Presence Of Sulfur Dioxide Research Articles

Influence of SO2 on CO2 capture by adsorption on activated carbon: Individual pore performance via multiscale simulation

Carbon capture under post-combustion conditions has been the topic of numerous studies in the last decade. Although exhaust gases typically contain different components other than CO2, they are commonly neglected in these studies. The presence of sulfur dioxide, for example, tends to interfere in the carbon capture process through different mechanisms. The present work aimed to evaluate the effects of SO2 on the CO2 retention capacity through the integration of experimental evaluation, column dynamics modeling and molecular simulation (multiscale modeling) for an activated carbon sample under typical conditions found in the post-combustion environment. Results indicate that, under typical post-combustion flue gas conditions, SO2 has little influence on the CO2 retention capacity of the carbon in comparison to other adsorbent materials. The highest concentration of SO2 (5 000 ppmv) led to a decrease of approximately 10 % in the CO2 capture capacity. Significant deactivation (around 40 %) was observed experimentally and by molecular simulation only for very high concentrations of SO2 (50 000 ppmv). Additionally, no evidence of reactions with the material was found and both captured components could be completely desorbed by means of suitable regeneration methods. To access individual pore performance, molecular simulations were implemented for SO2 adsorption using, for the first time, a rigorous heterogeneous pore model (rMD). The results revealed a large deactivation for the 7.0 Å pore, a surprising cooperative effect for the 8.9 Å pore, and indifference for the larger 18.5 and 27.9 Å pores. For SO2 concentrations up to 5 000 ppmv, the use of carbon-based adsorbent could rule out the need of a pre-treatment operation to remove SO2 in carbon capture processes. For higher concentrations, molecular simulation showed that tailoring carbon porosity in the range of 7 Å to 8.9 Å considerably reduces the interference of SO2. Results also point out that the IAST and Langmuir models diverge from the molecular simulation results, particularly at low loadings (up to 5 000 ppmv SO2), indicating the need for caution when applying these models in systems where competitive interactions between molecules are relevant, as is the case with mixtures of CO2 and SO2.

Selective Catalytic Oxidation of Ammonia over Cr-Ce Mixed Oxide Catalysts in the Presence of Sulfur Dioxide

Selective Catalytic Oxidation of Ammonia over Cr-Ce Mixed Oxide Catalysts in the Presence of Sulfur Dioxide

The Effect of Yeast, Sugar and Sulfur Dioxide on the Volatile Compounds in Wine

This study compares three yeast strains: two wild Saccharomyces cerevisiae strains (Sc1 and Sc5) and a commercial strain (Lc). The objective is to assess their fermentation efficiency and volatile compound production. The factors examined are yeast strain, initial sugar concentration of the must, and the presence of sulfur dioxide. Volatile aroma compounds, determined via GC–MS, were categorized into aromatic series based on aroma descriptors. Out of the volatile compounds analyzed, the yeast strain influenced 39, while sugar content and sulfur dioxide affected 16 and 23 compounds, respectively. Twelve compounds displayed odor activity values exceeding unity, with notable contributions from ethyl esters, β-damascenone, and β-ionone, impacting fruit, floral, and herbal aromatic series. Overall, the Sc1 yeast strain exhibited higher values in the aromatic series compared to the Lc strain. Multivariate analysis revealed that the Sc1 strain highlighted green fruit, citrus, and spice series, while the Lc strain stood out for smoky and herbal aromas. Cluster and principal component analyses emphasized that the aromatic composition of wines produced with wild yeast strains is more influenced by sulfur dioxide than initial sugar content, whereas the opposite holds true for the commercial strain. The key aroma series distinguishing between yeast strains were fruity, green fruit, and citrus for Sc1, and herbal, floral, and smoky for Lc. In conclusion, the Sc1 wild yeast strain showed similar fermentation behavior to the commercial strain, resulting in increased aroma compound presence. The distinctive aromatic profiles contributed by each strain enable winemakers to leverage this diversity and create wines that emphasize specific aromas.

ESTUDIO COMPARATIVO DE LA DECLARACIÓN DE ALÉRGENOS Y FRASES DE ADVERTENCIA EN RÓTULOS DE ALIMENTOS ENTRE LOS AÑOS 2019 Y 2022

ABSTRACT Introduction: the labeling of food allergens in products is today one of the issues that generates great concern in the population. Objective: was to evaluate how different companies adapted to current legislation on allergens in Argentina. Materials and methods: in 2019, sixteen sweet and salty food products were surveyed, coded as: ME, MN, TO, PA, GD, F, MLV, QM, BB, BT, TR, TM, PFK, BQK, CHB and CM. To compare the allergen declarations, in mid-2022 the sixteen products were surveyed again, finding three discontinued products. The analysis of the label included verification of compliance with the allergen declaration, use of warning phrases (FA), and presentation of information. Results and Discution: in 2019, the declaration of allergens includes expressions such as: “contains gluten”, in 50% of the products analyzed. On the other hand, in five of the fifteen products with FA, there are expressions such as "may contain traces...". Likewise, it is included in five products, sesame, an allergen contemplated by legislations other than Argentina. Regarding the presence of sulfur dioxide and sulphites, there are two products that declare them below the list of ingredients and two other products that declare sulphites in their warning phrases. When analyzing the labels in 2022, 80% of the analyzed products do not present inconsistencies with regard to the presentation of the information. Conclusions: in the comparative study, an improvement is observed in the correct declaration of allergens and warning phrases. However, more than five years after the end of the period granted to the industries for the adaptation of the labels for an adequate declaration of allergens, some errors persist in them. Keywords: food allergen; food labeling; Argentine food code; food allergy; allergen labeling.

Effect of sulfur dioxide on adsorption capacity of zeolite sorbents for carbon dioxide

The article discusses a rather serious problem limit-ing the use of adsorption for the CO2 capture from flue gas, in the presence of sulfur dioxide. An apparatus with a vertical batch adsorber was constructed to study adsorption under elevated pressure in a wide range of temperatures and evaluation of CO2 breakthrough curves with an infrared analyzer. The article summarizes the results of experiments conducted with zeolite clinoptilolite, which represented natural materials, and molecular sieve 13X as a representative of synthetic sorbents. Adsorption capacities achieved during cyclically repeated tests with a model gaseous mixture free of SO2 and a mixture of the same composition but enriched with a low volume fraction of SO2 (0.3 %) were compared. Adsorption took place at a temperature of 20 °C and at two overpressures (200 and 500 kPa) of the gas with a 13 % volume fraction of CO2. Each sub-experiment consisted of five adsorption and desorption cycles, where desorption was based on depressurization followed by temperature increase to 120 °C under nitrogen atmosphere. There were no changes in capacities when tested with the gaseous mixture without SO2. Relative to the weight of the sample, the 13X sample at an overpressure of 500 kPa had a capacity of 11.3 % and clinoptilolite 3.8 %. Tests in the presence of SO2 led to a permanent reduction of the equilibrium capacities for both samples and at both pressures. At the overpressure of 500 kPa, the capacity decreased to 7.4 % for the 13X and to 2.5 % for the clinoptilolite. A more intensive desorption involving a thermal and vacuum step did not lead to any improvement for the 13X sample. In contrast, the effect for clinoptilolite was very positive. Its capacity in the fifth cycle reached 3.4 % close to the state without SO2 exposition. In the case when SO2 in the gas was accompanied with 40 % relative humidity, vacuum desorption did not lead to positive results in any case. After five cycles, the capacity of 13X dropped to 3.2 % and clinoptilolite to 1.4 %. When moisture, SO2 and the presence of O2 (volume fraction of 6 %) in the model mixture were further combined, the capacity of 13X decreased to 1.4 % and clinoptilolite to 0.4 % after five cycles. Tests with SO2 (dry gas) caused a decrease in the specific surface area from 512 to 211 m2.g‒1 for the 13X sample. On the other hand, for clinoptilolite it decreased from only 29 to 28 m2.g‒1 under the same conditions. Ac-cording to XRF, it was not possible to remove sorbed SO2 from the 13X sample even by evacuation followed by heating up to 200 °C. Using the XRD method, it was found that SO2 remains in the matrix, although it does not undergo transition to the crystalline phase. The study verified that synthetic molecular sieve 13X, unlike natural clinoptilolite, is not applicable for CO2 adsorption from SO2 containing flue gas.

Post combustion CO2 capture with calcium and lithium hydroxide

A small-scale plant was built for measuring the ability of solid sorbents towards the capture of carbon dioxide (CO2) in exhaust flue gas from an internal combustion engine. The investigated sorbents were calcium and lithium hydroxides. Both sorbents are low cost and used in the breathing gas purification systems. The carbonation capacity of each sorbent was measured for different sorbent granulometry (pellets and powder), different temperature (from ambient up to 300 °C), gas space velocity, moisture content and chemical composition of the gaseous stream. The aim was, in fact, to expose the sorbents to a gas stream with chemical and physical parameters close to those at the exhaust of an internal combustion engine. Carbonation capacity was measured with a double technique: on-line by continuously CO2 measurement with a non-dispersive infrared analyzer and off-line by using scanning electron microscopy on carbonated sorbents. Experimental results showed good CO2 uptake capacity of calcium hydroxide at low temperature (between 20 and 150 °C). Performance improvements came from the fine granulometry due to the increased exposed surface area; moreover, the presence of the moisture in gas stream also enhanced CO2 capture. The presence of sulphur dioxide and nitric oxide, instead, greatly decreased the carbonation capacity of sorbents.

Kinetic Study of the Elimination of Nickel from Cobalt Sulfate Solutions by Sulfur Cementation on Cobalt in the Presence of Sulfur Dioxide and Elemental Sulfur

Kinetic Study of the Elimination of Nickel from Cobalt Sulfate Solutions by Sulfur Cementation on Cobalt in the Presence of Sulfur Dioxide and Elemental Sulfur

Air pollution emission from the copper smelter Complex Bor in Serbia

Ever since the industrial revolution, air got significantly polluted by the industry. Air pollution is even more concentrated in cities that have an industrial zone. Especially in these zones, the presence of Sulfur-dioxide (SO2) and suspended Particles (PM) in the air is very high. Prolonged exposure to SO2 and PM can cause cancer, cardiovascular and respiratory disorders in humans. The aim of this paper was to a review available literature on air pollution by sulfur dioxide and suspended particles in the air region of Bor Copper complex, as well as to determine whether the investigated results are contradictory. Studies from prior years (2004-2015), as well as 2019, indicate rise of SO2 and PM air pollutants in the atmosphere in the region of the copper smelter of the Bor Complex in Serbia, which can cause serious consequences for human well-being. However, the results of research by different authors for the same years are not in agreement, with that said, a review of the literature indicates significant differences. In addition, no continuous research on any air pollutants has been done for several consecutive years. This can be an interesting question for the scientific public in Serbia. Review of available literature indicates that in Serbia, solving this problem must be taken more seriously.

Design of pH Responsive Textile as a Sensor Material for Acid Rain.

The chemical composition of rainwater can serve as an indicator of the excess of acidifying air pollutants. The pH value of rainwater in the presence of sulphur dioxide and nitrogen oxides, the precursors of acid rain, falls below pH 5.6, which is the limit value for acid rain. In this research, the tailoring of halochromic textile was examined for the design of a functional textile that can serve as a sensor and inform the wearer about the presence of pollutants in the air by means of an immediate colour change. For this purpose, a polyamide 6 fabric was dyed with the pH-sensitive Bromocresol green dye, which causes a colour change below pH 3.6 (yellow) and above pH 5.4 (blue). In addition, the dyed polyamide 6 fabric was treated with a water and oil repellent finish. Colour and colour change before and after immersion of unfinished and finished dyed samples in buffer solutions with different pH values were evaluated spectrophotometrically using the CIELAB colour space. The colour fastness to rubbing, washing, and light, and the water and oil repellency of the dyed fabrics were determined according to valid SIST EN ISO standards. The results showed that the unfinished dyed polyamide 6 fabric undergoes a reversible colour change faster and more clearly than the finished dyed polyamide 6 fabric. The dyed polyamide 6 fabric had good colour fastness to rubbing and domestic and commercial laundering, while the colour fastness to light was poor. In addition, the dyed polyamide 6 fabric was pH-sensitive, despite dye degradation under xenon light, regardless of whether it was finished.

Protective Effectiveness of Oil Compositions in the Presence of Sulfur-Containing Corrosion Stimulators

The protective effectiveness of oil compositions in the presence of sulfur dioxide was studied. The moisture permeability of oil films and the corrosion rate of steels both protected and unprotected by oil films increase with increasing relative humidity and initial sulfur dioxide concentration in the atmosphere. The contribution of individual components to the protective effect of a film of synthetic Mobil-1 oil inhibited by the additive Emulgin in the presence of sulfur dioxide is considered. The total protective effectiveness of the system can reach 93-96% after one day in 0.5 M sodium chloride solution containing sulfur dioxide and the products of its interaction with water. The slowdown of steel corrosion under a layer of inhibited and non-inhibited oil film is mainly due to retardation of the cathodic process with slight inhibition of the anodic reaction.

Impact fragmentation of limestone-based sorbents for calcium looping: The effect of steam and sulphur dioxide

Calcium Looping (CaL) for CO2 capture and utilisation is affected by the presence of SO2 and/or H2O in the flue gases that are processed in the carbonator. The influence regards both the course of carbonation as well as the mechanisms and extent of attrition and fragmentation phenomena to which sorbent particles are exposed in Dual Interconnected Fluidised Beds (DIFB) that are commonly used for this process. Fragmentation by impact has been comparatively less investigated with reference to operating conditions entailing the presence of SO2 and/or H2O. In this study, two high-calcium commercial limestones, similar in chemical composition but different in reactivity, have been subjected to CaL tests in a lab-scale DIFB apparatus in presence of sulphur dioxide and/or steam. Calcination was carried out at 940 °C in an atmosphere containing 70% CO2. Carbonation was carried out at 650 °C in an atmosphere containing 15% CO2. The effect of SO2 and/or H2O was assessed with reference to six carbonation atmospheres, with different concentrations of steam (0 and 10%v) and sulphur dioxide (0, 75 and 1500 ppmv). After ten CaL cycles, the particles were tested ex-situ in an impact test rig, consisting of a duct where samples were entrained in a gas stream at a controlled velocity and impacted against a target. The apparatus was operated at room temperature at various impact velocities (six values from 10 to 45 m/s). The extent and pattern of impact fragmentation was assessed by characterising the particle size distribution of the debris and the fractional mass of generated fragments. Results are discussed in the light of the different sorbent nature and of the CaL FB operating conditions.

Global Sulfur Dioxide Emissions and the Driving Forces.

The presence of sulfur dioxide (SO2) in the air is a global concern because of its severe environmental and public health impacts. Recent evidence from satellite observations shows rapid changes in the spatial distribution of global SO2 emissions, but such features are generally missing in global emission inventories that use a bottom-up method due to the lack of up-to-date information, especially in developing countries. Here, we rely on the latest data available on emission activities, control measures, and emission factors to estimate global SO2 emissions for the period 1960-2014 on a 0.1° × 0.1° spatial resolution. We design two counterfactual scenarios to isolate the contributions of emission activity growth and control measure deployment on historical SO2 emission changes. We find that activity growth has been the major factor driving global SO2 emission changes overall, but control measure deployment is playing an increasingly important role. With effective control measures deployed in developed countries, the predominant emission contributor has shifted from developed countries in the early 1960s (61%) to developing countries at present (83%). Developing countries show divergency in mitigation strategies and thus in SO2 emission trends. Stringent controls in China are driving the recent decline in global emissions. A further reduction in SO2 emissions would come from a large number of developing nations that currently lack effective SO2 emission controls.

Characterization and winemaking application of a novel pectin-degrading enzyme complex from Aspergillus sojae ATCC 20235

A novel pectin-degrading enzyme complex produced by Aspergillus sojae ATCC 20235 (PC-AS) using low- cost substrates was characterised in terms of its enzyme activities relevant in winemaking. This novel PC-AS was applied at the maceration/fermentation stage during the elaboration of 'Tempranillo' red wines to study its effect on colour development and the phenolic and amino acid wine composition. PC-AS polygalacturonase activity was the major enzyme activity detected and quantified under winemaking conditions (pH 3.5, 20 °C) and proved being stable and active in the presence of sulfur dioxide. Xylanase activity, albeit in lesser amounts, was also present in PC-AS, and neither pectinesterase, which produces methanol, nor β-glucosidase, which is detrimental to wine colour, were detected in PC-AS. This pectin-degrading complex promoted a faster colour extraction since maximum colour intensity of the enzyme treated wines was reached earlier compared to their controls. After 6 months of storage under winery conditions, wines elaborated with PC-AS presented higher concentrations of caffeic acid, coumaric acid and aspartic acid (p ˂ 0.05), suggesting an improved extraction of grape cell components. In conclusion, the application of PC-AS yielded results that showed that it can be used in red winemaking to shorten the maceration time needed to reach high CI values and to improve the extraction of some phenolics and other compounds that enhance the quality of the final product.

Sulfur Dioxide Modifies Aerosol Particle Formation and Growth by Ozonolysis of Monoterpenes and Isoprene

AbstractThe effect of sulfur dioxide on particle formation and growth by ozonolysis of three monoterpenes (α‐pinene, β‐pinene, and limonene) and isoprene was investigated in the presence of monodisperse ammonium sulfate seed particles and an OH scavenger in a flow tube under dry conditions. Without sulfur dioxide, new particle formation was not observed, and seed particle growth was consistent with condensation of low‐volatility oxidation products produced from each organic precursor. With sulfur dioxide, new particle formation was observed from every precursor studied, consistent with sulfuric acid formation by reaction of sulfur dioxide with stabilized Criegee Intermediates. The presence of sulfur dioxide did not significantly affect seed particle growth rates from α‐pinene and limonene ozonolysis, although chemical composition measurements revealed the presence of organosulfates in the particles following SO2 exposure. Contrarily, the growth of seeds by β‐pinene and isoprene ozonolysis was considerably enhanced by sulfur dioxide, and chemical composition measurements revealed that the enhanced growth was not due to additional organic material, suggesting that inorganic sulfate was likely responsible. The results suggest that a previously unconsidered particle‐phase pathway to growth activated by sulfur dioxide may alter production of cloud condensation nuclei over regions with significant SO2‐alkene interactions.

Ultraviolet Spectroscopy and Photochemistry of SO2/H2O Ices

The presence of sulfur dioxide on the trailing hemisphere of Europa’s surface is well-established, and both its presence and its chemistry are influenced by sulfur ion implantation. Particle irradiation is known to be a significant radiolysis source, particularly on the trailing surface, which is subject to particles in Jupiter’s plasma torus. Photochemistry driven by solar ultraviolet (UV) photons is also significant. To date, most studies have investigated the effects of vacuum UV radiation, while photochemistry at longer wavelengths is less well-studied. This work investigates chemical changes in thin, cryogenic films of SO2/H2O at temperatures and pressures relevant to Europa’s surface when subjected to temperature changes and UV radiation at 147, 206, 254, and 284 nm. Spectra were collected in both the mid-infrared range and the UV range, which elucidates electronic transitions that are less diagnostic but perhaps more applicable to reflectance spectra of solar system bodies. These experiments show irreversible red shifting of the B̃ ← X̃ absorption peak upon heating likely as a result of crystallization and/or thermal chemical reactions. Further, photons with wavelengths up to 284 nm are shown to induce significant chemistry in SO2/H2O mixtures. This in conjunction with the increased solar flux compared to more energetic wavelengths and the strong C̃ ← X̃ and B̃ ← X̃ absorption bands in SO2 suggests that far-UV radiation plays a significant role in the sulfur cycle on Europa.

Study on transformation and enrichment behavior of selenium in particulate matter in combustion flame

ABSTRACTAn ethylene/air inverse diffusion flame (IDF) burner was employed to generate a stable flame, and selenium was introduced into the combustion flame in vapor phase under different air-fuel ratio (A/F) with SO2 additive. At different height above burner (HAB) along the flame edge, selenium of different speciation (gaseous selenium and particulate selenium) was sampled via the U.S. EPA method 29, and the samples were determined by hydride generation atomic fluorescence spectrometry (HG-AFS), in order to study the mechanism of transformation and enrichment behavior of selenium during the combustion process. The results showed that selenium presented in vapor phase, crossing the flame into air, which means gaseous phase is the main form of selenium during combustion process. Both gaseous selenium and particulate selenium increased with elevated temperature from 820K to 1650K, suggesting that higher temperature is beneficial to the release of selenium. Low concentration of sulfur dioxide would increase the concentration of particulate selenium and gaseous selenium, and accelerate the release of selenium.Implications: The enrichment behavior of selenium and its transformation in combustion flame were studied. The results showed that gaseous selenium is found in higher quantity in compared to particulate selenium during combustion. Higher temperature and air–fuel ratio will cause an increase in the formation of selenium. While the presence of sulfur dioxide in a range of 0–200 ppm will promote the release of selenium, higher sulfur dioxide level in a range of 200–350 ppm will have a reverse effect.

Influence of Rust Permeability on Corrosion of E690 Steel in Industrial and Non-industrial Marine Splash Zones

The corrosion behaviour of E690 steel in industrial and non-industrial marine splash environments was studied by environmental testing, morphology analysis, electrochemical measurements, and scanning Kelvin probe microscopy. Chloride and sulphide anions were found to diffuse across the rust layer following the evaporation of seawater splashed on the steel’s surface. The cation-selective permeability of the rust layer resulted in an anion concentration gradient across the rust layer, which was more significant in the presence of sulphur dioxide. In addition, sulphur dioxide enhanced the formation of α-FeOOH, which led to the formation of distinct anode and cathode areas at the rust/steel interface.

Effect of Oxidation Process on Complex Refractive Index of Secondary Organic Aerosol Generated from Isoprene.

Oxidation of isoprene by hydroxyl radical (OH), ozone (O3), or nitrate radical (NO3) leads to the formation of secondary organic aerosol (SOA) in the atmosphere. This SOA contributes to the radiation balance by scattering and absorbing solar radiation. In this study, the effect of oxidation processes on the wavelength-dependent complex refractive index (RI) of SOA generated from isoprene was examined. Oxidation conditions did not have a large effect on magnitude and wavelength dependence of the real part of the RI. In the case of SOA generated in the presence of sulfur dioxide (SO2), significant light absorption at short visible and ultraviolet wavelengths with the imaginary part of the RI, up to 0.011 at 375 nm, was observed during oxidation with OH. However, smaller and negligible values were observed during oxidation with O3 and NO3, respectively. Moreover, in the absence of SO2, light absorption was not observed regardless of the oxidation process. There was an empirical correlation between the imaginary part of the RI and the average degree of unsaturation of organic molecules. The results obtained herein demonstrate that oxidation processes should be considered for estimating the radiative effect of isoprene-derived SOA.

Directed evolution of Oenococcus oeni strains for more efficient malolactic fermentation in a multi-stressor wine environment

High concentrations of ethanol, low pH, the presence of sulfur dioxide and some polyphenols have been reported to inhibit Oenococcus oeni growth, thereby negatively affecting malolactic fermentation (MLF) of wine. In order to generate superior O. oeni strains that can conduct more efficient MLF, despite these multiple stressors, a continuous culture approach was designed to directly evolve an existing ethanol tolerant O. oeni strain, A90. The strain was grown for ∼350 generations in a red wine-like environment with increasing levels of stressors. Three strains were selected from screening experiments based on their completion of fermentation in a synthetic wine/wine blend with 15.1% (v/v) ethanol, 26 mg/L SO2 at pH 3.35 within 160 h, while the parent strain fermented no more than two thirds of l-malic acid in this medium. These superior strains also fermented faster and/or had a larger population in four different wines. A reduced or equivalent amount of the undesirable volatile, acetic acid, was produced by the optimised strains compared to a commercial strain in Mouvedre and Merlot wines. These findings demonstrate the feasibility of using directed evolution as a tool to generate more efficient MLF starters tailored for wines with multiple stressors.

First evaluation of a multicomponent flue gas cleaning concept using chlorine dioxide gas – Experiments on chemistry and process performance

This work has investigated a multi-pollutant flue gas cleaning concept based on oxidation using chlorine dioxide (ClO2) gas with subsequent absorption. The chlorine dioxide gas converts the relatively insoluble nitric oxide (NO) to the more soluble nitrogen dioxide (NO2). This makes a downstream wet scrubbing process feasible for simultaneous removal of sulphur oxides (SOx) and nitrogen dioxide (NO2).An experimental evaluation of the proposed process using chlorine dioxide gas has been performed on a laboratory scale. The experimental setup, designed and built by Akzo Nobel, consists of a reactor for oxidation, a flue gas condenser and a wet scrubber. The results show that ClO2 gas oxidises NO with high efficiencies under a wide range of process conditions, also in the presence of sulphur dioxide (SO2). The more ClO2 gas is added, the higher the degree of NO oxidation and the total nitrogen oxides (NOx) removal efficiency becomes. The results also show that the presence of water strongly increases the removal of SO2, which is believed to be an effect of liquid phase nitrogen-sulphur interactions. The absorption solution, sodium carbonate and sodium sulphite, is efficient in removing NOx (especially NO2) from the oxidised flue gas. The total NOx reduction at 0.6 ClO2:NO mole ratio and subsequent wet scrubbing is between 79% and 94%, depending on the process conditions used. The total SO2 reduction in the scrubber is between 97% and 100% independent of ClO2 gas addition. Furthermore, the total NOx balance shows that the major part of the NOx is converted to nitrate in the condensate liquor and as nitrite in the absorption solution. A higher ClO2 gas addition and a higher reactor temperature convert more of the NOx to nitrite in the absorption solution.