Covid-19 was first reported in Morocco on March 2, 2020. Since then, to prevent its propagation, the Moroccan government declared a state of health emergency. A set of rapid and strict ...countermeasures have taken, including locking down cities, limiting population's mobility and prohibiting almost all avoidable activities. In the present study, we attempted to evaluate the changes in levels of some air pollutants (mainly PM10, NO2 and SO2) in Salé city (North-Western Morocco) during the lockdown measures. In this context, a continuous measurement of PM10, SO2 and NO2 was carried before and during the Covid-19 lockdown period. As a consequence of the security measures and control actions undertaken, the emissions from vehicle exhaust and industrial production were significantly reduced, which contribute to the decrease in the concentrations of the studied pollutants. The obtained results showed that the difference between the concentrations recorded before and during the lockdown period were respectively 75%, 49% and 96% for PM10, SO2 and NO2. PM10 levels were much less reduced than NO2. The three-dimensional air mass backward trajectories, using the HYSPLIT model, demonstrated the benefits of PM10 local emission reductions related to the lockdown were overwhelmed by the contribution of long-range transported aerosols outside areas. In addition, noteworthy differences in the air mass back trajectories and the meteorology between these two periods were evidenced.
Daily average concentrations of SO2 and NO2 from March 11th to April 2nd in Salé city. Display omitted
•PM10, NO2 and SO2 concentrations were reduced by more than half during the covid-19 lockdown period.•Covid-19 countermeasures contribute to reduce all pollutant concentrations but with significant differences among them.•Long-range transported aerosols contributions overcame the PM10 local emission reductions benefits related to the lockdown.
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•Sm can significantly enhance the SO2 and H2O resistance of W-Zr catalyst.•Sm can preferentially react with SO2 than chemisorbed oxygen.•The Sm species decreased the oxidation of SO2 ...on the catalyst surface.•The Sm can effectively decrease the generation of ammonium sulfate species.
The WO3-ZrO2 for NH3-SCR catalyst has excellent NO conversion, especially at high temperature, which are appropriate for the diesel engine after-treatment system. However, the diesel engine NH3-SCR catalysts can be affected by SO2 toxicity. Thus, a series of xSm-WZZ catalysts were prepared by sol–gel method, and the Sm species as the promoter were applied to enhancing the SO2 resistance and regeneration performance of the catalyst. 1Sm-WZZ catalyst exhibited the best SO2 and H2O resistance and slightly improved the NH3-SCR activity, in which 100% NO conversion and N2 selectivity can be achieved at 400–600 ℃. Moreover, compared with WZZ catalyst, 1Sm-WZZ catalyst showed excellent regeneration performance, which could be regenerated by thermal treatment at 350 ℃. The results of XPS, CO2-TPD and H2-TPR revealed that the Sm could decrease the amount of alkaline sites and redox ability of catalyst, which may be the main reason for the reduction of the adsorption and oxidation of SO2. Additionally, the Sm decreased the formation of ammonium sulfate salts on catalyst, which were verified by the TGA and FTIR spectrum experiments. Furthermore, the Sm could preferentially react with SO2 than chemisorbed oxygen, which restrains the reaction of chemisorbed oxygen with SO2, thereby reducing the generation of sulfate around the chemisorbed oxygen. In addition, the in-situ DRIFTS tests indicated that the Sm could reduce the generation of S = O for tridentate sulfate species and SO3 on the catalyst.
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•Cu modified Mn3O4 spinel showed excellent SCR performance and SO2 resistance.•The Eley-Rideal mechanism predominated in the low temperature SCR reaction.•The formation of MnSO4 was ...mainly responsible for the deactivation of Mn3O4.•Cu doping restrained MnSO4 generation by reducing the amounts of adjacent Mn.
Mn-based oxides are regarded as one of the most promising catalysts for selective catalytic reduction (SCR) of NOx by NH3 at low temperatures, but their applications are extremely restricted by the irreversible poisoning of SO2. Improving the SO2 tolerance of Mn-based catalyst has longtime received the most attentions from both academia and industry. In this work, a series of Cu-modified Mn3O4 spinels were synthesized, and the roles of the Cu dopant were investigated. The (Cu1.0Mn2.0)1–δO4 spinel showed both excellent SCR performance and SO2 resistance at low temperature. Cu doping improved the BET surface area, the quantities of active Mn4+ and the acid sites of Mn3O4 spinels, all of which contributed to the increase in low-temperature SCR activity. The formation of MnSO4 was mainly responsible for the irreversible deactivation of the Mn3O4 spinel upon exposure to SO2. DFT calculations suggested that SO2 was more likely to be adsorbed as “–Mn–O–S–O–Mn–” on Mn3O4 and (Cu1.0Mn2.0)1–δO4 spinels. Therefore, the formation of MnSO4 on the (Cu1.0Mn2.0)1–δO4 spinel was significantly mitigated by Cu doping, mainly due to reduced amounts of adjacent Mn. Moreover, resulting from the electronic transfer between copper and manganese cations within the spinel lattice (Cu2+ + Mn3+ ⇄ Mn4++ Cu+), the (Cu1.0Mn2.0)1–δO4 spinel retained a high surface ratio of Mn4+/Mntotal, which maintained an excellent low-temperature SCR activity under the SO2-containing condition. This work shows that doping with the low–valence dopant of Cu can significantly improve the low-temperature SCR activity and SO2 tolerance of the Mn3O4 spinel, which could be a strategy for the further design of Mn-based SCR catalysts.
In a scenario when haze and smog events are wreaking havoc in many parts of the world, accurate information on ambient sulfur dioxide (SO2) sources is a required input to models for prediction and ...mitigation of air pollution. Globally, India is one of the highest emitters of anthropogenic SO2. However, the Ozone Monitoring Instrument (OMI) data reveal that unlike many other anthropogenic air pollutants, the strongest anthropogenic SO2 sources are not located in the Indo-Gangetic plain (IGP) but over the coal belts of North Eastern peninsular India. In this study, we report SO2 measurements conducted at Bhubaneswar, a rapidly developing smart city in the Eastern Coast of India. The city is ideally located just downwind of the Indian SO2 hotspots during winter, when SO2 concentrations are the highest, reaching 14.3 ppbv for hourly averaged data. The measurements, reported here from the summer of 2010 to the summer of 2012, show that despite being a rapidly developing location, SO2 over Bhubaneswar is dominated by regional emissions rather than local sources like vehicular exhausts. The influence of regional emissions is strongest in winter as the city is directly downwind of 6 of the 10 largest thermal power plants and 7 out of the 13 largest integrated steel plants in India with a mean SO2 concentration of 3.2 ppbv. This is evinced by multiple pointers viz. Concentration-Weighted Trajectory (CWT) analysis for surface SO2 data, correlation analysis for OMI SO2 data, analysis of surface concentrations of SO2, organic carbon, black carbon and carbon monoxide; which reveal SO2 emissions from the industrial and mining regions of Chhattisgarh and north-west Odisha. This is the same region that shows up as hotspots of SO2 in OMI retrievals over India. However, despite being downwind of major SO2 sources during winter, SO2 concentrations in Bhubaneswar are lower than over some other cities (Kolkata, Kanpur) in the IGP, due to influence of strong local sources in the later cases. Unlike most other urban regions in India, the diurnal variation of SO2 over Bhubaneswar shows elevated daytime values due to predominant influence of regional emissions.
•SO2 measurements reported over a city downwind of Indian SO2 hotspots in winter.•Multiple proxies: Trajectory, satellite & chemical analysis to find source regions.•SO2 concentrations increasing over Bhubaneswar.
As the main source of atmospheric sulfate aerosol, the aqueous-phase oxidation of SO2 has been of great concern. Traditionally, the aqueous-phase oxidation of SO2 is considered a consumption process ...of atmospheric oxidation capacity; however, we report here that •OH radicals and other reactive oxygen species (ROS) can be generated in the photochemical reactions of bulk HSO3− solution. This •OH production pathway results in the fast sulfate formation in the photooxidation of dissolved SO2. The photochemical process is determined to be pH-dependent in which sulfate formation is promoted by decreasing pH. Hence, a light - driven acidic positive feedback mechanism is proposed that the oxidation of dissolved SO2 and the formation of •OH radicals have a synergistic promoting effect. These results indicate that the photochemistry of dissolved SO2 could be a missing source of aqueous •OH radicals as well as sulfate at regional to global scales.
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•Aqueous-phase photooxidation of SO2 is an important sulfate formation pathway.•Acidity promotes rather than inhibits the aqueous-phase photooxidation of SO2.•SO2 is not only a consumer but also an initiator of reactive oxygen species.
Inflammation is an innate defense response of an organism to tissue damage which is accompanied by biological processes such as depolarization, autophagy, and endogenous bisulfite production. As a ...novel type of iron-dependent programmed apoptosis, ferroptosis accumulates an excessive lipid peroxide, leading to fluctuations of polarity and SO2. To study the dynamic correlation between SO2 and polarity of these two diseases is of great significance for revealing the precise regulation mechanism of inflammation and ferroptosis. In this research, a multicolor fluorescent probe BDMOB was developed by coupling a sulfur dioxide response site with push-pull electrons, realizing orange and near-infrared fluorescence emission, allowing to the simultaneous detection of polarity and SO2. With its attractive AIE and NIR properties, BDMOB is able to effectively prevent background interference and effectively solve the problem of fluorescence quenching. For the first time, the slight fluctuations in SO2 and polarity during inflammation and ferroptosis is shown by examining parameter changes during aberrant processes at the in vivo and in vitro levels. This offers fresh insights into the diagnosis and therapy of disease processes.
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•Three-channel independent visualization of SO2 and polarity fluctuations was recorded by BDMOB.•The therapeutic process of inflammation and ferroptosis is examined by fluorescence.•Endogenous and exogenous SO2 derivatives can be sensitively monitored by BDMOB.•The application of discriminating cancer cells from normal ones was discussed.
•Rb modification can improve the CO-SCR performance of Ir@SBA-15.•The channels of SBA-15 inhibited the agglomeration of Ir nanoparticles.•SO2 can inhibit the adsorption of NO and the oxidation of CO ...at high temperatures.•More CO can be used for NOx reduction when SO2 present in the reaction atmosphere.
Selective catalytic reduction of NOx by CO (CO-SCR) is a promising technology to remove NOx by CO for the flue gas which both contain CO and NO simultaneously. However, it is quite difficult to acquire satisfied NOx removal efficiency in the presence of O2 which owing to the quick consumption of CO by O2. In this work, a Rb modified Ir@SBA-15 (IrRb0.5@SBA-15) is developed for CO-SCR reaction in the presence of 5 % O2 which 80.3 % NOx conversion can be obtained. The Ir species have loaded into the mesoporous channels of SBA-15 which then grew into Ir nanoparticles after pretreating by H2. The improved NOx removal efficiency of IrRb0.5@SBA-15 catalyst is owing to Rb modification can improve the adsorption ability of the catalyst for reactants and improve the anti-oxidation ability of Ir0 sites. The presence of SO2 inhibits the consumption of CO at high temperatures which leading to the increase of NOx conversion on the catalysts. Furthermore, the presence of CO at high temperatures also can inhibits the formation of NO2. This work provides a new insight for the effect of SO2 on CO-SCR reaction for Ir-based catalysts.
This study reports on temporal variations of NO2, O3, and SO2 pollutants and their related health effects in urban air of Khorramabad, Iran using AirQ 2.2.3 software. Based on data between 2015 and ...2021, hourly NO2, O3, and SO2 concentrations increase starting at 6:00 a.m. local time until 9:00 p.m., 3:00 p.m., and 7:00 p.m. local time, respectively, before gradually decreasing. The highest monthly NO2, O3, and SO2 concentrations are observed in October, August, and September, respectively. Annual median NO2, O3, and SO2 concentrations range between 17 ppb and 38.8 ppb, 17.5 ppb–36.6 ppb, and ∼14 ppb–30.8 ppb, respectively. Two to 93 days and 17–156 days between 2015 and 2021 exhibit daily concentrations of NO2 and SO2 ≤ WHO AQGs, respectively, while 187–294 days have 8-h maximum O3 concentrations ≤ WHO AQGs. The mean excess mortality ascribed to respiratory mortality, cardiovascular mortality, hospital admissions for COPD, and acute myocardial infraction are 121, 603, 39, and 145 during 2015–2021, respectively. O3 is found to exert more significant health effects compared to SO2 and NO2, resulting in higher cardiovascular mortality. The gradual increase in NO2 and possibly O3 over the study period is suspected to be due to economic sanctions, while SO2 decreased due to regulatory activity. Sustainable control strategies such as improving fuel quality, promoting public transportation and vehicle retirement, applying subsidies for purchase of electric vehicles, and application of European emission standards on automobiles can help decrease target pollutant levels in ambient air of cities in developing countries.
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•Annual median NO2, O3, and SO2 concentrations range between ∼14–38.8 ppb.•NO2 and O3 gradually increase and SO2 decrease over the study period duration.•2–294 days had NO2, SO2, and O3 concentrations less than or equal to WHO AQGs.•O3 poses more significant health effects compared to NO2 and SO2.•Expanding public transportation systems can help decrease target pollutant levels.
The urgent need for effective SO2 capture materials has driven research into the development of novel nanoporous organic polymers (NOPs). Herein, we developed a triphenylamine-based nanoporous ...organic polymer, designated as ANOP-5, through the self-condensation of an AB2 triphenylamine monomer. The adsorption/separation properties of SO2 and CO2 are comparatively evaluated through the investigation of static gas adsorption isotherms. At 273 K and 100 kPa, ANOP-5 displays a high SO2 adsorption capacity of 399 cm3 g−1 and a high selectivity of 388 for SO2/CO2, with a molar ratio of SO2 to CO2 at 10/90. The exceptional performance of desulfurization is attributed to the strong interaction between ANOP-5 and SO2, in addition to the ultramicroporous structure. These findings are further supported by the dispersion-corrected density functional theory calculations. This study contributes valuable insights into the design and preparation of NOPs with high gas adsorption properties, particularly for addressing environmental pollution challenges related to SO2 emissions.
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•ANOP-5 was synthesized through the self-condensation of an AB2 triphenylamine monomer.•ANOP-5 exhibits high SO2 absorption capacity (399 cm3 g−1) and notable SO2/CO2 selectivity (388).•DFT analysis emphasizes the role of triphenylamine groups in SO2 adsorption.
Removal of gaseous arsenic from copper smelting flue gas by solid-phase adsorption effectively reduces the emission of arsenic-containing pollutants into the atmosphere. Nevertheless, the high ...concentration of SO2 in the flue gas unavoidably impacts the effectiveness of the adsorbent in capturing gaseous arsenic. Currently, there is no research focusing on the adsorption capacity of pyrolusite (PY) for As2O3(g), including the influence of SO2. This study examines the capacities of PY to capture As2O3(g) with and without SO2 under different conditions and delves into the mechanism by which SO2 affects the capture of As2O3(g) by PY. Compared to the states without SO2, the As2O3(g) capture by PY in an atmosphere containing SO2 (2.5 v/v% SO2) decreased to 89.1 % at 400 °C. SO2 can diminish the As2O3(g) capture capacity of PY by competing for active sites, generating sulfate (MnSO4), inhibiting arsenic oxidation, and obstructing the pores of the adsorbent. In addition, SO2 enhances PY's As2O3(g) capture capacity by creating (As2O2)SO4 and forming new active centers. Moreover, the phase transition of PY guided by the high concentration of SO2 during As2O3(g) capture also favors arsenic capture. This research confirms that PY has substantial potential for effectively removing As2O3(g) from high-SO2 flue gas.
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