Weak Oxidation Research Articles

Old Sulfidic Ore Tailing Dump: Ground Features, Mineralogy, Biodiversity—A Case Study from Sibay, Russia

The Urals (Russia) are among the largest mining areas in the world, with millions of tons of mine waste deposited. An old sulfidic tailing dump formed over decades of mining activities at the Sibay ore-processing plant is a typical cause of acid mine drainage (AMD) formation, posing a threat to ecosystems of neighboring environments. In this study, the formation of oxidized surface soil layers in four zones of the Sibay tailing dump was revealed, and their chemical–mineralogical and physical–mechanical characteristics were analyzed. According to the results of the metabarcoding of hypervariable regions of the 16S rRNA genes, oxidation in soil layers was associated with the activity of sulfur- and iron-oxidizing acidophiles represented by a few genera: Ferroacidibacillus, Sulfoacidibacillus, Sulfobacillus, and Ferroplasma. The structure of the microbial communities in soil layers differed depending on the zone and depth of sampling. In the samples characterized by the weak oxidation of sulfide minerals, microbial communities were dominated by bacteria of the genus Pseudomonas. The data obtained in this research are of importance to predict the oxidation/leaching processes in mine wastes and their negative environmental impacts in the mining region, as well as to develop technologies for processing these raw materials.

Electro-Chemo-Mechanical Coupling in Hierarchical Nanoporous Gold-Polypyrrole-Water Hybrids

Nanoporous (np) metals made by dealloying is a novel class of nanostructured materials that offers numerous functionalities, ranging from sensing, energy storage, to (electro-)catalysis and beyond. A substantial amount of research in np materials has been focused on np gold due to its excellent structural and chemical stability, adjustable pore size, high conductivity, biocompatibility, and easy fabrication process via free corrosion or electrochemical dealloying. A considerable number of studies have been conducted to investigate np gold infiltrated with an aqueous electrolyte [1]. In that way, the material is considered as a hybrid so that one can reversibly tune the gold surface state by manipulating the superficial charge densities or adsorbate coverages via the applied electric potential [1]. The above-mentioned approach results in a number of intriguing properties of np Au revealed upon electrode potential variation in aqueous electrolytes such as actuation [2, 3], sensing [4], tunable strength [5] and elastic modulus [6]. The behavior is well-studied in case of weak ion adsorption and surface oxidation.One of the promising methods towards further improvement of functional and mechanical properties of np metals was implemented by Roschning and Weissmueller [7]. It was shown that the actuation strain of np Au can be enhanced via electrodeposition of a conductive polymer polypyrrole (PPy) on the gold surfaces. The actuation strain of the np Au-PPy hybrids strongly scales with the PPy phase fraction. Moreover, Li et al. [8] observed variations of effective elastic modulus in np Au-PPy-water hybrids. Thus, introducing the conductive polymer into a pore space of the np metal yields a hybrid actuator with a significantly improved actuation amplitude and yield strength.Here, we employ PPy for surface functionalization of hierarchical (hc) np Au (Figure 1) to explore the impact of the conductive polymer coating on the functional behavior of the hierarchically structured np metals. Np metals with structural hierarchy made by dealloying [9] open up new opportunities for multifunctional hard-soft hybrids. The larger pores at the higher hierarchical level (characterized by diameters around 120 nm) can promote fast mass exchange, while nanopores at the lower hierarchy level (below 30 nm) provide a large surface area and high chemical activity. Actuation behavior of the hybrid materials was analyzed in situ in a dilatometer upon potential cycling in a 1 M HClO4 aqueous electrolyte. The elastic response was examined in situ in a dynamic mechanical analyzer in the same electrolyte. We revealed pronounced changes of the macroscopic length and Young’s modulus in response to the voltage-induced redox reactions of the polymer films at the np electrodes. In the contribution, we discuss the origin of the electro-chemo-mechanical coupling phenomena.[1] Shao et al., in Nanoporous Gold: From an ancient technology to a high-tech material. RSC (2012).[2] Kramer et al. Nano Lett., 4(5) 793 (2004).[3] Jin et al. Nano Lett., 10(1) 187 (2010).[4] Stenner et al., Adv. Funct. Mater. 26 (28), 5174 (2016).[5] Jin et al., Science 332, 1179 (2011.)[6] Mameka et al., Acta Mater. 76, 272 (2014).[7] Roschning et al., Adv. Mater. Interfaces, 2001415 (2020).[8] Li et al., Acta Mater., 212 (1), 116852 (2021).[9] Shi et al., Science 371, 1026 (2021).Figure 1. Scanning electron micrograph of hierarchical nanoporous Au-PPy hybrid microstructure. Figure 1

(Invited) Dye-Sensitized Molecular Photoelectrodes for CO2 Reduction Using Water as a Reductant

Photocatalytic CO2 reduction using visible light and water as a reductant has been one of the important targets for solving global warming problem and shortage of energy and carbon resources. In this presentation, I talk about two projects, i.e., (1) supramolecular photocatalysts with both functions as photosensitizer and catalysts and (2) photocatalytic CO2 reduction coupled to water oxidation.(1) Highly efficient supramolecular photocatalysts for CO2 reduction1-3 Since CO2 is the most oxidized state of carbon, one-electron reduction of CO2 is an extraordinarily high endergonic reaction. From the viewpoints of low-energy light application, the multi-electron reduction of CO2 via chemical reactions promises to be a more valuable process. This is a main reason why both a photosensitizer and a catalyst are required to promote efficient photocatalytic CO2 reduction. We have developed so-called supramolecular photocatalyts that have both the photosensitizer and the catalyst units. This bonding in the supramolecular photocatalysts can accelerate electron transfer between the two units, which improves the performance of the photocatalytic system, especially on the surface of photofunctional solid materials as described below.(2) Molecular photoelectrodes for photocatalytic CO2 reduction with water as a reductant 1,4 The molecular photocatalytic systems have a weakness, i.e., weak oxidation power in the excited state. For practical application, water should be used as an electron donor. For overcoming this problem, we have developed a hybrid system consisting of the supramolecular photocatalyst and semiconductor electrodes. The hybrid photoelectrochemical cell consisting of this hybrid photocathode and n-type semiconductor photoanode induced visible-light-driven CO2 reduction with water as a reductant to generate CO and O2. References “Photocatalytic Systems for CO2 Reduction: Metal-Complex Photocatalysts and Their Hybrids with Photofunctional Solid Materials” Kumagai, H.; Tamaki, Y.; Ishitani, O., Acc. Chem. Res. 2022, 55, 978-990.“Mechanistic study of photocatalytic CO2 reduction using a Ru(II)-Re(I) supramolecular photocatalyst” Kamogawa, K.; Shimoda, Y.; Miyata, K.; Onda, K.; Yamazaki, Y.; Tamaki, Y.; Ishitani, O., Chem. Sci. 2021, 12, 9682-9693.“Supramolecular Photocatalysts for the Reduction of CO2” Tamaki, Y.; Ishitani, O., ACS Cat. 2017, 7, 3394-3409.“Supramolecular photocatalysts fixed on the inside of the polypyrrole layer in dye sensitized molecular photocathodes: application to photocatalytic CO2 reduction coupled with water oxidation. Kuttassery, F.; Kumagai, H.; Kamata, R.; Ebato, Y.; Higashi, M.; Suzuki, H.; Abe, R.; Ishitani, O., Chem. Sci. 2021, 12, 13216-13232. Figure 1

Synergistic reduction on PM and NO source emissions during preheating-combustion of pulverized coal

The present research focuses on the synergistic source control of particulate matter (PM) and NOx formation from pulverized coal combustion. Comparative experiments of preheating-combustion and conventional combustion were conducted in a lab-scale high-temperature preheating-combustion furnace, and PM10 and NO were measured by an electrical low pressure impactor and a flue gas analyzer, respectively. The results of the experiment indicate that preheating-combustion has a significant reduction in PM10 (especially PM0.3 up to 37.51 %) and NO, which can achieve the synergistic control of PM10 and NO source emissions during the combustion process. The fragmentation in preheating-combustion was weaker compared to the conventional combustion. Meanwhile, the relatively weak preheating-combustion coal char oxidation reaction leads to a decrease in ultrafine mode PM yielded due to the inhibition on vaporization of mineral inclusions. The PM0.3/PM1 mass ratio of the preheating-combustion has a decreasing trend, implying an elevated yield of PM0.3-1 and a shift of the average PM1 particle size toward a larger particle size. Higher preheating temperature (Tp) presented the potential to further reduce NO formation, and the NO reduction efficiency increased from 46.59 % to 56.60 % when the Tp was increased from 1200 K to 1600 K. All our preliminary results throw light on the nature of synergistic source control of preheating-combustion PM and NO formation.

Color origin and its sedimentary and paleoenvironmental significance of the Permian-Triassic strata in the Ordos Basin, China

The Permian-Triassic strata in the Ordos Basin deposit a colorful set of strata. Although there have been many studies on oil and gas resources here, little attention has been paid to the genesis mechanism of its color. To analyze the color origin of the Permian-Triassic claystones and to clarify the dialectical relationship between rock color and sedimentary environment, petrological and geochemical methods such as polarization microscope, scan electron microscope, X-ray diffractometer, and inductively coupled plasma-mass spectrometer are used. The results indicate that the minerals with different colors, composition, and content serve as colorants in sedimentary rocks, with the predominant dyeing component in dark claystones being the organic matter, whereas red beds primarily acquire their color from hematite and other ferric minerals. In addition, different rock colors correspond to distinct chemical composition variations. The black-gray rocks of the Yanchang and Shihezi Formations have high total organic carbon content, Fe2+/Fe3+, V/Cr, and low CaO/(MgO × Al2O3) and Sr/Cu, whereas the red-brown rocks of the Liujiagou and Heshanggou Formations exhibit the opposite. Therefore, different colors of the rocks stem from their different mineral and chemical compositions, which in turn influenced by the changes in the paleoclimate, paleoenvironment, and tectonic movements. Comprehensive analysis of color, mineral, and chemical composition reveals the evolution process of paleoclimate and paleoenvironment in the Ordos Basin from the late Permian to Triassic, beginning with a warm humid climate characterized by a weak oxidation environment in the Shihezi and Shiqianfeng Formations, transitioning to a hot arid climate in the Liujiagou and Heshanggou Formations, and returning to a warm humid climate with a weak oxidation environment in the Zhifang and Yanchang Formations. This evolution history aligns with the global tectonic and climate evolution. Overall, systematic analysis of sedimentary rock color can provide an important basis for the study of the paleoclimate and paleoenvironment.

Structure, mechanical, tribological properties and corrosion resistance of C/N dual doping Mo-S-C-N films

Transition metal dichalcogenides (TMDs) show poor mechanical properties and weak corrosion and oxidation resistance in ambient atmosphere, which results in the limit application and the lower work life. Doping TMDs based films with the enhanced performance show the potential to apply in harsh environment. The C/N dual-doping Mo-S-C-N films were deposited by magnetron sputtering, and the evolution of alternative microstructure composed of TMDs phase and amorphous inclusions was analyzed. The enhancement on mechanical, tribological and anti-corrosion properties of films with C/N dual-doping were evaluated. The strengthened TMDs phase and inclusions with MoCx/MoNx hard phase result in the improvement of mechanical properties (hardness 8.57–19.09 GPa). The superior tribological performance was obtained from film with 10.67 at. % of C and 17.36 at. % of N (wear rate 8.24 × 10-7 mm3/Nm, average friction coefficient (CoF) 0.188) and film with 14.87 at. % of C and 15.02 at. % of N (wear rate 8.02 × 10-7 mm3/Nm, average CoF 0.166). The balance between the effect of lubricating phase and mechanical performance strengthen by C/N dopants were achieved in these two films. The passivation of reactive sites in MoS2 leads to the improvement of corrosion resistance, while excessive dopants induce more pathways for corrosive medium, which leads to the corrosion failure of films.

Distribution and dynamics of antibiotic resistance genes in sludge under discharge plasma oxidation

Antibiotic resistance genes (ARGs), emerging environmental contaminants, have been largely accumulated in sludge during wastewater treatment. Discharge plasma oxidation, an advanced oxidation technology, has been demonstrated as an effective strategy in sludge pretreatment. However, the effect of plasma oxidation on the distribution and dynamics of ARGs in sludge is unknown. Herein, the variations of four typical ARGs (tetC, tetW, blaTEM-1, aac(3)-Ⅱ) and one integron (intI-1) in sludge during discharge plasma treatment were investigated. The results showed that under low discharge voltage or short treatment time, weak plasma oxidation enriched the contents of ARGs and intI-1 in sludge (with 1.14 log unit maximum increment) via proliferating biomass or promoting horizontal gene transfer. Further increasing discharge voltage or prolonging treatment time, strong plasma oxidation eliminated target genes due to the destroyed bacteria or inhibited horizontal transfer of ARGs. Especially, the homogeneous condition greatly promoted the reduction of ARGs in liquid phase (up to 1.52 log unit reduction). Furthermore, the correlation analysis between intI-1 and ARGs implied that tetC and tetW abundances might be significantly affected by intI-1 through horizontal transfer. At the same time, the microbial communities in sludge were investigated to help understand the effect of plasma oxidation on ARGs variation. Notably, the most predominant phylum Proteobacteria and genus Acinetobacter resisted the oxidative infringement from plasma to maintain high relative abundances (52.05 % in solid phase and 84.10 % in liquid phase for Proteobacteria, 13.82 % in solid phase and 78.00 % in liquid phase for Acinetobacter at 20 kV). Meanwhile, the co-occurrence analysis between genes and dominant genera further showed that Romboutsia sp. might be a potential host bacteria of ARGs and intI-1 in solid phase, and Acidovorax sp., Parachlamydia sp., and Armatimonadetes_gp5 sp. might be the potential hosts of tetW, tetC, and intI-1 in liquid phase.

Oxygen vacancy-driven strong metal-support interactions on AuPd/TiO2 catalysts for high-efficient air-oxidation of 5-hydroxymethylfurfural

The regulation ofstrong metal-support interactions (SMSI) has emerged as a powerful strategy in boosting catalytic activity and controlling product selectivity. However, directly tuning the metal-supportinteractions in oxide supported metal nanocatalysts remains challenging. Herein, citric acid (CA)‑assisted synthesized TiO2 layer on halloysite nanotubes (HNTs) with varied oxygen vacancies (Ov) concentrations was designed for loading AuPd nanoparticles. SMSI between the AuPd nanoparticles and the TiO2-xCA@HNTs support was successfully induced by adjustable Ov concentrations. The synthesized catalyst was employed for air-oxidation of bio-based 5-hydroxymethylfurfural (HMF) to bioplastic monomer 2,5-furandicarboxylic acid (FDCA) in water. A satisfactory FDCA yield of 98.4 %, accompany with an outstanding FDCA formation rate of 900.9 mmol·g−1·h−1 and an excellent TOF value at 441.2 h−1 was afforded. Based on catalysts characterizations and experimental studies, the catalytic performance was significantly affected by Ov concentrations. The kinetic study showed that the supported gold nanoparticles in alkaline environment had strong aldehyde oxidation activity but weak alcohol oxidation ability. On the contrary, supported palladium nanoparticles were more conducive to alcohol oxidation. This imbalance was overcome by the loading of AuPd nanoparticles, which enhanced the activity for air-oxidation of HMF. Mechanistic studies demonstrated that the stronginteractions between noble metal nanocatalysts and supports were regulated by Ov, which not only increased the adsorption capacity of the substrate and crucial intermediate, but also facilitated the adsorption and activation of molecular oxygen to generate oxygen active species of superoxide radicals. The possible catalytic mechanism for air-oxidation of HMF over Ov-driven SMSI on the obtained catalysts was proposed. This work sheds lights on the design of supported metal catalysts with SMSI for the catalytic upgrading of biomass-derived platform chemicals.

Improving low-temperature NH3-SCR denitration activity and resistance to H2O and SO2 over Nb-modified NbaSn0.3CeOx catalysts by enhancing acidity to compensate for its weak oxidation ability

In this paper, a series of Nb-modified NbaSn0.3CeOx (a = 0.2, 0.4, 0.5) catalysts for denitrification were prepared using a facile co-precipitation method. In order to explore the various individual properties of the samples, the catalysts were characterized by XRD, Raman, N2 adsorption and desorption, TEM, NH3-TPD, H2-TPR, XPS and in-situ DRIFTS tests to understand the influences of the Nb introduction on the NH3-SCR reaction. Among these catalysts, the Nb0.4Sn0.3CeOx catalyst exhibit excellent NH3-SCR performance in the temperature range of 155–450 °C with more than 90 % NO conversion, 100 % N2 selectivity, and possess good resistance to H2O and SO2. Compared with the Sn0.3CeOx catalyst, we believe that the improvement of the low-temperature NH3-SCR performance of the Nb0.4Sn0.3CeOx catalysts is mainly due to the change in the amount of acid, special for the increase in B acid content, which compensates for the effect of the weaken oxidizing ability on the low-temperature activity. Beyond that, the good H2O and SO2 resistance at low temperature after the introduction of Nb into Nb0.4Sn0.3CeOx catalysts was analyzed by using in-situ DRIFTS characterization in detail, and the results indicate that the incorporation of Nb can inhibit the oxidation of SO2 to form sulfate on the catalysts, and prevent the competing adsorption of H2O and NOx, but the adsorption of NH3 is not affected. This work proves that the acidity regulation can improve low-temperature SCR activity by the synergistic effect between oxidation capacity and acidity.

Aging effects on residential biomass burning emissions under quasi-real atmospheric conditions

Emissions from biomass burning (BB) vastly contribute to the atmospheric trace gases and particles, which affect air quality and human health. After emission, the chemical evolution changes the mass and composition of organic aerosol (OA) in the diluted and aged plume. In this study, we used a quasi-real atmospheric smog chamber system to conduct aging experiments and investigated the multiphase oxidation of primary organic aerosol (POA) and the formation of secondary organic aerosols (SOA) in residential biomass burning plumes. We found that the emissions in the gas and particle phases were interlinked during the plume evolution. During photochemical aging, more oxidized OA was produced, and SOA formation increased by a factor of 2 due to functionalization reactions of gaseous precursors such as furans, phenols, and carbonyls. On the other hand, dark aging resulted in a lower OA mass enhancement by a factor of 1.2, with weaker oxidation from gaseous reactions. Dark aging experiments resulted in the generation of substantial quantities of nitrogen-containing organic compounds in both gas and particulate phases, while photochemical aging led to a notable increase in the concentration of gaseous carboxylic acids. Our observations show that the properties of SOA are influenced by exposure to sunlight radiation and oxidants such as OH or NO3 radicals. These results reflect the aging process of BB plumes in real-world atmospheric conditions and highlight the importance of considering various aging mechanisms.

Enhanced corrosion resistance of ammonium heptamolybdate (AHM) sealed Li[sbnd]Al LDHs conversion coating on aluminum alloy

In this study, we prepared a hierarchical structured coating via a versatile two-step approach for the protection of 6N01 aluminum alloy. On the basis of as-prepared secondary alkane sulphonate (SAS) modified LiAl LDHs conversion coating (SLDH) by in-situ synthesis method, ammonium heptamolybdate (AHM) was introduced in the post-treatment to fabricate AHM@SLDH with enhanced corrosion resistance. The surface morphology, chemical composition and corrosion performance are characterized by means of scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS), etc. The hybrid coating has a persistence corrosion resistance in 3.5 wt% NaCl aqueous solution with protective efficiency of 99.64 %. As a highlight, a self-repairing function is detected in the immersion test, which is attributed to the weak oxidation function of Mo (VI). We believe that AHM@SLDH in-situ grown on aluminum substrate can provide a promising route for its corrosion prevention.

Study on the role of solution treatment on corrosion behavior of duplex lightweight steel in different environments

Diverse microstructure and complex application environments increases the uncertainty of the corrosion resistance of lightweight steels. The effect of solution treatment on the corrosion behavior of Fe–16Mn–10Al–1.5C–0.1Ti lightweight steel in Cl−, HSO3− and Cl−–HSO3− environments was investigated using electrochemical measurement, scanning electron microscope (SEM) and X–ray photoelectron spectroscopy (XPS). The lightweight steels are dominated by austenite and contain a small amount of ferrite. The increase in solution treatment temperature leads to more ferrite formation, but it has less effect on grain size. The decrease in austenite content results in more corrosion microcells and a porous oxide film; therefore, the corrosion resistance of the steel deteriorates with increasing temperature. In addition, in the Cl−–HSO3− environment, the synergistic effect of Cl− and HSO3− leads to the formation of a weak protective oxide film, resulting in a significant increase in corrosion rate compared to the Cl−and HSO3− environment.

Fe-Ni bimetallic adsorbent for efficient As2O3 removal from coal-fired flue gas under a wide temperature range: Experimental and DFT study

Adding metal oxides in the furnace can effectively control the emission of heavy metal arsenic in the coal-fired flue gas, and α-Fe2O3 has excellent adsorption performance. However, single metal oxides still have defects such as easy sintering or weak oxidation ability during use, which significantly impact the adsorption effect of arsenic. In this work, a new Fe-Ni bimetallic adsorbent was prepared by hydrothermal calcination, and its mechanism of As2O3 adsorption was investigated in depth through the combination of experiment and theory. The experimental results show that the FN8 (Ni-doped molar percentage is 8%) adsorbent exhibits excellent performance, and its arsenic adsorption capacity reaches 405.60 mg/kg, which is more than twice the adsorption capacity of α-Fe2O3. Ni doping can not only regulate the electron transfer between the α-Fe2O3 interface and As, but also promote the conversion of lattice oxygen to chemisorbed oxygen in the system. In the temperature range of 500 °C–900 °C, the prepared FN8 adsorbent can maintain a good microsphere structure, avoid sintering and provide more adsorption sites, and its arsenic capture capacity is stronger than α-Fe2O3. The density functional theory further reveals the microscopic mechanism of improving the oxidation performance of Fe-Ni adsorbent. The results show that Fe-Ni adsorbent has lower adsorption energy than α-Fe2O3. This is due to the synergism of Ni and O, which leads to the redistribution of electrons on the α-Fe2O3 (001) surface, and the Ni atom provides more free electrons for O atoms, which ultimately promotes the oxidation ability of Fe-Ni adsorbent and forms an As-O covalent bond. The Fe-Ni bimetallic composite adsorbent proposed in this work provides a new idea of bimetallic adsorbent for the effective adsorption of arsenic in the flue gas.

Suzuki-Miyaura Type Regioselective C-H Arylation of Aromatic Aldehydes by a Transient Directing Strategy.

Herein, we disclose a common approach for palladium-catalyzed direct coupling of the ortho-C-H bond of aromatic aldehydes with various organoboronic reagents by a transient directing strategy. In contrast to widely used cross-coupling reactions of C-H bonds with aryl halides, which generally need silver salt as a halide removal reagent, the method which used BQ/TFA as weak oxidation system for the PdII/Pd0 redox cycle is cost-effective, ecofriendly, and more aligned with green catalysis. This broadly applicable method opens up a new and efficient Suzuki-Miyaura coupling route for the direct formation of carbon-carbon bonds by C-H bond activation.

Influence of adding Nb on oxidation resistance of hypoeutectic high-chromium cast iron

This experiment investigates the effect of Nb on the oxidation resistance of high-chromium cast iron by adding different contents of Nb to high-chromium cast iron. The experimental results show that the oxidation resistance of high-chromium cast iron with the addition of 1 wt% Nb is increased by 43% compared with high-chromium cast iron without the addition of Nb, which may be related to the formation of a large area of weak oxidation area on the surface of high-chromium cast iron. When more than 2.5 wt% Nb is added to high-chromium cast iron, the oxidation resistance of high-chromium cast iron deteriorates significantly due to a large amount of Fe oxide formed around the Nb2O5. However, as the subsequent Nb content continues to increase to 5 wt%, the oxidation resistance of high-chromium cast iron is improved compared to 2.5 wt% Nb because the dispersion of NbC in the matrix decreases.

Clarification of the role of singlet oxygen for pollutant abatement during persulfate-based advanced oxidation processes: Co3O4@CNTs activated peroxymonosulfate as an example

Singlet oxygen (1O2) has often been identified by the popularly used quenching method as a more important reactive species (RS) than sulfate radicals (SO4•−) and hydroxyl radicals (•OH) for pollutant abatement during persulfate-based advanced oxidation processes (PS-AOPs), especially those activated by carbon-based catalysts. However, latest studies have demonstrated that the quenching method actually can often mislead the interpretations of the role of RS for pollutant abatement during AOPs due to various confounding effects caused by adding high-concentration quenchers in the system. To clarify the role of 1O2 in PS-AOPs, this study developed a probe compound-based experimental and kinetic model to quantify the concentrations and exposures of 1O2, SO4•−, and •OH, as well as their relative contributions to pollutant abatement during a cobalt oxide incorporated carbon nanotubes activated peroxymonosulfate (Co3O4@CNTs/PMS) process. Results show that during the Co3O4@CNTs/PMS process, the exposures and transient concentrations of 1O2 were about 19.6 and 41.3 times higher than those of SO4•− and •OH, respectively. However, the relative contribution of 1O2 to the abatement of most pollutants tested in this study (e.g., sulfisoxazole, sulfamethoxyprazine, trimethoprim, and metoprolol) is generally negligible (f1O2 ≤ 8%) compared to that of SO4•− and •OH (fSO4•− = 15%−98% and f•OH = 2%−78%) because of the significantly lower reactivity of 1O2 with these compounds than that of SO4•− and •OH. Reasons for misidentifying 1O2 as the dominant RS for pollutant abatement by the quenching method were then analyzed based on reaction kinetics principles. The results of this study highlight that while 1O2 can be generated in significant amounts and be present at higher concentrations than SO4•− and •OH in PS-AOP systems, 1O2 is unlikely to be the dominant RS for the abatement of most pollutants during the PS-AOPs because of its weak and selective oxidation capacity, and caution should be taken when using the quenching method to evaluate the role of RS for pollutant abatement by the PS-AOPs.

Sedimentary Environment and Organic Matter Enrichment Model of Saline Lake Source Rock in the Linhe Depression, Hetao Basin, China

The well-developed mudstone and gypsum mudstone in the Oligocene Linhe Formation (E3l) in the Hetao Basin are the main source rocks for gypsum. However, the sedimentary environment and organic matter (OM) enrichment factors of E3l are not clear, and this inhibits the prediction of hydrocarbon source rock distribution and resource calculation. Major and trace elements, total organic carbon (TOC), pyrolysis using the Rock-Eval II, and saturated hydrocarbon gas chromatography–mass spectrometry (GC–MS) analyses were performed in this study. The results show that E3l was deposited in brackish water and saline–ultrasaline water, with weak oxidation reduction in an arid and hot environment. Terrestrial input inhibits OM enrichment, while the redox, paleosalinity, paleoclimate, and paleoproductivity play a catalytic role. The main controlling factors of the same lithologic source rocks are different: terrestrial input and paleoclimate have a greater impact on mudstone, and the redox and paleosalinity were more favorable to gypsum mudstone. Although the main controlling factors are different for different lithologies, their OM enrichment characteristics are still consistent. The E3l water body was deep, and the contribution of nutrients from terrigenous debris to OM enrichment was less. In addition, the water retention environment changed significantly during the E3l sedimentary period, resulting in fewer nutrients, which limited the improvement of surface water paleoproductivity. The arid climate increased water evaporation and salinity, which to some extent prevented consumption and decomposition. Weak oxidation-reduction fluctuations and the stratification of the water body were obvious, and this was not only conducive to the enrichment of OM but also to its preservation.

Proteinaceous Matter in PM2.5 in Suburban Guiyang, Southwestern China: Decreased Importance in Long‐Range Transport and Atmospheric Degradation

AbstractProteinaceous matter (PrM) is a substantial constituent in bioaerosols. However, the sources and atmospheric processes of PrM remain large uncertainties. The characterizations, sources, and potential atmospheric processes of free amino acids (FAAs) and combined amino acids (CAAs) were investigated via a set of 1‐year fine particle (PM2.5) samples collected in suburban Guiyang (a hilly basin area in Southwest China). The annual average concentrations of FAAs and CAAs were 156.31 ± 41.52 and 315.36 ± 147.66 ng m−3, respectively. The dominant FAA and CAA species were proline, which was different from previous observations with glycine as a major species. The results indicated that the sources or atmospheric processes of aerosol PrM at this study site were different from previous observations in the urban and suburban areas. The analysis of AA‐nitrogen isotope compositions and air mass back trajectories suggested that the abundances of aerosol FAAs and CAAs were highly controlled by primary sources (particularly plants) with less impact from long‐range transport. Furthermore, the contributions of PrM degradation by ozone‐ and hydroxyl radical‐related processes to total FAAs were found to be minor. The overall results suggested that the long‐range transport and atmospheric degradation of PrM were insignificant factors affecting aerosol PrM abundance in this suburban area with the weak atmospheric oxidation capacity, high cloud cover rate, and frequent precipitation. Thus, the findings improve our understanding of the sources and atmospheric processes of aerosol PrM.

Effect of CO2 and methyl groups reaction kinetics on the ignition and combustion of diesel surrogate fuel: Part Ⅰ. Reaction mechanisms

The study aims to examine the impact of CO2 concentration gradient on the ignition and combustion of a diesel surrogate fuel composed of 70% C7H16 and 30% C7H8. The investigation focuses on the weak oxidation of CO2 through its reaction with methyl groups (CH, CH2, and CH3 radicals). Firstly, the molecular bond-breaking recombination process between CO2 and methyl groups is calculated using Born-Oppenheimer molecular dynamics with the UB3LYP/6–311++g (d, p) level of theory. Subsequently, the electronic distribution and competition of the molecule surface are analyzed through various wave function analyses to identify the reactive sites. Secondly, the precise potential energy surface and reaction rate are calculated based on the acquired reaction process information. This calculation employs the B2PLYP/def2-TZVP level of theory and transition state theory. Finally, extensive molecular dynamics simulations of CO2 and methyl groups are conducted using reaction force fields. These simulations provide insights into the temperature-energy variation within the system and the resulting chemical reaction network. The optimized combustion mechanism for the binary fuel is derived, focusing exclusively on the influences of CO2 and O2 while excluding those of N2 and other extraneous gases. The results demonstrate exothermic reactions of CO2 with CH and CH2 radicals at 850 K, yielding ΔG values of −238.91 kJ/mol and −209.96 kJ/mol, respectively. Conversely, CO2 reacts with CH3 radicals in heat-absorbing reactions at 850 K, resulting in a ΔG of 491.73 kJ/mol. Additionally, the chemical impact of CO2 exhibits both promotional and inhibitory effects on combustion. The CO2 molecule exhibits weak oxidation properties due to the presence of active sites on its surface characterized by minimal values of electrostatic potential (-50.17 kJ/mol) and average local ionization energy (61.92 kJ/mol) at the O-atomic end. The molecular dynamics process involving the methyl groups and CO2 system exhibits a heat absorption phenomenon. This behavior can be attributed to the participation of CO2 not only in the reactions with methyl groups but also with formaldehyde and ethylene, among others.

Geochemical Characteristics and Development Model of the Coal-Measure Source Rock in the Kuqa Depression of Tarim Basin

The development model of the coal-measure source rock may be different from that of the lacustrine source rock. The depositional environment of the coal-measure source rock is dominated by weak oxidation and weak reduction, and the majority of the organic material originates from terrestrial higher plants. Taking the Jurassic coal-measure source rock in the Kuqa Depression as the research object, the geochemical characteristics of the source rock are comprehensively analyzed, the primary controlling elements of source rock development are made clear, and the development model of the coal-measure source rock is established. This study contributes to the field of source rock prediction and oil and gas exploration. The lithology of the coal-measure source rock in the Kuqa Depression is mainly mudstone, carbonaceous mudstone, and coal, which are medium- to good-quality source rocks, and the organic matter type is mainly II2 and III. Terrestrial organic matter is a key factor in controlling the formation of coal-measure source rocks, and the sedimentation rate also has a certain influence. The redox degree of the depositional environment, water salinity, and clay mineral content has little influence on the development of coal-measure source rocks. By integrating the main control factors, the development model of the coal-measure source rock is established. It is considered that the development model and distribution characteristics of the coal-measure source rock are different from the traditional understanding of lacustrine source rocks, and it is pointed out that the coal-measure source rock in the gentle slope zone is more developed than the sag area.