Presence Of SO2 Research Articles

Solar light promoted degradation of bisphenol s in carbonate/peroxymonosulfate system through accelerating singlet oxygen generation

This study investigated for the first time the potential of the novel combination of peroxymonosulfate (PMS) and carbonate (CO32−) toward bisphenol S (BPS) under solar light irradiation. Compared with the Na2CO3/PMS and solar/PMS system, the solar/Na2CO3/PMS system significantly reduces the time required for the degradation of BPS. The excellent removal performance is possible due to the synergistic effect between enhanced light absorption and PMS activation, which accelerated the decomposition of PMS to generate more reactive oxygen species. Scavenging tests and electron paramagnetic resonance analysis revealed that the singlet oxygen (1O2) was the dominant oxidant formed and contributed to BPS elimination with a small proportion of superoxide anion radical (O2•–), rather than sulfate radical (SO4•−) and hydroxyl radical (HO•). The addition of Cl− could promote the degradation of BPS, but the addition of HA and a higher HCO3− concentration inhibited this process. The presence of SO42− and NO3− slightly promote the degradation of BPS. Besides, the solar/Na2CO3/PMS system represented significant degradation efficiency in a wide initial pH range (5.02–10.96). Such a system is favorable for the application in actual water matrices such as domestic wastewater, river water, lake water, and tap water. Meanwhile, based on the intermediates identified, the possible degradation pathways of BPS were proposed. In addition, most of the degradation intermediates of BPS were less toxic to different organisms than the parent compound. Moreover, the highly efficient degradation of several typical organic contaminants was also achieved using the solar/Na2CO3/PMS system under simulated and natural solar light irradiation. This study provides a novel idea and demonstrates the great potential for the elimination of organic pollutants in water.

Thermodynamics, Kinetics, and Mechanisms of the Co-Removal of Arsenate and Arsenite by Sepiolite-Supported Nanoscale Zero-Valent Iron in Aqueous Solution.

In this study, a newly synthesized sepiolite-supported nanoscale zero-valent iron (S-nZVI) adsorbent was tested for the efficient removal of As(III) and As(V) in aqueous solution. Compared with ZVI nanoparticles, the As(III) and As(V) adsorption abilities of S-nZVI were substantially enhanced to 165.86 mg/g and 95.76 mg/g, respectively, owing to the good dispersion of nZVI on sepiolite. The results showed that the adsorption kinetics were well fitted with the pseudo-second-order model, and the adsorption isotherms were fitted with the Freundlich model, denoting a multilayer chemical adsorption process. The increase in the initial solution pH of the solution inhibited As(III) and As(V) adsorption, but a weaker influence on As(III) than As(V) adsorption was observed with increasing pH. Additionally, the presence of SO42− and NO3− ions had no pronounced effect on As(III) and As(V) removal, while PO43− and humic acid (HA) significantly restrained the As(III) and As(V) adsorption ability, and Mg2+/Ca2+ promoted the As(V) adsorption efficiency. Spectral analysis showed that As(III) and As(V) formed inner-sphere complexes on S-nZVI. As(III) oxidation and As(V) reduction occurred with the adsorption process on S-nZVI. Overall, the study demonstrated a potential adsorbent, S-nZVI, for the efficient removal of As(III) and As(V) from contaminated water.

Aquatic toxicity prediction of diverse pesticides on two algal species using QSTR modeling approach.

With the aim of identification of toxic nature of the diverse pesticides on the aquatic compartment, a large dataset of pesticides (n = 325) with experimental toxicity data on two algal test species (Pseudokirchneriella subcapitata (PS) (synonym: Raphidocelis subcapitata, Selenastrum capricornutum) and Scenedemus subspicatus (SS)) was gathered and subjected to quantitative structure toxicity relationship (QSTR) analysis to predict aquatic toxicity of pesticides. The QSTR models were developed by multiple linear regressions (MLRs), and the genetic algorithm (GA) was used for the variable selection. The developed GA-MLR models were statistically robust enough internally (Q2LOO = 0.620-0.663) and externally (Q2Fn = 0.693-0.868, CCCext = 0.843-0.877). The leverage approach of applicability domain (AD) and prediction reliability indicator assured the reliability of the developed models. The mechanistic interpretation highlighted that the presence of SO2, F and aromatic rings influenced the toxicity of pesticides towards PS species while the presence of alkyl, alkyl halide, aromatic rings and carbonyl was responsible for the toxicity of pesticides towards SS species. Additionally, we have reported the application of developed models to pesticides without experimental value and the cumulative toxicity of pesticides on the aquatic environment by using principal component analysis (PCA). The reliable prediction and prioritization of toxic compounds from the developed models will be useful in the aquatic toxicity assessment of pesticides.

Oxygen deficient Ce doped CO supported on alumina catalyst for low-temperature CO oxidation in presence of H2O and SO2

The carbon monoxide (CO) oxidation has been carried out using Ce doped Co/Al2O3 prepared by coprecipitation followed by deposition precipitation. The 0.1 mol Ce doped Co supported on alumina showed maximum CO oxidation activity compared to the undoped catalyst at a low temperature. The physicochemical characteristics of synthesized catalysts were investigated by FTIR, XRD, Raman, XPS, 27Al solid-state NMR, H2-TPR, HR-TEM, etc. Ce doping promoted a distortion in the cobalt lattice structure. The distortion leads to an increase in reactive oxygen and the number of oxygen vacancies. In addition, Ce modification prevents the generation of the cobalt aluminate phase and stimulates the production of the Co3O4 active phase for CO oxidation. The presence of hexa and penta-coordinated alumina increases the defect and oxygen vacancy formation, which was responsible for a higher CO oxidation rate. The Ce doped Co/Al2O3 catalyst showed maximum water and SO2 tolerance due to the Ce doping. The mechanistic and kinetic details for CO oxidation have been explained by correlating with characterization.

Novel synthesis of reed flower-like SmMnOx catalyst with enhanced low-temperature activity and SO2 resistance for NH3-SCR

In this work, a novel co-precipitation coupled solvothermal procedure is proposed to prepare a SmMnOx catalyst (SmMnOx-CP + ST) with a reed flower-like structure for the selective catalytic reduction of NOx by NH3 (NH3-SCR). Over 90% NOx conversion and N2 selectivity was achieved at a low temperature range (25–200 °C), and 96% NOx conversion was achieved in the presence of 100 ppm SO2 at 75 °C. While the NH3-SCR of the SmMnOx catalysts prepared by co-precipitation (SmMnOx-CP) and solvothermal (SmMnOx-ST) methods performed much poorer than the SmMnOx-CP + ST catalyst. All catalysts were characterized by XRD, BET, SEM, XPS, H2-TPR, NH3-TPD, NOx-TPD, and FT-IR. The results revealed that the superior performance of the SmMnOx-CP + ST is due to the unique reed flower-like structure morphology, which endows the SmMnOx-CP + ST with the largest surface area, the strongest synergistic reaction of Sm and Mn, abundant surface oxygen species and surface active sites, and significantly enhances the redox ability. Furthermore, the amorphous reed flower-like structure showed strong short-range ordered interaction between the active components and weaken the formation of sulfates species. In addition, the highest content of Mn4+ and Mn3++Mn4+ greatly promotes the redox cycles of Sm2+↔Mn4+ and Sm2+↔Mn3+, and suppresses the production of sulfate species in the presence of SO2.

A multifunctional fluorescent probe for dual-color visualization of intracellular mitochondria and lipid droplets and monitoring of SO2 in vivo

Mitochondria and lipid droplets (LDs) are organelles involved in intracellular lipid and energy metabolism, and their complicated interplays are critical for maintaining cellular homeostasis. However, the fluorescent probes capable of simultaneously and discriminatively visualizing mitochondria and LDs are severely insufficient, which greatly limits the investigation of the interaction between two organelles in cells. In addition, abnormal SO2 levels can have harmful effects on living organisms. Monitoring the changes of SO2 levels in vivo is of great significance for biological and medical research. In this work, a SO2-dependent strategy was proposed for the first time to construct the new functional fluorescence conversion probe MLD-SO2 for two-color visualization of mitochondria and LDs. Under normal physiological conditions, the cationic form enabled the probe to selectively target the mitochondria and emit red fluorescence. In addition, based on SO2-driven nucleophilic addition reaction, the probe MLD-SO2 was converted to the neutral lipophilic structure in the presence of SO2, which targeted to LDs and displayed a strong blue emission. Importantly, mitochondria and LDs could be visualized simultaneously in the red and blue emission channels under the appropriate amount of SO2 exposure. Furthermore, the probe MLD-SO2 has been successfully employed to monitor the SO2 changes in zebrafish and mung bean sprouts. The remarkable imaging performances render the novel probe MLD-SO2 as a powerful tool for deciphering the interactions between mitochondrial and LDs and monitoring SO2 in different organisms.

Enhancing the oxidation efficiency of elemental mercury in the presence of NO and SO2 by using Cu(II)O doped TiO2 photothermal catalysts: Kinetics and mechanisms

This study aimed to apply sol–gel synthesized Cu(II)O doped TiO2 to enhance the oxidation of gaseous elemental mercury (Hg0) in the flue gases containing NO and SO2 at the temperatures of 120-180℃ under the irradiation of near-ultraviolet (near-UV). The influences of SO2 and NO on the oxidation efficiency of Hg0 were investigated by in-situ diffuse reflection infrared spectroscopy (DRIFT) and density functional theory (DFT). Experimental results showed that an optimal 5 %Cu(II)O/TiO2 had the oxidation efficiencies of Hg0 from 40 to 100 % at 120-180℃. The oxidation efficiencies of Hg0 were 85 and 70 % at 120℃, and 40 and 5 % at 180 °C, in the presence of solely SO2 and NO, respectively. Surface characterization showed that Cu(II)O was evenly dispersed over the surface of TiO2 catalysts. NO could inhibit the oxidation of Hg0 since it consumed the chemisorbed oxygen (Oα) and compete with Hg0 at the surface active sites. In contrast, SO2 could promote the oxidation efficiency of Hg0 due to the formation of HgSO4 on the surface of Cu(II)O/TiO2 catalysts. In the exposure of NO/SO2, NO and SO2 can be adsorbed on the catalyst surface reacting with ̇OH. The photothermal oxidation reactivity of Hg0 was inhibited due to the competitive adsorption between NO/SO2 and Hg0. The Langmuir-Hinshelwood (L-H) kinetic model successfully simulated the oxidation rate of Hg0. Moreover, DFT was further applied to estimate the binding energies of different gas molecules confirming the competence for active sites on the surface of Cu(II)O/TiO2 between NO/SO2 and Hg0.

Improvement of sulfur and water resistance with Fe-modified S-MnCoCe/Ti/Si catalyst for low-temperature selective catalytic reduction of NO with NH3.

The low-temperature SCR of NOx by NH3 is restricted in application since the catalysts is easily poisoned by sulfur and water. The Fe modified Mn-Co-Ce/TiO2/SiO2 catalysts synthesized via impregnation method and sulfating were evaluated for low-temperature NH3-SCR in the presence of SO2 and H2O. The calcination temperature and loading amounts of Mn, Fe, Co and Ce were optimized. Adding of Fe into S-MnCoCe/Ti/Si played an important role in resistance to sulfur and water poisoning. The optimal calcination temperature was 380°C and the optical mass loading of the catalyst was 10% of Mn, 10% of Fe, 1% of Co and 4% of Ce. The optimal S-MnFeCoCe/Ti/Si catalyst maintained high NOx conversion of 93% at reaction temperature of 160°C in the presence of 50ppm SO2 and 10vol% H2O. The catalytic activity did not continue to fall after two times of repeated used in the temperature range of 100-200°C, indicating its excellent sulfur and water durability and stability in the presence of SO2 and H2O. The interaction between MnOx and FeOx enhanced sulfur and water durability rather than other bi-metal interactions. Furthermore, the mechanism of Fe improving resistance to SO2 and H2O was discussed.

Tuning the high-temperature hydrothermal stability of one-pot derived Cu-SSZ-13 in the presence of SO2 for selective catalytic reduction of NOx by ammonia

The high temperature hydrothermal stability in the presence of SO2 of the one-pot synthesized Cu-SSZ-13 was investigated for selective catalytic reduction of NOx by NH3 (NH3-SCR). The uncalcined samples were treated with HNO3 (pH = 1.0–1.1) with different duration (3, 6, and 9 h) and then calcined, finally subjected to 750 oC hydrothermal aging without/with the presence of SO2. Various characterization results indicate that different duration of HNO3 treatment results in dealumination but has almost no effect on the distribution of Al and Si species. In contrast, it leads to difference in the content of Cu species and finally in their distribution. The 6 and 9 h samples contain higher content of more stable Cu species, which contribute to the high hydrothermal stability in the presence of SO2. H2-temperature programmed reduction (H2-TPR) is a powerful technique to reveal the properties of Cu-SSZ-13; the reduction behavior at lower temperatures (Cu2+ → Cu+) determines the NH3-SCR activity whilst the case at higher temperatures (Cu+ → Cu0) determines the high-temperature hydrothermal stability in the presence of SO2. This work demonstrates that the hydrothermal stability of Cu-SSZ-13 in the presence of SO2 can be tuned by engineering the distribution of Cu species via post HNO3 treatment.

Effects of Coal-Fired Flue Gas Components on Mercury Removal by the Mechanochemical S-Modified Petroleum Coke.

In this work, the effects of coal-fired flue gas components (O2, CO2, SO2, and NO) on the Hg0 removal by the promising mercury removal adsorbent mechanochemical S-modified petroleum coke were characterized and analyzed in terms of the Hg0 removal efficiency, mercury adsorption capacity, and mercury mass balance. The results show that the mechanochemical S-modified petroleum coke with a theoretical sulfur content of 21% (named TSC-21) is the best candidate for mercury removal based on the Hg0 removal efficiency, Hg0 removal capacity, and difference ratio of Hg0 removal capacity (anti-interference ability) in the basic and full-component simulated flue gas atmosphere (N2 + O2 + CO2, N2 + O2 + CO2 + SO2 + NO). The maximum value (MV) and stable value (SV) of the Hg0 removal efficiency of TSC-21 in the basic simulated flue gas atmosphere are 99.25% (MV) and 91.17% (SV), respectively. O2, CO2, and NO all promote the Hg0 removal by the adsorbent, but they benefit the Hg0 oxidation while inhibiting the Hg0 adsorption. The promoting effect of O2 on the Hg0 removal by TSC-21 is affected by the reaction time, which is especially obvious after 1 min. The presence of SO2 inhibits the oxidation and adsorption of Hg0, which in turn reduces the Hg0 removal performance of the adsorbent. The improving effects on the oxidative escape of Hg0 by CO2 is higher than that by NO and O2. TSC-21 acts more as an oxidant than an adsorbent for Hg0 removal.

Promotion effect of bulk sulfates over CeO2 for selective catalytic reduction of NO by NH3 at high temperatures

Understanding the influence of sulfates over catalysts for selective catalytic reduction of NO with NH3 (NH3-SCR) is crucial due to the universal presence of SO2 in exhaust gas. Depending on the degree of sulfation, there mainly exist surface and bulk sulfates and NH3-SCR activity is generally considered to suffer more from bulk sulfates. Herein, the unique function of bulk sulfates over CeO2 in promoting high-temperature SCR reaction is revealed. Notably, compared with CeO2 dominated with surface sulfates (S-CeO2–4h) and commercial V2O5-WO3/TiO2, CeO2 with bulk sulfates (S-CeO2–72h) exhibits admirable NO conversion at the temperature range of 400–550 °C. Bulk sulfates provide more Brønsted acid sites with stronger strength for NH3 adsorption. Moreover, the oxidation ability of CeO2 is significantly inhibited due to electron-withdrawing effect from bulk sulfates, which alleviates NH3 oxidation at high temperatures. More NH3 adsorption with high stability and limited NH3 oxidation capacity ensure the excellent catalytic performance for S-CeO2–72h in high-temperature denitration. This work provides new insight of bulk sulfates in promoting SCR activity and open a new avenue to design deNOx catalysts employed at high temperatures.

Effects of OH radical and SO2 concentrations on photochemical reactions of mixed anthropogenic organic gases

Abstract. Vehicle exhaust, as a major source of air pollutants in urban areas, contains a complex mixture of organic vapours including long-chain alkanes and aromatic hydrocarbons. The atmospheric oxidation of vehicle emissions is a highly complex system as inorganic gases (e.g. NOx and SO2) from other urban sources coexist and therefore remains poorly understood. In this work, the photooxidation of n-dodecane, 1,3,5-trimethylbenzene, and their mixture is studied in the presence of NOx and SO2 to mimic the atmospheric oxidation of urban vehicle emissions (including diesel and gasoline vehicles), and the formation of ozone and secondary aerosols is investigated. It is found that ozone formation is enhanced by higher OH concentration and higher temperature, but is influenced little by SO2 concentration. However, SO2 can largely enhance the particle formation in both number and mass concentrations, likely due to the promoted new particle formation and acid-catalysed heterogeneous reactions from the formation of sulfuric acid. In addition, organo-sulfates and organo-nitrates are detected in the formed particles, and the presence of SO2 can promote the formation of organo-sulfates. These results provide a scientific basis for systematically evaluating the effects of SO2, OH concentration, and temperature on the oxidation of mixed organic gases in the atmosphere that produce ozone and secondary particles.

Construction of mitochondria targeted and FRET based ratiometric sensing nanoplatform for sulfur dioxide accurate detection in vitro and in vivo

Sulfur dioxide (SO2) is a key molecule in organisms that is involved in the regulation of different physiological procedures. Aberrant SO2 causes a variety of diseases, such as cancer and neurodegeneration. Thus, sensitive and selective detection of SO2 is of great importance. Based on the Förster resonance energy transfer (FRET) between green fluorescence carbon dots (GCDs) donor and amide-linked near-infrared fluorescence emissive organic small molecular dye (CDDBT) acceptor, one ratiometric fluorescent nano platform, Mito-GCDs-CDDBT for mitochondria SO2 sensing was constructed. In this FRET sensing system, CDDBT served as the receptor for SO2, and the presence of SO2 enhanced GCDs green fluorescence signal and quenched CDDBT near-infrared fluorescence signal due to the disruption of FRET. Mito-GCDs-CDDBT could sensitively detect SO2 with a detection limit of as low as 0.701 μM. Meanwhile, Mito-GCDs-CDDBT achieved fluorescence imaging to measure the response of cellular exogenous and endogenous SO2 with remarkable mitochondrial targeting. Moreover, Mito-GCDs-CDDBT also realized SO2 sensing in vivo including zebrafish and mice. The as-prepared versatile nanoplatform displayed several advantages, such as mitochondria targeting, FRET-based sensitive detection, and sensing capabilities in biological milieu. Potentially, it could be applied in the diagnostics of SO2 involved diseases.

Simultaneous absorption of SO2 and NO from flue gas by ammonia solution with a wetted-wall column

In a self-designed wetted column, the effects of absorption concentration, initial pH, liquid-gas ratio, SO2 inlet concentration, NO inlet concentration on desulfurization and denitration efficiency were studied with ammonia solution. The results show that the removal efficiency of SO2 and NO can be improved by increasing the concentration of absorption liquid and liquid-gas ratio. The presence of SO2 can promote the removal of NO. Increasing SO2 concentration and NO concentration are not conducive to removing SO2. The liquid-phase and gas-phase mass transfer coefficients of SO2 in the system were determined. The results demonstrate that when inlet concentration of SO2 and NO is about 1100 mg/m3 and 500 mg/m3 respectively, the best technical parameters are 4 to 5 L/m3 for the liquid-gas ratio, 6.0 to 7.0 for the pH of absorption, 3%(wt) for Ammonia concentration. Under the best experimental conditions, the removal efficiency of SO2 can reach above 99%, and that of NO can reach above 50%.

The Initial Corrosion Behavior of AZ31B Magnesium Alloy in Chloride and Sulfate Solutions

The initial corrosion of Mg alloys is important for the conversion coating treatment, by which the conversion coating is formed in a few minutes of immersion in the conversion solution. This study detailed the initial corrosion of AZ31B Mg alloy in chloride and sulfate solutions by acquiring the open circuit potential, optical image and hydrogen evolution, together with the post-immersion TEM and XPS characterization. Before the breakdown of the surface film, more hydrogen evolved in the SO4 2− solution than in Cl− solution, and the corrosion products formed in the former were thicker than in the latter. The initial corrosion of AZ31B was thus more severe in SO4 2− solution than in Cl− solution, which is different from the typical role of Cl− ions in metal corrosion. Local attack at nanometric scales was observed in Cl− solution, but not in SO4 2− solution. The presence of SO4 2− in Cl− solution mitigated local attack and the corrosion products were more uniform, due to the competitive adsorption effect of SO4 2−.

Modeling the synchronous absorption and oxidation of NO and SO2 by activated peroxydisulfate in a lab-scale bubble reactor

Sulfate-radical advanced oxidation technology is emerging for environmental remediation, and current research attention has been on applications to air pollution control. This study uses a physicochemical model to investigate and compare the kinetics of NO removal alone or synchronously with SO2 by heat-activated aqueous peroxydisulfate (or persulfate). The model allowed for the validations of experimental fractional conversion data for both NO and SO2 with remarkable agreements; and predictions of reaction species and nitrogen-sulfur product concentrations, new kinetic data, and lumped-kinetic rate constants with corresponding activation energies. The model also predicted increases in mass transfer coefficients (KLa) for NO with temperature (in the range 30–90 °C) in the absence of SO2. However, in the presence of SO2, KLa values for NO are significantly enhanced (especially at the lower temperatures) compared to the case for NO-only absorption and oxidation. The results should provide useful guidance to designing cost-effective single vessels for multicomponent flue gas treatments.

Mechanism for the promotional formation of NH4+ by SO2 on different mineral dust surfaces

Ammonium is an important atmospheric particulate component that dictates many environmental processes. The promotion of the heterogeneous conversion of NH3 to NH4+ by SO2 on different mineral dust surfaces displays remarkable discrepancies, especially on MgO and α-Fe2O3 surfaces, however, the underlying mechanisms are not well known. Here, using periodic density functional theory (DFT) calculation and Born-Oppenheimer molecular dynamics (BOMD) simulation, we explored the heterogeneous adsorption of NH3 on MgO (110) and α-Fe2O3 (001) surfaces in the presence and absence of SO2. The results show that on MgO (110) surface, hydrogen-bonding interactions of NH3 on both adsorbed hydroxyl or bisulfite/bisulfate sites are observed no matter whether SO2 is present or not. While, on the α-Fe2O3 (001) surface, significant conversion of NH3 to NH4+ occurs with the coexistence of SO2, which is due to the hydrogen transfer reaction from surface HSO4 to N in NH3. The fundamental reason may be that the stronger electron affinity of Fe3+ than Mg2+ results in adsorbed bisulfate and/or bisulfite with greater acidity on α-Fe2O3 surface than MgO surface. Our results give a molecular-level explanation for the heterogeneous conversion of NH3 to NH4+ on different mineral dust surfaces under complex air pollution conditions. Considering the fact that ammonium is abundant in secondary particulates, this work would help in understanding the rapid conversion of ammonia to ammonium and in developing classification governance policies for the key precursor pollutants in China.

Effect mechanism of SO2 on Hg0 adsorption over CuMn2O4 sorbent

SO2 is an important acid flue gas component during solid fuel combustion. The effects of SO2 on the Hg0 removal performance of CuMn2O4 sorbent and its reaction mechanism were investigated by conducting the mercury adsorption experiments and theoretical calculations. The results showed that SO2 concentration coupling with the high temperature was the predominant factor affecting the Hg0 removal performance of CuMn2O4 sorbent. At a relatively high temperature (≥200 °C), the presence of SO2 significantly inhibited Hg0 removal by CuMn2O4 sorbent, and the inhibitory effect was significantly enhanced with the increase of temperature. Hg0 removal efficiency decreased from 88.2 % at 200 ℃ to 17.98 % at 350 °C due to the SO2 sulfation of sorbent surface. Hg0 removal performance of CuMn2O4 sorbent was not sensitive to the variation of SO2 concentration at the low temperature of 150 °C. DFT calculation results showed that SO2 is chemically adsorbed on the sorbent surface, and the adsorption energy of the most stable configuration is −111.78 kJ/mol. The chemisorption of SO2 on the sorbent surface is attributed to the orbital hybridization among Cu, Mn and O atoms. The adsorption energy of Hg0 on the CuMn2O4 surface decreased in the presence of SO2. The transformation pathway of Hg0 in the presence of SO2 includes three steps: Hg0 adsorption, O2 adsorption, and Hg*-to-HgO conversion. The presence of SO2 increased the activation energy barrier of Hg* oxidation into HgO.

Gas adsorption effects of monolayer GeSe in terms of anisotropic transport properties

Two-dimensional layered semiconducting material germanium selenide (GeSe) has attracted significant attention due to its environmental friendship, anisotropic electronic structures, and strong air-stability. To evaluate the candidacy of monolayer GeSe as a potential gas sensing material, the adsorption characteristics of various small gas molecules on monolayer GeSe are comprehensively studied combining density functional theory calculations and non-equilibrium Green’s function formalism. The charge transfer reaction between gas molecules and monolayer GeSe leads to the marked change of the carrier density, which further affects the anisotropic transport characteristics of monolayer GeSe. The calculated band structures and I–V curves reveal distinctive responses of monolayer GeSe to the different gas molecules, and higher sensitivity of the monolayer GeSe in presence of SO2, NH3, NO2 gas molecules along the zigzag direction is obtained. These results suggest that monolayer GeSe along the zigzag direction has promising application in gas detector.

The Synthesis of FeCl3-Modified Char from Phoenix Tree Fruit and Its Application for Hg0 Adsorption in Flue Gas

A sample of FeCl3-modified phoenix tree fruit char (MPTFC) was prepared using pyrolysis and a facile chemical immersion method; it was proposed as an effective sorbent for Hg0 adsorption in flue gas. The BET, SEM, FTIR, and XPS methods were adopted for the characterizations of the sorbents, and a series of Hg0 adsorption tests were conducted on a bench-scale Hg0 removal setup in the lab. The morphological analysis of the sorbent indicated that the hollow fiber in phoenix tree fruit (PTF) shifted to organized directional porous tubular columns in phoenix tree fruit char (PTFC) after pyrolysis. The surface area of MPTFC increased slightly in comparison with PTF and PTFC. The MPTFC showed excellent performance for Hg0 adsorption at 200 °C in flue gas ambiance, and the Hg0 removal efficiency approached 95% with 5% (wt.%) FeCl3 modification. The presence of O2 may help to activate the MPTFC for Hg0 adsorption in flue gas, thus greatly promoting Hg0 adsorption capability. NO had a positive effect on Hg0 adsorption, while the presence of SO2 in flue gas restrained Hg0 adsorption by MPTFC. Functional groups, such as C-Cl and Fe-O, were successfully decorated on the surface of PTFC by FeCl3 modification, which contributed greatly to Hg0 adsorption. In addition, C=O, lattice oxygen (Oα), and adsorbed oxygen (Oβ) also contributed to Hg0 adsorption and oxidization.