Presence Of SO2 Research Articles

Catalytic oxidation of CO over Pt/TiO2 with low Pt loading: The effect of H2O and SO2

Anatase TiO2 loaded with 0.1wt.% Pt catalyst (0.1Pt/TiO2-A) was prepared via the impregnation method, and its CO catalytic oxidation activity was investigated. Noteworthy, introduction of H2O into the reaction atmosphere apparently facilitated the catalytic oxidation of CO. Besides, introduction of SO2 inhibited the catalytic oxidation of CO. In presence of H2O and SO2, 0.1Pt/TiO2-A showed outstanding catalytic stability, and X-ray photoelectron spectroscopy (XPS) and thermogravimetric (TG) characterizations suggested that the amount of sulfate species deposited on the 0.1Pt/TiO2-A treated at 230 °C did not increase with time extension, which might be an important reason for the high sulfur resistance of 0.1Pt/TiO2-A. XPS results also demonstrated that the dissociation of H2O led to considerably increase of hydroxyl groups over the catalyst surface. H218O isotope-labeling experiments unambiguously showed that C16O18O was the main product accounting for 88.9%, revealing that the other oxygen atom in the product CO2 was mostly from H2O. Consequently, based on previous researches and our experimental results, the mechanism of H2O promoting CO oxidation on 0.1Pt/TiO2-A catalyst was proposed.

Insight into the Promoting Role of Er Modification on SO2 Resistance for NH3-SCR at Low Temperature over FeMn/TiO2 Catalysts

Er-modified FeMn/TiO2 catalysts were prepared through the wet impregnation method, and their NH3-SCR activities were tested. The results showed that Er modification could obviously promote SO2 resistance of FeMn/TiO2 catalysts at a low temperature. The promoting effect and mechanism were explored in detail using various techniques, such as BET, XRD, H2-TPR, XPS, TG, and in-situ DRIFTS. The characterization results indicated that Er modification on FeMn/TiO2 catalysts could increase the Mn4+ concentration and surface chemisorbed labile oxygen ratio, which was favorable for NO oxidation to NO2, further accelerating low-temperature SCR activity through the “fast SCR” reaction. As fast SCR reaction could accelerate the consumption of adsorbed NH3 species, it would benefit to restrain the competitive adsorption of SO2 and limit the reaction between adsorbed SO2 and NH3 species. XPS results indicated that ammonium sulfates and Mn sulfates formed were found on Er-modified FeMn/TiO2 catalyst surface seemed much less than those on FeMn/TiO2 catalyst surface, suggested that Er modification was helpful for reducing the generation or deposition of sulfate salts on the catalyst surface. According to in-situ DRIFTS the results of, the presence of SO2 in feeding gas imposed a stronger impact on the NO adsorption than NH3 adsorption on Lewis acid sites of Er-modified FeMn/TiO2 catalysts, gradually making NH3-SCR reaction to proceed in E–R mechanism rather than L–H mechanism.

Capture of elemental mercury from flue gas over a magnetic and sulfur-resistant sorbent prepared from Fe-containing sewage sludge activated with sulfuric acid

By the pyrolysis of Fe-containing sewage sludge activated with sulfuric acid, a magnetic and sulfur-resistant sorbent (FSS-SA) was obtained, and it was used for capturing elemental mercury from flue gas. Sulfuric acid activation improved the pore structure, increased the contents of Fe3+, Oβ and polysulfide and promoted the redox activity of the sorbent, leading to the enhanced Hg0 removal activity. Both active oxygen and sulfur species derived from Fe2O3 and ferric polysulfide were the active sites for Hg0 removal. The increased surface acidity due to sulfuric acid activation suppressed the interaction of SO2 with FSS-SA and the polysulfide maintained the function of capturing Hg0 with SO2 presence. The Hg0 adsorption capacity of FSS-SA under simulated flue gas was estimated to be 14.8 mg/g. Meanwhile, FSS-SA exhibited superparamagnetic property with the saturation magnetization of 13.49 emu·g−1. It could be separated from fly ash mixture by using a magnetic separator. Utilizing the sludge for production of mercury sorbent can reduce the cost of sorbent and also help to find a way for resource utilization of the sewage sludge. FSS-SA might be a promising mercury sorbent due to its simple preparation method, low cost, magnetic property, good tolerance to SO2 and excellent performance.

Evidence of boron-rich aqueous and crystalline phases associated with fumarolic emissions at Guallatiri volcano, northern Chile

This work presents the first record of boron-rich aqueous solutions in barite-, anhydrite-, and sassolite-hosted fluid inclusions found in the fumarolic deposits of the Guallatiri volcano, an active and quiescently degassing volcano located in northern Chile. These findings offer a unique opportunity to investigate the mineral-forming and depositional processes in fumarolic environments. Chemical and mineral characterization was performed using XRD and SEM-EDS techniques, whereas petrologic and microthermometry methods, in addition to Raman and FTIR spectroscopy, were conducted to the physicochemical characterization of fluid inclusions. Characterizations of these fluid inclusions show high‑boron concentrations associated with crystalline phases of sassolite and boron-rich aqueous solutions in fluid inclusions. Analyses based on fluid inclusions reveal two potentially fluid sources: (i) a deep source with higher temperatures (up to 220 °C) and saline fluids (>8 wt% NaCl equivalent), in the presence of CO2, H2S, SO2, and CH4; and (ii) a shallower source with lower temperatures (between 113 and 163 °C) and salinities (<6 wt% NaCl equivalent). Those fluids from the shallower source were affected by dilution processes within the hydrothermal system of the Guallatiri volcano. Concentrations up to 30 wt% B(OH)3 were found in fluid inclusions from the deeper source. The mineralogical and petrological evidence suggests that sassolite was formed by direct deposition of the gas phase. In contrast, sulfate minerals were formed from condensation, leaching, and precipitation processes before being deposited at the surface. These results are a significant contribution to the knowledge of boron-rich fluid inclusions associated with active magmatic-hydrothermal systems.

Sulfur Poisoning and Performance Recovery of SOFC Air Electrodes

The sulfur poisoning and performance recovery of the state-of-the-art SOFC cathodes (La0.80Sr0.20)0.95MnO3±δ (LSM) and (La0.60Sr0.40)0.95Co0.20Fe0.80O3–δ (LSCF), have been studied. Electrochemical impedance spectroscopy measurements of LSCF|GDC and LSM|YSZ half-cells are carried out in alternating atmospheres of air and SO2–air at 700°C for hundreds of hours. In the presence of SO2, the electrochemical performance of both the cells decays with ohmic and non-ohmic losses, owing to the absorption and chemical interaction of SO2 with the electrodes. In LSCF, the SrO segregated on the surface tends to absorb and react with SO2, forming SrSO4 followed by the exsolution of Co-Fe. As for LSM, SO2 is absorbed onto the Sr-rich areas of LSM, including the active reaction sites near the TPBs, leading to Sr exsolution and SrSO4 formation, leaving a Sr-deficient LSM. During the subsequent exposure to air, the performance of the sulfur-contaminated LSM is almost restored. The LSM particles, exposed to alternating atmospheres of air and SO2-air during the electrochemical tests, show a relatively clean surface with sparsely distributed SrSO4 particles, indicating a high stability against sulfur poisoning. It is suggested that the loosely adsorbed SO2 at the TPBs is readily swept away by the SO2-free air flow, recovering its ORR activity, whereas the Sr-deficient LSM due to Sr-exsolution stays modified, contributing to the incomplete performance restoration. Unlike the case of LSM, the performance of the sulfur-poisoned LSCF partially recovers during the subsequent exposure to air. Correspondingly, the LSCF particles have a modified morphology covered with numerous nanoparticles, mostly SrSO4, showing the irreversible aspect of the sulfur poisoning. The morphology modification is not concentrated near the electrode/electrolyte interface but over the entire cathode, indicating that the degree of recovery from sulfur poisoning is closely related to the presence of SrO and chemical activity of Sr in the electrodes at the solid-gas interface. These results also show the potential application of LSM for a sulfur sensor available in high-temperature harsh conditions.

Effect of NOx on secondary organic aerosol formation from the photochemical transformation of allyl acetate

Smog chamber experiments were conducted to explore the photochemical degradation of allyl acetate (AA) in the presence of SO2 and to assess the role of NOx on the secondary organic aerosol (SOA) formation potential. A one-product gas-particle partitioning absorption model was used to express the formed organic aerosol. The experimental results showed a clear dependence of SOA formation potential on the NOx level. The particle mass concentrations at low NOx conditions (AA/NOx > 3) were commonly higher than those at high NOx conditions (AA/NOx < 3). The SOA yields increased with the increasing NOx concentration under low NOx conditions and decreased with the increasing NOx concentration under high NOx conditions due to the different reaction pathways of RO2 radicals. Gas chromatography-mass spectrometry (GC-MS) and Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) analysis suggested that organic nitrates and organic sulfates were formed during photochemistry experiments. Based on detected products, the mechanisms of AA photooxidation were proposed. The results of this study show the different effects of NOx concentrations on promoting and inhibiting aerosol formation, and highlight the pronounced formation of SOA from the photooxidation of AA in polluted environment.

Electrooxidation of simulated wastewater containing pharmaceutical amoxicillin on thermally prepared IrO2/Ti

&lt;p&gt;The electrooxidation of amoxicillin (AMX) on the iridium oxide electrode thermally prepared (400°C) has been investigated by cyclic voltammetry and preparative electrolysis. Physical characterization by Scanning Electron Microscopy (SEM) showed that the IrO&lt;sub&gt;2&lt;/sub&gt; electrode has a rough surface with pores' presence. In cyclic voltammetry, the oxidation of AMX occurs directly at the anode's surface or via the higher degree oxide of iridium oxide (IrO&lt;sub&gt;3&lt;/sub&gt;). It is noted that the oxidation process of AMX can be controlled by diffusion combined with the phenomenon of adsorption. In preparative electrolysis, the effect of several parameters has been investigated. These are the current density, the support medium, the initial pH. The findings obtained show a weak degradation of amoxicillin. The Chemical Oxygen Demand (COD) reduction rate is less than 11% under our experimental conditions, indicating that the IrO2 electrode leads to the parent compound's conversion. Also, the degradation of the organic compound is favored in a very acidic medium.&lt;strong&gt;&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;Furthermore, the effect of inorganic ions such as SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt;, PO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;3-&lt;/sup&gt;, NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;, Cl&lt;sup&gt;-&lt;/sup&gt; was evaluated. Investigations show that these ions' effects are diverse, with COD reduction rates ranging from 2.47%; 2.68%; 7.7%; 16.41%, and 71.65%, respectively, in the absence and the presence of SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt;, PO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;3-&lt;/sup&gt;, NO&lt;sub&gt;3&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;, Cl&lt;sup&gt;- &lt;/sup&gt;ions. SO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;2-&lt;/sup&gt; have virtually no effect on enhancing the degradation of amoxicillin. PO&lt;sub&gt;4&lt;/sub&gt;&lt;sup&gt;3-&lt;/sup&gt; ions provide a slight improvement in amoxicillin degradation. As for nitrate ions, their influence is 2.31 times that of phosphate ions. Chloride ions improve the performance of the electrooxidation of amoxicillin on IrO2 very significantly. The presence of chloride ions makes it possible to go from 2928.35 (absence of inorganic ions) to 33.19 kWh per Kg of COD. This represents an energy gain of over 98%.&lt;/p&gt;

Sulfur Poisoning of a Cu-SSZ-13 SCR Catalyst under Simulated Diesel Engine Operating Conditions

&lt;div class="section abstract"&gt;&lt;div class="htmlview paragraph"&gt;Cu-SSZ-13 catalysts are widely used for diesel aftertreatment applications for NO&lt;sub&gt;x&lt;/sub&gt; (NO and NO&lt;sub&gt;2&lt;/sub&gt;) abatement via selective catalytic reaction (SCR) due to their high conversion efficiency and excellent hydrothermal stability. Diesel engine exhaust contains small amounts of SO&lt;sub&gt;x&lt;/sub&gt; due to the combustion of sulfur compounds in diesel fuel. The engine out SO&lt;sub&gt;x&lt;/sub&gt; level mainly depends on the sulfur content in the diesel fuel. The presence of SO&lt;sub&gt;x&lt;/sub&gt; from engine exhaust can deteriorate the SCR performance of Cu-SSZ-13 catalysts in real-world applications. This work is focused on the sulfur-induced deactivation process of a Cu-SSZ-13 catalyst under a range of simulated diesel engine operating conditions. Two catalyst deactivation modes, namely chemical poisoning and physical poisoning, are identified, primarily depending on the operating temperature. Chemical poisoning mainly results from the interaction between SO&lt;sub&gt;x&lt;/sub&gt; and Cu species within the zeolite framework. Physical poisoning is a consequence of the accumulation of ammonium (bi) sulfate formed from the interaction between SO&lt;sub&gt;x&lt;/sub&gt; and NH&lt;sub&gt;3&lt;/sub&gt;, especially at low temperature conditions. Temperature programmed desorption (TPD) experiments were conducted to characterize the deactivated catalyst. In addition, a modeling approach was applied to quantify the deactivation process as well as the decomposition of the sulfur species on the poisoned catalyst to optimize the catalyst reactivation strategy.&lt;/div&gt;&lt;/div&gt;

Ionic Strength Effect Triggers Brown Carbon Formation through Heterogeneous Ozone Processing of Ortho-Vanillin.

Methoxyphenols are an important class of compounds emerging from biomass combustion, and their reactions with ozone can generate secondary organic aerosols in the atmosphere. Here, we use a vertical wetted wall flow tube reactor to evaluate the effect of ionic strength on the heterogeneous reaction of gas-phase ozone (O3) with a liquid film of o-vanillin (o-VL) (2-hydroxy-3-methoxybenzaldehyde), as a proxy for methoxyphenols. Typical for moderately acidic aerosols, at fixed pH = 5.6, the uptake coefficients (γ) of O3 on o-VL ([o-VL] = 1 × 10-5 mol L-1) increase from γ = (1.9 ± 0.1) × 10-7 in the absence of Na2SO4 to γ = (6.8 ± 0.3) × 10-7 at I = 0.2 mol L-1, and then, it decreases again. The addition of NO3- ions only slightly decreases the uptakes of O3. Ultrahigh-resolution electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) reveals that the formation of multicore aromatic compounds is favored upon heterogeneous O3 reaction with o-VL, in the presence of SO42- and NO3- ions. The addition of NO3- ions favors the formation of nitrooxy (-ONO2) or oxygenated nitrooxy group of organonitrates, which are components of brown carbon that can affect both climate and air quality.

Ca-Poisoning Effect on V2O5-WO3/TiO2 and V2O5-WO3-CeO2/TiO2 Catalysts with Different Vanadium Loading

Ca poisoning behavior is inevitable for high-calcium content flue gas, so V2O5-WO3/TiO2 (VWT) and V2O5-WO3-CeO2/TiO2 (VWCeT) catalysts with different vanadium content have been prepared and the Ca-doped catalysts are compared in this manuscript. The result shows Ce addition can both promote the NO conversion and the alkali resistance. Lower Ca addition for 0.1VWCeT catalyst promotes its oxidability and Ce modification is more suitable for low vanadium catalysts. The total acidity and the reducibility of catalysts decline after Ca doping, and the reducibility of the active species on catalysts has been strengthened by Ce addition. CeO2 based catalysts with lower Ca loading struggle to resist sulfur poisoning, while higher Ca loading favors SO2 adsorption and also physically reduces the cerium acidification process. In the presence of SO2, additional Brønsted acid sites are formed in Ca rich catalyst. The dynamic NH3 adsorption has been investigated, shows that Ca doping content on catalyst is critical for SCR reaction, and the catalyst is more susceptible to SO2 initially in alkali flue gas during the actual application, but the sulfur resistance may increase with the alkali-poisoning effect aggravated by Ca doping.

A new insight into catalytic ozonation of ammonia by MgO/Co3O4 composite: The effects, reaction kinetics and mechanism

• NH 4 + was high-efficiently degraded to gaseous nitrogen by catalytic ozonation. • The oxygen vacancy of MgO/Co 3 O 4 facilitated the indirect oxidation of NH 4 + by ozone. • NH 4 + and Cl − decreased linearly with reaction time and followed pseudo-zero kinetics. • The affecting factors for removal of NH 4 + by catalytic ozonation were examined. It is highly concerned to explore heterogeneous catalysts of metal oxides to remove NH 4 + -N in the wastewater, in which NH 4 + -N can be greatly oxidized as gaseous nitrogen in the mild reaction conditions. Herein, the high-efficient catalyst cobalt oxide modified by Mg was prepared, and the structures of catalyst were thoroughly characterized by SEM, XRD, ICP, Raman and ESR. Furthermore, the reaction kinetics of ammonia and affecting ammonia removal factors were investigated. In addition, the mechanism of catalytic ozonation for degrading NH 4 + to gaseous nitrogen was also clarified. At the condition of 30 °C, initial pH = 8.0 and catalyst dosage of 2.0 g/L, 30.00 mg/L NH 4 + -N (source: NH 4 Cl) was almost completely oxidized and TN removal efficiency was 84.26% after 60 min. The degradation of ammonia and the conversion of Cl − both followed pseudo-zero kinetics. The presence of SO 4 2− , CO 3 2− and PO 4 3− inhibited the degradation of ammonia with the order: SO 4 2− < CO 3 2− < PO 4 3− , while the coexistence of Br − greatly promoted the ammonia conversion to gas. It was assumed that ozone transfers an oxygen atom to the Cl − ion at the active site on the catalyst surface, producing ClO − ions to form intermediates, which further oxidized NH 4 + -N to NO 2 − , NO 3 − and other gaseous nitrogen compounds. These results achieved might encourage the development of novel heterogeneous catalysts to active O 3 for indirect oxidation of ammonia to gaseous nitrogen effectively.

Rationally designed Co3O4-SnO2 activated peroxymonosulfate for the elimination of chloramphenicol

In this study, the Co3O4-SnO2 composite derived from bimetallic oxalates was rationally fabricated and utilized as a catalyst for peroxymonosulfate (PMS) activation towards the destruction of chloramphenicol (CAP). The physicochemical properties of the Co3O4-SnO2 were systematically characterized to discover the relationship between its structure and catalytic performance. SnO2 as a cocatalyst with high conductivity and stability immensely improved the activity of Co3O4 in the Co3O4-SnO2 composite. Approximately 98% of CAP (10 mg/L) was eliminated by the Co3O4-SnO2 (0.1 g/L) activated PMS (1.0 mmol/L) at initial pH 7 within 20 min. The rationally designed Co3O4-SnO2 composite exhibited higher catalytic activity than Co3O4, SnO2, and other cobalt-based bimetallic oxides (such as Co-Fe, Co-Mn, and Co-Cu) in the PMS activation for the CAP degradation. The synergistic effect of Co3O4 and SnO2 endowed the Co3O4-SnO2 composite with higher conductivity and more electron transfer, which was proved by the electrochemical tests. The presence of SO4•−, •OH, O2•−, and 1O2 during the CAP degradation was testified by both quenching experiments and electron paramagnetic resonance (EPR) spectroscopy. In addition, the catalytic mechanism and degradation pathways were further proposed via the characterization of X-ray photoelectron spectroscopy (XPS) and the identification of transformation products, respectively. This work provides a new insight into the preparation of novel catalysts and their application in wastewater treatment.

Experimental and density functional theory study of the synergistic effect between steam and SO2 on CO2 capture of calcium-based sorbents

Calcium looping is a fast-developing second generation CO2 capture technology. In practical looping of Ca-based sorbents, steam and SO2 are naturally present in the flue gas subjected to CO2 capture, due to the combustion of fossil fuels. Until now, the single effect of steam or SO2 has been reported to have a significant impact on the CO2 capture of sorbents. However, there are few studies on the synergistic effect of steam and SO2 on the CO2 sorption characteristics of sorbents, and it is poorly understood. In this study, experiments and DFT calculation are employed to clearly understand the synergistic effect of steam and SO2 on the carbonation behaviors of sorbents. Tests were first performed under typical calcium looping (CaL) conditions with and without the presence of steam and SO2 during the carbonation process. Results indicated that the enhancement of steam on the sulfation is obviously stronger than that on the carbonation as the CaL cycles increased, which is then verified by a series of characterization methods. According to quantitative analysis through DFT calculation, the adsorption energy of SO2 on CaO (100) surface was found to be more than that of CO2 in the presence of steam, indicating the preferential adsorption of SO2 in the presence of H2O molecules on the CaO (100) surface. Therefore, the experimental results were verified and the competitive adsorption mechanism of SO2 and CO2 in the presence of steam during the carbonation process was further understood from microscopic aspect.

The effects of sulphur dioxide on wine metabolites: New insights from 1H NMR spectroscopy based in-situ screening, detection, identification and quantification

The wine industry routinely employs sulphur dioxide (SO2) as an additive for antiseptic, antioxidasic and antioxidant activities. Some of the most important wine metabolites such as acetaldehyde, diacetyl, pyruvic acid, α-ketoglutaric acid, hydroxymethylfurfural, furfural and acetoin are known to react with SO2 over time to form adducts. 1H NMR spectroscopy of wine can be tricky as metabolites exist either in original form or as O-adducts or as S-adducts at different SO2 concentrations. We are proposing a methodology for metabolites identification including all the possible SO2 generated species. 1H NMR spectroscopy is able to highlight the structural changes that a metabolite undergoes in wine in the presence of SO2. The 1H NMR spectra of the main wine metabolites known to react with SO2 were recorded in wine-model solutions at SO2 concentrations at 0, 50, 100 and 150 mg/L that are all below the maximum level allowed by the European Union regulations. Acetaldehyde was completely transformed into the corresponding hydroxysulfonate at a SO2 concentration of 100 mg/L. The concentration of this metabolite was assayed in ten commercial Moscato wine samples including the 1H NMR resonances of all its identified forms. The results corresponded to those determined according to the OIV standard protocols.

Industrial pollution and vegetable farming in sharada industrial layout of Kano municipal area council

This work examined the effects of industrial effluents on surface water used for vegetable irrigation in Kano City of Kano State. As the population of Kano increases, more demand is placed on these industries for products thus leading to the generation of large volumes of effluents that are discharged directly into nearby streams without treatment. The usage of this surface water for vegetable irrigation by a significant number of vegetable farmers is a matter of major concern due to the presence of pollutants. Some of the field measurements were carried out insitu while others were taken to the laboratory for analysis. Groundwater samples were taken from a borehole and two hand-dug wells while surface water was taken from point of discharge and two other points along the Challawa River which is the main source of water for vegetable irrigation. Composite soil samples were taken from four points within the vegetable farms. The Federal Environmental Protection Agency and the Federal Ministry of Environment standards were used as baseline standards for limits. Results show that presence of Fe, Pb, Mn, Cr and Cd were found to be above the FMEnv limits in the soil, the presence of SO4, Cu and K were also found to be above the FMEnv limits as well in groundwater while BOD, NO2 and Cr were above the FEPA limit for surface water. Some of the recommendations include constant monitoring for the presence of heavy metals in soils and irrigation water and that the need for the construction of both primary and secondary treatment plants has become essential.

Preparation and Performance of Cerium-Based Catalysts for Selective Catalytic Reduction of Nitrogen Oxides: A Critical Review

Selective catalytic reduction of nitrogen oxides with NH3 (NH3-SCR) is still the most commonly used control technology for nitrogen oxides emission. Specifically, the application of rare earth materials has become more and more extensive. CeO2 was widely developed in NH3-SCR reaction due to its good redox performance, proper surface acidity and abundant resource reserves. Therefore, a large number of papers in the literature have described the research of cerium-based catalysts. This review critically summarized the development of the different components of cerium-based catalysts, and characterized the preparation methods, the catalytic performance and reaction mechanisms of the cerium-based catalysts for NH3-SCR. The purpose of this review is to highlight: (1) the modification effect of the various metal elements for cerium-based catalysts; (2) various synthesis methods of the cerium-based catalysts; and (3) the physicochemical properties of the various catalysts and clarify their relations to catalytic performances, particularly in the presence of SO2 and H2O. Finally, we hope that this work can give timely technical guidance and valuable insights for the applications of NH3-SCR in the field of NOx control.

The effect of gaseous SO2 secondary sintering on the cement composition and crystal structure

This paper explored the influence of gaseous SO2 at different temperatures on the composition and structure of the secondary sintered cement clinker. The combination of X-ray powder diffraction (XRD) and rietveld refinement was used to study the composition and content changes of clinker phase. The morphology and clinker sintering history of the clinker phase were determined by the petrographic analysis. The structure of alite was identified by XRD and transmission electron microscopy (TEM) analysis. The experimental results showed that the presence of gaseous SO2 promoted the decomposition of alite and increased the value of M1-alite%/(M1-alite% + M3-alite%). The hydration exothermic curve showed that the activity of M1-alite was higher than that of M3-alite.

Synergetic degradation of atenolol by hydrodynamic cavitation coupled with sodium persulfate as zero-waste discharge process: Effect of coexisting anions

Abstract This research investigates atenolol (ATL) removal from the aqueous solution by a combination of hydrodynamic cavitation (HC) and sodium persulfate (HC-PS) as zero-waste discharge process. The effect of pH, reaction time, PS dose, initial ATL concentration, coexisting anions and natural organic matters (NOMs) has been studied. The highest ATL removal by HC and HC-PS processes was obtained at pH 3 and 6, respectively. The presence of coexisting anions viz., Cl−, NO3−, I−, SO42−, and PO43− promoted the degradation of ATL, while the efficiency of ATL degradation was inhibited by the presence HCO3− and CO32− anions and NOMs. The highest synergetic and strongest inhibition effect of ATL degradation by the HC-PS process was observed in the presence of SO42− ions (synergetic index value, 4.61) and CO32− ions (synergetic index value, 0.44). Radical trapping experiments showed that the relative contributions of hydroxyl and sulfate radical to degrade ATL were 41.7% and 58.3%, respectively. In case of HC-PS process, degradation initiated with the protonation of ATL in the presence of free active radicals was followed by the ether bond cleavage, oxidation of primary and secondary amine moieties, and finally mineralization. The HC-PS process is proved to be a potential treatment method to destroy pharmaceutical pollutants from water and wastewater sources.

SO2 Tolerance and Mechanism of Elemental Mercury Removal from Flue Gas by a Magnetic Recyclable Fe6Mn0.8Ce0.2Oy Sorbent

A Ce-doped Fe–Mn magnetic sorbent (Fe₆Mn₀.₈Ce₀.₂Oy) was developed using the coprecipitation method. The effects of O₂, H₂O, flue gas temperature, SO₂ concentration, and Ce doping on the SO₂ tolerance of the Fe₆Mn₀.₈Ce₀.₂Oy sorbent for mercury removal were explored in a fixed-bed system. Combined with mercury temperature-programmed desorption (Hg-TPD) and X-ray photoelectron spectroscopy (XPS) analysis, the mechanism of mercury removal by the Fe₆Mn₀.₈Ce₀.₂Oy sorbent in the presence of SO₂ was analyzed. The results show that the Fe₆Mn₀.₈Ce₀.₂Oy sorbent is a promising sorbent for circulating mercury removal with high SO₂ tolerance. Ce doping significantly enhances the SO₂ tolerance of the Fe₆Mn₀.₈Ce₀.₂Oy sorbent for mercury removal by protecting the Mn⁴⁺ active sites from SO₂ poisoning. This is because Ce has a stronger affinity with SO₂ compared to that of Mn, and most of SO₂ will preferentially react with CeO₂ instead of MnO₂ to form Ce₂(SO₄)₃. O₂ in flue gas improves the SO₂ tolerance of the Fe₆Mn₀.₈Ce₀.₂Oy sorbent by timely supplementing the oxygen vacancies. H₂O coexisting with SO₂ in flue gas further reduces the mercury removal rate because of the competitive adsorption between H₂O and mercury. Mercury is mainly adsorbed by MnO₂ in the Fe₆Mn₀.₈Ce₀.₂Oy sorbent by the Mars–Maessen mechanism, and SO₂ in flue gas causes the generation of a small amount of Hg₂SO₄ and HgSO₄.

Washcoat Overlayer for Improved Activity and Stability of Natural Gas Vehicle Monolith Catalysts Operating in the Presence of H2O and SO2

A γ-AlOOH/γ-Al₂O₃ washcoat overlayer, applied to a PdO(Pt/CeO₂)/γ-AlOOH/γ-Al₂O₃ on cordierite (2MgO·2Al₂O₃·5SiO₂) mini-monolith catalyst (400 cells per square inch, 1 cm diameter × 2.5 cm length), is shown to reduce the impact of H₂O and SO₂ on the catalyst activity and stability during CH₄ oxidation at low temperatures (<500 °C). The washcoat overlayer covered the Pd (and Ce and Pt when present) and decreased the catalyst CH₄ oxidation activity in a dry feed gas (0.07 vol % CH₄, 8.5 vol % O₂, 0.06 vol % CO, 8 vol % CO₂) at a gas hourly space velocity (GHSV) of 36 000 h–¹. However, when H₂O (2, 5, and 10 vol %) and SO₂ (2 and 5 ppm) were added to the feed gas, the loss in catalyst activity was reduced and the catalyst stability was improved. The overlayer provided additional sites for both SOₓ and H₂O adsorption, thereby reducing their adsorption on the active phase of the catalysts, and consequently, the catalysts maintained higher activity in the presence of both SO₂ and H₂O over periods of up to 200 h.