Characterization of apparent sulfur oxidation activity of thermophilic archaea in bioleaching of chalcopyrite

The apparent sulfur oxidation activities of four pure thermophilic archaea, Acidianus brierleyi （JCM 8954）, Metallosphaera sedula （YN 23）, Acidianus manzaensis （YN 25） and Sulfolobus metallicus （YN 24） and their mixture in bioleaching chalcopyrite were compared, which were characterized indirectly by the evolution of the cells concentration, pH value and sulfate ions concentration in solution. The results show that the mixed culture contributed significantly to the raising of leaching rate, which suggests that the mixed culture had a higher sulfur oxidation activity than the pure culture. Meanwhile, the results also indicate that the changes of parameters characterizing the sulfur oxidation activity of thermophilic archaea are often influenced by many factors, so it is hard to reflect accurately the specific sulfur oxidation activities among the different sulfur-oxidizing microbes when bioleaching chalcopyrite at different conditions. Accordingly, an efficient method to characterize microbial sulfur oxidation activity appears to be desirable.

Tailorable Multi-Photoresponsive Behavior Triggered by Different Sulfur Oxidation States

Photoresponsive materials are considered as promising systems for intelligent technology applications owing to the contactless spatial and temporal control.Herein,controllable multi-photoresponsive behaviors are realized in benzo[b]thiophene derivatives(o-DMP-S,o-DMP-SO,and o-DMP-SO_(2))by modulating the sulfur oxidation state.Among them,o-DMP-S is photo-unreactive but possesses denser molecular packing upon ultraviolet(UV)light irradiation,exhibiting photoenhanced room-temperature phosphorescence properties.Through stoichiometric oxidation of the sulfur atom in o-DMP-S,the resulting sulfoxide compound o-DMP-SO undergoes a radical photolysis reaction involving photodeoxygenation and photochemical rearrangement,thereby leading to the photomechanical effect.The sulfone compound o-DMP-SO_(2)displays prominent reversible photochromism,resulting from the radical photocyclization under 365 nm UV light irradiation.Based on comprehensive experimental and computational investigations,the diverse photoresponsive behaviors of these benzo[b]thiophene derivatives are demonstrated to depend on the intersystem crossing efficiency and radical-mediated photochemical reaction activity in excited states due to the different sulfur oxidation states.This work provides an insightful understanding of the relationship between molecular structure and photoresponsive behavior and opens up the opportunity for the development of photoresponsive materials with potential applications.

Electrogenic sulfur oxidation mediated by cable bacteria and its ecological effects

At the sediment-water interfaces,filamentous cable bacteria transport electrons from sulfide oxidation along their filaments towards oxygen or nitrate as electron acceptors.These multicellular bacteria belonging to the family Desulfobulbaceae thus form a biogeobattery that mediates redox processes between multiple elements.Cable bacteria were first reported in 2012.In the past years,cable bacteria have been found to be widely distributed across the globe.Their potential in shaping the surface water environments has been extensively studied but is not fully elucidated.In this review,the biogeochemical characteristics,conduction mechanisms,and geographical distribution of cable bacteria,as well as their ecological effects,are systematically reviewed and discussed.Novel insights for understanding and applying the role of cable bacteria in aquatic ecology are summarized.

Biological methane production coupled with sulfur oxidation in a microbial electrosynthesis system without organic substrates

Methane is produced in a microbial electrosynthesis system(MES) without organic substrates. However, a relatively high applied voltage is required for the bioelectrical reactions.In this study, we demonstrated that electrotrophic methane production at the biocathode was achieved even at a very low voltage of 0.1 V in an MES, in which abiotic HS-oxidized to SO_(4)^(2-) at the anodic carbon-cloth surface coated with platinum powder. In addition, microbial community analysis revealed the most probable pathway for methane production from electrons. First, electrotrophic H_(2) was produced by syntrophic bacteria, such as Syntrophorhabdus, Syntrophobacter, Syntrophus, Leptolinea, and Aminicenantales, with the direct acceptance of electrons at the biocathode. Subsequently, most of the produced H_(2) was converted to acetate by homoacetogens, such as Clostridium and Spirochaeta 2. In conclusion,the majority of the methane was indirectly produced by a large population of acetoclastic methanogens, namely Methanosaeta, via acetate. Further, hydrogenotrophic methanogens,including Methanobacterium and Methanolinea, produced methane via H_(2).

Diverse transformations of sulfur in seabird-affected sediments revealed by microbial and stable isotope analyses

Microbial communities,sulfur isotope of sulfides(δ^(34)S_(AVS)and δ^(34)S_(CRS)),and sulfur and oxygen isotopes of sulfate(δ^(34)S_(SO_(4))and δ^(18)O_(SO_(4)))in sediments were analyzed to reveal the biogeochemical transformations of sulfur in a seabird-affected lake Y2 and a se abird-free YO from Fildes Peninsula,Antarctic Peninsula.The microbial communities in Y2 were mainly associated with penguin activities,while those in YO were limited by nutrients.The much enriched δ^(34)S_(SO_(4))recorded at depth of 30,41,and 52 cm in Y2indicates very strong sulfate reduction therein.The sulfur-degrading bacteria Pseudomonas in 0-23 cm of Y2 was 3.5 time s as abundant as that of sulfur oxidizing bacteria(SOB),indicating remarkable remineralization of organic sulfur.The abundant SOB and ^(34)S-depleted sulfate indicate considerable sulfur oxidation in 34-56-cm layer in Y2.In YO sediments,the highest abundance of Desulfotalea and the most enriched δ^(34)S_(SO_(4))(35.2‰)and δ^(34)S_(CRS)(2.5‰)indicate the strongest sulfate reduction in 28-cm layer.High abundance of Pseudomonas indicates active remineralization of organic sulfur in 3-5-cm layer in YO.The medium δ^(34)S_(SO_(4))and considerable abundance of SOB and sulfate-reducing bacteria(SRB)indicate concurrence of sulfur oxidation and sulfate reduction in other layers in YO.Therefore,a high level of organic matter input from penguin populations supported the diverse microbial community and transformations of sulfur in aquatic ecosystems in Antarctica.

Differential utilization of cyclic, orthorhombic α- and chain-like polymeric μ-sulfur by Acidithiobacillus ferrooxidans

The differential utilization of cyclic, orthorhombic α-sulfur （α-S） and chain-like polymeric g-sulfur （μ-S） by Acidithiobacillus ferrooxidans was investigated. The growth and sulfur oxidation results indicated that utilization of μ-S by A. ferrooxidans was clearly different from α-S. Even if the planktonic cells were produced, the fall of pH and the rise of sulfate concentration were the same after 300 h on each substrate, the speeds of the planktonic cells increase, pH decrease and sulfate concentration increase in the earlier cultivation stage were faster on polymeric sulfur compared with the orthorhombic form. The adsorption capacity of the cells was higher on μ-S than on α-S, The results of SEM, DRIFTS and XRD analyses indicated that the surfaces of α-S and μ -S were modified differently by cells. Differential expression of 11 selected sulfur adsorption-activation and metabolism relevant genes was detected by RT-qPCR. The results showed that the expression of the hydrophobic substrate transport proteins and the sulfur metabolism related proteins was up-regulated, and the adsorption and activation related proteins were down-regulated when the cells were grown on μS, suggesting that μ-S could be more easily bio-adapted and activated than α-S.

Isolation and characterization of ferrous-and sulfur-oxidizing bacteria from Tengchong solfataric region,China

Microbial oxidation and reduction of iron and sulfur are important parts of biogeochemical cycles in acidic environments such as geothermal solfataric regions. Species of Acidithiobacillus and Leptospirillum are the common ferrous-iron and sulfur oxidizers from such environments. This study focused on the Tengchong sofataric region, located in Yunnan Province, Southwest China. Based on cultivation, 9 strains that grow on ferrous-iron and sulfuric compounds were obtained. Analysis of 16S rRNA genes of the 9 strains indicated that they were affiliated to AcidithiobaciUus, Alicyclobacillus, Sulfobacillus, Leptospirillum and Acidiphilium. Physiological and phylogenetic studies indicated that two strains （TC-34 and TC-71） might represent two novel members of Alicyclobacillus. Strain TC-34 and TC-71 showed 94.8%-97.1% 16S rRNA gene identities to other species of Alicyclobacillus. Different from the previously described Alicyclobacillus species, strains TC-34 and TC-71 were mesophilic and their cellular fatty acids do not contain w-cyclic fatty acids. Strain TC-71 was obligately dependent on ferrous-iron for growth. It was concluded that the ferrous-iron oxidizers were diversified and Alicyclobacillus species were proposed to take part in biochemical geocycling of iron in the Tengchong solfataric region.

Multi-Pollutant Formation and Control in Pressurized Oxy-Combustion:SO_(x),NO_(x),Particulate Matter,and Mercury

Oxy-combustion is a promising carbon-capture technology,but atmospheric-pressure oxy-combustion has a relatively low net efficiency,limiting its application in power plants.In pressurized oxycombustion(POC),the boiler,air separation unit,flue gas recirculation unit,and CO_(2)purification and compression unit are all operated at elevated pressure;this makes the process more efficient,with many advantages over atmospheric pressure,such as low NO_(x)emissions,a smaller boiler size,and more.POC is also more promising for industrial application and has attracted widespread research interest in recent years.It can produce high-pressure CO_(2)with a purity of approximately 95%,which can be used directly for enhanced oil recovery or geo-sequestration.However,the pollutant emissions must meet the standards for carbon capture,storage,and utilization.Because of the high oxygen and moisture concentrations in POC,the formation of acids via the oxidation and solution of SO_(x)and NO_(x)can be increased,causing the corrosion of pipelines and equipment.Furthermore,particulate matter(PM)and mercury emissions can harm the environment and human health.The main distinction between pressurized and atmospheric-pressure oxy-combustion is the former’s elevated pressure;thus,the effect of this pressure on the pollutants emitted from POC—including SO_(x),NO_(x),PM,and mercury—must be understood,and effective control methodologies must be incorporated to control the formation of these pollutants.This paper reviews recent advances in research on SO_(x),NO_(x),PM,and mercury formation and control in POC systems that can aid in pollutant control in such systems.

Relationships among bioleaching performance, additional elemental sulfur, microbial population dynamics and its energy metabolism in bioleaching of chalcopyrite

To estimate the relationships among bioleaching performance, additional elemental sulfur （S0）, microbial population dynamics and its energy metabolism, bioleaching of chalcopyrite by three typical sulfur- and/or iron-oxidizing bacteria, Acidithiobacillus ferrooxidans, Leptospirillum ferriphilum and Acidithiobacillus thiooxidans with different levels of sulfur were studied in batch shake flask cultures incubated at 30 °C. Copper dissolution capability （71%） was increased with the addition of 3.193 g/L S0, compared to that （67%） without S0. However, lower copper extraction was obtained in bioleaching with excessive sulfur. Microbial population dynamics during chalcopyrite bioleaching process was monitored by using PCR-restriction fragment length polymorphism （PCR-RFLP）. Additional S0 accelerated the growth of sulfur-oxidizing bacteria, inhibited the iron-oxidizing metabolism and led to the decrease of iron-oxidizing microorganisms, finally affected iron concentration, redox potential and bioleaching performance. It is suggested that mixed iron and sulfur-oxidizing microorganisms with further optimized additional S0 concentration could improve copper recovery from chalcopyrite.

Simultaneous Determination of Halogen Compounds and Sulfur Oxides in Flue Gas by Ion Chromatography

Ion chromatography （IC） is a suitable analytical method for the determination of anions. As analytical methods for the halogen compounds in flue gas, those of bromine compound, fluorine compound, chlorine （Cl2） and hydrogen chloride （HCI） are listed in JIS. However, IC has not been adopted in JIS except for HCI and C12. Because the carbon dioxide in flue gas is absorbed in a 0.1 M sodium hydroxide solution as an absorber, it is interfered with the measurement of F^- and Cl^- ions. This paper describes the development of the pretreatment equipment for the flue gas analysis by IC, and its applications to real flue gas analysis. The F^-, Cl^-, Br^- and SO4^2- in the absorbing solution can be clearly separated by IC using the pretreatment equipment. The halogen compounds and sulfur oxides in flue gas can be simultaneously determined by IC.

Effects of selenium and sulfur on antioxidants and physiological parameters of garlic plants during senescence

A hydroponic study was conducted to determine the effects of selenium（Se： 0, 3, 6 μmol L^-1） on senescence-related oxidative stress in garlic plants grown under two sulfur（S） levels. We evaluated the yields of plants harvested at 160 and 200 days after sowing. Plants grown under a low Se dose（0.3 μmol L^-1） at low S level showed higher yields（12.0% increase in fresh weight yield, 13.7% increase in dry weight yield） than the controls, despite a decrease in chlorophyll concentration. Compared with control plants, the Se-treated plants showed lower levels of lipid peroxidation. The Se-treated plants also showed higher activities of glut athione peroxidase and catalase, but lower superoxide dismutase activities. Changes in Fv/Fm values and proline contents were affected more strongly by S than by Se. On the basis of our results, we can conclude that Se plays a key role in the antioxidant systems in garlic seedlings. It delays senescence by alleviating the peroxide stress, but it can be toxic at high levels. A high S level may increase tolerance to high Se concentrations through reducing Se accumulation in plants.

Leaching kinetics of gold bearing pyrite in H_2SO_4-Fe_2(SO_4)_3 system

Gold bearing pyrite leaching was conducted in H2SO4-Fe2（SO4）3 system at different reaction temperatures,with different ferric ion concentrations,sulfuric acid concentrations and stirring speeds.The leaching kinetics and mechanism were studied.When the temperature ranged between 30-75 °C,the pyrite leaching was mainly controlled by chemical reaction with positive correlation to the ferric ion concentration.The activation energy obtained from Arrhenius empirical formula is 51.39 k J/mol.The EDS and XPS analyses suggest that the oxidation of sulfur within pyrite is through a series of intermediate stages,and eventually is oxidized to sulphate accompanied with the formation of element sulfur.This indicates a thiosulfate oxidation pathway of the gold bearing pyrite oxidation in H2SO4-Fe2（SO4）3 system.

New microbial electrosynthesis system for methane production from carbon dioxide coupled with oxidation of sulfide to sulfate

Microbial electrosynthesis system (MES) is a promising method that can use carbon dioxide,which is a greenhouse gas,to produce methane which acts as an energy source,without using organic substances.However,this bioelectrical reduction reaction can proceed at a certain high applied voltage when coupled with water oxidation in the anode coated with metallic catalyst.When coupled with the oxidation of HS–to SO_(4)^(2-),methane production is thermodynamically more feasible,thus implying its production at a considerably lower applied voltage.In this study,we demonstrated the possibility of electrotrophic methane production coupled with HS–oxidation in a cost-effective bioanode chamber in the MES without organic substrates at a low applied voltage of 0.2 V.In addition,microbial community analyses of biomass enriched in the bioanode and biocathode were used to reveal the most probable pathway for methane production from HS–oxidation.In the bioanode,electroautotrophic SO_(4)^(2-)production accompanied with electron donation to the electrode is performed mainly by the following two steps:first,incomplete sulfide oxidation to sulfur cycle intermediates (SCI) is performed;then the produced SCI are disproportionated to HS^(–)and SO_(4)^(2-).In the biocathode,methane is produced mainly via H_(2)and acetate by electronaccepting syntrophic bacteria,homoacetogens,and acetoclastic archaea.Here,a new ecofriendly MES with biological H_(2)S removal is established.

The FCC Flue Gas SOx Transfer Additive RFS Developed by RIPP

The present paper introduces the development of FCC flue gas SOx transfer additives by RIPP with a brief discussion of SOx transfer mechanism. The second-generation SO transfer additives of the RFS series are RIPP＇s proprietary additives with significantly improved performances. The results of commercial tests indicate that the RFS additive can effectively control SO emission of the FCC regenerator while maintaining product yields and product quality when the additive is used in a proper concentra- tion range.

Embedding partial sulfurization of iron-cobalt oxide nanoparticles into carbon nanofibers as an efficient electrode for the advanced asymmetric supercapacitor

In this paper,a series of partially sulfurized iron-cobalt oxide(FCOS) nanoparticles were embedded in carbon nanofibers(FCOS@CNF) via a simple electrospinning method and followed by a hydrothermal sulfurization process.The sulfurization degree of iron-cobalt oxide nanoparticles can be further controlled by tuning the hydrothermal reaction time.The self-supported FCOS@CNF samples with hierarchical nanostructure can not only effectively prevent the detaching of the FCOS nanoparticles but also provide abundant electrochemical active sites.When used as a supercapacitor electrode,the FCOS@CNF^(-1)0 electrode presents a high specific capacitance(1039 F·g^(-1)at 1 A·g^(-1)),a good rate performance(over 69.4%of capacitance retention from 1 to 15 A·g^(-1)),and a long cycle lifespan(88.3% of capacitance retention after 4000 cycles at10 A·g^(-1)).A unique(FCOS@CNF^(-1)0//F-RGO) asymmetric supercapacitor device was assembled using the FCOS@CNF^(-1)0 sample as the positive electrode and the freeze-dried reductive graphene oxide(F-RGO) as the negative electrode.The hybrid device exhibits excellent electrochemical properties,including a high specific capacity,a long cycle life(86% after5000 cycles at 10 A·g^(-1)),and a maximum energy density of 24.2 Wh·kg^(-1)@725.4 W·kg^(-1).

Field Studies on the Removal Characteristics of Particulate Matter and SO_(x) in Ultra-Low Emission Coal-Fired Power Plant

In order to reduce the environmental smog caused by coal combustion,air pollution control devices have been widely used in coal-fired power plants,especially of wet flue gas desulfurization(WFGD)and wet electrostatic precipitator(WESP).In this work,particulate matter with aerodynamic diameter less than 10μm(PM_(10))and sulfur oxides(SO_(x))have been studied in a coal-fired power plant.The plant is equipped with selective catalytic reduction,electrostatic precipitator,WFGD,WESP.The results show that the PM_(10)removal efficiencies in WFGD and WESP are 54.34%and 50.39%,respectively,and the overall removal efficiency is 77.35%.WFGD and WESP have effects on the particle size distribution.After WFGD,the peak of particles shifts from 1.62 to 0.95μm,and the mass concentration of fine particles with aerodynamic diameter less than 0.61μm increases.After WESP,the peak of particle size shifts from 0.95 to 1.61μm.The differences are due to the agglomeration and growth of small particles.The SO_(3)mass concentration increases after SCR,but WFGD has a great influence on SO_(x)with the efficiency of 96.56%.WESP can remove SO_(x),but the efficiency is 20.91%.The final emission factors of SO_(2),SO_(3),PM_(1),PM_(2.5)and PM_(10)are 0.1597,0.0450,0.0154,0.0267 and 0.0215(kg·t^(−1)),respectively.Compared with the research results without ultra-low emission retrofit,the emission factors are reduced by 1~2 orders of magnitude,and the emission control level of air pollutants is greatly improved.

Sulfur metabolism by marine heterotrophic bacteria involved in sulfur cycling in the ocean

Sulfur cycling in the biosphere is tightly interwoven with the cycling of carbon and nitrogen,through various biological and geochemical processes.Marine microorganisms,due to their high abundance,diverse metabolic activities,and tremendous adaptation potential,play an essential role in the functioning of global biogeochemical cycles and linking sulfur transformation to the cycling of carbon and nitrogen.Currently many coastal regions are severely stressed by hypoxic or anoxic conditions,leading to the accumulation of toxic sulfide.A number of recent studies have demonstrated that dissimilatory sulfur oxidation by heterotrophic bacteria can protect marine ecosystems from sulfide toxicity.Sulfur-oxidizing bacteria have evolved diverse phylogenetic and metabolic characteristics to fill an array of ecological niches in various marine habitats.Here,we review the recent findings on the microbial communities that are involved in the oxidation of inorganic sulfur compounds and address how the two elements of sulfur and carbon are interlinked and influence the ecology and biogeochemistry in the ocean.Delineating the metabolic enzymes and pathways of sulfur-oxidizing bacteria not only provides an insight into the microbial sulfur metabolism,but also helps us understand the effects of changing environmental conditions on marine sulfur cycling and reinforces the close connection between sulfur and carbon cycling in the ocean.

Hybrid zeolite-based ion-exchange and sulfur oxidizing denitrification for advanced slaughterhouse wastewater treatment

The discharge of slaughterhouse wastewater(SWW)is increasing and its wastewater has to be treated thoroughly to avoid the eutrophication.The hybrid zeolite-based ion-exchange and sulfur autotrophic denitrification(IX-AD)process was developed to advanced treat SWW after traditional secondary biological process.Compared with traditional sulfur oxidizing denitrification(SOD),this study found that IX-AD column showed:(1)stronger ability to resist NO_(3)^(-) pollution load,(2)lower SO_(4)^(2-) productivity,and(3)higher microbial diversity and richness.Liaoning zeolites addition guaranteed not only the standard discharge of NH_(4)^(+)-N,but also the denitrification performance and effluent TN.Especially,when the ahead secondary biological treatment process run at the ultra-high load,NO_(3)-N removal efficiency for IX-AD column was still~100%,whereas only 64.2%for control SOD column.The corresponding average effluent TN concentrations for IX-AD and SOD columns were 5.89 and 65.55 mg/L,respectively.Therefore,IX-AD is a promising technology for advanced SWW treatment and should be widely researched and popularized.

Roles of SO_2 oxidation in new particle formation events

The oxidation of SO2 is commonly regarded as a major driver for new particle formation（NPF） in the atmosphere. In this study, we explored the connection between measured mixing ratio of SO2 and observed long-term（duration 〉 3 hr） and short-term（duration〈 1.5 hr） NPF events at a semi-urban site in Toronto. Apparent NPF rates（J30） showed a moderate correlation with the concentration of sulfuric acid（[H2SO4]） calculated from the measured mixing ratio of SO2 in long-term NPF events and some short-term NPF events（Category I）（R^2= 0.66）. The exponent in the fitting line of J30~ [H2SO4]nin these events was1.6. It was also found that SO2 mixing ratios varied a lot during long-term NPF events,leading to a significant variation of new particle counts. In the SO2-unexplained short-term NPF events（Category II）, analysis showed that new particles were formed aloft and then mixed down to the ground level. Further calculation results showed that sulfuric acid oxidized from SO2 probably made a negligible contribution to the growth of 〉 10 nm new particles.

Pyrolyzed bacterial cellulose/graphene oxide sandwich interlayer for lithium–sulfur batteries

Herein, a facile strategy for the synthesis of sandwich pyrolyzed bacterial cellulose（PBC）/graphene oxide（GO） composite was reported simply by utilizing the large-scale regenerated biomass bacterial cellulose as precursor. The unique and delicate structure where three-dimensional interconnected bacterial cellulose（BC） network embedded in two-dimensional GO skeleton could not only work as an effective barrier to retard polysulfide diffusion during the charge/discharge process to enhance the cyclic stability of the Li–S battery, but also offer a continuous electron transport pathway for the improved rate capability.As a result, by utilizing pure sulfur as cathodes, the Li–S batteries assembled with PBC/GO interlayer can still exhibit a capacity of nearly 600 mAh·g^-1 at 3C and only 0.055% capacity decay per cycle can be observed over 200 cycles. Additionally, the cost-efficient and environmentfriendly raw materials may enable the PBC/GO sandwich interlayer to be an advanced configuration for Li–S batteries.