Simultaneous nitrification and autotrophic denitrification in fluidized bed reactors using pyrite and elemental sulfur as electron donors

In this study, simultaneous nitrification and autotrophic denitrification (SNAD) with either elemental sulfur or pyrite were investigated in fluidized bed reactors in mesophilic conditions. The reactor performance was evaluated at different ammonium (12-40 mg/L of NH4+-N), nitrate (35-45 mg/L of NO3--N), and dissolved oxygen (DO) (0.1-1.5 mg/L) concentrations, with a hydraulic retention time of 12 h. The pyrite reactor supported the SNAD process with a maximum nitrogen removal efficiency of 139.5 mg/(L·d) when the DO concentration was in the range of 0.8-1.5 mg/L. This range, however, limited the denitrification efficiency of the reactor, which decreased from 90.0% ± 5.3% in phases II-V to 67.9% ± 7.2% in phases VI and VII. Sulfate precipitated as iron sulfate (FeSO4/Fe2(SO4)3) and sodium sulfate (Na2SO4) minerals during the experiment. The sulfur reactor did not respond well to nitrification with a low and unstable ammonium removal efficiency, while denitrification occurred with a nitrate removal efficiency of 97.8%. In the pyrite system, the nitrifying bacterium Nitrosomonas sp. was present, and its relative abundance increased from 0.1% to 1.1%, while the autotrophic denitrifying genera Terrimonas, Ferruginibacter, and Denitratimonas dominated the community. Thiobacillus, Sulfurovum, and Trichlorobacter were the most abundant genera in the sulfur reactor during the entire experiment.

Elemental sulfur effects on Pb and Zn uptake by Indian mustard and winter wheat

A pot experiment was conducted to investigate the influence of elemental sulfur to contaminated soil on plant uptake by a heavy metal hyperaccumulator, Indian mustard(Brassica juncea) and a field crop, winter wheat(Triticum.aestivum). Elemental sulfur(S) with different rates was carried out, they were 0(S 0), 20(S 20), 40(S 40), 80(S 80), and 160(S 160) mmol/kg respectively. Extra pots with the same rates of S but without plants were used for soil sampling to monitor pH and CaCl 2-extractable heavy metal changes. The results showed that S enhanced phytoextraction of Pb and Zn from contaminated soil. Application S effectively decreased soil pH down to 1.1 as the most at the rate of S 160. The concentrations of CaCl 2-extractable Pb and Zn in soil and uptake of Pb and Zn by the plants were increased with soil pH decreased. A good correlation between CaCl 2-extractable Pb/Zn and soil pH was found(R 2 Pb = 0.847 and R 2 Zn = 0.991, n=25). With S application, soil CaCl 2-extractable Pb and Zn concentrations, concentration of Pb and Zn in plants and the amount of removal by plant uptake were significantly higher than those without S. Under the treatment of S 160, the highest CaCl 2-extractable Pb and Zn were observed, they were 4.23 mg/kg and 0.40 mg/kg, 2.7 and 2.0 times as that of the control(S 0) respectively. At the highest rates of S(S 160), both Indian mustard and winter wheat reached the highest uptake of Pb and Zn. The highest Pb concentrations in wheat and Indian mustard were 32.8 mg/kg and 537.0 mg/kg, all 1.8 times as that of the control, and the highest Zn concentrations in wheat and Indian mustard were 215.5 mg/kg and 404.0 mg/kg, 2.4 and 2.0 times as that of the control respectively. The highest removals of Pb and Zn from the contaminated soil were 0.41 mg/pot and 0.31 mg/pot by Indian mustard in the treatment of S 160 through 50 days growth.

In-depth study on the solubility of elemental sulfur in sour gas mixtures based on the Chrastil's association model

Accurately predicting the solubility of elemental sulfur in sour gas mixtures is a primary task.As a current and widely-used model on the solubility of elemental sulfur in sour gas mixtures,Chrastil's association model has a big error in the process of predicting experimental data based on different fitting methods.This paper combined with experimental data reported by relevant scholars about elemental sulfur solubility in sour gases and selected density,temperature and pressure as three important influential factors.According to different fitting methods,we can calculate the correlation parameters in Chrastil's model.Then different solubility formulas can be used to predict the solubility of elemental sulfur in sour gas mixtures.Through in-depth research and analysis of Chrastil's solubility model from numerical aspects,it's easy to find the irrationality about Chrastil's solubility model and fitting methods.Especially in fitting methods,further improvement of the fitting method is proposed and used to predict the solubility of elemental sulfur in sour gas mixtures.The calculation results show that some improvements of the predicting precision have been achieved by using the improved fitting method in Chrastil's association model.

Carbon,Nitrogen,and Sulfur Contents in Marine Phytoplankton Cells and Biomass Conversion

In this study,we isolated and cultured phytoplankton along the coast of China and measured the cellular carbon,nitrogen,and sulfur contents under four temperatures.The results showed that the contents of the cellular elements varied widely among different phytoplankton.We found that temperature is one of the important factors affecting the carbon,nitrogen,and sulfur contents in phytoplankton cells;however,the degree of influence of temperature is different for different kinds of phytoplankton.By measuring the nitrogen content in cells,we found that the C:N ratio indirectly measured in the experiment fluctuated in the range of 3.50-8.97,and the average C:N ratio was 5.52.In this experiment,we accurately measured the cell elemental contents at different temperatures and transformed the cell count results into carbon,nitrogen,and sulfur contents to express the biomass.This method ensures that the contribution of species that are small in number but with a large cell volume in biomass is considered.Moreover,this method comprehensively considers the interspecific differences of species and the uneven distribution of elements in phytoplankton cells,which is of significance in the estimation of marine carbon and nitrogen budget.The distribution of nitrogen content in marine phytoplankton can well indicate the marine eutrophication caused by human activities.Climate change can affect the community structure and element composition of marine phytoplankton,meanwhile marine carbon and nitrogen element can regulate the climate to a certain extent.

Research Progress on High Specific Energy Cathode Materials for Rechargeable Lithium Sulfur Batteries

An overview of the developing survey, research actuality and the future development of high specific energy and power lithium sulfur rechargeable batteries was presented systemically. By introducing the character of sulfur composite material and discussing some promising cathode materials, it may provide some foundation for people to go deep into researching and empoldering the sulfur composite material.

Reduced inorganic sulfur in the sediments of the Yellow Sea and East China Sea

Cold diffusion methods are used to separate and quantify the three reduced inorganic sulfur species into acid volatile sulfide （AVS）, pyrite-S and element sulfur （ES） in the sediments of the Yellow and East China Seas. The results show that up to 25.02 pmol/g of AVS, 113.1 pmol/g of pyrite-S and 44.4 pmol/g of ES are observed in the sediments of the Yellow Sea and East China Sea. Pyrite-S is the predominant sulfide mineral in the sediments, while the concentration of AVS is quite low at most stations in the study area. The amounts and reactivity of organic matter are the primary limited factor for the sulfide formation, while an iron limitation and a sulfate limitation are not observed in the sediments of the Yellow Sea and East China Sea. The irregular profiles of the three reduced inorganic sulfur sediment composition and sedimentation rates. species also reflected the comprehensive influence of

汽油中元素硫组成变化对其定量分析的影响

The structure of elemental sulfur (S0) in naphtha and gasoline was studied basing on that a new analytical method for determination of S0 was developed using gas chromatography-mass spectrometry (GC-MS).The test showed that the structure of S0 has changed and a small quantity of S2,S6,S7 has resulted and the mass proportion of S2∶S6∶S7∶S8 was 0.13:0.05:0.04:1.00 under the analysis condition.So the change of S0 structure with temperature had no effect on its quantity analysis.

Synthesis and Characterization of [(C_5H_4SiMe_2~tBu)_2Ln(μ-S^nBu)]_2 (Ln=Y,Er)

（C5H4SiMe2^tBu）2Ln^nBu reacted with 1 equiv, of elemental sulfur in toluene at ambient temperature to yield the corresponding lanthanocene thiolates [（C5H4SiMe2^tBu）2Ln（μ-S^nBu）]2 （Ln = Y （1）, Er （2））. Complexes 1 and 2 have been characterized by elemental analysis, IR, mass spectroscopy and X-ray single-crystal diffraction analysis. Both complexes are of monoclinic with space group P21/c, formula C52H94S2Si4Y2 1 （C52H94S2Si4Er2 2） Mr = 1073.57 （1230.27）, a = 8.495（2） （8.41（2））, b = 26.913（8） （26.67（7））, c = 13.756（4） （13.68（4）） A, α = 90（90）, β = 101.184（5） （101.57（4））, γ = 90 （90）°, V= 3085.1（15） （3007（14）） A^3, Dc = 1.156 （1.359） g·cm^-3, Z= 2 （2）, F（000） = 1144 （1260）, μ = 2.046 （2.951） cm^-1, R = 0.0687 （0.0749） and wR = 0.1306 （0.1507） for observed reflections with I 〉 2σ（I）. X-ray structures of 1 and 2 definitively prove that only one sulfur atom is inserted into the Ln-C（^nBu） bond, forming a thiolate ligand.

Multicomponent polymerization of sulfur, chloroform and diamine toward polythiourea

The efficient utilization of elemental sulfur(S8) for developing high value-added chemicals is a global concern considering its abundant sources and yearly accelerating environmental issues. However, it has been a long-standing challenge to directly transform elemental sulfur to sulfur-containing polymer, especially via an environmentally benign manner. Herein, a unique chemo-differentiating multicomponent polymerization(MCP) of elemental sulfur, chloroform, and diamine is reported to construct polythiourea based on amine-involved two sequential reactions including isothiocyanation and nucleophilic addition.This strategy features isocynide-free monomers as starting materials, mild conditions, high molecular weights(up to72,900 g/mol) and desired yields(up to 83%). With the advantages of inactive isocyanation and active nucleophilic addition, the stoichiometric balance of amine and isothiocyanate could be delicately controlled to afford various polythioureas with high molecular weights. The polythioureas have been further utilized in the Cu-based aqueous catalysis and Hg-based ion adsorption.

Effect of lubricant sulfur on the morphology and elemental composition of diesel exhaust particles

This work investigates the effects of lubricant sulfur contents on the morphology,nanostructure,size distribution and elemental composition of diesel exhaust particle on a light-duty diesel engine. Three kinds of lubricant（LS-oil,MS-oil and HS-oil,all of which have different sulfur contents：0.182%,0.583% and 1.06%,respectively）were used in this study. The morphologies and nanostructures of exhaust particles were analyzed using high-resolution transmission electron microscopy（TEM）. Size distributions of primary particles were determined through advanced image-processing software. Elemental compositions of exhaust particles were obtained through X-ray energy dispersive spectroscopy（EDS）. Results show that as lubricant sulfur contents increase,the macroscopic structure of diesel exhaust particles turn from chain-like to a more complex agglomerate. The inner cores of the core-shell structure belonging to these primary particles change little; the shell thickness decreases,and the spacing of carbon layer gradually descends,and amorphous materials that attached onto outer carbon layer of primary particles increase. Size distributions of primary particles present a unimodal and normal distribution,and higher sulfur contents lead to larger size primary particles. The sulfur content in lubricants directly affects the chemical composition in the particles. The content of C（carbon）decreases as sulfur increases in the lubricants,while the contents of O（oxygen）,S（sulfur）and trace elements（including S,Si（silicon）,Fe（ferrum）,P（phosphorus）,Ca（calcium）,Zn（zinc）,Mg（magnesium）,Cl（chlorine）and Ni（nickel））all increase in particles.

Synthesis of biheteroaryls via 2-methyl quinoline C(sp^(3))-H functionalization under metal-free conditions

An acetic acid-promoted C(sp^(3))-H functionalization of 2-methyl quinoline,enaminoesters and elemental sulfur for the synthesis of 3,4,5-trisubstituted isothiazoles under metal-free conditions has been developed.This approach provides viable access to various 5-(quinolin-2-yl)isothiazoles in moderate to good yields with good functional group tolerance.Moreover,the success of the gram-scale reaction gives this reaction a great potential application.

Microbial community functional structure in response to micro-aerobic conditions in sulfate-reducing sulfur-producing bioreactor

Limited oxygen supply to anaerobic wastewater treatment systems had been demonstrated as an effective strategy to improve elemental sulfur （So） recovery, coupling sulfate reduction and sulfide oxidation. However, little is known about the impact of dissolved oxygen （DO） on the microbial functional structures in these systems. We used a high throughput tool （GeoChip） to evaluate the microbial community structures in a biological desulfurization reactor under micro-aerobic conditions （DO： 0.02-0.33 rag/L）. The results indicated that the microbial community functional compositions and structures were dramatically altered with elevated DO levels. The abundances of dsrA/B genes involved in sulfate reduction processes significantly decreased （p 〈 0.05, LSD test） at relatively high DO concentration （DO： 0.33 mg/L）. The abundances of sox and fccA/B genes involved in sulfur/sulfide oxidation processes significantly increased （p 〈 0.05, LSD test） in low DO concentration conditions （DO： 0.09 mg/L） and then gradually decreased with continuously elevated DO levels. Their abundances coincided with the change of sulfate removal efliciencies and elemental sulfur （S^0） conversion efficiencies in the bioreactor. In addition, the abundance of carbon degradation genes increased with the raising of DO levels, showing that the heterotrophic microorganisms （e.g., fermentative microorganisms） were thriving under micro-aerobic condition. This study provides new insights into the impacts of micro-aerobic conditions on the microbial functional structure of sulfate- reducing sulfur-producing bioreactors, and revealed the potential linkage between functional microbial communities and reactor performance.

Investigation of colloidal biogenic sulfur flocculation:Optimization using response surface analysis

The colloidal properties of biogenic elemental sulfur（S^0）cause solid–liquid separation problems,such as poor settling and membrane fouling.In this study,the separation of S^0 from bulk liquids was performed using flocculation.Polyaluminum chloride（PAC）,polyacrylamide（PAM）and microbial flocculant（MBF）were compared to investigate their abilities to flocculate S^0 produced during the treatment of sulfate-containing wastewater.A novel approach with response surface methodology（RSM）was employed to evaluate the effects and interactions of flocculant dose,pH and stirring intensity,on the treatment efficiency in terms of the S^0 flocculation and the supernatant turbidity removal.The dose optimization results indicated that the S^0 flocculation efficiency decreased in the following order PAC〉MBF〉PAM.Optimum S^0 flocculation conditions were observed at pH 4.73,a stirring speed of 129 r/min and a flocculant dose of 2.42 mg PAC/mg S.During optimum flocculation conditions,the S^0f locculation rate reached 97.53%.Confirmation experiments demonstrated that employing PAC for S^0 flocculation is feasible and RSM is an efficient approach for optimizing the process of S^0 flocculation.The results provide basic parameters and conditions for recovering sulfur during the treatment of sulfate-laden wastewaters.

Stress corrosion cracking of L360NS pipeline steel in sulfur environment

Slow strain rate test(SSRT)and tensile fracture observation are applied to study the stress corrosion cracking(SCC)of L360NS pipeline steel.5.0 wt.%sodium chloride solution containing elemental sulfur and 0.5 wt.%glacial acetic acid solution containing elemental sulfur are used.The results show that brittle fracture mainly occurs on the samples in high sulfur environment.In the sulfur suspension solution,the SCC sensitivity of L360NS pipeline steel increases along elemental sulfur content.In sulfur melting cladding condition,obvious corrosion can be observed with a large amount of corrosion pits appearing on the gauge section of the sample.The corrosion products are Fe1txS,black easily detached,and H2.In sulfur suspension and sulfur melting cladding conditions,stress oriented hydrogen induced cracking(SOHIC)is the main cracking,which is caused by the joint effect of SCC and hydrogen induced cracking(HIC).

Corrosion behavior of low alloy steel for cargo oil tank under upper deck conditions

A simulated corrosion test apparatus was used to investigate the corrosion behavior of a low alloy steel under simulated upper deck conditions in a cargo oil tank. The estimated corrosion loss of conventional E36 class ship plate steel is 4.27 mm, which is clearly inadequate compared with the standard adopted by International Maritime Organization. Outer rust layer of specimens starts to peel off after 77 days and becomes fragmented after 98 days. X-ray diffraction, scanning electron micros- copy, and Raman spectroscopy revealed that the resulting rust is composed of σ-FeOOH （the main protective phase）, Fe2O3, FeS, elemental S, and FeSO4. FeSO4 in the interface of the base and rust layer leads to localized corrosion. Elemental sulfur forms on the surface of σ-FeOOH, and the quantity and size thereof increase with increasing corrosion time. Furthermore, layered elemental sulfur promotes fracture and peels off the rust layer.

Design and synthesis of unique thiazoloisoquinolinium thiolates and derivatives

Natural isoquinolinium alkaloids possess a wide range of biological activities.The design and synthesis of mesoionic isoquinoliniums is of great importance.This paper reports the synthesis of unique mesoionic thiazoloisoquinolinium thiolates stabilized by aromatization and 1,3-dipolarization.Such compounds can be synthesized via the three component [2 + 2 + 1] cycloaddition reaction of isoquinolines with ethyl propionate and elemental sulfur in the absence of any metal catalyst and additives.Importantly,thiazoloisoquinolinium thiolates can be transformed to thioether-containing thiazoloisoquinolinium halides.A selective [4 + 2] cycloaddition can also be used to form S-bridged fused tetracyclic compounds with a thiothiamide ring unit and two quarternary carbon centres.Compound I-1 shows good bioactivity against the chlorophyll of duckweed(Lemna minor) with inhibition rate of 51.5 mg/mL.