxidation Reduction Potential and pH Control

Removal of SO2 and NO from the flue gas using an aqueous sodium chlorite solution was achieved in a bubbling reactor, ORP and pH were used as monitoring parameter. The effect of pH, NaClO2 feeding rate and SO2 concentration on simultaneous removal of SO2 and NOx efficiencies were systematical investigated. The results showed that SO2 removal efficiency was always 100% and NOx removal efficiency could achieve 65% at optimized conditions, the optimized pH value of 5-5.5 was observed. The correlation analysis among ORP, original pH, NaClO2 feeding rate and input SO2 concentration was established using multiple regression equations.

Photochemical removal of NO and SO2 from flue gas using UV irradiation

ABSTRACTThe simultaneous oxidation and removal efficiencies of SO2 and NO from simulated coal‐fired flue gas by UV irradiation were investigated experimentally. The influencing factors, such as the reaction temperature, the content of O2, H2O, SO2, and NO, on the removal of SO2 and NO were studied. The results indicated that NO had positive effect on the removal of SO2. Compared with the NO‐free case, the removal efficiency of SO2 was improved from 8% to 55% in the presence of 250 ppm NO. When the NO concentration rose from 250 to 700 ppm, the SO2 removal efficiency further increased from 55% to 64%. The increasing of reaction temperature enhanced the removal efficiencies of SO2 and NO, which increased by 28% and 36%, respectively, with the reaction temperature rising from 270 to 350 °C. It was found that O2 was conducive to the photochemical oxidization due to the generation of free radicals. As the O2 content increased from 0% to 8%, the removal efficiencies of NO and SO2 reached 40% and 55%, respectively. The positive effect of H2O on the simultaneous removal of NO and SO2 was also observed. The optimal conditions (250 ppm NO, 100 ppm SO2, 8% O2, 5% H2O, and reaction temperature 350 °C) were determined, and the removal efficiencies of SO2 and NO were 55% and 40%, respectively. © 2014 Curtin University of Technology and John Wiley & Sons, Ltd.

SO2 Removal by Seawater in a Packed–Bed Tower: Experimental Study and Mathematical Modeling

Flue gas desulfurization of industrial plants using seawater is studied experimentally and theoretically in a counter–current packed–bed tower. Experiments are carried out based on a 16–run orthogonal array of the Taguchi method (five factors, four levels) and ANOVA table created to determine the most significant controlling factors on SO2 removal efficiency. Liquid flow rate (1.5–4 l/min), gas temperature (50–350°C), gas flow rate (8–20 m3/h), and SO2 concentration (500–2000 ppmv) are revealed as important factors, while the pH of seawater (8–9.5) is not significant. Experimental results show that an increase in gas temperature causes a decrease in the removal efficiency. A mathematical model is developed for the removal of SO2 by seawater for non-isothermal operating conditions. In the modeling procedure the equilibrium reactions of eight dissolved species within the liquid phase are considered to calculate the kinetic of reaction correctly. The results of this study confirm the capability of seawater for SO2 removal in packed-bed towers.