• Korean Chemical Engineering Research
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• v.48 no.2
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• pp.205-211
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• 2010

The water-sewage cohesion agent(polyaluminumchloride(PAC)) and NaOH were used to synthesize $Al(OH)_3$. For various additions of NaOH, characteristics of the synthesized $Al(OH)_3$ was analysed by XRD, SEM and PSA. According to XRD analysis, small amount of NaOH(NaOH:PAC=15g:100g) resulted in amorphous form of $Al(OH)_3$. By increasing NaOH(NaOH:PAC=20g:100g), the mixture of gibbsite(37%), bayerite(35%) and boehmite(28%) were produced. By adding more NaOH(NaOH:PAC=25g:100g), binary mixtures of gibbsite(67%) and bayerite(33%) were formed. Finally, high addition of NaOH(NaOH:PAC=30g:100g) gave the high concentration of gibbsite(gibbsite:bayerite=83:17). Also, SEM analysis indicated that the product featured the plate form with 20 and 30g of NaOH addition. Furthermore it was found that the particle size of the product decreased with the addition of NaOH.

• Resources Recycling
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• v.14 no.6 s.68
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• pp.37-43
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• 2005

[ $LiCoO_{2}$ ] nanoparticles were synthesized from leach liquor of lithium ion battery waste using flame spray pyrolysis. Electrode Materials containing lithium and cobalt could be concentrated with thermal and mechanical treatment. After dissolution of used cathode materials of the lithium battery with nitric acid, the molar ratio of Li/Co in the leach liquor was adjusted at 1.0 by adding a fresh $LiNO_{3}$ solution. The nanoparticles synthesized by the flame spray pyrolysis showed clear crystallinity and were nearly spherical, and their average primary particle diameters ranged from 11 to 35 nm. The average particle diameter increased with an increase in the molar concentration of the precursor. Raising the maximum flame temperature by controlling the gas flow rates also led to an increase in the average diameter of the particles. The $LiCoO_{2}$ powder was proved to have good characteristics as cathode active materials in charge/discharge capacity and cyclic performance.

• Resources Recycling
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• v.18 no.2
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• pp.56-61
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• 2009

The dissolution of domestic aluminum hydroxide of 99.7% purity has been performed with mineral and organic acid prior to the synthesis of aluminum compounds from aluminum solution. Mean particle size of aluminum hydroxide used in the work was $14.4{\mu}m$, $22.9{\mu}m$ and $62.3{\mu}m$, respectively and the effect of reaction temperature, concentration of acid and reaction time on the dissolution of aluminum hydroxide has been examined. As a result, the dissolution of aluminum hydroxide was increased with the concentration of HCl and more than 70% dissolution was obtained with 5 mole/l HCl at $70^{\circ}C$ for reaction time of 4 hr. As far as the dissolution of aluminum hydroxide with sulfuric acid was concerned, it was found that the optimum concentration of sulfuric acid was about 6 mole/l for the effective dissolution of aluminum hydroxide. When oxalic acid was used for the dissolution of aluminum hydroxide, nearly complete dissolution could be obtained by the dissolution for 16 hr with 1.0 mole/l oxalic acid at $90^{\circ}C$.

• Applied Chemistry for Engineering
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• v.27 no.2
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• pp.171-178
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• 2016

Extensive efforts from all over the world have been made to solve energy problems, such as high oil prices, global warning due to the depletion of oil. Among them, biofuel has been drawing attention as a clean energy, which can replace fossil fuels. However, conventional biofuels were often converted from eatable biomass such as sugar cane, corn and soy which should be replaced with uneatable biomass. In this study, a techno-economical evaluation of the gasification of biomass waste with mixed alcohol synthesis process was performed. Considering available domestic biomass wastes, a 2000 ton/day conversion plant were assumed to produce 533000 L/day ethanol. Also, financial data from previous studies were evaluated and used and economical sensitivities with various operation conditions were established. Economic analysis were conducted by the payback period and internal rate of return (IRR) and net present value (NPV). Sensitivity analyses of raw material costs, initial investment, the major process cost, ethanol price changes and operating costs were all performed.

• Particle and aerosol research
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• v.14 no.4
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• pp.145-151
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• 2018

Rod shaped Potassium hexatitanate ($K_2Ti_6O_{13}$) was synthesized from colloidal mixture of $TiO_2$, KOH and graphene oxide (GO) by aerosol spray drying and post heat treatment. Firstly, $TiO_2-KOH-GO$ composites were fabricated by aerosol spray drying in argon atmosphere. The composites were then calcined to form a rod shaped morphology of potassium titanate (KTO) in the presence of graphene at $900^{\circ}C$ for 3 h in argon atmosphere. Finally, the rod shaped KTO was obtained after removal of graphene (GR) at $800^{\circ}C$ and 3 h in air atmosphere. Characterization of the synthesized $K_2Ti_6O_{13}$ was carried out using the XRD, BET and FE-SEM. The length and diameter of the synthesized $K_2Ti_6O_{13}$ could be controlled by weight fraction of GO in the aerosol precursor. The length of $K_2Ti_6O_{13}$ rod increased with decreasing its diameter as GO concentration increased. The aspect ratio of the synthesized $K_2Ti_6O_{13}$ rod was controlled from 5 to 13.

• Journal of the Mineralogical Society of Korea
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• v.20 no.3
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• pp.147-153
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• 2007

Kaolinite [$Al_2Si_2O_5(OH)_4$] was successfully synthesized by a hydrothermal process from amorphous $Al(OH)_3$ and $SiO_2$ at $230^{\circ}C$ under the pressure of $30 kg/cm^2$. The experiments were performed varying temperatures ($180{\sim}280^{\circ}C$), pressure ($10{\sim}60kg/cm^2$), chemistry ($Al_2O_3/SiO_2 = 0.5{\sim}0.38$) and pH ($0.3{\sim}9.5$) of the solution. The autoclaving was carried out in a closed stainless steel vessel. Kaolinite appears from the starting composition of $Al_2O_3/SiO_2= 0.5$ with boehmite and was stable as a single phase with the composition of $Al_2O_3/SiO_2=0.45$. Boehmite was a stable phase below $200^{\circ}C$ for the 240 h period of autoclaving, but kaolinite appeared even in 20 h at $230^{\circ}C$. The single kaolinite phase of a good crystallinity was observed at pH ranging 2 to 6. That indicates that pH is one of the most critical parameters for the successful formation of kaolinite. The optimal molar ratio of $Al_2O_3$ to $SiO_2$ was determined to be 0.45. The XRD pattern of the synthesized kaolinite coincided with that of natural one and its morphology was the cluster type of the kaolinite crystals (diameter = ${\sim}3{\mu}m$), irrespective of starting material, composition and temperature.

• Microbiology and Biotechnology Letters
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• v.17 no.5
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• pp.461-467
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• 1989

The regulation of the synthesis of alcohol-oxidase (E.C.1.1.3.13.) was investigated in the methanol-utilizing yeasts during growth on different carbon sources. For this experiment, Hansenula polymoypha CBS 4132, Hansenula polymoypha CBM 11 and Hansenula polymoypha Cooney were cultured in mineral salt medium by changing its carbon sources. The production of alcohol-oxidase was varied by the carbon sources. For exmaple, alcohol-oxidase was undetectable: in all strains submitted to the test in the medium with glucose, but its production was rapidly increased when the carbon source was changed from glucose to methanol after 30 hrs of incubation. Moreover, this enzyme was not synthesized during growth on the primary aliphatic alcohols alone (ethanol, propanol, butanol or pentanol) or on the mixed substrates (0.5% methanol + 0.5% primary aliphatic alcohols). When cells were grown on the various carbon sources (glucose, xylose, lactose, glycerol, galactose, saccharose, sorbose, lactic acid or acetic acid), the alcohol-oxidase was about one-tenth of the activity found in cells grown on methanol alone. These carbon sources together with methanol yielded far better synthesis of alcohol-oxidase than in case of carbon sources alone. Especially, the alcohol-oxidase activity of the cells grown on lactose or lactic acid together with methanol was far better or similar than that of cells grown on methanol alone. The synthetic activity of alcohol-oxidase of Hansenula polymoypha CBS 4132 was the strongest among the three strains tested in every respect.

• Journal of the Korean Society of Food Science and Nutrition
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• v.18 no.4
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• pp.435-443
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• 1989

The regulation of the synthesis of alcohol-oxidase(E. C. 1. 1. 3. 13) was investigated in the methanol-utilizing yeasts during growth on different carbon sources. For this experiment, Pichia pastoris CBS 2612 and Pichia pastoris CBM 10 were cultured in mineral salt medium by changing its carbon sources. The production of alcohol-oxidase was varied by the carbon sources. For example, alcohol-oxidase was undetectable in all strains submitted to the test in the medium with glucose, but its production was rapidely increased when the carbon source was changed from glucose to methanol after 48hrs of incubation. Moreover, this enzyme was not synthesized during growth on the primary aliphatic alcohols alone(ethanol, propanol, butanol or pentanol) or on the mixed substrates(0.5% methanol+0.5% primary aliphatic alcohols). When cells were grown on the various carbon sources(glucose, xylose, lactose, glycerol, galactose, saccharose, sorbose, lactic acid or acetic acid), The alcohol-oxidase activity was detected a very little amounts. These carbon sources together with methnol yieled far better synthesis of alcohol-oxidase than in case of carbon sources alone. Especially, the alcohol-oxidase activity of the cells grown on sorbose, lactose or lactic acid together with methanol was far better or similar than that of cells grown on methanol alone. The apparent Km values for the methanol of Pichia pastoris CBS 2612 and Pichia pastoris CBM 10 enzymes were 1.92 and 210 mM, respectively. It is also active towards alcohols of shorter alkyl-chain length than $C_7$, insaturated alcohols(allylalcohol, crotyl-alcohol) and secondary alcohols (iso-amylacohol, iso-butylalcohol). The affinity of alcohol-oxidase for this alcohols decreased with the increasing length of the alkyl-chain.

• Korean Journal of Materials Research
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• v.25 no.9
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• pp.492-496
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• 2015

Hydroxyapatite (HA), which is an important calcium phosphate mineral, has been applied in orthopedics, dentistry, and many other fields depending upon its morphology. HA can be synthesized with different morphologies through controlling the synthesis method and several parameters. Here, we synthesize various morphologies of HA using two simple methods: hydrothermal combustion and solution combustion. The phase purity of the synthesized HA is confirmed using X-ray diffractometry. It demonstrates that pure phased hydroxyapatite can be synthesized using both methods. The morphology of the synthesized powder is examined using scanning electron microscopy. The effects of pH and temperature on the final powder are also investigated. At $140^{\circ}C$, using the hydrothermal method, nano-micro HA rods with a hexagonal crystal structure can be synthesized, whereas using solution combustion method at $600^{\circ}C$, a dense cubic morphology can be synthesized, which exhibits monoclinic crystal structures.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.469-471
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• 2001

Dry grinding of a mixture of CaCO$_3$ and Ca(H$_2$PO$_4$)$_2$.$H_2O$ was conducted using a planetary ball mill in order to investigate solid state reaction for a synthesis of hydroxyapatite(Ca$_{10}$(PO$_4$)$_{6}$(OH)$_2$, HAp) through mechanochemical treatment method. The raw materials, which are composed of waste oyster and calcium biphosphate Ca(H$_2$PO$_4$)$_2$.$H_2O$, were mixed and then treated mechanochemically. The synthesis of hydroxyapatite(Ca$_{10}$(PO$_4$)$_{6}$(OH)$_2$, HAp) from the mixture was almost completed by about 60 minute grinding. The formation of HAp monophase in the ground mixture was characterized through X-ray diffraction (XRD) analysis. Moreover, the formation of HAp monophase depending on the grinding time was improved by increasing the grinding time.ime.ime.