• Clean Technology
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• v.28 no.2
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• pp.97-102
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• 2022

Lithium sulfur (Li-S) batteries have attracted considerable attention as a promising candidate for next-generation power sources due to their high theoretical energy density, low cost, and eco-friendliness. However, the poor electrical conductivity of sulfur and its insoluble discharging products (Li₂S₂/Li₂S), large volume changes, severe self-discharge, and dissolution of lithium polysulfide intermediates result in rapid capacity fading, low Coulombic efficiency, and safety risks, hindering Li-S battery commercial development. In this study, a three-dimensionally (3D) connected hierarchical porous carbon framework (HPCF) derived from waste sunflower seed shells was synthesized as a sulfur host for Li-S batteries via a chemical activation method. The natural 3D connected structure of the HPCF, originating from the raw material, can effectively enhance the conductivity and accessibility of the electrolyte, accelerating the Li⁺/electron transfer. Additionally, the generated micropores of the HPCF, originated from the chemical activation process, can prevent polysulfide dissolution due to the limited space, thereby improving the electrochemical performance and cycling stability. The HPCF/S cell shows a superior capacity retention of 540 mA h g^-1 after 70 cycles at 0.1 C, and an excellent cycling stability at 2 C for 700 cycles. This study provides a potential biomass-derived material for low-cost long-life Li-S batteries.

• Journal of Microbiology and Biotechnology
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• v.16 no.7
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• pp.999-1009
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• 2006

Physiological, biochemical and genetic studies of Corynebacterium glutamicum, a workhorse of white biotechnology used for amino acid production, led to a waste knowledge mainly about amino acid biosynthetic pathways and the central carbon metabolism of this bacterium. Spurred by the availability of the genome sequence and of genome-based experimental methods such as DNA microarray analysis, research on genetic regulation came into focus. Recent progress on mechanisms of genetic regulation of the carbon, nitrogen, sulfur and phosphorus metabolism in C. glutamicum will be discussed.

• Asian Journal of Atmospheric Environment
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• v.2 no.2
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• pp.102-108
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• 2008

In China, energy and environmental problems are becoming serious owing to rapid economic development. Coal is the most problematic energy source because it causes indoor and outdoor air pollution, acid rain, and global warming. One type of clean coal technology that has been developed is the coal-biomass briquette (or bio-briquette, BB) technique. BBs, which are produced from pulverized coal, biomass (typically, agricultural waste), and a sulfur fixation agent (slaked lime, $Ca(OH)_2$) under high pressure without any binder, have a high sulfur-fixation effect. In addition, BB combustion ash, that is, the waste material, can be used as a neutralization agent for acidic soil because of its high alkalinity, which originates from the added slaked lime. In this study, we evaluated the suitability of alternative biomass sources, namely, aquatic plants, as a BB constituent from the perspective of their use as a source of energy. We selected three types of aquatic plants for use in BB preparation and compared the fuel, handling, and environmental characteristics of the new BBs with those of conventional BBs. Our results showed that air-dried aquatic plants had a higher calorific value, which was in proportion to their carbon content, than agricultural waste biomass; the compressive strength of the new BBs, which depends on the lignin content of the biomass, was high enough to bear long-range intracontinental transport in China; and the new BBs had the same emission control capacity as the conventional BBs.

• Plant Journal
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• v.13 no.3
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• pp.36-46
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• 2017

In the reaction furnace of modified Claus process, chemical equilibrium reactions and kinetic reactions occur simultaneously. The main kinetic components are hydrogen ($H_2$), carbon monoxide (CO), carbonyl sulphide (COS) and carbon disulphide ($CS_2$). The equilibrium calculations, empirical correlations and sulfur recovery technology providers' (licensors) data for kinetic components (COS and $CS_2$) in the reaction furnace were analyzed to evaluate the amount of kinetic components by applying them to five different projects in which GS Engineering & Construction participated. Kinetic components ($H_2$ and CO) are also calculated and the results are analyzed to evaluate the impact of temperature in the reaction furnace and the waste heat boiler. Total required $O_2$ deviations for combustion in the reaction furnace are additionally shown, with and without side reactions. A full understanding of side reactions in the modified Claus process can help to improve sulfur recovery efficiency and optimize equipment design.

• Journal of Environmental Health Sciences
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• v.13 no.1
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• pp.17-33
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• 1987

As a result of technical advances and industrialization, the characteristics of domestic and industrial wastes are becoming more complex. Accordingly, improved treatment and disposal systems are being continuously sought to take account of complex characteristics and to comply with economic restrictions. In this study, an application of pyrolysis to the treatment of industrial wastes, including waste scrap rubber, waste raw material used in making the slipper bottom and waste PVC pipe, and the effectiveness of pyrolysis in resource recovery from these wastes were investigated. Batches of wastes were pyrolysed by external heating to a temperature of 400-800$\circ$C in a 32 mm diameter x 0.9 m long silica tube to produce combustible gases, oils and chars. Before the start of pyrolysis runs, the entire system was purged with nitrogen gas to exclude the air. The temperature inside the retort was controlled by the thermocouple in the gas stream, and referred to as the pyrolysis temperature. Under these conditions three products were separately collected and further analyzed. The results were summarized as follows. 1. More gases and less chars were produced with higher pyrolyzing temperature and with higher rates of heating, but the yields of oils tended downwards at temperatures above 700$\circ$C. Accordingly, operating conditions of pyrolysis should be varied with desired material. 2. Calorific values and sulfur contents of produced oils were sufficient and suitable for fuel use. Chars from waste rubber had high heating values with low sulfur contents, but calorific values of chars from waste PVC and waste slipper were as low as 3, 065-4, 273 kcal/kg and 942-2, 545 kcal/kg, respectively. Therefore, char from these wastes are inappropriate for fuel. 3. Soluble contents of Pb, Cd, Cu and Zn in chars from waste rubber and waste slipper were below the Specific Hazardous Waste Treatment Standards. However soluble contents of Pb and Cd in chars from waste PVC were one or two times and five or seven times exceedingly the Specific Hazardous Waste Treatment Standards, respectively. 4. Post high heating is desirable for treatment method of waste PVC which generates toxic hydrogen chloride. 5. The proportions of hydrogen, methane and ethane in produced gases were in the range of 3.99-35.61% V/V, 18.22-32.50% V/V and 5.17-5.87% V/V, respectively. 6. Pyrolysis is a useful disposal method in case of waste slipper, which was hardly combustible, and thus investigations of this kind of materials are required for effective management of industrial waste. 7. Based upon the possible market development for products, overall pyroly economics to take account of treatment values of noncombustible or hazardous materials should be evaluated.

• Journal of Environmental Science International
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• v.7 no.6
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• pp.783-791
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• 1998

The objectives of this study were to investigate the characteristics of desulfurization under different experimental conditions and the effects of desulfurization bed fluidized bed combuster installed with the screen. The experimental results were as follows ; First, as the height of fluidized bed combustor becomes higher, the concentrations of $SO_2$ mainly increased and sulfur retion of paper sludge was higher than that of natural limestone. Second, the desulfurzation by natural limestone occurred at in-bed and the desulfurization by paper sludge occurred in the whole of fluidized bed combuster. In addition, we identified calcium sulfate by the analysis of SEM and XRD. Third, screen at splash region increased sulfur retention 2~5%, air velocity and anthracite fraction had a little effect on the sulfur retention.

• Elastomers and Composites
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• v.32 no.5
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• pp.325-329
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• 1997

Microbial treatment of the powdered waste tire was studied to recycle the waste tires. Chemoautotrophic acidophilic, iron-oxidizing bacterium was employed to unvulcanize the powdered tires. Biotreated rubber powder was compared to a untreated and a chemically treated powder. The results showed sulfur content of rubber powder(1.33%) were decreased to 1.22% by chemical treatment and 1.12% by microbial treatment for 20 days, 0.88%, for 30 days. One of the problems of the powdered utilization of the waste tires is that rubber powder leads to decrease mechanical properties when it is compounded with other virgin polymers. When tee biotreated powder was compounded with natural rubber, the mechanical properties were less decreased when untreated or chemically treated powder. Therefore, the microbial treatment can be one of useful methods to recycle the waste tire.

• Resources Recycling
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• v.22 no.1
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• pp.20-28
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• 2013

Recently, as the registration of vehicles increases, the utilization of the waste tires is emerging as environmental issues. Crumb rubber reproduced by scrap tires has been reused up to 25% in the construction field. The purpose of this paper is to investigate the mechanical properties of sulfur-rubber concrete (SRC) and to suggest the optimum mix design in terms of the compressive strength. Specimens were prepared with various mixing parameters: amount of sulfur, rubber, and micro-fillers. Two casting processes were also mentioned; dry process and wet process. The results mainly showed that the compressive strength of SRC decreased with an increment of rubber content. However, adding micro-filler and adjusting sulfur contents could improve the compressive strength of SRC. Optimum values of sulfur and rubber content were selected by workability and compressive strength of SRC. SRC can be applied to road constructions where high strength of concrete is not concerned, to wall panels that require low unit weight, to construction of median in highways to resist high impact load, and in sound barriers to absorb sound waves.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.5
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• pp.515-524
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• 2005

In this study, the concentrations of major reduced sulfur compounds (RSC: $H_{2}S,\;CH_{3}SH$, DMS, $CS_2$ and DMDS) were determined from various emission sources of individual companies located within the Ban Wal industrial complex of Ansan city, Korea. We investigated the emission concentration levels of RSC from a total of 47 individual companies during June 2004 to January 2005. The results of our study indicate that the emission concentration levels of RSC vary in a highly complicated manner in relation with industrial sectors and emission source types. It was found that both $H_{2}S\;and\;CH_{3}SH$ make the highest contribution to nuisance in the leather industry. Likewise, DMS showed its maximum contribution from food production sector, while DMDS for chemical production sector. When the emission data sets were compared between different emission sources, regardless of industrial types or activities, $H_{2}S\;and\;CH_{3}SH$ concentrations were seen most significant at waste treatment process. The overall results of our study suggest that the emission concentrations of sulfur compounds can be used to distinguish different sources of malodor released by different industrial activities.

• Resources Recycling
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• v.12 no.2
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• pp.28-35
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• 2003

The powder utilization is the one of the best recycling methods for the waste tires. However, economic problem still exist. In order to overcome an economic problem the ground rubber particles are surface modified, which induced to the rubber particles that have good mechanical properties and higher compatibility. In this study, we investigated ultrasonic treatment and reduced rubber particle size. Results showed that sulfur cross-linkage network of the waste rubber is changed by the ultrasonic treatment.