• Journal of Electrochemical Science and Technology
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• v.15 no.1
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• pp.198-206
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• 2024

Given the high theoretical capacity (1,675 mAh g^-1) and the inherent affordability and ubiquity of elemental sulfur, it stands out as a prominent cathode material for advanced lithium metal batteries. Traditionally, sulfur was sequestered within conductive porous carbons, rooted in the understanding that their inherent conductivity could offset sulfur's non-conductive nature. This study, however, pivots toward a transformative approach by utilizing diatom shell (DS, diatomite)-a naturally abundant and economically viable siliceous mineral-as a sulfur host. This approach enabled the development of a sulfurlayered diatomite/S composite (DS/S) for cathodic applications. Even in the face of the insulating nature of both diatomite and sulfur, the DS/S composite displayed vigorous participation in the electrochemical conversion process. Furthermore, this composite substantially curbed the loss of soluble polysulfides and minimized structural wear during cycling. As a testament to its efficacy, our Li-S battery, integrating this composite, exhibited an excellent cycling performance: a specific capacity of 732 mAh g^-1 after 100 cycles and a robust 77% capacity retention. These findings challenge the erstwhile conviction of requiring a conductive host for sulfur. Owing to diatomite's hierarchical porous architecture, eco-friendliness, and accessibility, the DS/S electrode boasts optimal sulfur utilization, elevated specific capacity, enhanced rate capabilities at intensified C rates, and steadfast cycling stability that underscore its vast commercial promise.

• Transactions of the Korean hydrogen and new energy society
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• v.13 no.4
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• pp.259-269
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• 2002

A battery based on the lithium/elemental sulfur redox couple has the advantage of high theoretical specific capacity of 1,675 mAh/g-sulfur. However, Li/S battery has bad cyclic durability at room temperature due to sulfur active material loss resulting from lithium polysulfide dissolution. To improve the cycle life of Li/S battery, PEGDME (Poly(ethylene glycol) dimethyl ether) 500 containing 1M LiTFSI salt which has high viscosity was used as electrolyte to retard the polysulfide dissolution and nano-sized $Mg_{0.6}Ni_{0.4}O$ was added to sulfur cathode as additive to adsorb soluble polysulfide within sulfur cathode. From experimental results, the improvement of the capacity and cycle life of Li/S battery was observed( maximum discharge capacity : 1,185 mAh/g-sulfur, C50/C1 = 85 % ). Through the charge-discharge test, we knew that PEGDME 500 played a role of preventing incomplete charge-discharge $behavior^{1,2)$. And then, in sulfur dissolution analysis and rate capability test, we first confirmed that nano-sized $Mg_{0.6}Ni_{0.4}O$ had polysulfide adsorbing effect and catalytic effect of promoting the Li/S redox reaction. In addition, from BET surface area analysis, we also verified that it played the part of increasing the porosity of sulfur cathode.

• Bulletin of the Korean Chemical Society
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• v.35 no.7
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• pp.2057-2064
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• 2014

Thermochemical sulfate reduction (TSR) was conducted in autoclave on the system of crude oil and $MgSO_4$ at different temperatures. Gas chromatography pulsed flame photometric detector (GC-PFPD) was used to detected the composition of organic sulfur compounds in oil phase products. The results of the analysis indicate that with increased temperature, the contents of organic sulfur compounds with high molecular weight and thermal stability, such as benzothiophenes and dibenzothiophenes, gradually became dominated. In order to gain greater insight into the formation and distribution of organic sulphur compounds from TSR, positive ion electrospray Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used in detecting the detailed elemental composition and distribution of them. The mass spectra showed that the mass range of sulfur compounds was 200-550 Da. Four sulfur class species, $S_1$, $N_1S_1$, $O_1S_1$ and $O_2S_1$, were assigned in the positive-ion spectrum. Among the identified sulfur compounds, the $S_1$ class species was dominant. The most abundant $S_1$ class species increase associated with the DBE value and carbon number increasing which also indicates the evolution of organic sulfur compounds in TSR is from the labile series to the stable one. In pure blank pyrolysis experiments with crude oil cracking without TSR, different composition and distribution of organic sulfur compounds in oil phase products were seen from mass spectra in order to evaluate their pyrolysis behaviors without $MgSO_4$. FT-IR and XRD were used in analyzing the products of solid phases. Two distinct crystallographic phases MgO and $MgSO_4$ are found to coexist in the products which demonstrated the transformation of inorganic sulfur compounds into organosulfur compounds exist in TSR.

• Asian Journal of Atmospheric Environment
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• v.5 no.3
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• pp.196-203
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• 2011

The main aim of this study is to establish methods of morphological preservation and elemental quantification for individual snow crystals. Individual snow crystals were collected at a height of 20 m above ground level. To stabilize and preserve the original morphologies of the snow crystals, cyanoacrylate, which has been used to fix liquid droplets, was applied (Kasahara et al., 2000). Several different kinds of snow crystals (dendrite, sectored plate, quasi-sectored plate, and hexagonal plate) were successively stabilized using this method. The stabilized snow crystals were pretreated with acetone, and then the elemental components contained in a whole snow crystal were quantified with the Particle Induced X-ray Emission (PIXE) analytical technique. The snow crystal residual composition determined in the present study was dominated by sulfur and mineral components, and the elemental mass showed an apparent crystal size dependence, where the elemental mass gradually decreased as the crystal size increased.

• Korean Journal of Microbiology
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• v.48 no.1
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• pp.42-47
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• 2012

Hydrothermal vents (HTV) provide special environments for evolution of lives independent on solar energy. HTV samples were gained from Tofua arc trench in Tonga, South Pacific. We investigated archaeal diversity enriched using combinations of various electron donors (yeast extract and $H_2$) and electron acceptors [Iron (III), elemental sulfur ($S^0$) and nitrate. PCR amplification was performed to detect archaeal 16S rRNA genes after the cultures were incubated $65^{\circ}C$ and $80^{\circ}C$ for 2 weeks. The cultures showing archaeal growth were transferred using the dilution-to-extinction method. 16S rRNA gene PCR-Denaturing Gradient Gel Electrophoresis was used to identify the enriched archaea in the highest dilutions where archaeal growth was observed. Most of cultured archaea belonged to genus of Thermococcus (T. alcaliphilius, T. litoralis, T. celer, T. barossii, T. thoreducens, T. coalescens) with 98-99% 16S rRNA gene similarities. Interestingly, archaeal growth was observed in the cultures with Iron (III) and nitrate as an electron acceptor. It was supposed that archaea might use the elemental sulfur generated from oxidation of the reducing agent, sulfide. To cultivate diverse archaea excluding Thermococcus, it would be required to use other reducing agents instead of sulfide.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.6
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• pp.555-562
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• 2010

For the rapid and reliable detection of toxic compounds in water, a novel toxicity detection methodology based on sulfur-oxidizing bacteria (SOB) has been developed. The methodology exploits the ability of SOB to oxidize elemental sulfur to sulfuric acid in the presence of oxygen. The reaction results in an increase in electrical conductivity (EC) and a decrease in pH. Using a synthetic stream water (EC=0.12 mS/cm and pH=7.2), the baseline steady-state EC and pH values were 0.5~1.2 mS/cm and ~2.5 over 7 days of testing at HRT 30 minutes. When nitrite compounds were added to the system, the effluent EC decreased and the pH increased due to the inhibition of the SOB. Optimum HRT was 30 min and this HRT could be decresed by using smaller sulfur particles.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.10
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• pp.1366-1376
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• 2009

Effect of sulfur (S) on utilization efficiency of fresh cassava foliage and cassava hay in dairy cows was evaluated using thirty-two $1^{st}-2^{nd}$ lactation Holstein-Friesian crossbred dairy cows. The experimental treatment was a 2${\times}$2 factorial arrangement in a randomized complete block design (RCBD) using two roughages (rice straw+fresh cassava foliage (FCF) and rice straw+cassava hay (CH)) and two elemental sulfur (S) levels (0.15 and 0.4% S of dry matter (DM)), respectively. Four dietary treatments (FCF+0.15, FCF+0.4, CH+0.15 and CH+0.4) were offered ad libitum in the form of a total mixed ration (TMR) with concentrate to roughage (chopped rice straw+chopped cassava foliage) ratio at 60:40. Fresh cassava foliage or cassava hay resulted in similar dry mater intake, rumen ecology parameters, total tract digestibility, blood chemistry, milk production and composition. However, HCN intake, blood and milk thiocyanate concentration were significantly higher (p<0.01) in cows fed fresh cassava foliage with no sign of potential toxicity. Dry matter intake, body weight changes, molar percentage of propionate in rumen, neutral detergent fiber (NDF) digestibility and nitrogen (N) retention of cows tended to be increased while DM digestibility (65.6, 72.7, 68.6 and 72.1% of total DM intake for the respective treatments), rumen bacteria population (1.4, 1.7, 1.6 and $1.7{\times}10^{11}$ cell/ml for respective treatments), fungal zoospore population (0.4, 0.6, 0.4 and $0.5{\times}10^{6}$ cell/ml for respective treatments), urinary allantoin (25.3, 28.0, 26.3 and 27.6 g/d for respective treatments), microbial N yield (136.0, 154.6, 142.8 and 151.3 g N/d for respective treatments) and milk protein content (3.4, 3.5, 3.2 and 3.5% for respective treatments) were significantly (p<0.05) higher in cows fed on supplemented sulfur at 0.4% of DM in comparison with 0.15% S-supplemented diets. Based on these results, it is concluded that cassava foliage could be used as a portion of roughage for dairy cows and supplementation of S would be nutritionally beneficial.

• Korean Journal of Environmental Biology
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• v.29 no.4
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• pp.265-273
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• 2011

Bacterial diversity based on the denaturing gradient gel electrophoresis (DGGE) analysis of PCR-amplified 16S rRNA gene sequences was determined for soil samples from two abandoned mine sites and the corresponding enrichment cultures using soil sample as key inoculum. Sequencing analysis of DGGE bands obtained from both the soil samples matched mostly with sequences of uncultured and newly described organisms, or organisms recently associated with the acid mine drainage environment. However, the enrichment of soil samples in ferrous sulfate and elemental sulfur media yielded sequences that were consistent with well-known iron- and sulfur-oxidizing acidophilic bacteria. Analysis of enrichment cultures of soil samples from Dalsung mine revealed abundant ${\gamma}$-$Proteobacteria$, whereas that of Gubong mine sample displayed acidophilic groups of ${\gamma}$-$Proteobacteria$, ${\alpha}$-$Proteobacteria$, $Actinobacteria$ and $Firmicutes$. Chemical elemental analysis of the mine samples indicated that the Dalsung site contained more iron and sulfate along with other toxic components as compared with those of the Gubong site. Biogeochemistry was believed to be the primary control on the acidophilic bacterial group in the enrichment samples.

• Resources Recycling
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• v.16 no.2 s.76
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• pp.12-16
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• 2007

The influence of oxidation on the floatability of sulfide minerals contained in mine failings has been investigated employing chalcopyrite as a target material. The critical surface tension of chalcopyrite was estimated to be about 15.5 dyne/cm based on Zisman plot and the floatability of chalcopyrite was observed to increase with the concentration of collector. The enhanced float-ability of chalcopyrite at its initial stage of oxidation was considered to be due to the transformation of disulfide to elemental sulfur and the decrease in its floatability at further oxidation was presumably caused by the formation of sulfate and/or disulfur trioxide from elemental sulfur. When the oxidized chalcopyrite was reduced, its floatability was increased and the variation of the critical surface tension of chalcopyrite according to tile oxidation/reduction was interpreted by an energy diagram constructed by different bond energies between atoms.

• Journal of Korean Society for Atmospheric Environment
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• v.12 no.5
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• pp.523-528
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• 1996

Aerosol Particles were collected in a heaby traffic region in pusan. Samples were collected in two size fractions with a two-stage sampler during the day and the night. Elemental concentrations of these aerosol particles were determined by a PIXE(Proton Induced X-ray Emission) analysis method. The results suggest that the elements originating mainly from natural sources such as Si, Ca, Fe, Cl, and K are dominent in the coarse fraction, but the elements such as S, Pb, Br, and Zn are dominent in the fine fraction. Br/Pb ratio are evaluated in both coarse and fine size fraction, and which are mainly emitted automobile sources. The study further also discussed other Br/Pb ratio related works described elsewhere. Sulfur in the fine fraction was continuously increased during the sampling period without time variation.