• Journal of the Korean Ceramic Society
• /
• v.47 no.6
• /
• pp.566-571
• /
• 2010

Dispersion behavior of the slurries consisted of bimodal-type AlN powders was examined in non-aqueous solvent system. Azotropic solvent system and copolymer acidic dispersant were applied to the slurries. Measurements of the sedimentation height and the viscosity of the each slurry, and the test of particle size distribution of the each powder sample were conducted as examinations for the dispersion behavior at the various dispersant contents. The bimodal-type particle size distribution was continued after addition of the dispersant and small particle portions were increased as the dispersant content increases. The density of the green sheet was also increased as the dispersant content increases and a green density of $2.114\;g/cm^3$ was obtained at the sample prepared from 2.4 wt% dispersant content. The increase of large particle portions resulted in the surface defects of the green sheets.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.14 no.2
• /
• pp.246-263
• /
• 2011

Mankind has just begun to recognize that the most crucial factor to achieve the sustainable society in the future is green technology. Most countries support the development of green technology to prevent catastrophes from global warming, mainly in the areas of reducing carbon dioxide from the atmosphere. However, most products we consume in everyday life are produced through chemical processes, and we often oversee the fact that the huge amount of waste and energy during these chemical processes will seriously influence our goal to achieve our future society sustainable. Thus the technologies to minimize the amount of disposed waste and energy consumption during chemical processes may be more important than to reduce the greenhouse gases. In this regard this review introduces the recent status of green chemistry and future prospects in order to help our chemists and engineers establish research projects based on the green chemistry principles.

• Advances in Energy Research
• /
• v.4 no.4
• /
• pp.325-337
• /
• 2016

Cerbera Odollam (sea mango) is a proven promising feedstock for the production of biodiesel due to its high oil content. Fatty acid methyl esters (FAME) were produced as the final reaction product in the transesterification reflux condensation reaction of sea mango oil and methyl acetate (MA). Potassium methoxide was used as catalyst to study its reacting potential as a homogeneous base catalyst. The initial part of this project studied the optimum conditions to extract crude sea mango oil. It was found that the content of sea mango sea mango oil was 55%. This optimum amount was obtained by using 18 g of grinded sea mango seeds in 250 ml hexane. The extraction was carried out for 24 hours using solvent extraction method. Response surface methodology (RSM) was employed to determine the optimum conditions of the reaction. The three manipulated variables in this reaction were the reaction time, oil to solvent molar ratio, and catalyst wt%. The optimum condition for this reaction determined was 5 hours reaction time, 0.28 wt% of catalyst and 1:35 mol/mol of oil: solvent molar ratio. A series of test were conducted on the final FAME product of this study, namely the FTIR test, GC-FID, calorimeter bomb and viscometer test.

• Journal of the Korean Chemical Society
• /
• v.58 no.5
• /
• pp.445-449
• /
• 2014

A convenient and efficient method has been developed for the one-pot synthesis of dihydropyrimidinones (DHPMs) compounds. Dihydropyrimidinone derivatives were synthesized in good yields using ethyl acetoacetate, aldehyde (aromatic and aliphatic) and urea or thiourea in the presence of ZnO nanoparticles as a catalyst in $H_2O$ as solvent at $80^{\circ}C$. This green chemistry procedure applied to the Biginelli reaction using ZnO nanoparticles as catalyst and illustrated as a rapid preparation of DHPMs in water as solvent. The products were identified by physical data (mp) by comparison with those reported in the literatures.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.12
• /
• pp.3677-3680
• /
• 2013

Novel tri- and tetra-substituted pyrimido[4,5-d]pyridazines-2(1H,3H,7H)-ones have been synthesized via the regiospecific condensation reaction of hydrazine derivatives with 5-acetyl-4-aryloyl-6-methyl-3,4-dihydropyrimidinones in the presence of $SiO_2-Y(NO_3)_3$ as a green and recyclable catalyst under solvent-free conditions. All products were obtained in high yields and short reaction time. Employing this method is in accord with green chemistry principles.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.11
• /
• pp.3410-3414
• /
• 2013

Atom-economical esterification is of great importance in green chemistry. In this work, we demonstrated the catalyst and additive free esterification of alcohols by their reaction with 2-acyl-4,5-dichloropyridazin-3(2H)-ones without solvent at $100^{\circ}C$. Aliphatic and aromatic alcohols were converted into the corresponding esters in good to excellent yields. It is noteworthy that the reaction is solvent-free, atom-economic, easy-workup, and rapid and that the process is inexpensive.

• Journal of Microbiology and Biotechnology
• /
• v.14 no.5
• /
• pp.932-937
• /
• 2004

In situ extraction by organic solvent was studied in order to improve the recovery yield of hydrocarbon from the culture of Botryococcus braunii, a green colonial microalga. When the solvent mixture of octanol as an extractive solvent and n-octane as a biocompatible solvent was added to a two-phase column, the algal growth was seriously inhibited, even at a low concentration of polar octanol. Therefore, a two-stage cell-recycle extraction process was proposed to improve the contact area between the organic phase and the aqueous phase. The hydrocarbon recovery with in situ cell-recycle extraction showed a three-fold increase (57% of cell) in yield over that with two-phase extraction. In addition, over 60% of the hydrocarbon could be recovered without serious cell damage by downstream separation when this process was applied to the culture broth after batch fermentation.

• Journal of the Semiconductor & Display Technology
• /
• v.14 no.4
• /
• pp.8-12
• /
• 2015

As NMP (N-Methyl-2pyrrolidone) is becoming important in many fields, the demand for it is also rising rapidly. With its chemical property of high boiling point, low vapor pressure and high water solubility, it is easy to recover it after processing. Therefore, it is increasingly needed to develop a system that effectively recovers NMP solvent. The study produced a system modeling using AMESim software before developing high purity solvent recovery (HPSR) system to recover NMP solvent. Then, it verified reliability by comparing the simulation model with the test result.

• ALGAE
• /
• v.36 no.1
• /
• pp.61-72
• /
• 2021

Increased proliferation of bacterial resistance to antibiotics is a critical issue that has increased the demand for novel antibacterial compounds. Antibacterial activities have been evaluated in extracts from photosynthetic green microalgae, with varying levels of subsequent potential for development based on the strain of algae, strain of bacterial pathogen, and solvent used to extract the metabolites. Green microalgae from extreme environmental conditions have had to adapt to conditions that exclude many other organisms. The production of antibacterial compounds aids directly or indirectly in the survival of green microalgae in these extreme environments, as well as potentially serve other roles. This review investigates antibacterial activities of green microalgae from both extreme in-situ environmental conditions and induced extreme laboratory conditions and highlights.

• Clean Technology
• /
• v.20 no.2
• /
• pp.123-129
• /
• 2014

A green procedure is described for the preparation of a series of ionic liquids where two 3-methylimidazolium cations were bridged with ethylene glycol chain as linkers. Diethylene glycol-bis(3-methylimidazolium) ditosylate, triethylene glycolbis(3-methylimidazolium) ditosylate, and tetraethylene glycol-bis(3-methylimidazolium) ditosylate were heated with 3-methylimidazole under solvent-free condition to give the corresponding bis(3-methylimidazolium) ditosylate ionic liquids efficiently in a short time.