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First-ever measurements of particulate matter (PM2.5, PM10, and TSP) along with gaseous pollutants (CO, NO2, and SO2) were performed from June 2019 to April 2020 in Faisalabad, Metropolitan, Pakistan, to assess their seasonal variations; Summer 2019, Autumn 2019, Winter 2019-2020, and Spring 2020. Pollutant measurements were carried out at 30 locations with a 3-km grid distance from the Sitara Chemical Industry in District Faisalabad to Bhianwala, Sargodha Road, Tehsil Lalian, District Chiniot. ArcGIS 10.8 was used to interpolate pollutant concentrations using the inverse distance weightage method. PM2.5, PM10, and TSP concentrations were highest in summer, and lowest in autumn or winter. CO, NO2, and SO2 concentrations were highest in summer or spring and lowest in winter. Seasonal average NO2 and SO2 concentrations exceeded WHO annual air quality guide values. For all 4 seasons, some sites had better air quality than others. Even in these cleaner sites air quality index (AQI) was unhealthy for sensitive groups and the less good sites showed Very critical AQI (> 500). Dust-bound carbon and sulfur contents were higher in spring (64 mg g-1) and summer (1.17 mg g-1) and lower in autumn (55 mg g-1) and winter (1.08 mg g-1). Venous blood analysis of 20 individuals showed cadmium and lead concentrations higher than WHO permissible limits. Those individuals exposed to direct roadside pollution for longer periods because of their occupation tended to show higher Pb and Cd blood concentrations. It is concluded that air quality along the roadside is extremely poor and potentially damaging to the health of exposed workers.

The Permian Basin is the largest petroleum producing region in the United States. Few studies have investigated impact the Petroleum Industry had on the air quality of the Permian Basin. Industry operations in the Basin has two primary impacts on air quality, (a) it significantly contributes carbon dioxide (CO2) and methane (CH4) to the atmosphere during extraction, transport and use of fossil fuels, (b) industry operations influence public health especially when populations are in proximity to all categories of oil and gas facilities. The advent of Covid-19 in late 2019 and a severe drought that began prior to 2019 in West Texas have created unusual circumstances regarding air quality and public health in the Permian Basin. This study has monitored airborne pollen, spores, fungal spores, and other organically derived particles, and inorganic particulate matter (1, 2.5, 10-micron particulate matter (PM) and total suspended particles (TSP)), volatile organic compounds (VOCs), and sulfur dioxide (SO2). The pandemic caused a historic reduction in oil and gas production slowing operations in the Permian Basin to near zero during the study period, reducing environmental effects on air quality and concomitantly an increase in flaring of natural gas. Although there were increases in the release of VOCs fixed base monitors detected no notable increase. However, an increase in the concentration of airborne pollutants (VOCs and SO2) shows a close correlation with proximity to oil and gas facilities and the intensity of industry operations. This phenomenon is attributed to the highly local nature of flaring and CH4 plume emissions from leaking oil and gas facilities. Air quality improved in the Permian Basin due to reduction in production activity because of the Covid-19 pandemic, and the reduction of particulate matter due to the ongoing drought during the study period. [ABSTRACT FROM AUTHOR]

This study focuses on the S-to-H2SO4 industry by investigating the chemical looping combustion (CLC) process utilizing Fe-based and Cu-based oxygen carriers (OCs), which are widely applied in CLC technology. The primary objective is to conduct combined CLC reactions of these two metal carriers in a three-zone temperature tube furnace, aiming to achieve a higher SO2 yield than what is attainable by reacting a single metal carrier with S. The investigation reveals promising industrial applications, offering potential benefits in terms of reducing equipment costs, enhancing energy efficiency, and lowering the emissions of the H2SO4 production industry. Through a series of experiments, the study examines the effects of reaction temperature and material molar ratios on SO2 generation. The solid reaction products were characterized using X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), and X-ray photoelectron spectroscopy (XPS). The experimental results indicate that the combined Cu-based and Fe-based OCs exhibit a higher SO2 yield during the reduction stage compared to using either Fe-based or Cu-based OCs independently. Under optimal conditions, with a carrier gas flow rate of 300 mL/min, an Fe2O3/S molar ratio of 6:1 in the second temperature zone, and a reaction temperature of 900 °C, the total SO2 yield in the third temperature zone reached approximately 85%. This was achieved at a reaction temperature of 850 °C, with an Fe2O3/S molar ratio of 6:1 in the first half of the zone and a CuO/S molar ratio of 12:1 in the second half of the zone. SEM-EDS analysis further revealed that the combined OCs showed no significant signs of agglomeration or sintering after 10 cycles of the reaction. However, Cu-based carrier particles increased in size by 50%, while Fe-based carrier particles remained relatively stable. Additionally, the low mass-to-atom ratio of S on the surface of OCs after the cyclic reaction suggests that the reduced-state OCs can be fully oxidized and regenerated following the release of SO2 during oxidation. [ABSTRACT FROM AUTHOR]

A flue gas condenser (FGC) system recovers heat from exhaust flue gases in energy production and chemical plants, reducing air pollution due to dust, SOx, and HCl. An FGC system is divided into indirect contact condenser (ICC) and direct contact condenser (DCC) types. In an ICC, the exhaust gases do not mix with the working fluid, and a water film is formed during flue gas condensation for partial SOx removal. In a DCC, direct mixing of the exhaust flue gas with the cooling fluid (mainly water) occurs, with simultaneous absorption of SOx. In this study, we investigated the SO2 removal efficiency and heat recovery of an ICC, a DCC, and a DCC–ICC hybrid system, and compared the results of the hybrid system with those obtained for a single DCC type at the same liquid-to-gas (L/G) ratio. The SO2 removal characteristics of the hybrid system were examined based on the L/G ratio and absorbent-to-SO2 molar ratio. In the reference ICC-type FGC system, the exit temperature of the mixed gas was 28 °C, with the condensed water ratio and heat recovery efficiency being 80.9% and 93.4%, respectively. At an L/G ratio of 1.5–3.5, the SO2 removal efficiency of a single DCC was 31.5–65.9%, whereas that of the hybrid FGC system (with packing material) increased from 47.1% to 72.3%, which further increased to ~90% upon the addition of NaOH at a molar ratio of 0.7 and an L/G ratio of 1.5. [ABSTRACT FROM AUTHOR]

The problem of SO2 pollution in industrial flue gas has brought great pressure to environmental governance. In this study, a new type of activated carbon fixed bed device was designed and built for flue gas desulfurization. The results showed that activated carbons (AC1-AC5) were microporous activated carbons with abundant functional groups on the surface, and the desulfurization performance was ranked as AC1 > AC2 > AC3 > AC4 > AC5. The specific surface area of AC1 was as high as 624.98 m2/g, and the maximum adsorption capacity was 29.03 mg·g−1 under the optimum reaction conditions. The Freundlich adsorption isotherm model and Bangham pore diffusion model are more suitable for describing the dynamic adsorption process of SO2 on AC1. Combined with thermodynamic research, it is shown that the adsorption process of SO2 is a spontaneous, exothermic, and chaotic reduction process, which is mainly a physical adsorption between single-layer adsorption and multi-layer adsorption. Finally, the desulfurization-washing regeneration cycle experiment results showed that the regeneration rate of AC1 increases with the washing time and washing temperature, up to 95%, which provides data reference for industrial application. [ABSTRACT FROM AUTHOR]

The distribution of surface particulate matter (PM2.5) exhibits significant spatiotemporal patterns, especially with a spatial clustering effect. Therefore, resolving spatial characteristics is essential in the modeling process. This study proposes a space–time varying coefficients (STVC-LG) model by considering spatial effects from the perspective of eigenvector spatial filtering and incorporating spatial effects and temporal features into the LightGBM model to estimate ground PM2.5. A site-based cross-validation result of the estimated daily 1 km PM2.5 concentration in China from 2016 to 2020 shows that the proposed model offers high accuracy, an R2 of 0.88, and an RMSE of 12.21 μg/m3 (17% and 32% enhanced compared to the original LightGBM model). It uses a series of spatial eigenvectors to describe different spatial patterns. It then constructs spatial interaction terms by combining the eigenvectors and influencing variables, allowing the values of the variable to vary spatially with the eigenvectors. The obtained PM2.5, with a decreasing trend, had a clear distributional consistency with NO2 and SO2 according to the co-occurrence distribution maps, particularly in winter. In areas where high concentrations co-occur, both NO2 and SO2 concentrations are Granger-causing PM2.5 concentrations from a statistical perspective.

Abstract In this study, we have examined the air quality within a revitalized, post-industrial urban area in Łódź, Poland. The use of Dron technology with mobile measurement equipment allowed for accurate assessment of air quality (particulate matter and gaseous pollutants) and factors influencing air quality (wind speed and direction) on a local scale in an area of 0.18 km2 and altitudes from 2 to 50 m. The results show that the revitalization carried out in the Lodz special economic zone area contributed to eliminate internal air pollution emitters through the use of ecological and effective heat sources. The exceedances permissible concentration values were local, and concerned mainly the higher measurement zones of the troposphere (more than 30 m above ground level). In the case of gaseous pollutants, higher wind speeds were associated with a decrease in the concentration of SO2 and an increase in H2S concentration. In both cases, the wind contributed to the occurrence of local areas of accumulation of these gaseous pollutants in the spaces between buildings or wooded areas.

Context: Amino acids are a highly effective and environmentally friendly adsorbent for SO2. However, there has been no comprehensive study of the binding modes between amino acids and SO2 at the molecular level. In this paper, the binding modes of three amino acids (Asp, Lys, and Val) with SO2 are studied comprehensively and in detail using quantum chemical calculations. The results indicate that each amino acid has multiple binding modes: 22 for Asp, 49 for Lys, and 10 for Val. Both the amino and carboxyl groups in amino acids, as well as those in side chains, can serve as binding sites for chalcogen bonds. The binding energies range from − 6.42 to − 1.06 kcal/mol for Asp, − 12.43 to − 1.63 kcal/mol for Lys, and − 7.42 to − 0.60 kcal/mol for Val. Chalcogen and hydrogen bonds play a crucial role in the stronger binding modes. The chalcogen bond is the strongest when interacting with an amino group, with an adiabatic force constant of 0.475 mDyn/Å. Energy decomposition analysis indicates that the interaction is primarily electrostatic attraction, with the orbital and dispersive interactions dependent on the binding mode. Methods: Amino acids and complexes of amino acids with SO2 were used to do semi-empirical MD using Molclus combined with xtb at the GFN2 level. Optimization and frequency calculations of the structures were conducted using density-functional theory (DFT) B3LYP/6-311G* (with DFT-D3 correction). Single-point energy calculations were performed for all structures using DLPNO-CCSD(T)/aug-cc-pVTZ with tightPNO. Further analysis of the structures was conducted using ESP, AIM, IGMH, and sob-EDA to gain a deeper understanding of the interactions between amino acids and SO2. [ABSTRACT FROM AUTHOR]

Zeolites exhibit significant potential as porous materials for selective carbon dioxide (CO2) capture, leveraging their distinctive adsorption properties. However, the presence of moisture (H2O) and sulfur dioxide (SO2) in flue gas streams can significantly affect the efficiency of CO2 capture. This study investigates the CO2 adsorption characteristics of zeolites FAU 5A and LTA 13X, revealing the competitive adsorption mechanism between H2O(g), SO2, and CO2. The zeolites exhibit CO2 adsorption capacities of 93.19 mg/g and 95.80 mg/g for 5A and 13X, respectively, and demonstrate good regeneration potential. Metal cations correlated positively with CO2 adsorption. H2O(g), SO2, and CO2 exhibit a competitive adsorption relationship, with H2O(g) having the highest adsorption capacity, followed by SO2 and CO2. Additionally, the synergistic effect of SO2 and H2O(g) on CO2 adsorption is elucidated. These findings provide valuable insights into the competitive adsorption behavior of moisture and SO2 for CO2 capture using zeolites LTA 5A and FAU 13X, contributing to the development of more efficient CO2 capture processes and the design of tailored adsorbents for industrial applications. [ABSTRACT FROM AUTHOR]

Increasing concentrations of toxic gases caused by the burning of fossil fuels necessitates the development of efficient porous materials for gas capture. Metal-organic frameworks (MOFs) have attracted a lot of attention as potential porous materials due to their effectiveness in adsorption of toxic gases. In particular, square-pillared metal-organic frameworks stand out for their exceptional potential toward gas adsorption, attributed to their remarkable surface area, thermal and chemical stabilities, and tunable properties. In this context, molecular simulations have been executed to observe and analyze the adsorption process of toxic flue gases such as SO2 and CO2 on MOFs. The present work deals with two different stable fluorinated MOFs named [Ni-(4,4'-bipyridine)2(AlF5)]n (ALFFIVE-Ni-bipy) and [Ni-(4,4'-bipyridine)2(NbOF5)]n, (NBOFFIVE-Ni-bipy) featuring AlF52- and NbOF52- anion pillars, respectively, comprising 4,4'-bipyridine as organic ligand and nickel as the central metal. The significance of utilizing the 4,4'-bipyridine ligands in these fluorinated MOFs enhances the SO2 gas adsorption and selectivity in the framework. Density functional theory has been implemented for geometry optimization, and Grand Canonical Monte Carlo simulations have been performed to forecast the adsorption isotherms. Both ALFFIVE-Ni-bipy (11.4 mmol/g) and NBOFFIVE-Ni-bipy (8.7 mmol/g) showed high SO2 adsorption capacity at 1 bar pressure, but ALFFIVE-Ni-bipy showed very good adsorption than other square-pillared MOFs and also unveiled good selectivity of SO2 gas. The coadsorption of binary SO2/CO2 and ternary SO2/CO2/N2 gas mixtures at ambient conditions indicated that the cost-effective aluminum (Al)-based square-pillared ALFFIVE-Ni-bipy is particularly suitable for acid gas adsorption. [ABSTRACT FROM AUTHOR]

In this study, we have examined the air quality within a revitalized, post-industrial urban area in Łódź, Poland. The use of Dron technology with mobile measurement equipment allowed for accurate assessment of air quality (particulate matter and gaseous pollutants) and factors influencing air quality (wind speed and direction) on a local scale in an area of 0.18 km2 and altitudes from 2 to 50 m. The results show that the revitalization carried out in the Lodz special economic zone area contributed to eliminate internal air pollution emitters through the use of ecological and effective heat sources. The exceedances permissible concentration values were local, and concerned mainly the higher measurement zones of the troposphere (more than 30 m above ground level). In the case of gaseous pollutants, higher wind speeds were associated with a decrease in the concentration of SO2 and an increase in H2S concentration. In both cases, the wind contributed to the occurrence of local areas of accumulation of these gaseous pollutants in the spaces between buildings or wooded areas. [ABSTRACT FROM AUTHOR]

Sulfur dioxide (SO2), a common environmental and industrial air pollutant, possesses a potent effect in eliciting cough reflex, but the primary type of airway sensory receptors involved in its tussive action has not been clearly identified. This study was carried out to determine the relative roles of three major types of vagal bronchopulmonary afferents [slowly adapting receptors (SARs), rapidly adapting receptors (RARs), and C-fibers] in regulating the cough response to inhaled SO2. Our results showed that inhalation of SO2 (300 or 600 ppm for 8 min) evoked an abrupt and intense stimulatory effect on bronchopulmonary C-fibers, which continued for the entire duration of inhalation challenge and returned toward the baseline in 1–2 min after resuming room air-breathing in anesthetized and mechanically ventilated mice. In stark contrast, the same SO2 inhalation challenge generated a distinct and consistent inhibitory effect on both SARs and phasic RARs; their phasic discharges synchronized with respiratory cycles during the baseline (breathing room air) began to decline progressively within 1–3 min after the onset of SO2 inhalation, ceased completely before termination of the 8-min inhalation challenge, and then slowly returned toward the baseline after >40 min. In a parallel study in awake mice, inhalation of SO2 at the same concentration and duration as that in the nerve recording experiments evoked cough responses in a pattern and time course similar to that observed in the C-fiber responses. Based on these results, we concluded that stimulation of vagal bronchopulmonary C-fibers is primarily responsible for triggering the cough response to inhaled SO2. NEW & NOTEWORTHY: This study demonstrated that inhalation of a high concentration of sulfur dioxide, an irritant gas and common air pollutant, completely and reversibly inhibited the neural activities of both slowly adapting receptor and rapidly adapting receptor, two major types of mechanoreceptors in the lungs with their activities conducted by myelinated fibers. Furthermore, the results of this study suggested that stimulation of vagal bronchopulmonary C-fibers is primarily responsible for triggering the cough reflex responses to inhaled sulfur dioxide. [ABSTRACT FROM AUTHOR]

The port of Cartagena, south-east Spain, is noted for its intense activity. This paper presents the influence of the COVID-19 pandemic on the recorded levels of six pollutants. Fifteen years of measurements were used, with two objectives. The first was to investigate how these pollutants evolved, together with their usual cycles. The second objective was to ascertain whether the COVID-19 pandemic had an impact on the concentrations recorded. The results showed that nitrogen oxide concentrations remained steady in the first half of the measurement period and decreased in the second half. SO2 concentrations decreased irregularly, whereas O3 and PM10 presented steady concentrations. The annual cycle was observed for nitrogen oxides and O3. Only SO2 evidenced no weekly cycle. Finally, the analysis of pre- and post-pandemic concentrations revealed a sharp decrease in nitrogen oxides, whereas the pandemic was not seen to have had any impact on the other pollutants. In addition, NO2 emerged as the best indicator of human activity—represented by car and maritime traffic—due to its response to the relaxation measures. Finally, Lamb weather types were calculated. The unclassified type was the most frequent. However, the greatest concentration changes were observed for anticyclonic and eastern flow types. [ABSTRACT FROM AUTHOR]

The technology for the selective catalytic reduction of NOx by CO (CO-SCR) has the capability to simultaneously eliminate CO and NOx from industrial flue gas and automobile exhaust, thus making it a promising denitrification method. The advancement of cost-effective and high-performing catalysts is crucial for the commercialization of this technology. Mn-based catalysts demonstrate enhanced catalytic efficiency under conditions of low temperature and low oxygen content when compared to other transition metal-based catalysts, indicating significant potential for practical applications. This review outlines the diverse Mn-based catalysts, including bulk or supported MnOx catalysts, bulk or supported Mn-based composite oxide catalysts, and the use of MnOx as dopants. Subsequently, the synthesis methods and catalytic mechanism employed by Mn-based catalysts are presented. The following section examines the impact of O2, H2O, and SO2 on the catalytic performance. Finally, the potential and implications of this reaction are deliberated. This work aims to offer theoretical guidance for the rational design of highly efficient Mn-based catalysts in the CO-SCR reaction for industrial applications. [ABSTRACT FROM AUTHOR]

The mechanisms of medium- and low-temperature denitrations using selective catalytic reduction (SCR) by combined CO + NH3 on Mn–Ce/activated carbon (AC) catalysts and their poisoning by SO2 were investigated. Several Mn–Ce/AC catalysts prepared and then poisoned by SO2 were used in the study. The physicochemical properties of the catalysts were systematically characterized before and after poisoning, and the mechanism of SO2 poisoning was proposed. SO2 poisoning considerably affects the Mn–Ce/AC catalyst, decreasing its denitration rate from 98% to 47.9% and N2 selectivity from 96 to 85%. This can be attributed to several phenomena. SO2 poisoning increases the surface roughness of the catalyst and results in the formation of Mn(SO4)2, other sulfates, and other substances, which block the catalyst pores and reduce the content of the C and O elements on the catalyst surface as well as its specific surface area, consequently decreasing the adsorption area available for the reaction gas. Moreover, the crystallinity of MnOx on the surface of the catalyst increases, decreasing the contents of Mn4+, Ce4+ and chemosorbed oxygen. In addition, the surface functional groups, such as –COOH, –OH, and C=O, are destroyed, reducing the adsorption sites of the reaction gas and the adsorption capacity of the catalyst, consequently inhibiting the SCR reaction. Ce can reduce the effects of SO2 poisoning on the catalyst because Ce4+ can improve its oxygen storage capacity, increase the adsorption sites for the reaction gas, and react with SO2, preventing sulfate formation and pore blockage. However, excessive Ce loading causes metal agglomeration on the catalyst surface, reducing its denitration efficiency. After SO2 poisoning, the contents of Mn4+, Mn3+, and Ce4+ decreased in the Mn -Ce/AC catalysts, inhibiting the synergistic reaction between Mn and Ce, which decreased the number of oxygen vacancies and Oβ, consequently inhibit the reaction's conversion to fast selective catalytic reduction. Thus, SO2 destroyed the functional groups; occupied the oxygen vacancies and active site; and destroyed the –COOH, O–H, and C=O functional groups on the surface of the Mn–Ce/AC catalyst, reducing the acidity and number of active sites on the catalyst surface. [ABSTRACT FROM AUTHOR]

Kemiri Muka is a village in Beji Subdistrict, Depok City, Indonesia. Based on a preliminary survey conducted in one of the neighborhood units of Kemiri Muka Village, the residential had a high density of houses and was close to traditional markets, toll roads, the main road of Depok City, and landfills. This caused the air quality in the village area to decline. This study aimed to analyze risks to public health and the environment from exposure to toxic substances, SO2 and NO2, which are high in the air due to transportation on the highway and population density. The sample from this study consisted of three age groups: 15 adults, 3 school-age children, and 5 toddlers. This study used the Environmental Health Risk Analysis to analyze the data. Based on the results, the risk quotient (RQ) of non-carcinogenic effects by exposure to inhalation of chemical agents, NO2 and SO2, were also included in safe risk because all RQ values were <1. The public should remain alert to their health conditions and continue to take preventive measures. [ABSTRACT FROM AUTHOR]

This review investigates the ship emission measurements using multirotor unmanned aerial vehicles (UAVs). The monitoring of emissions from shipping is a priority globally, because of the necessity to reduce air pollution and greenhouse gas emissions. Moreover, there is widespread global effort to extensively measure vessel fuel sulfur content (FSC). The majority of studies indicate that more commonly used methods for measuring ship emission with UAVs is the sniffing method. Most of the research is concerned with determining the fuel sulfur content. Fuel sulfur content can be determined by the ratio of CO2 and SO2 concentration in the exhaust gas plume. For CO2, the non-dispersive infrared (NDIR) method is used, the most common measuring range reaches 0–2000 ppm, the overall measuring range 0–10,000 ppm, and detection accuracy is ±5–300 ppm. For SO2, the electrochemical (EC) method is used, the measuring range reaches 0–100 ppm, and the detection accuracy is ±5 ppm. Common UAV characteristics, used in measurement with ships, involve the following: 8–10 m/s of wind resistance, 5–6 kg maximum payload, and a flight distance ranging from 5 to 10 km. This can change in the near future, since a variety of emission measuring devices that can be mounted on UAVs are available on the market. The range of available elements differs from device to device, but available ranges are allowed and the accuracy provides good possibilities for wider research into ship emissions. [ABSTRACT FROM AUTHOR]

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Multiple evidence has supported that air pollution exposure has detrimental effects on the cardiovascular and respiratory systems. However, most investigations focus on the general population, with limited research conducted on medically insured populations. To address this gap, the current research was designed to examine the acute effects of inhalable particulate matter (PM2.5 and PM10), nitrogen dioxide (NO2), ground-level ozone (O3), and sulfur dioxide (SO2) on the incidence of upper respiratory tract infections (URTI), utilizing medical insurance data in Wuhan, China. Data on URTI were collected from the China Medical Insurance Basic Database for Wuhan covering the period from 2014 to 2018, while air pollutant data was gathered from ten national monitoring stations situated in Wuhan city. Statistical analysis was performed using generalized additive models for quasi-Poisson distribution with a log link function. The analysis indicated that except for ozone, higher exposure to four other pollutants (NO2, SO2, PM2.5, and PM10) were significantly linked to an elevated risk of URTI, particularly during the previous 0–3 days and previous 0–4 days. Additionally, NO2 and SO2 were found to be positively linked with laryngitis. Furthermore, the effects of air pollutants on the risk of URTI were more pronounced during cold seasons than hot seasons. Notably, females and the employed population were more susceptible to infection than males and non-employed individuals. Our findings gave solid proof of the link between ambient air pollution exposure and the risk of URTI in medically insured populations. [ABSTRACT FROM AUTHOR]

Flue gas generated by power plants is considered one of the primary sources of CO2 emissions. Flue gas can be injected into depleted gas reservoirs to minimize the impact of CO2 and other pollutants such as sulfur dioxide (SO2) and nitrogen oxides (NOx). This work investigates the impact of gas impurities in flue gas on CO2 enhanced gas recovery in sandstone and carbonate reservoirs. Sorption analysis was conducted using flue gas with and without gas impurities on carbonate and sandstone rock samples at a temperature range between 50 and 100 °C and pressure up to 45 bar. The results showed that low clay content sandstone has the highest adsorption (17.3 mg/g) of purified flue gas (80%N2/20%CO2) compared to about 13 mg/g for clay-rich sandstone at a temperature of 50 °C and a pressure of 45 bar, which is believed to be a result of pore filling mechanism besides the van der Waals forces between the gas molecules and rock surface. Indiana limestone with low permeability revealed about 11 mg/g at similar conditions. The total gas uptake decreased by an average of 56% in sandstone rocks and 31% in limestone by injecting the flue gas that contained SO2 and NOx, which could be attributed to the higher affinity of these gas impurities to rock surface compared to CO2 and N2. The adsorption/desorption hysteresis in sandstone and carbonate rocks showed that the adsorption is physisorption in all cases. Increasing the temperature decreased the flue gas adsorption without any effect on its nature. [ABSTRACT FROM AUTHOR]

Providing life on Earth with air is one of the most fundamental requirements. Thus, the quality of air affects life on Earth to a large extent. Air quality in the concerned city of Amravati is degrading, presenting a significant hazard to the residents. Three monitoring stations in Amravati city, including the residential area, the industrial area, and the commercial area, were used in this study to analyze the average daily concentrations of Respirable Suspended Particulate Matter (RSPM-PM10), nitrogen oxides (NOx), sulfur dioxide (SO2). In recent years, resource utilization needs have increased dramatically, resulting in a change in the chemical composition of the air in the atmosphere. These pollution parameters and meteorological parameters are collected for Amravati City from 2008 to 2018. To analyze the ambient air quality present at three stations in the study area by assessing the following: Annual Variations of pollutants; Seasonal Variations of pollutants; Exceedance factor; Meteorological Parameters Correlation Analysis and Wind rose Diagram. This study uses an Artificial Neural Network (ANN) model called LSTM (Long Short-Term Memory) to predict pollution parameters. Based on past data of 10 years, i.e., 2008-2018, the pollution parameters for 2019 are calculated using MATLAB software. Compared with the actual monitoring of the data, this model gives very desirable results. [ABSTRACT FROM AUTHOR]

The Coronavirus Disease 2019 (COVID-19) broke out in 2019 and spread rapidly to the whole world. Lockdown policies were adopted by Pakistan to control the rapid dispersion of COVID-19. These lockdown measures restricted economic and human activities immensely to lower number of the COVID-19 cases and associated illnesses. Additionally, air pollution and meteorological conditions also play a crucial role in the spread of COVID-19 in Pakistan. Therefore, this study mainly focuses on the changes in concentrations of selected air pollutants (coarse particulate matter (PM10), fine particulate matter (PM2.5), sulphur dioxide (SO2) and Ozone (O3)) along with meteorological parameters (relative humidity, temperature, and wind speed) during March 1 to April 25 from 2018 to 2020. The present study acquired available air pollutants data from Environmental Protection Department, meteorological parameters from the wunderground, vertical profiles and backward trajectories from National Oceanic and Atmospheric Administration (NOAA) portal. Ground-based observations showed a decline in the mean concentrations of PM2.5 and PM10 by 51.3 and 65.7% and an increase in concentrations of O3 and SO2 by 82.6 and 21.1%, respectively in 2020 compared to those measured in the year 2019. During phase 4 (lockdown) of 2020, PM10 and PM2.5 decreased by 88.0 and 82.9% compared to 2019 and 2018, respectively. Moreover, the SO2 concentrations were reduced by 59.1% in phase 3 of 2020 compared to those measured in 2019. In phase 4, O3 concentrations decreased by 29.4% in 2020 compared to 2018 but no reduction was observed in O3 compared to 2019. The findings indicate a decline in concentrations of air pollutants during the lockdown due to the restrictions on human, transportation, commercial and industrial activities. These results would be important for policymakers to develop some air pollutant control action plans to mitigate air pollution problems in Pakistan. [ABSTRACT FROM AUTHOR]

The present study explores the efficiency of selenomethionine (Semeth), an organic form of Se, as an antioxidant compared with commonly used antioxidants (ascorbic acid, glutathione, and potassium metabisulfite) in preventing oxidative browning in Greek white wines (Malagouzia and Retsina). The experimental procedure involved an accelerated browning test conducted over 12 days at 55 °C, measurement of antioxidant activity values (using the Folin—Ciocalteau and the free radical diphenylpicrylhydrazyl (DPPH) methods), determination of free sulfhydryl groups using the Ellman's method, and High-Performance Liquid Chromatographic analysis of selected phenolic compounds. Semeth consistently exhibited a preserving effect on total and free SO2 content and antioxidant activity values of Malagouzia wines. Semeth also showed a protecting effect on free sulfhydryl groups (-SH), even higher than that of SO2 suggesting that its role in maintaining wine color involves more mechanisms than just the prevention of SO2 reduction. Moreover, Semeth demonstrated promising effects in preserving individual phenolic content, in particular (+)-catechin and fertaric acid, compared to the other antioxidant additions. Both browning rate constants and percentage color change values of Retsina where higher than the corresponding values of Malagouzia wines indicating greater susceptibility to browning. Browning development was dependent on the particular antioxidant added, with ascorbic acid being the least effective. The results of this study suggest that Semeth could be an important candidate for enhancing the oxidative stability of white wines, offering at the same time valuable information for optimizing antioxidant strategies in winemaking practices. [ABSTRACT FROM AUTHOR]

Non-Saccharomyces yeasts, particularly Metschnikowia pulcherrima, are considered alternatives to SO2 in winemaking, combating specific microorganisms. The sensory profile of the wine is contingent upon the type of yeast, the fermentation conditions, and the concentration and mode of application with Saccharomyces cerevisiae strains (whether pure or used in mixed/sequential co-fermentation). This study assessed the aroma in red wines produced with S. cerevisiae (Sc) and M. pulcherrima (Mp, non-Sc), incorporating variations in the method of addition and the inclusion or exclusion of SO2. The enological parameters of the wines were slightly affected. Volatile compounds were analysed in the wines through gas chromatography–mass spectrometry (GC-MS) at three moments: at the end of malolactic fermentation (MLF) and after 6 and 9 months of bottle ageing. Sequential fermentation of Sc and Mp reduced the concentration of most identified alcohols and acids, which is favourable, as these compounds can yield undesirable aromas at high concentrations. Regardless of the yeast mixture and Mp dose, a majority of the acetate esters and ethyl esters were quantified at concentrations above their perception thresholds, thus enhancing the sensory quality of the wines. Sensory analysis of wines showed generally positive evaluations. Using non-Saccharomyces as an alternative to SO2 improves the aromatic profile of wines. [ABSTRACT FROM AUTHOR]

In the wine industry, sulfur dioxide (SO2) has an important role, as an antioxidant, and antiseptic additive. Lately, manufacturers of products specific to wine production technology are developing biological protocols for treating musts and wines using different types of yeasts. The purpose of the research is to study the impact of replacing SO2 in the first phase of the winemaking process with biological methods on the flavonoids, polyphenols, and antioxidant potential in Fetească neagră wine. The red wine from Fetească neagră, 2021 harvest - Dealu Mare Vineyard was made through two methods: treated with SO2 6% (25 mg/L) and treated with Primaflora VR Bio (7 g/hL). The IC50 value for the variant treated with Primaflora VR BIO was 722 mg/mL and the variant treated with SO2 recorded a 724 mg/ml, the differences being non-significant. Primaflora VR Bio is an effective and promising alternative in terms of the quality of oenological and biochemical parameters, and a basic variant for ecological, biological wines with a low sulfite content.

CO2 and SO2 gases are utilized in various industrial applications and are subjects of environmental research. However, these gases are considered toxic and pose dangers at certain concentrations. Therefore, it is crucial to monitor and control the exposure to these gases in the environment to prevent reaching hazardous levels that could endanger both humans and the environment. A non-contact detection and monitoring system is essential to minimize the adverse effects of direct gas exposure. In this research, a non-contact detection system for CO2, SO2, and mixed gases was developed using optical imaging analysis generated by infrared cameras. The images were captured using the FLIR Vue Pro-R infrared camera, with infrared absorbing gas sourced from a 50-watt tungsten lamp. Visual identification of these gases through optical imaging is challenging; however, this study successfully identified these gases using a Convolutional Neural Network (CNN). The CNN architecture used in this study is DenseNet (Densely Connected Convolutional Networks), comprising 169 convolution layers. The CNN model was trained and tested on experimental optical imaging data, categorized into three classes: CO2, SO2, and a mixture of gases. A total of 1030 optical imaging data points were utilized for training. Training was conducted using the AdamW optimization function over 28 epochs. The evaluation of results yielded accuracy, precision, recall, and F1-score metrics. The novelty of this study lies in the successful identification of CO2, SO2, and their mixture by the CNN model with an accuracy of 85%. Precision, recall, and F1-score values are all 0.85. These results indicate that the CNN model effectively distinguishes optical imaging of each gas (CO2, SO2, and their mixture) consistently and accurately. Consequently, it can be concluded that the CNN model performs well in distinguishing between these gases in optical imaging analysis.

Barren Island volcano is the only active stratovolcano within Indian territory. Following the 2004 Indian Ocean earthquake, which had a magnitude of 9.3 Mw, the volcano gained global attention due to its sudden unrest and violent behaviour. It has been intermittently active since then, between 2005 and 2022. Due to the remote location and inaccessibility of the volcano, Earth Observation technology is the only feasible approach for regular monitoring. The present study utilizes satellite images and their derived products, such as volcanic radiative power, fire information for resource management system, and SO2 data, to understand various volcanic features and assess the volcanic characteristics and patterns during the active phases over the last two decades. The results demonstrated the effectiveness of the multi-source satellite datasets in monitoring India's lone active volcano. [ABSTRACT FROM AUTHOR]

The reaction characteristics of the SO2 oxidation catalyst by the catalyst preparation method were analyzed by investigating the catalyst properties on the TiO2 support using a vanadium-alkali (K) compound containing the catalyst. The slurry mix method and the dry ball milling method were used for the production of the catalyst. In this process, the difference in interaction between the active material (V) and the support (TiO2) has been confirmed. Especially, the high proportion of non-stoichiometric species of the initial catalyst reflects the high interaction between vanadium and TiO2. Therefore, an increase in non-stoichiometric species such as V4+ indicates an increase in the interaction between TiO2 and V2O5. In particular, the interaction between the support-active material improves the transfer of SO2 adsorbed on the support TiO2 to the active material (V2O5). Therefore, it induces the production of a high proportion of the active substance (VVO)2O(SO4)44− and consequently increases the SO2 oxidation performance. [ABSTRACT FROM AUTHOR]

In the wine industry, sulfur dioxide (SO2) has an important role, as an antioxidant, and antiseptic additive. Lately, manufacturers of products specific to wine production technology are developing biological protocols for treating musts and wines using different types of yeasts. The purpose of the research is to study the impact of replacing SO2 in the first phase of the winemaking process with biological methods on the flavonoids, polyphenols, and antioxidant potential in Fetească neagră wine. The red wine from Fetească neagră, 2021 harvest - Dealu Mare Vineyard was made through two methods: treated with SO2 6% (25 mg/L) and treated with Primaflora VR Bio (7 g/hL). The IC50 value for the variant treated with Primaflora VR BIO was 722 mg/mL and the variant treated with SO2 recorded a 724 mg/ml, the differences being non-significant. Primaflora VR Bio is an effective and promising alternative in terms of the quality of oenological and biochemical parameters, and a basic variant for ecological, biological wines with a low sulfite content. [ABSTRACT FROM AUTHOR]

Reduction in the consumption of operational (primary) energy and emissions of harmful gases has recently become the focus of attention of the civil engineering sector. In this context, there is also emphasized the energy consumption and emission production values associated with the whole life cycle of the construction materials used, which is referred to as "bundled energy consumption" and "bundled emissions". This paper analyses the energy performance certificates in combination with the SBToolCZ methodology. Sustainability Building Tool is a methodology designed to assess the sustainability of buildings. This methodology is used to assess the environmental impact of buildings at different stages of their life cycle, such as production, operation and demolition of the building. The amount of carbon dioxide and sulphur dioxide produced during the life cycle of buildings was determined by analysing and extending the building assessment data by the SBToolCZ methodology, which was subsequently valued and incorporated into the lifetime costs. The data from 17 case studies from the Czech environment were analysed. Taking these environmental impacts into account, valuing them and analysing the cash flows of investors and society shows the importance of paying increased attention to sustainable construction and reducing its negative impact on the environment and climate. Research data shows that 30% of the operating costs of buildings are the societal costs associated with CO 2,eqv. and SO 2,eqv. production. [ABSTRACT FROM AUTHOR]

The presence of HCl and SO2 gas imposes limitations on syngas utilization obtained from household waste in a wide range of applications. The hydrotalcite-like compounds (HTLs) have been proved that could remove HCl efficiency. However, the research on impact of synthesis conditions of HTLs and SO2 on HCl removal was limited. In this study, a range of Ca–Mg–Al mixed oxide sorbents was synthesized by calcining HTLs, with variations in crystallization temperature, solution pH, and the Ca/Mg molar ratio. These sorbents were examined for their effectiveness in removing HCl at medium–high temperatures under diverse conditions. The adsorption performance of selected sorbents for the removal of HCl, SO2, and HCl-SO2 mixed gas at temperature of 350 °C, 450 °C, and 550 °C, respectively, was evaluated using thermogravimetric analysis (TGA). It was observed that the HTL synthesis parameters significantly influenced the HCl adsorption capacity of Ca–Mg–Al mixed oxides. Notably, HTLs synthesized at 60 °C, a solution pH of 10–11, and a Ca/Mg ratio of 4 exhibited superior crystallinity and optimal adsorption characteristics. For individual HCl and SO2 removal, temperature had a minor effect on HCl adsorption but significantly impacted SO2 adsorption rates. At temperatures above 550 °C, SO2 removal efficiency substantially decreased. When exposed to a mixed gas, the Ca–Mg–Al mixed oxides could efficiently remove both HCl and SO2 at temperatures below 550 °C, with HCl dominating the adsorption process at higher temperatures. This dual-action capability is attributed to several mechanisms through which HTL sorbents interacted with HCl, including pore filling, ion exchange, and cation exchange. Initially, HCl absorbed onto specific sites created by water and CO2 removal due to the surface's polarity. Subsequently, HCl reacted with CaCO3 and CaO formed during HTL decomposition. [ABSTRACT FROM AUTHOR]

Studying non-Saccharomyces yeasts as bio-protectors can help find new alternatives to the chemical additive SO2 in winemaking. The present article evaluates the effect of two native yeasts, Candida oleophila and Candida boidinii, as potential bio-protectors to replace SO2 during the production of Sauvignon Blanc wine. Fermentation was conducted on simple and mixed inoculum at two concentrations, 1 × 106 and 1 × 107 cells/mL. We monitored the population of deterioration microorganisms, including lactic acid bacteria (LAB), acetic acid bacteria (AAB), and Brettanomyces bruxellensis (BB), apart from the final chemical and volatile composition of the wine. The results were compared with fermentations protected with SO2, where Candida oleophila yeast was more effective against lactic acid bacteria, whereas Candida boidinii was more effective against acetic acid bacteria and Brettanomyces bruxellensis; meanwhile, the fermentations with the initial inoculum of 1 × 107 cells/mL showed better results than those with an inoculum of 1 × 106 cells/mL. Bio-protector use did not negatively affect wine quality, equaling the effectiveness of SO2 for spoilage microorganism inhibition. This study reveals for the first time the potential of Candida oleophila and Candida boidinii yeasts as bio-protectors in microbiological wine stabilization. [ABSTRACT FROM AUTHOR]

A theoretical molecular simulation study of the encapsulation of gaseous SO2 at different temperature conditions in a type II porous liquid is presented here. The system is composed of cage cryptophane-111 molecules that are dispersed in dichloromethane, and it is described using an atomistic modelling of molecular dynamics. Gaseous SO2 tended to almost fully occupy cryptophane-111 cavities throughout the simulation. Calculations were performed at 300 K and 283 K, and some insights into the different adsorption found in each case were obtained. Simulations with different system sizes were also studied. An experimental-like approach was also employed by inserting a SO2 bubble in the simulation box. Finally, an evaluation of the radial distribution function of cryptophane-111 and gaseous SO2 was also performed. From the results obtained, the feasibility of a renewable separation and storage method for SO2 using porous liquids is mentioned. [ABSTRACT FROM AUTHOR]

The removal of air pollutants is an important research topic in order to improve the environment. In addition, many common pollutants can affect human health to varying degrees. In this work, we investigate NO and SO2 conversion by reaction with a commonly used metal oxide catalyst, TiO2. Rutile TiO2(110) single crystals and industrial powder samples used in sunscreen are studied using near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) as a main tool. This allows in situ monitoring of the gas conversion process. We find Ti3+ defects (oxygen vacancies) or Mn oxides/cations (MnO) at the TiO2 surfaces can improve the conversion of NO and SO2 to surface-bound species. MnO and Ti3+ defects at the surface of rutile TiO2(110) exhibit a synergistic effect on the conversion of NO and SO2 that is significantly improved by nearly an order of magnitude. The by-products are mainly in the form of NO3−, SO32−, and SO42−. We find the main oxidation products formed on the single crystals are subtly different from those on the industrial powder samples. For TiO2 nanopowders (undoped and Mndoped), the presence of Mn also shows improvement in toxic gas adsorption capacity. Overall, it is believed that the outcome obtained from NAP-XPS in this research provides useful insights for the future use of TiO2 in pollutant gas capture. [ABSTRACT FROM AUTHOR]

Air pollution is a serious issue that has an impact on human health all over the world. Improving air quality is a main part of environmental sustainability, and it begins with identifying contaminants and their sources. This paper examines air quality in urban areas and the background levels of pollutants in Kuwait by analyzing pollutant data from a number of fixed monitoring stations managed by the Environment Public Authority in the State of Kuwait. The concentrations of SO2, CO, O3, NO, and PM10 were measured at several sites in Kuwait. This study examines time series and wind rose plots for temporal and spatial variation, and pollutant sources. The results of this study show different variation patterns for SO2, which could be linked to traffic levels. There were similar daily profiles for CO, NO, and O3 at all the sites. Most of these pollutants exceeded the limits set by air quality standards. [ABSTRACT FROM AUTHOR]

Abstract Background Air pollution is a serious worldwide issue, where both outdoor and indoor air quality have a substantial impact on the health of children. Children are more vulnerable to the effects of air pollution due to their developing respiratory systems and higher respiration rates than adults. These children dedicate a substantial amount of time to the preschool setting. The study sought to evaluate the concentration of NO2 and SO2 in both outdoor and indoor environments of preschool facilities. Methods Concurrently, the levels of NO2 and SO2 were measured indoors and outdoors at 13 randomly selected preschools in 7 districts in Mpumalanga Province, South Africa. Radiello passive air samplers were employed to collect gaseous samples. Results The mean levels of NO2 indoors and outdoors were within the recommended criteria outlined by the World Health Organization (WHO), specifically target levels 1–3. Additionally, these values were also below the air quality guides outlined by South Africa, both for yearly and 1‐h mean measurements. Nevertheless, both levels remained above the suitable threshold of 10 µg m−3 outlined by the WHO air quality guidelines. Conclusions It is important to implement proactive measures such as enhancing airflow systems, employing air filters and reducing potential sources of air pollution in preschools, to aid in reducing exposure to indoor and outdoor NO2 and SO2.

The aim of the research was to develop mathematical models describing the emission of selected pollutants correlated with the residual oxygen content in the flue gas. The correlation was made for low-temperature combustion of wood pellets in biomass boilers and furnaces. The developed models can be used in modern control systems of boilers, furnaces or for precise calculation of emission factors for the discussed group of heating devices. The description was made for devices with a stationary wood pellet combustion process with a heat output range from 12 kW to 30 kW. The obtained models, not currently used in this group of devices, will allow controlling the operation of heating boilers in a sustainable and ecological way, taking into account the environmental burden.

The removal of air pollutants is an important research topic in order to improve the environment. In addition, many common pollutants can affect human health to varying degrees. In this work, we investigate NO and SO2 conversion by reaction with a commonly used metal oxide catalyst, TiO2. Rutile TiO2(110) single crystals and industrial powder samples used in sunscreen are studied using near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) as a main tool. This allows in situ monitoring of the gas conversion process. We find Ti3+ defects (oxygen vacancies) or Mn oxides/cations (MnO) at the TiO2 surfaces can improve the conversion of NO and SO2 to surface-bound species. MnO and Ti3+ defects at the surface of rutile TiO2(110) exhibit a synergistic effect on the conversion of NO and SO2 that is significantly improved by nearly an order of magnitude. The by-products are mainly in the form of NO3−, SO32−, and SO42−. We find the main oxidation products formed on the single crystals are subtly different from those on the industrial powder samples. For TiO2 nanopowders (undoped and Mndoped), the presence of Mn also shows improvement in toxic gas adsorption capacity. Overall, it is believed that the outcome obtained from NAP-XPS in this research provides useful insights for the future use of TiO2 in pollutant gas capture.

Air pollution has become a global issue and contributes significantly to climate change, mainly due to the massive energy consumption in industry and the transportation sector. Emissions of harmful gases from burning fuels such as NOx and SO2 are the most significant sources of environmental pollution, which have negative impacts on the environment, such as the greenhouse effect, damage to the ozone layer, photochemical smog, and acid rain, and can interfere with the respiratory system in humans. This study utilizes hollow fiber membrane modules, which act as a reactor on the shell side of the membrane module and a gas distributor by the membrane fiber to remove NOx and SO2 spontaneously. The oxidant solutions used were a pair of hydrogen peroxide and sodium hydroxide (H2O2-NaOH) solutions, a pair of sodium chlorite and sodium hydroxide (NaClO2-NaOH) solutions, and a pair of sodium chlorate and sodium hydroxide (NaClO3-NaOH) solutions. Based on the results of experiments, SO2 can be removed entirely in the process, while NOx depends on the feed gas flow rate and the concentration of the oxidant solution used. H2O2 is the most effective oxidizing agent in removing NOx and SO2 because of its higher oxidative properties than NaCLO2 and NaClO3. The increase in feed gas flow rate resulted in a decrease in the efficiency of NOx removal even though the NOx mass transfer flux and NOx loading increased. Meanwhile, an increase in the concentration of oxidants increases the efficiency of NOx removal and mass transfer flux but decreases NOx loading. Based on the experimental results, the maximum NOx removal efficiency achieved by the oxidant solutions is 93.9, 91.1, and 88.3% for H2O2-NaOH, NaClO2-NaOH, and NaClO3-NaOH, respectively.

Mount Semeru, an active volcano in East Java, Indonesia, erupted on December 4, 2021, following extreme rainfall that caused an avalanche of hot pyroclastic flows and lava. The tropospheric conditions and dominant particle components in the atmosphere can be monitored using Global Navigation Satellite System (GNSS) technology and remote sensing satellites. GNSS signal propagation delay in Precise Point Positioning (PPP) processing can be used to determine Zenith Tropospheric Delay (ZTD) and Precipitable Water Vapor (PWV) variables so that atmospheric conditions can be generated. In addition, by using remote sensing satellite data, it is possible to obtain rainfall data with high temporal resolution as well as the dominant particle and gas content values during eruptions. During the eruption period, the high value of PWV was dominated by the high intensity of precipitation during the rainy season. High rainfall before the eruption caused activity inside the mountain to increase, which occurred in avalanche type eruption. Apart from that, the atmosphere around Semeru was also dominated by SO2 content, which spreaded for tens of kilometers. SO2 content began to be detected significantly by remote sensing sensors on December 7, 2021. In this study, deformation and atmospheric monitoring were also carried out using low-cost GNSS at the Semeru Monitoring Station on September 9–15, 2022. The results of the ZTD and ZWD values show the dominance of the wet component, which is directly proportional to rainfall activity in this period.

Governments worldwide have established lockdowns to limit the spread of COVID-19 during the pandemic. The restrictions on travel and reduction of economic activity have led to a temporary improvement in air quality in several countries, especially in urban areas. This study investigates the changes in concentration levels of air pollutants (PM10, PM2.5, SO2, NO2, and bacterial aerosol) in the Upper Silesia Region of Southern Poland, during three periods: pre (March 2018 and 2019), during (March 2020, and 2021) and post-COVID-19 lockdown period (March 2022 and 2023). Our findings indicate that COVID-19 restrictions had a moderate impact on PM10 levels in comparison to pre- and post-COVID-19 periods. PM2.5 during lockdown was significantly lower than in the pre-COVID period and not significantly higher after COVID. PM10 and PM2.5 average concentrations decreased during COVID-19 restrictions by 27.8% and 12.7%, respectively. Compared with the results from the pre-COVID-19 phase, the reductions in NO2 and SO2 during the lockdown were 9.5% and 34.0%. Among other pollutants, bacterial aerosol (BA) concentrations also decreased during the lockdown by 23.0%, compared to the results from the pre-COVID-19 period.

This study focuses on the S-to-H2SO4 industry by investigating the chemical looping combustion (CLC) process utilizing Fe-based and Cu-based oxygen carriers (OCs), which are widely applied in CLC technology. The primary objective is to conduct combined CLC reactions of these two metal carriers in a three-zone temperature tube furnace, aiming to achieve a higher SO2 yield than what is attainable by reacting a single metal carrier with S. The investigation reveals promising industrial applications, offering potential benefits in terms of reducing equipment costs, enhancing energy efficiency, and lowering the emissions of the H2SO4 production industry. Through a series of experiments, the study examines the effects of reaction temperature and material molar ratios on SO2 generation. The solid reaction products were characterized using X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), and X-ray photoelectron spectroscopy (XPS). The experimental results indicate that the combined Cu-based and Fe-based OCs exhibit a higher SO2 yield during the reduction stage compared to using either Fe-based or Cu-based OCs independently. Under optimal conditions, with a carrier gas flow rate of 300 mL/min, an Fe2O3/S molar ratio of 6:1 in the second temperature zone, and a reaction temperature of 900 °C, the total SO2 yield in the third temperature zone reached approximately 85%. This was achieved at a reaction temperature of 850 °C, with an Fe2O3/S molar ratio of 6:1 in the first half of the zone and a CuO/S molar ratio of 12:1 in the second half of the zone. SEM-EDS analysis further revealed that the combined OCs showed no significant signs of agglomeration or sintering after 10 cycles of the reaction. However, Cu-based carrier particles increased in size by 50%, while Fe-based carrier particles remained relatively stable. Additionally, the low mass-to-atom ratio of S on the surface of OCs after the cyclic reaction suggests that the reduced-state OCs can be fully oxidized and regenerated following the release of SO2 during oxidation.