Presence Of SO2 Research Articles

Kinetic studies on the sulfathiazole degradation by activated persulfate with ascorbic acid and cysteine

AbstractIn this study, ascorbic acid (AA) and cysteine (Cys) were used as homogeneous potassium persulfate (S2O82−) activators. The efficiency of the S2O82−/AA and S2O82−/Cys systems was investigated to generate sulfate radicals (SO4−•) for the oxidation of sulfathiazole (STZ). The presence of AA and Cys displayed a promoting effect on the activation of S2O82−. The results indicated that the STZ/S2O82− redox reaction followed pseudo‐first order kinetics with respect to STZ concentrations. The oxidative degradation of STZ is accelerated by temperature, dose of S2O82−, AA, Cys, and pH with S2O82−/AA and/or S2O82−/Cys systems. The degradation rates of STZ followed the order S2O82−/AA > S2O82−/Cys > S2O82− under similar experimental conditions. The presence of SO4−• and HO• were tested with two radical scavengers, tertiary butanol (TBA) and ethanol, in which HO• was mainly responsible for STZ degradation at higher pH. In summary, S2O82−/AA and S2O82−/Cys systems might provide a potentially useful technique for remediation of water contaminants.

Study on the Adsorption Mechanism of Cu2+ by ZnAl-LDH-Containing Exchangeable Interlayer Chloride Ions.

Different Zn/Al ratios of Cl- intercalated ZnAl-layered double hydroxide (ZnAl-LDH) were prepared using the coprecipitation method, and their adsorption performance for Cu2+ in aqueous solution was evaluated. The factors affecting adsorption properties, such as dosage, reaction time, and pH, were determined by adsorption experiments. Then, the adsorption kinetics and isotherm models were fitted to evaluate the adsorption mechanism. The results show that the Zn/Al ratio has a great influence on the adsorption effect, the best adsorption effect is obtained when the Zn/Al ratio is 4:1, and the maximum adsorption capacity of Cu2+ is 213 mg/g. The mechanism study shows that the adsorption of Cu2+ by ZnAl-LDH is mainly an isomorphic substitution. Additionally, during the adsorption of CuSO4, the presence of SO42- undergoes interlayer anion exchange with Cl-, and the process of SO42- entering the interlayer facilitates the isomorphic substitution of Cu2+ and Zn2+. X-ray diffraction (XRD) analysis shows that as the Zn/Al ratio increases, the interlayer spacing of ZnAl-LDH increases, and the crystallinity decreases. The adsorption process conforms to the pseudo-second-order kinetic process and the Langmuir isotherm adsorption model. Therefore, the adsorption type of ZnAl-LDH for Cu2+ is monolayer chemical adsorption. The adsorption thermodynamic results indicate that the adsorption of Cu2+ is a spontaneous endothermic process. The research results revealed the mechanism of ZnAl-LDH adsorbing Cu2+, providing ideas for removing and recovering copper-containing electroplating wastewater.

Recent Advancements in Fe-Based Catalysts for the Efficient Reduction of NOx by CO.

The technology of CO selective catalytic reduction of NOx (CO-SCR) showcases the potential to simultaneously eliminate CO and NOx from industrial flue gas and automobile exhaust, making it a promising denitrification method. The development of cost-effective catalysts is crucial for the widespread implementation of this technology. Transition metal catalysts are more economically viable than noble metal catalysts. Among these, Fe emerges as a prominent choice due to its abundant availability and cost-effectiveness, exhibiting excellent catalytic performance at moderate reaction temperatures. However, a significant challenge lies in achieving high catalytic activity at low temperatures, particularly in the presence of O2, SO2, and H2O, which are prevalent in specific industrial flue gas streams. This review examines the use of Fe-based catalysts in the CO-SCR reaction and elucidates their catalytic mechanism. Furthermore, it also discusses various strategies devised to enhance low-temperature conversion, taking into account factors such as crystal phase, valence states, and oxygen vacancies. Subsequently, the review outlines the challenges encountered by Fe-based catalysts and offers recommendations to improve their catalytic efficiency for use in low-temperature and oxygen-rich environments.

The Catalytic Mechanisms and Design Strategies of Noble Metal Catalysts for Selective Reduction of NOx with CO

AbstractThe selective catalytic reduction of NOx by CO (CO‐SCR) is a viable method for simultaneously mitigating NOx and CO emissions in motor vehicle exhaust and industrial flue gases. Extensive research has been conducted on noble metal catalysts because of their superior catalytic activity and stability compared to non‐noble metals. Noble metal catalysts demonstrate efficient NOx conversion and high selectivity for N2. However, achieving high conversion, selectivity, and stability over a wide temperature range in the presence of excess O2, H2O, and SO2 remains a significant challenge. This review summarizes recent advancements in CO‐SCR over noble metal catalysts, providing insights for the development of CO‐SCR catalysts. This paper first examines the reaction mechanisms of CO‐SCR, followed by a discussion on the design and optimization strategies of noble metal catalysts, with a focus on composition and structural effects. This includes creating active metal sites, selecting appropriate supports, integrating catalytic additives, choosing monometallic nanoparticles, alloying, and using single‐atom catalysts. Finally, remaining challenges and potential avenues for future research have been suggested. The discovery of negatively charged noble metal single‐atom‐site catalysts presents new research opportunities.

The Performance and Mechanism of Solvothermal Synthesis of a Ca-Fe-La Composite for Enhanced Removal of Phosphate from Aqueous Solutions

Since it is a limiting nutrient element in rivers and lakes, the effective removal of phosphorus is key to alleviating eutrophication. In this study, the one-pot solvothermal method was adopted to prepare an environmentally friendly Ca-Fe-La composite. This is an amorphous material with a large specific surface area of 278.41 m2 g−1. The effects of coexisting anions and pH on the phosphate removal performance were explored. Phosphate adsorption mechanisms were revealed by various characterization techniques. The phosphate adsorption obeyed the fractal-like pseudo-second-order (PSO) kinetic model, implying that the overall adsorption system was highly heterogeneous. In this work, the maximum adsorption capacity predicted by the Langmuir model was 93.0 mg g−1 (as PO43−-P). The phosphate-loaded Ca-Fe-La composite could be used as a slow-release fertilizer, achieving waste management and resource utilization. The presence of SO42−, CO32− and HCO3− anions inhibited the phosphate adsorption significantly. It was unfavorable for phosphate removal at a high pH value. Inner-sphere complexation and electrostatic attraction were mainly responsible for phosphate adsorption onto the Ca-Fe-La composite.

Coupling mechanism of trace elements and maceral in medium and high sulphur coal in the Jurassic terrestrial environment of Zhongyuan mine in the Hengshan mining area and adjacent areas

ABSTRACT Considering the urgency of resource utilization and environmental protection, the geochemistry of anomalous trace transition metal elements in coal formed in terrestrial environments has been studied using methods such as inductively coupled plasma atomic emission spectrometry analysis, electron probe micro-area analysis, sequential chemical extraction procedures, and correlation analysis. The results indicate that minerals in the coal samples included pyrite, kaolinite, quartz, dolomite, calcite, and celestite. Furthermore, compared with the average values of coals in China and the upper continental crust, the coal samples were rich in transition metal trace elements such as Ni, Cr, and Sr and were deficient in Be, Cd, Cu, Co, Ga, Mo, Sb, Tl, V, Zn, and Ti. We found that Ni preferentially occurred in the organic matter over minerals, while Cr primarily bonded with sulfide minerals and to a lesser extent with the iron-manganese oxide minerals. Sr had a low correlation with organic matter but adhered to clay minerals and celestite. Ni enrichment in coal samples was the result of terrigenous input, while the Cr enrichment was related to intrusion of magmatic hydrothermal fluids. Sr enrichment was caused by the presence of SO4 2- in the terrigenous debris and the influence of Sr-rich water underground.

Liquid Nitrogen Exfoliation and Nanodispersion of WS2 for Thermocatalysts.

The efficient and clean exfoliation of single and/or few-layer nanosheets of WS2, a two-dimensional transition metal dichalcogenides, remains a significant challenge. In this study, a simple exfoliation method was proposed to produce ultrathin WS2 nanosheets by combining the liquid nitrogen exfoliation and nanodispersion techniques. This approach efficiently exfoliated WS2 into several layers of nanosheets via rapid temperature changes and mechanical stress without inducing defects or contamination. After five cycles of heating/liquid nitrogen and nanodispersion, the resulting WS2 nanosheets (WS2-5N ND) were confirmed to have been successfully exfoliated into 1-4 layers. When applied as a promoter in a thermocatalyst for the selective catalytic reduction of NOX using NH3, 2V3WS2/Ti (WS2-5N ND) exhibited excellent NOX conversion and N2 selectivity, along with excellent durability even in the presence of SO2. This result was greater than 2V3WS2/Ti (WS2-5N) subjected to only liquid nitrogen exfoliation, proving the importance of the simultaneous action of both methods. This method is expected to be an important contribution to ongoing research on high-performance WS2-based catalysts, thereby opening up potential opportunities for a wide range of applications.

Strong enhancement on diclofenac degradation in Cu(II)/H2O2 system by adding ascorbic acid: Efficiency, mechanism and influencing factors

Utilization of trace Cu(II) (at μM level) inherently existing in wastewater to activate hydrogen peroxide (H2O2) has exhibited significant potential to remove aqueous organic contaminants. Nevertheless, the Cu(II)/H2O2 system was only efficient under alkaline conditions. Herein, ascorbic acid (H2A), an environmentally benign and natural reductant, was introduced to broaden pH range of Cu(Ⅱ)/H2O2 process by expediting the Cu(II)/Cu(I) cycle. The H2A/Cu(Ⅱ)/H2O2 system performed well in degrading diclofenac across a wide pH range from 4.0 to 9.0, and its kinetic rate constant of diclofenac elimination was 247 times greater than its counterpart without H2A at the optimal pH of 6.0, outperforming the performance of most previously reported reductant-enhanced Cu(Ⅱ)/H2O2 system. Electron paramagnetic resonance analysis, periodate colorimetric method, and in situ Raman spectroscopy tests indicated that hydroxyl radical (HO), rather than Cu(III), was the dominant reactive species of diclofenac degradation. Thirteen degradation products of diclofenac were identified by LC-Q-TOF-MS, and five different elimination pathways were proposed. Furthermore, the presence of SO42− exerted an insignificant influence on diclofenac degradation, while the addition of Cl−, HCO3− and humic acid slightly suppressed the abatement of diclofenac. H2A/Cu(Ⅱ)/H2O2 system was still highly efficient in degrading diclofenac in actual water matrix (i.e., reservoir water and lake water). Overall, this study provided an eco-friendly approach to enhance the oxidation capacity of the Cu(II)/H2O2 system over a wide pH range, which might be a potential technology for degrading refractory organic pollutants in water treatment.

Sulfur-resistant mechanism of MnOx@CeO2@MgO core-shell catalyst in simultaneous removal of NOx and chlorobenzene

Herein, Mn-Ce based catalysts with different structures were rationally designed to explore their sulfur-resistant mechanism for simultaneous removal of NOx and chlorobenzene (CB) from waste incineration at low temperature. In the presence of SO2, MnOx@CeO2@MgO exhibits the highest sulfur resistance among prepared catalysts. Both NOx and CB conversion over MnOx@CeO2@MgO can reach up to 80% at 300 °C. However, the significant deactivation is observed for MnCeMgOx within all temperature ranges. For the selectivity of products, MnOx@CeO2@MgO displays the excellent N2 selectivity (93%) and good CO2 selectivity (80%) at 300 °C. Compared with NO reduction, SO2 has a greater impact on CB destruction due to the consumption of reactive oxygen species during SO2 oxidation. The reduction of active oxygen is proposed to be the reason for the significant inhibition of CB oxidation. The addition of MgO shell increases the proportion of lattice oxygen, which is beneficial to improving the sulfur resistance of MnOx@CeO2@MgO catalyst. In addition, SO2 can react with MgO preferentially to protect the active sites and improve the sulfur resistance. This work indicates that MnOx@CeO2@MgO core-shell catalyst with good sulfur tolerance and stability is expected to be applied in the potential application.

New insights into the combined effect of steam and SO2 on CaCO3 decomposition: Experimental study and DFT calculation

Calcium cycling is a second-generation CO2 capture technology characterized by rapid development and high technical maturity. In practical applications, steam and SO2 are commonly present in the calcination reactor due to the oxygen-rich combustion of coal. Previous studies have shown that steam accelerates the decomposition of CaCO3 and shortens the calcination time. However, steam also significantly enhances sulfation in the presence of SO2, and there remains no consensus in the literature regarding the combined effects of steam and SO2 on the decomposition of CaCO3. This study investigates the decomposition characteristics of CaCO3 over time under various reaction atmospheres. The results indicate that while steam accelerates the decomposition of CaCO3, the presence of SO2 almost neutralizes the positive effect of steam. Notably, steam promotes rapid sulfation during the early stages of calcination, which subsequently inhibits the decomposition of CaCO3. Physicochemical characterization reveals that the simultaneous presence of steam and SO2 leads to the rapid formation of CaSO4 on the sorbent surface, with steam-induced pore expansion further enhancing sulfation in the internal pores of the grains. Additionally, this study elucidates the mechanism by which steam accelerates CaCO3 decomposition. It was found that the presence of steam increases the adsorption energy of the CaCO3 (1 0–1 4) surface for SO2 and that H2O molecules facilitate a lower activation energy for the formation of HSO3* compared to SO3*. These findings validate the experimental results and provide a deeper understanding of the combined effects of steam and SO2 during the calcination process from a microscopic perspective.

Corrosion behavior and mechanism of Cr10Mo1 steel subjected to different corrosive ions in simulated concrete pore solution

The corrosion of pre-passivated Cr10Mo1 steels in simulated concrete pore solution of saturated Ca(OH)2 induced by different corrosive ions were investigated, namely Cl−, SO2- 4, and combination of Cl− and SO2- 4. Electrochemical methods, Pourbaix analysis of Fe–Cr–H2O system and DFT calculation were adopted to characterize corrosion behavior and reveal underlying mechanism. Results showed that while sulfate may induce corrosion at higher threshold value, the scenario of chloride alone leads to lowest corrosion potential, linear polarization resistance and highest corrosion rate, and the presence of SO2- 4 ions mitigate corrosion risk under the coexistence condition of chloride and sulfate. A two-step reaction model of competitive adsorption-catalytic corrosion was proposed based on theoretical analysis and DFT calculation results.

Nitrogen-Doped High-Surface-Area activated carbon: Innovative adsorbent for enhanced SO2 and benzene removal

In this paper, we investigated the properties of nitrogen-doped activated carbon produced via the co-activation of KSCN and KOH, using hydrothermal lignin as a precursor. The resulting activated carbon exhibited a high specific surface area of 3504 m2/g and contained 3.37 % nitrogen from KSCN, which enhanced its adsorption efficiency. The adsorption capacities for SO2 and benzene at 273 K were measured at 2260.68 mg/g and 1668.90 mg/g, respectively. Competitive adsorption experiments at 298 K showed that in the presence of SO2, the activated carbon maintained a high adsorption capacity for benzene at 1008.81 mg/g, while the adsorption capacity for SO2 decreased to only 12.31 mg/g, indicating a higher affinity for benzene. The selectivity coefficient, calculated using the Ideal Adsorbed Solution Theory (IAST), reached 44.76 at a benzene-to-SO2 ratio of 2:1. To gain deeper insights into the selective adsorption mechanism, Density Functional Theory (DFT) simulations were conducted. These simulations confirmed the experimental findings, indicating that benzene can be selectively adsorbed and effectively separated from SO2 flue gas.

Effect of multi-component gas on removal of trace hydrogen sulfide activity from blast furnace gas using activated carbon adsorbent

Abstract In the steel industry, blast furnace gas (BFG) is huge with complex components. The existence of hydrogen sulfide (H2S) in the BFG can produce sulfur dioxide (SO2) after combustion, which will increase the source of SO2 pollution and make the desulphurization more difficult, to be threat to people health. At present, the removal of H2S by dry adsorption with modified activated carbon adsorbent is a high-precision and low-cost desulphurization method. However, the effect of complex gas components in BFG on the adsorption of H2S by activated carbon adsorbent is not sufficient. Based on the fixed bed adsorbent evaluation system, a new type of highly efficient copper-cerium oxide (Cu–Ce–O) modified activated carbon H2S adsorbent was developed. And the effects of carbon monoxide (CO), carbon dioxide (CO2), hydrogen (H2), oxygen (O2), sulfur dioxide and hydrogen chloride (HCl) in BFG on the desulfurization activity of adsorbents were investigated. The results showed that the performance of H2S removal decreased in the presence of CO, CO2, HCl and SO2, and improved in the presence of H2 and O2. Other parameters were also studied which might influence the process. The application of modified activated carbon adsorbent in simulated BFG is basically stable. According to the fitting results of adsorption kinetics for the five adsorption models, as the atmosphere becomes BFG from N2, pore diffusion becomes the main adsorption form. However, the effects of internal diffusion, chemical adsorption and external mass transfer decreased. The Bangham model is the most suitable model to describe H2S adsorption process.

The possibility of using the Zn (II) Butadiyne-linked porphyrin nanoring for detection and adsorption of AsH3, NO2, H2O, SO2, CS2, CO, and CO2 gases

The present research aims to study the probability of applying the Zn (II)-Butadiyne-linked porphyrin (ZBPN) nanoring for detection and adsorption of some of the most important air pollutants such as AsH3, NO2, H2O, SO2, CS2, CO, and CO2 gases by using the density functional theory (DFT) method. The key results of the thermodynamic calculations indicated that ZBPN nanoring is able to absorb SO2, AsH3, NO2, and H2O gases; while, it could not strongly adsorb CS2, CO, or CO2. Subsequent to the thermodynamic results, the changes of band gaps and the frontier molecular orbital (FMO) calculations show that ZBPN nanoring might release stronger signals in the presence of SO2 (σ = 1.64(1010) s), AsH3 (σ = 1.35(1010) s), and H2O (σ = 1.11(1010) s) single molecules compared to the other considered ones. Therefore, ZBPN could be used as a relatively good sensor for detection of SO2, AsH3, and H2O (compared to CS2, CO, CO2, and NO2 gases). Regarding the key findings of this research, it hopes that in the future, the results of the work be helpful for experimental synthesis of ZBPN nanoring for adsorption and sensing of the mentioned gases.

Uncovering the roles of Ce and Mn for NH3-SCR over Mn-Ce/IM-5 with extraordinarily superior wide-temperature performance

The development of wide-temperature catalyst with glorious activity and the resistance of SO2 for NH3-SCR reaction are of great importance. However, the preparation of wide-temperature catalyst with outstanding NH3-SCR performance and the resistance of SO2 is still challenging. In this work, Mn and Ce modified IM-5 molecular sieve catalyst (MC-5) was synthesized by incipient wetness impregnation method and the relationship of structure-activity was studied. MC-5 exhibited superior NOx conversion and it was more than 87% in the temperature range of 150-500 °C and ca. 100% at 225 °C due to the high concentration of Mn4+ and chemisorbed oxygen, the excellent redox ability and the synergistic effect of Mn and Ce. Meanwhile, the redox cycle of Mn4++Ce3+↔Mn3++Ce4+ promoted the electron transfer. 27Al NMR spectra and NH3-TPD confirmed Mn ion was mainly located on the bridge hydroxyl group (Brønsted acid sites). The localization energies ΔE of (Al, Mn) for IM-5 was determined by theoretical calculation and the reaction mechanism of M-5 catalyst on Brønsted acid sites was proposed. The reaction mechanism of M-5 catalyst on Brønsted acid sites followed L-H mechanism. And interestingly enough, the NH3-SCR activity of MC-5 significantly increased in the presence of SO2 at 200 °C. One of the reasons was that Ce binded more easily to SO42- and thus protected the active site Mn from sulfation. The other reason was the generation of more acid sites.

Evaluation of potential adsorbents for simultaneous adsorption of phosphate and ammonium at low concentrations

Evaluation of potential adsorbents to tackle eutrophication caused by low concentrations of phosphate and ammonium are rarely reported in the literature. Besides, the dynamics/mechanisms for removal of these pollutants at low concentration are yet to be explored. In this study we used five different adsorbents, including La-modified zeolite (LMZ), MgFe-modified biochar (MgFe-BC), phoslock, activated alumina (AA), and diatomaceous earth (DE) to evaluate the removal of these pollutants. Among the selected adsorbents in this study, LMZ and AA both exhibited effective and simultaneous adsorption for phosphate and ammonium and the maximum adsorption capacities were 2.47 mg/g and 3.07 mg/g, respectively. The presence of SO42− and CO32− negatively impacted phosphate adsorption, while Fe3+ and K+ ions inhibited ammonium adsorption. LMZ adsorption kinetics was over 3 times faster than other adsorbents within 60 min reaction time. Kinetics studies and isotherms revealed that the removal of phosphate and ammonium was primarily driven by chemical interactions and monolayer adsorption and were better fitted by Langmuir isotherm than the Freundlich isotherm and kinetic study was effectively described by Pseudo-second-order kinetic model. FTIR and XPS analysis revealed that the key mechanisms for phosphate adsorption were electrostatic attraction and inner sphere complexation through ligand exchange, whereas ammonium adsorption was mainly governed by ion exchange. Desorption study revealed that LMZ material was stable after three desorption cycles. This study offers vital knowledge on the nature of adsorption and interactions of potential mesoporous adsorbents with eutrophication-causing pollutants in lakes and rivers and proposes effective remedial mean.

Mercury Capture Performance and Kinetics of CCl4-Adsorbed Activated Carbon Pretreated by the Mechanochemical Method.

In the present work, CCl4-adsorbed activated carbon pretreated by the mechanochemical method (CCl4-AC) was produced for gas-phase mercury capture. The physicochemical properties of the CCl4-AC sorbent were analyzed via N2 adsorption, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The mercury capture performance of the CCl4-AC sorbent under different flue gas components was investigated in a fixed-bed experimental device. The programmed temperature desorption of mercury was used to determine the mercury capture product of the spent CCl4-AC. Finally, the mass transfer factor model proposed by Fulazzaky was used to analyze mercury capture on the CCl4-AC for clarifying its characteristics. The results showed that the prepared CCl4-AC can be used as a mercury sorbent because of its high mercury capture performance. Mercury capture by the CCl4-AC was interfered by SO2 and promoted by O2 and H2O. Hg-temperature programmed desorption (Hg-TPD) analysis indicated that the main mercury capture products of the CCl4-AC were HgCl2 and HgO. Because of the presence of SO2 in flue gas, there was a little Hg2SO4 formation on the sorbent. XPS analysis showed that the functional group of C-Cl played the dominant role in Hg0 capture, and part of the C-Cl groups were converted into Cl- after mercury capture. The mercury desorption energy of the spent CCl4-AC was 50.49 kJ/mol and stronger compared with that of raw activated carbon. Mass transfer analysis displayed that surface adsorption was the main form at the beginning of mercury adsorption, and the external mass transfer was the mercury adsorption rate-controlling step. Then, mercury adsorption entered the second stage; internal diffusion adsorption stage with internal mass transfer became the adsorption rate control step.

Novel green synthesis approach of eco-friendly magnetic/semiconductor nanocomposites as magnetically separable and reusable photocatalyst for organic dye degradation

Eco-friendly and effective separation of photocatalytic nanoparticles from the reaction mixture is crucial to facilitate their repeated use in photocatalysis. The development of magnetic/semiconductor nanocomposites with high catalytic performance and easy separation is an efficient strategy for wastewater treatments. In this study, we explore the potential of combination of magnetic (CoFe2O4) and semiconductor (ZnS) synthesized via a green approach using Moringa oleifera leaf extract as magnetically separable photocatalysts for dye degradation. X-ray diffraction analysis confirmed the presence of the cubic spinel ferrite phase of CoFe2O4 and the cubic zinc blend phase of ZnS within the nanocomposites. The micrographs illustrated nearly spherical nanoparticles with average particle sizes of 12 nm for CoFe2O4 and 26 nm for CoFe2O4/ZnS, respectively. The presence of SO suggested the incorporation of ZnS on the surface of CoFe2O4/ZnS nanocomposites. The UV–visible spectra revealed an increase in the band gap energy from 3.7 to 4.5 eV with increasing ZnS concentrations. Magnetic properties analysis signified that the CoFe2O4/ZnS nanocomposites exhibited ferromagnetic characteristics. The optimal degradation efficiency of photodegradation methylene blue was observed for CoFe2O4/ZnS 50 %, achieving 78.3 % degradation within 80 min with intervals 20 min. The magnetically separable capability allows for the recycling of nanocomposites after three consecutive cycles. Therefore, CoFe2O4/ZnS nanocomposites emerge as promising candidates as separable photocatalysts for the removal of organic pollutants in environments.

Phographene as a new carbon allotrope for adsorption and detection of SO2, AsH3, NO2, CF3H, and CO2 air pollutant gaseous species.

Phographene and its family member structures are of the newly proposed semiconductors for detection of chemicals. That is, in this project, the potential of using α-phographene (α-POG) both for adsorption and detection of five types of the most important air pollutant gases containing SO2, AsH3, CF3H, NO2, and CO2 species were investigated. The results of the time dependent density functional theory (TD-DFT) calculations indicate that during the adsorption of NO2, and SO2 by the sorbent, big redshifts occur (up to 866.2 nm, and 936.5, respectively) resulting in considerable changes in the orbitals and the electronic structures of the systems. Moreover, the results of the thermodynamic calculations reveal that α-POG could selectively adsorb SO2, NO2, and AsH3 gases (with different orders), but it could not adsorb the two other gases.Finally, the outcome of the band gap calculations shows that between all mentioned gases, α-POG could selectively detect the presence of SO2, and then NO2; while, this nanosheet could not sense the existence of AsH3, CF3H, or CO2 gases. All of the calculations were carried out by using the Gaussian 03 quantum chemical package. In addition, the physiochemical parameters were extracted from the output files for further calculations. Studies on all saddle points and the following calculations were performed applying the B3LYP/6-311g(d,p) level of theory.

Hollow tubular MnOx prepared by flame annealing with cotton fiber as sacrificial template and its applications for Hg0 adsorption in flue gas

The mass discharge of mercury from coal-fired power plant has caused great harm, abating mercury emissions is of preoccupation for protecting public environmental safety and human health. Metal oxides are often used for Hg0 removal in the flue gas. In this paper, a hollow tubular MnOx(MnCot) was successfully prepared by rapid flame annealing using cotton fiber as a sacrificial template. The MnCot were then well characterized and tested for its capability for Hg0 removal in flue gas. The results indicate that the flame assisted synthesis method for rapidly prototyping metal oxides with typical structures is achievable. The hollow tubular structure of the cotton fiber is well reprinted with good crystallization of Mn3O4. The inner diameter of the hollow tubular MnCot is about 10 μm, and the thickness of the tube is about 1 μm. The Hg0 removal efficiency on MnCot can be maintained as high as 90 % under simulated flue gas atmosphere below 240°C. O2 and NO have a positive effect on the Hg0 removal, which can act as the fresh active sits thus enhancing its capability for Hg0 removal. However, the presence of SO2 will result in the surface sulfation on MnCot, thus deteriorating its capability for Hg0 removal. Further, the competitive adsorption between SO2 and Hg0 on the material will also weaken its capability for Hg0 removal. The hollow tubular MnOx rapidly prepared by one-step flame annealing has a good industrial application potential for Hg0 removal in coal-fired flue gas.