• Journal of the Korean Electrochemical Society
• /
• v.22 no.3
• /
• pp.79-86
• /
• 2019

Most of low-grad heat (< $200^{\circ}C$) generated from industrial process and human body, is abandoned as waste heat. To harvest the waste heat, the thermoelectrics (TE) technology has been widely investigated so far. However, TE suffers from poor performance and high material cost. As an alternative to the TE device, the thermoelectrical cell (TEC) is gaining growing attention these days. The TEC features several advantages such as high Seebeck coefficient, low cost and design flexibility compared to TE, but its commercial viability was limited by its low heat-to-electricity conversion efficiency. However, recent reports have demonstrated that the performance of TEC can be markedly improved by employing novel electrode/electrolyte materials and by optimizing cell design. This article summarizes the recent progress of TECs in terms of the redox couples, electrolyte solvents and additives, electrode materials and cell design.

• Bulletin of the Korean Chemical Society
• /
• v.26 no.12
• /
• pp.1996-2000
• /
• 2005

Headspace hanging drop liquid phase micro-extraction (HS-HD-LPME) is studied as a novel solvent-based sample pretreatment method for floral volatile aroma compounds. This paper reports on application of the HSHD- LPME combined with GC-MS for the analysis of linalool component emitted from evening primrose flowers. The effect of several variables on the method performance was investigated. Additionally, the separation of enantiomers on a cyclodextrin capillary column was performed to identify chirality of (−)-linalool component. Since the unsurpassed volume of a few micro-liters of solvent is used, there is minimal waste or exposure to toxic organic solvents. This method enables to combine extraction, enrichment, clean-up, and sample introduction into a single step prior to the chromatographic process.

• Journal of Environmental Health Sciences
• /
• v.24 no.3
• /
• pp.48-53
• /
• 1998

Chitin is known as biodegradable natural polymer. But, in spite of various application of chitin from waste marine sources, commercial use of chitin has been limited due to highly resistance to chemicals and the absense of proper solvents. We made various viscosity of chitosan from chitin by change of Mima's method through the deacetylation which is various condition of NaOH concentration, reaction time and temperature. Also, Polyvinyl alcohol/chitosan blend films were prepared by different solution blends containing the ratio of 5, 10, 15 and 20% chitosan and low, medium, high molecular weight of chitosan to find a more useful biodegradable polymer. Thermal and mechanical properties of PVA/chitosan blend films such as DSC, impact strength, tensile strength and morphological changes by SEM were determined. The 10-15% PVA/chitosan(low, medium) blend films were similar to PVA. Also, PVA/chitosan blend films at the laboratory soil test(Pot Test) were completely degraded in month with four kinds of soils by microorganisms.

• Resources Recycling
• /
• v.9 no.4
• /
• pp.28-36
• /
• 2000

This study describes to analyze the characteristics for separation and recovery of both the dried particles and the purified solvent from the waste solvent through the vaporization process by the continuous and instantaneous vacuum drying system. The vacuum drying system for the waste solvents recovery consists of a feeding pump, a double pipe heat exchanger, a vacuum spray chamber, and a condenser. The vacuum drying system heats the waste solvent to the vapor in the double pipe heat exchanger and the expanded vapor is sprayed at the end of the tube. The vaporized solvent in the condenser are recovered. The particles in the waste solvent are separated and dried from the vapor in the vacuum spray chamber. Performance evaluation of the vacuum drying system was conducted using the mixture of the dried pigment particles and benzene or alkylbenzene as test samples. For the mixture of 10 wt% pigment particles an 90% benzene, the recovery efficiency of benzene was 88% with the purity of 99% and the recovery efficiency of dried particles was 94% with the moisture of 1.1 wt%. The size of pigment particles was decreased from $6.5\mu\textrm{m}$ to $5.6\mu\textrm{m}$ in diameter due to high speed spraying and dispersion in the vacuum drying system during drying process. Therefore, the vacuum drying system showed to be an effective method for separating particles and solvent in the waste solvent.

• Polymer(Korea)
• /
• v.35 no.5
• /
• pp.458-466
• /
• 2011

In the mixed system of supercritical carbon dioxide/organic solvents, poly(vinyl alcohol)(PVA) film of high degree of hydrolysis could be dyed with a dichroic dye of C. I. direct black 22(DB22) and as a result, high durability was obtained. Especially, as a dye dispersant in a supercritical fluid phase, a mixed solvent system of ethylene glycol: dimethyl sulfoxide=4 : 6 weight ratio was investigated. Then the optimum pressure for dyeing could be reduced down to 200 bar. Using this supercritical fluid system, the maximum dyeing appeared as the transmittance of less than 1% and the waste amount was reduced to the level of 1/10. After 500% drawing of this PVA film, both the polarizing efficiency of 94% and the single piece transmittance of 30% were obtained. The limitation of DB22 and further improvements were also discussed.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.33 no.4
• /
• pp.139-144
• /
• 2023

Stone papers made of inorganic filler and plastic polymer do not use pulp, which is the main raw material of existing papers, so they contribute to the preservation of nature and can be used as more eco-friendly materials when they have biodegradability. Since most stone papers are manufactured by hot extrusion, the amount of ceramic fillers and related physical properties are limited to control manufacturing workability. In this study, the stone paper composition was prepared in a liquid form using solvents, so that there was little limitation on the amount of ceramic filler added and it was also easy to add additives to control biodegradability. They were fabricated from eco-friendly raw materials using waste oyster shells as an inorganic filler and (recyclable) PVC materials as an organic binder. After making a solution using common solvents for PVC, inorganic filler and cellulose to impart biodegradability were mixed and processed into sheets to prepare solvent-based stone papers, and their paper properties were evaluated.

• Resources Recycling
• /
• v.11 no.6
• /
• pp.38-46
• /
• 2002

Fundamental investigations were conducted far the recovery process of waste organic solvent by fractional distillation in the aspects of equilibrium and kinetics. Mixture of toluene and xylene, which were both being used in the largest amount as industrial organic solvent, was taken as the artificial waste organic solvent and their distillation behaviors were studied. The purity of recovered solvent was investigated by Cir Chromatography and shown to be in the range of 94～98%. Based upon equilibrium calculations, the changes in the Gibbs free energy, standard enthalpy, and standard entropy for distillation reaction have been estimated. The standard enthalpy changes for toluene and xylene were shown to be 44.833 and 47.044 kJ $mol^{-1}$ respectively, which were similar to their molar heats of evaporation. The activation energies of distillation fur toluene and xylene obtained from kinetic studies were 3.281 and 2.699 kJ $mol^{-1}$ and they were about one tenths of the standard enthalpy changes of distillation reaction. The highness of the purity of recovered organic solvents suggested the possibility that the recovered waste organic sol-vent could partly replace the original solvent.

• Journal of the Korean Applied Science and Technology
• /
• v.34 no.2
• /
• pp.210-216
• /
• 2017

Recovery of low level nitric acid and sulfuric acid ions, which were contained in wastewater of a wet scrubber for de-NOx and de-SOx from ship engines, was attempted as fertilizing materials. This study utilized a selective extraction method using four organic solvents to precipitate the solid salts of ammonium nitrate and ammonium sulfate. The IR analysis showed almost same composition of the extracted ammonium salts with a commercial product, and recovery rate of nitrogen and sulfuric ions was 89% and 80% respectively. It was found that the selectivity and solubility consequently could be the crucial factors to recover the low level ions from the waste scrubbing water.

• Clean Technology
• /
• v.13 no.4
• /
• pp.251-256
• /
• 2007

Several studies regarding depolymerization of polycarbonate waste to get the essential monomer, bisphenol A, have been reported in recent years. However, those methods have some environmental safety problems of using highly toxic organic solvents as well as product separation problem due to the use of alkali catalyst. In this study, we proposed the combination of glycolysis and methanolysis to depolymerize the polycarbonate waste. Glycolysis reaction reached at the reaction equilibrium after about 180 minat 473.15K and dissolution of the polycarbonate was found to be a rate controlling step of the reaction. The yield of BPA was improved with the aid of combination of glycolysis and methanolysis. The methanolysis was carried out at a temperature range of $303.15K{\sim}363.15K$ and MeOH/PC molar ratio $0.5{\sim}3$. The yield of BPA had a maximum at 1.0 MeOH/PC molar ratio and increased with the reaction temperature.

• Journal of the Korean Applied Science and Technology
• /
• v.32 no.1
• /
• pp.48-55
• /
• 2015

IMO to issue some restricted maritime legislation for reducing the adverse environmental impacts arising from such ship exhaust emissions. According to the IMO policy, every ship entering the Baltic SECAs has to equip the gas cleaning scrubber. The discharged waste solution by gas cleaning scrubber contains many types of salts, which to recover some valuable materials before disposal. This study try to achieve valuable salts including AN and AS throughout a few process such as selective organic solvents salting out, low temperature extraction and thermal evaporation. Amongst them, Thermal evaporation with repetition extraction using inorganic solvent was the most optimum to purify the extracted AN. This valuable salt was evaluated by Elemental analysis and Differential scanning calorimetry.