Sulfur-containing Pollutants Research Articles

An Expanded Substrate Spectrum of Sulfide:Quinone Oxidoreductase Found in Pollutant-Degrading Bacteria.

Sulfide:quinone oxidoreductase (Sqr) catalyzes the initial procedure on sulfide transformation, alongside sulfide (H2S, S2-) oxidization coupled with coenzyme Q (CoQ) reducing and reactive sulfur species (RSS) production. Here, we assessed the reactivity of propanethiol (PT) as an alternative substrate for Sqr to maintain intracellular homeostasis in strain S-1 capable of degrading emerging sulfur-containing pollutants. We deleted a gene encoding Sqr, and serial transcriptional difference induced by RSS dynamics was therefore revealed. Next, the reaction properties of two Sqr homologs from strains JMP134 and S-1 were comparatively characterized, respectively. As a result, an additional role of Sqr in yielding RSS from PT was found in reaction mixture prepared by cell-free extracts or purified enzymes. Interestingly, the transformation velocity of PT by Sqr was slower than that of sulfides. From this scenario, it was a rate-determining step that PT as a nucleophilic compound can be added into Sqr cysteine to form disulfide bond and likely serve nonoptimal sulfur recipient. In addition, the role of persulfidation driven by RSS in combating oxidative and sulfur stresses required to be further clarified. Nevertheless, this promiscuity of Sqr-binding organosulfur compounds and its catalytic modulation underscored that expanded substrates might benefit sulfide homeostasis in thiol-degrading bacteria.

Boosting catalytic hydrolysis of carbonyl sulfide over K+ modified CeO2 nanospheres at low-temperature

Carbonyl sulfide (COS) as one of typical atmospheric sulfur-containing pollutants widely emitted from various industrial processes, which has a significant impact on human health and environmental safety. Currently, developing highly efficient catalysts to eliminate COS is of great significance for both fundamental catalytic research and actual industrial application. Here we report a series of K+ doping spherical cerium oxide (CeO2-S) that showing promote activity for catalytic hydrolysis of COS. The research results demonstrated that the K+-doped CeO2-S formed more Ce3+ and oxygen vacancies than CeO2-S. The hydrolysis activity and stability of CeO2-S for COS were significantly improved by the introduction of K+. Among them, the 0.2 K/CeO2-S showed the optimal performance. Further in-situ DRIFTS results revealed that a slight increase in alkalinity could enhanced the activation of H2O over 0.2 K/CeO2-S, and the generated surface active hydroxyl groups reacted with adsorbed COS to produce the intermediate species (HSCO2-), leading to the formation of H2S and CO2. The catalysts prepared in this paper exhibited promoted activity with low-temperature and high stability for COS hydrolysis, which is beneficial for practical industrial scale-up applications and provides novel insights into designing efficacious catalysts with efficient low-temperature activity and superior stability for removing COS.

Sulfur migration mechanism of pig manure in supercritical water: A combined experimental and DFT study

Pig manure (PM) is a high concentration organic waste rich in sulfur, and its biofuel contains various sulfur-containing pollutants, which reduces the safety of the products. Supercritical water (SCW) can dissolve most organic matter, which is a technology worthy of further study. In order to reduce sulfur pollution in the process of PM resource utilization and better control the conversion path of sulfur, it is necessary to explore the migration mechanism of sulfur in the whole PM-SCW gasification process. The experimental results indicated that H2S was the only gaseous product. Only inorganic compounds (S2-, S2O32- and SO42-) were detected in the liquid. Sulfur in the solid mainly included thiol/thioether, thiophene and sulfone. The influence of different reaction conditions (temperature, residence time, PM concentration and catalysts) on sulfur migration was studied in a batch reactor. It was worth noting that the catalysts had a significant effect on H2S absorption. The lowest H2S yield was 3.2 * 10−4 mol/kg and more than 70% of the sulfur was distributed in the liquid under the condition of addition of K2CO3. While, the RTH2110 fixed most of the sulfur of PM (the maximum value reached 50.94%) in the solid. Thus, adding the catalysts flexibly can choose composition of the products. Furthermore, six possible pathways of sulfur migration in the solid were designed and the kinetic parameters were calculated by density functional theory (DFT). The results provided a basis for controlling sulfur in PM. Subsequently, the sulfur migration pathways during PM-SCW gasification process were comprehensively summarized through the combination of experiment and DFT. It provided a method for sulfur treatment in PM, which had guiding significance for the realization of pollution-free treatment of PM.

Hydrogen Sulfide Splitting into Hydrogen and Sulfur through Off-Field Electrocatalysis.

Hydrogen sulfide (H2S), a toxic gas abundant in natural gas fields and refineries, is currently being removed mainly via the Claus process. However, the emission of sulfur-containing pollutants is hard to be prevented and the hydrogen element is combined to water. Herein, we report an electron-mediated off-field electrocatalysis approach (OFEC) for complete splitting of H2S into H2 and S under ambient conditions. Fe(III)/Fe(II) and V(II)/V(III) redox mediators are used to fulfill the cycles for H2S oxidation and H2 production, respectively. Fe(III) effectively removes H2S with almost 100% conversion during its oxidation process. The H+ ions are reduced by V(II) on a nonprecious metal catalyst, tungsten carbide. The mediators are regenerated in an electrolyzer at a cell voltage of 1.05 V, close to the theoretical potential difference (1.02 V) between Fe(III)/Fe(II) and V(II)/V(III). In a laboratory bench-scale plant, the energy consumption for the production of H2 from H2S is estimated to be 2.8 kWh Nm-3 H2 using Fe(III)/Fe(II) and V(II)/V(III) mediators and further reduced to about 0.5 kWh Nm-3 H2 when employing well-designed heteropolyacid/quinone mediators. OFEC presents a cost-effective approach for the simultaneous production of H2 and elemental sulfur from H2S, along with the complete removal of H2S from industrial processes. It also provides a practical platform for electrochemical reactions involving solid precipitation and organic synthesis.

Cu/Biochar Bifunctional Catalytic Removal of COS and H2S:H2O Dissociation and CuO Anchoring Enhanced by Pyridine N.

Economic and environmentally friendly strategies are needed to promote the bifunctional catalytic removal of carbonyl sulfide (COS) by hydrolysis and hydrogen sulfide (H2S) by oxidation. N doping is considered to be an effective strategy, but the essential and intrinsic role of N dopants in catalysts is still not well understood. Herein, the conjugation of urea and biochar during Cu/biochar annealing produced pyridine N, which increased the combined COS/H2S capacity of the catalyst from 260.7 to 374.8 mg·g-1 and enhanced the turnover frequency of H2S from 2.50 × 10-4 to 5.35 × 10-4 s-1. The nucleophilic nature of pyridine N enhances the moderate basic sites of the catalyst, enabling the attack of protons and strong H2O dissociation. Moreover, pyridine N also forms cavity sites that anchor CuO, improving Cu dispersion and generating more reactive oxygen species. By providing original insight into the pyridine N-induced bifunctional catalytic removal of COS/H2S in a slightly oxygenated and humid atmosphere, this study offers valuable guidance for further C═S and C-S bond-breaking in the degradation of sulfur-containing pollutants.

Effect of electromagnetic induction drying on the drying–incineration process of dyeing sludge: focus on migration and conversion of sulfur

Secondary sulfur pollution in dyeing sludge (DS) during drying and incineration is a major environmental problem necessitating in-situ control. To robustly immobilise sulfur during drying–incineration, the authors introduce an electromagnetic induction (EMI) drying method and reveal the corresponding migration and conversion of sulfur in DS. The EMI-drying efficiency reached 10.69%/min, five times that of thermal drying. EMI drying increases the relative sulfoxide ratio from that of thermal drying. In a sludge–sulfur model, the proposed treatment promoted the oxidation and decomposition of organic sulfur without noticeably affecting the inorganic sulfur. The selective oxidation process during EMI drying promotes sulfur stabilisation in dried DS, decreasing the performance and stability of DS combustion. The sulfur-containing pollutants released during the incineration of DS mainly contain H2S, followed by CH3SH and SO2. EMI drying increases the outputs of SO2 and CH3SH but decreases the outputs H2S and total sulfur compared with the outputs of thermal drying. Under the sulfur-model conditions, EMI promoted the conversion of inorganic sulfur to sulfur-containing gases (especially H2S) during incineration. In contrast, the sulfur stabilised by partial oxidation of organic sulfur in the EMI-dried DS was not easily converted to gaseous sulfur during subsequent combustion. Overall, EMI inhibits the release of sulfur during the combined drying–incineration process of DS.

Influence of Carbonization Conditions on Structural and Surface Properties of K-Doped Mo2C Catalysts for the Synthesis of Methyl Mercaptan from CO/H2/H2S.

The cooperative transition of sulfur-containing pollutants of H2S/CO/H2 to the high-value chemical methyl mercaptan (CH3SH) is catalyzed by Mo-based catalysts and has good application prospects. Herein, a series of Al2O3-supported molybdenum carbide catalysts with K doping (denoted herein as K-Mo2C/Al2O3) are fabricated by the impregnation method, with the carbonization process occurring under different atmospheres and different temperatures between 400 and 600 °C. The CH4-K-Mo2C/Al2O3 catalyst carbonized by CH4/H2 at 500 °C displays unprecedented performance in the synthesis of CH3SH from CO/H2S/H2, with 66.1% selectivity and a 0.2990 g·gcat-1·h-1 formation rate of CH3SH at 325 °C. H2 temperature-programmed reduction, temperature-programmed desorption, X-ray diffraction and Raman and BET analyses reveal that the CH4-K-Mo2C/Al2O3 catalyst contains more Mo coordinatively unsaturated surface sites that are responsible for promoting the adsorption of reactants and the desorption of intermediate products, thereby improving the selectivity towards and production of CH3SH. This study systematically investigates the effects of catalyst carbonization and passivation conditions on catalyst activity, conclusively demonstrating that Mo2C-based catalyst systems can be highly selective for producing CH3SH from CO/H2S/H2.

Release characteristics of chromium and sulfur during cothermal disposal of waste tires and sludge: An experimental and DFT study

Chromium (Cr) and sulfur-containing pollutants (S) are released during thermal disposal of municipal sludge (MS) and waste tires (WTs). In this paper, the effects of the mixing ratio, temperature, atmosphere, and CaO on Cr release were determined, and the mechanism for Cr trapping during CaO sulfation was revealed with density functional theory (DFT). The MW (MS and WTs) thermal decomposition behavior, sulfur-containing pollutant release, and kinetic parameters were analyzed. The results showed that the thermal disposal of MW at 850 °C under flue gas immobilized the Cr, and the relative enrichment (RE) for Cr reached 92.66 % when the proportion of WTs was 50 %. DFT calculations revealed the effect of CaO sulfation on Cr adsorption. The energies for CrOOH adsorption on the (001) surface of CaO, and the (001) surface of CaSO4 decreased sequentially. The products of the CrOOH transformations in the flue gas, CrCl3 and CrO2Cl2, also diminished in that order for the corresponding surfaces. Typical decomposition steps were observed, including volatilization of water and small hydrocarbons, cracking of hydrocarbons, and transformations of inorganic materials at higher temperatures. H2S, SO2, CH3SH, and COS were the main sulfur-containing pollutants released during thermal disposal.

Bifunctional Cobalt–Nickel Sulfide Nanoflowers as Electrocatalysts for Concurrent Energy-Efficient Hydrogen Production and Sulfur Recycling

Electrocatalytic water splitting is an important approach for sustainable and green production of hydrogen but is greatly hampered by the sluggish oxygen evolution reaction (OER). Therefore, developing a favorable alternative reaction to replace OER for both energy-efficient coproduction of hydrogen and value-added chemicals is highly desirable. Herein, a thermodynamically favorable sulfion oxidation reaction (SOR) electrocatalyzed by CoNi2S4 nanoflowers (CoNi2S4 NFs) is reported to couple with the hydrogen evolution reaction (HER) for energy-efficient hydrogen production and sulfur recovery. In this coupled system, only a low cell voltage of 0.3 V is required to produce hydrogen at 10 mA cm–2, much lower than that of water splitting (1.76 V). Meanwhile, S2– ions are selectively electrooxidized to sulfur with a high yield of 220.5 g h–1 m–2, realizing electrochemical upcycling of sulfur-containing pollutants. This strategy provides an attractive route for both energy-effective hydrogen generation and sulfur recycling.

Mechanism of sulfur migration and conversion in pyrolysis/combustion staged conversion process of high sulfur coal

To investigate the effects of circulating ash heat carriers and dolomite catalysts on sulfur migration in the coal pyrolysis/circulating fluidized bed combustion staged conversion process, five experiments of coal pyrolysis, ash/coal co-pyrolysis, coal pyrolysis catalyzed by dolomite, ash/coal co-pyrolysis catalyzed by dolomite and combustion of pyrolysis solid products were designed and carried out. By examining the effects of pyrolysis temperature, heating rate, coal-ash ratio and dolomite species on sulfur migration, the final distribution of sulfur-containing pollutants throughout the staged conversion process was systematically analyzed. The results showed that the separate mixing of ash heat carrier at final pyrolysis temperature of 600 °C increased the residual sulfur in solid phase from 79.29 % of raw coal pyrolysis to 90.00 %. When dolomite catalyst was added individually, the sulfur released into gas phase and tar was reduced from 18.28 % and 2.43 % of the raw coal to 13.14 % and 1.94 %, respectively. And Fe additive significantly improved sulfur resistance of the dolomite catalyst. The regeneration process has little effect on the sulfur fixation capacity of natural dolomite. When ash heat carrier and dolomite catalyst were simultaneously added to the system, the sulfur fixed in ash increased from 79.29 % of the raw coal to 91.27 %, and the sulfur fixed in natural dolomite and modified dolomite accounted for 4.32 % and 4.46 % of the total sulfur, respectively. In the combustion experiments of pyrolysis solid phase products, 43.57 %, 65.57 % and 61.44 % of sulfur was retained in the solid phase residue after combustion with circulating ash, circulating ash/natural dolomite and circulating ash/modified dolomite were added, respectively. Compared with direct combustion of coal, the staged conversion process resulted in a 55 % reduction of sulfur in the boiler flue gas. This study provides a theoretical basis for the purification of sulfur-containing pollutants in the staged conversion process.

The influence of lanthanum (La) promoter on Mo/Al2O3 for the catalytic synthesis of methyl mercaptan (CH3SH) from COS/H2/H2S

The cooperative transition of sulfur-containing pollutants of COS/H2S/H2 to the chemical feedstock of methyl mercaptan (CH3SH) catalyzed by Mo-based catalysts has good application prospects. However, the role of rare earth elements as promoters in this reaction system has not been investigated currently. In this study, the effects of the rare earth of lanthanum (La) on the catalytic performance of Mo-based catalysts were investigated by XRD, Raman, TEM, H2-TPR, and XPS characterizations. The results showed that the addition of La species led to the formation of larger particle size and lower sulfidation degree of Mo species, but the higher, rather than lower, catalytic activity was obtained. This unusual phenomenon is confirmed to be due to the generation of La2(MoO4)3 crystals covered with surface MoS2 layers caused by the interaction of Mo oxide and La species at the sulfidation atmosphere. The presence of La2(MoO4)3 changes the electronic and chemical environment of MoS2 in the catalyst, which lead a positive effect on the catalytic activity, outweighing the negative effect caused by the larger particle size of Mo species and the reduced sulfidation.

Thermodynamic study of regenerative barium-based materials towards barium sulfide for catalytic sulfur dioxide reduction

Flue gas with high SO2 content presents a series of human health and environmental problems, which prompted Flue Gas Desulfurization (FGD) technologies widely utilised in industries. However, the conventional FGD using absorbents or adsorbents could generate secondary sulfur-containing pollutants. Thus, a regenerative FGD reaction system that eliminates secondary pollutants while recovering valuable S has been researched. Ba-based materials, viz. Ba(OH)2, BaCO3 and BaO as the precursors, are involved in a regenerative BaS/BaSO4 reaction system of this research. Current thermodynamic study via minimization of Gibbs free energy explored the feasibility of BaS production from these Ba-based materials and reviewed its potential in SO2 reduction to S. Formation of BaS from Ba-based materials was feasible but the yield depends strongly on the temperature and sulfidizing agent used. Compared to BaCO3-systems, Ba(OH)2- and BaO-systems showed better performance in BaS synthesis due to their high equilibrium conversion, even at temperatures< 773 K. Besides, H2S is a better sulfidizing agent for BaS synthesis due to higher BaS yield (maximum 99%). Synthesis routes of different Ba-systems were confirmed by their respective Keq profiles. The feasibility of BaS catalyst in SO2 reduction to S was proven by the excellent SO2 reducing activity and high S yield (100%) at 273 – 1173 K with S8 and S2 as major products. BaS regeneration via H2 was also validated by high BaS yield (100%) at 473 – 1273 K.

Mild Oxidation of Organosulfur Compounds with H2O2 over Metal-Containing Microporous and Mesoporous Catalysts

Mild catalytic oxidation of thioethers and thiophenes is an important reaction for the synthesis of molecules with pharmaceutical interest, as well as for the development of efficient processes able to remove sulfur-containing pollutants from fuels and wastewater. With respect to the green chemistry principles, hydrogen peroxide (H2O2) is the ideal oxidant and the Me-containing porous materials (Me = Ti, V, Mo, W, Zr) are among the best heterogeneous catalysts for these applications. The main classes of catalysts, including Me-microporous and mesoporous silicates, Me-layered double hydroxides, Me-metal–organic frameworks, are described in this review. The catalytic active species generated in the presence of H2O2, as well as the probable oxidation mechanisms, are also addressed. The reactivity of molecules in the sulfoxidation process and the role played by the solvents are explored.

Influence of atmospheric conditions on the role of trifluoroacetic acid in atmospheric sulfuric acid–dimethylamine nucleation

Abstract. Ambient measurements combined with theoretical simulations have shown evidence that the tropospheric degradation end-products of Freon alternatives, trifluoroacetic acid (TFA), one of the most important and abundant atmospheric organic substances, can enhance the nucleation process based on sulfuric acid (SA) and dimethylamine (DMA) in urban environments. However, TFA is widespread all over the world under different atmospheric conditions, such as temperature and nucleation precursor concentration, which are the most important factors potentially influencing the atmospheric nucleation process and thus inducing different nucleation mechanisms. Herein, using the density functional theory combined with the Atmospheric Cluster Dynamics Code, the influence of temperature and nucleation precursor concentrations on the role of TFA in the SA–DMA nucleation has been investigated. The results indicate that the growth trends of clusters involving TFA can increase with the decrease in temperature. The enhancement on particle formation rate by TFA and the contributions of the SA–DMA–TFA cluster to the cluster formation pathways can be up to 227-fold and 95 %, respectively, at relatively low temperature, low SA concentration, high TFA concentration, and high DMA concentration, such as in winter, at the relatively high atmospheric boundary layer, or in megacities far away from industrial sources of sulfur-containing pollutants. These results provide the perspective of the realistic role of TFA in different atmospheric environments, revealing the potential influence of the tropospheric degradation of Freon alternatives under a wide range of atmospheric conditions.

Mechanism study and determination kinetic of catalytic oxidation of mercaptans in Merox process

Sulfur-containing pollutants lead to reduced quality of end products and environmental problems. Mercaptans are one of those sulfur pollutants which not only are smelly and toxic but also have high corrosive property. Mercaptan catalytic oxidation is the most important method of oil production refining from mercaptan. Thus, cognition of the reaction kinetics and interrogation of effects of various factors on the process are of the most requirements of mercaptan removing units. Due to the inadequate efforts made on reaction kinetics determination of catalytic oxidation of light mercaptans available in liquefied petroleum gas (LPG), this study was done in this regards. First, rate-determining step (RDS) of reactions was determined by analyzing the experimental data obtained from the Merox unit. The experiments were carried out on a cobaltphthalocyanine liquid catalyst in a packed reactor. In order to better understand the process, design, and optimization, the kinetics were defined with respect to the limiting reaction. By investigating the effective parameters of the kinetics, it was determined that the mercaptide ion (RS-) confines the oxidation reaction rate and has the first order in the rate equation. Finally, optimal values were proposed for each of the parameters.

Release behaviors of sulfur-containing pollutants during combustion and gasification of coals by TG-MS

Sulfur-containing pollutants are released during coal thermal conversion processes and must be controlled to satisfy the requirements of industrial production and protect the environments. This study investigated the release behaviors of sulfur species in Zhundong (ZD) coal during combustion and gasification. H2O-washed ZD coal and Shenmu (SM) coal were also investigated as reference samples to compare with ZD coal and to obtain general release properties. The experiments were carried out using online thermogravimetric analysis coupled with mass spectrometry. Theoretical calculation of the released gas was obtained by a novel method and equivalent characteristic spectrum analysis. The mass flow rate, the release proportion and the release temperature range of individual sulfur-containing pollutant were evaluated. The results show that water washing process did not change the combustion reactivity and the sulfur release temperature ranges of ZD coal, but the maximum gasification rate and the SO2 release rate were decreased. H2S, COS and SO2 were observed in gasification of the coals, while COS and SO2 were observed in combustion. SO2 was always the main sulfur-containing gaseous product in both combustion and gasification. Some sulfur starts to release as SO2 at high temperature (at about 1000 °C for ZD coal and H2O-washed ZD coal, and at about 1100 °C for SM coal) due to the decomposition of sulfate, at which temperature carbon had already burned out in combustion, and the coal conversion in gasification reached about 90%. With combustion temperature lower than 1000 °C, the release of SO2 from ZD coal, H2O-washed ZD coal and SM coal can be decreased by 46.14%, 38.95% and 4.36%, respectively. With gasification temperature lower than 1000 °C, few SO2 from ZD coal and H2O-washed ZD coal and SM coal can be released. It was observed that the releases of sulfur species were related to their occurrence, reaction evolution, temperature and atmosphere. Controlling the temperature is helpful in reducing the release of SO2 in both combustion and gasification. This work also shows that it is possible to achieve high carbon conversion of ZD coal gasification at a moderate temperature and simultaneously reduce the release of sulfur.

Effect of ash and dolomite on the migration of sulfur from coal pyrolysis volatiles

For investigating the effectiveness of ash and dolomite on the migration of sulfur from coal pyrolysis volatiles, pyrolysis experiments of Xinzhou high-sulfur bitumite were executed in a self-designed reactor. The influences of heat carrier species, mass ratios of ash to coal, and ash particle sizes on the sulfur content in products were investigated. More importantly, the composition of sulfur-containing compound in tar was analyzed. The effect of different heat carriers on the volatiles was in the order of ash > fresh dolomite > deactivated dolomite. With ash and dolomite as heat carriers, H2 and CO decreased, and CO2 increased. In addition, H2S content was positively correlated with H2 content. The deactivated dolomite contains a large amount of CaS and MgS, and its influence on pyrolysis volatiles was weaker than that of fresh dolomite and CFB ash. When fresh and deactivated dolomites were used as heat carriers, the sulfur contents in tar and in heat carrier were higher than that in ash. Fe2O3, CaO, and MgO were the main components for sulfur fixation and tar catalysis in heat carriers. Mercaptan was easily oxidized by metal oxides. Ash and dolomite heat carriers had a certain catalytic effect on the cleavage reactions of thiopyrans and thiazoles. This research is worth for the purification of sulfur-containing pollutants in coal pyrolysis process by ash and dolomite.

Effects of Hydrothermal Modification on Sulfur Release of Low-Quality Coals During Thermal Transformation Process

In this paper, the effects of hydrothermal modification on sulfur-containing pollutants, such as sulfur dioxide (SO2) and carbonyl sulfide (COS), during coal pyrolysis and combustion, have been investigated. Three typical Chinese low-quality coals, Zhundong, Yimin, and Zhaotong coal (ZT), have been treated by hydrothermal modification at final modification temperatures of 200 °C, 250 °C, and 300 °C. Coal pyrolysis and combustion experiments using raw coal and modified coals were performed using a tube furnace. Results showed that SO2 and COS emission were suppressed after hydrothermal modification in the pyrolysis process. Lower emission of both SO2 and COS were also achieved when final hydrothermal modification was increased, this was attributed to the loss of aliphatic sulfur, e.g., sulfoxide, sulfone, and thiother, during the modification process. For ZT, hydrothermal modification also caused a delay in the release of sulfur-containing gases. In combustion experiments, hydrothermal modification reduced the SO2 emission for Yimin coal, but for ZT, the SO2 release amount almost doubled, and for Zhundong coal (ZD), it also increased, after hydrothermal modification. Hydrothermal modification also caused a delay in peak SO2 emission during the combustion of ZT; this is attributed to conversion of sulfur containing structures to stable aromatic compounds through hydrothermal modification.

Modern Views on the Influence of Gaseous Sulfur-Containing Toxicants on Homeostasis

Dynamic balance is important for maintaining the body. The main goal of the work is to study the effect of gaseous sulfur-containing toxicants on homeostasis. The author used various theoretical methods to achieve this goal. The author presented and summarized the literature data on the effect of sulfur-containing gaseous toxicants on humans under environmental conditions, as well as on exposure to animals of different concentrations (in H2S) and for different time periods (modeling of acute and chronic experiments). The obtained information will help to analyze the mechanisms underlying the development of the pathology of various organs and systems, to study the pathogenetic principles of the action of a number of protectors. These conclusions will further expand knowledge of the degree of severity of the effects of sulfur-containing pollutants in the postnatal development stages, systematize the nature of changes in the components of the peripheral and central parts of the erythron in the recovery period after intoxication, and use the most point protectors in pathogenetic terms.

Biotransformation of nitrogen- and sulfur-containing pollutants during coking wastewater treatment: Correspondence of performance to microbial community functional structure

Although coking wastewater is generally considered to contain high concentration of nitrogen- and sulfur-containing pollutants, the biotransformation processes of these compounds have not been well understood. Herein, a high throughput functional gene array (GeoChip 5.0) in combination with Illumina MiSeq sequencing of the 16S rRNA gene were used to identify microbial functional traits and their role in biotransformation of nitrogen- and sulfur-containing compounds in a bench-scale aerobic coking wastewater treatment system operated for 488 days. Biotransformation of nitrogen and sulfur-containing pollutants deteriorated when pH of the bioreactor was increased to >8.0, and the microbial community functional structure was significantly associated with pH (Mantels test, P < 0.05). The release of ammonia nitrogen and sulfate was correlated with both the taxonomic and functional microbial community structure (P < 0.05). Considering the abundance and correlation with the release of ammonia nitrogen and sulfate, aromatic dioxygenases (e.g. xylXY, nagG), nitrilases (e.g. nhh, nitrilase), dibenzothiophene oxidase (DbtAc), and thiocyanate hydrolase (scnABC) were important functional genes for biotransformation of nitrogen- and sulfur-containing pollutants. Functional characterization of taxa and network analysis suggested that Burkholderiales, Actinomycetales, Rhizobiales, Pseudomonadales, and Hydrogenophiliales (Thiobacillus) were key functional taxa. Variance partitioning analysis showed that pH and influent ammonia nitrogen jointly explained 25.9% and 35.5% of variation in organic pollutant degrading genes and microbial community structure, respectively. This study revealed a linkage between microbial community functional structure and the likely biotransformation of nitrogen- and sulfur-containing pollutants, along with a suitable range of pH (7.0–7.5) for stability of the biological system treating coking wastewater.