• Journal of Microbiology and Biotechnology
• /
• v.24 no.10
• /
• pp.1427-1437
• /
• 2014

Enzymatic hydrolysis of lignocellulosic biomass into fermentable sugars is a key step in the conversion of agricultural by-products to biofuels and value-added chemicals. Utilization of a robust microorganism for on-site production of biomass-degrading enzymes has gained increasing interest as an economical approach for supplying enzymes to biorefinery processes. In this study, production of multi-polysaccharide-degrading enzymes from Aspergillus aculeatus BCC199 by solid-state fermentation was improved through the statistical design approach. Among the operational parameters, yeast extract and soybean meal as well as the nonionic surfactant Tween 20 and initial pH were found as key parameters for maximizing production of cellulolytic and hemicellulolytic enzymes. Under the optimized condition, the production of FPase, endoglucanase, ${\beta}$-glucosidase, xylanase, and ${\beta}$-xylosidase was achieved at 23, 663, 88, 1,633, and 90 units/g of dry substrate, respectively. The multi-enzyme extract was highly efficient in the saccharification of alkaline-pretreated rice straw, corn cob, and corn stover. In comparison with commercial cellulase preparations, the BCC199 enzyme mixture was able to produce remarkable yields of glucose and xylose, as it contained higher relative activities of ${\beta}$-glucosidase and core hemicellulases (xylanase and ${\beta}$-xylosidase). These results suggested that the crude enzyme extract from A. aculeatus BCC199 possesses balanced cellulolytic and xylanolytic activities required for the efficient saccharification of lignocellulosic biomass feedstocks, and supplementation of external ${\beta}$-glucosidase or xylanase was dispensable. The work thus demonstrates the high potential of A. aculeatus BCC199 as a promising producer of lignocellulose-degrading enzymes for the biomass conversion industry.

• Korean Chemical Engineering Research
• /
• v.48 no.1
• /
• pp.10-15
• /
• 2010

Intensive works have been carried out to develop more efficient solid catalysts for biodiesel production from various feedstocks including refined oils and waste fats. Among many catalysts, metal oxides and ion exchange resins are the most intensively studied ones. With regard to metal oxide catalysts, major research activities have focused on the identification of the active compounds and their immobilizing methods on the supports. As metal oxide catalysts have strong thermal stability, they may be used in simultaneous transesterification and esterification of waste fats. However, ion exchange resin catalysts were mainly applied in the esterification of the free fatty acids in waste fats because of their lower thermal stability. For both solid catalysts, further works are needed to make them to be used in commercial process. Especially fast deactivation of the solid catalyst would be the most challenging problem.

• Journal of Hydrogen and New Energy
• /
• v.7 no.1
• /
• pp.29-37
• /
• 1996

Alkaline water electrolysis has been commercialized as the only large-scale method for a long time to produce hydrogen and the technology is superior to other methods such as photochemical, thermochemical water splitting, and thermal decomposition method in view of efficiency and related technical problem. However, such conventional electrolyzer do not have high electric efficiency and productivity to apply to large scale hydrogen production for energy or chemical feedstocks. Solid polymer electrolyte water electrolysis using a perfluorocation exchange membrane as an $H^+$ ion conductor is considered to be a promising method, because of capability for operating at high current densities and low cell voltages. So, this is a good technology for the storage of electricity generated by photovoltaic power plants, wind generators and other energy conversion systems. One of the most important R&D topics in electrolyser is how to minimize cell voltage and maximize current density in order to increase the productivity of the electrolyzer. A commercialized technology is the hot press method which the film type electrocatalyst is hot-pressed to soild polymer membrane in order to eliminate the contact resistance. Various technologies, electrocatalyst formed over Nafion membrane surface by means of nonelectrolytic plating process, porous sintered metal(titanium powder) or titanium mesh coated with electrocatalyst, have been studied for preparation of membrane-electrocatalyst composites. In this study some experiments have been conducted at a solid polymer electrolyte water electrolyzer, which consisted of single cell stack with an electrode area of $25cm^2$ in a unipolar arrangement using titanium mesh coated with electrocatalyst.

• KSBB Journal
• /
• v.21 no.6 s.101
• /
• pp.418-421
• /
• 2006

Fatty acid methyl esters, also referred to as biodiesel, have been determined to have a great deal of potential as substitutes for petro-diesel. In order to enhance productivity in the biodiesel production process, feedstocks were previously recommended to be anhydrous, with a free fatty acid content of less than 0.5%. In this study, the effects of several catalysts, methanol molar ratio, catalyst amount, and reaction time on the reduction of free fatty acid level were studied with a simulated feedstock consisting of 20% oleic acid in rapeseed oil. Ferric sulfate was selected as the best catalyst. Increasing the catalyst amount and methanol molar ratio is very effective in decreasing the acid value of the simulated mixture. Our results may provide useful information with regard to the development of more economic and efficient free fatty acid removal system.

• Korean Chemical Engineering Research
• /
• v.46 no.2
• /
• pp.248-257
• /
• 2008

Coal liquefaction technology was established in Germany in 1920s. Coal liquefaction refers to the process in which coal is converted into liquid fuels such as gasoline and diesel oil under certain conditions. Coal liquefaction is usually classified into direct coal liquefaction (DCL) and indirect coal liquefaction (ICL). Various technologies for coal liquefaction, conducted between 1970s and 2000s, resulted in the development and optimization of a communication ready technology for the production of petroleum substitutes as refinery feedstocks. The purpose of this paper is to review the research, development and demonstration of coal liquefaction. In these respects, various DCL and ICL processes under development were illustrated and compared. Also, the status and perspective of coal liquefaction projects in the world were viewed. Considering the scale, and technical difficulties of domestic coal liquefaction, the project has be leaded by the government.

• 한국신재생에너지학회:학술대회논문집
• /
• 2009.11a
• /
• pp.533-536
• /
• 2009

The gasification technology is a very flexible and versatile technology to produce a wide variety products such as electricity, steam, hydrogen, Fisher-Tropsch(FT) diesels, Dimethyl Ether(DME), methanol and SNG(Synthetic Natural Gas) with near-zero pollutant emissions. Gasification converts coal and other low-grade feedstocks such as biomass, wastes, residual oil, petroleum coke, etc. to a very clean and usable syngas. Syngas is produced from gasifier including CO, $H_2$, $CO_2$, $N_2$, particulates and smaller quantities of $CH_4$, $NH_3$, $H_2S$, COS and etc. After removing pollutants, syngas can be variously used in energy and environment fields. The pilot-scale coal gasification system has been operated since 1994 at Ajou University in Suwon, Korea. The pilot-scale gasification facility consists of the coal gasifier, the hot gas filtering system, and the acid gas removal (AGR) system. The acid gas such as $H_2S$ and COS is removed in the AGR system before generating electricity by gas engine and producing chemicals like Di-methyl Ether(DME) in the catalytic reactor. The designed operation temperature and pressure of the $H_2S$ removal system are below $50^{\circ}C$ and 8 kg/$cm^2$. The iron chelate solution is used as an absorbent. $H_2S$ is removed below 0.1 ppm in the H2S removal system.

• 한국신재생에너지학회:학술대회논문집
• /
• 2009.11a
• /
• pp.506-510
• /
• 2009

The effects of various organic wastes on anaerobic fermentative hydrogen production were studied using enriched mixed microflora in batch tests. Rotten fruit, corn powder and organic wastewater enriched with sulfate (up to 1,000 mg/L) were used for experiments. Maximum hydrogen production (547.1 mL) was observed from rotten apple with initial substrate concentration of 132.2 g COD/L. The experimental result on sulfate enriched organic wastewater indicated that hydrogen production is not adversely influenced by relatively high sulfate concentration. Residual sulfate content remained at 96-98 % after 75 hours of reaction, which showed that no major sulfate reduction was occurred at pH 5.3-5.5 in the reactor. The volatile fatty acid (VFA) fractions produced during the reaction was in the order of butyrate > acetate > propionate in all experiments. The results of this study would be useful for controlling the conditions on fermentative hydrogen production using different feedstocks.

• Applied Chemistry for Engineering
• /
• v.18 no.5
• /
• pp.401-406
• /
• 2007

The status of biodiesel (BD) production and consumption, specifications and market status in Korea are discussed in this review. The main feedstock to produce BD is soybean oil and waste cooking oil in domestic, and some companies have tried to diversify BD feedstocks. Ministry of Agriculture and Forestry (MAF) has begun a pilot project to produce BD feedstock from rapeseed for 3 years since 2007. In July 2006, Ministry of Commerce, Industry & Energy (MOCIE) and the domestic oil industry reached an agreement under which BD0.5 is supplied in market, and 158400 MT of BD would be supplied between 2007 and 2008. MOCIE reported that it will increase BD 0.5% every year to reach BD3 by 2012. It is expected that BD supply would continuously increase domestically in the future.

• Clean Technology
• /
• v.13 no.2
• /
• pp.104-108
• /
• 2007

Biodiesel is a fatty acid alkyl ester produced by chemical reaction of a vegetable oil or animal fat and an alcohol. It is getting attention as a clean alternative energy that can replace gas oils. In this study, strong acidic ion exchange resin was introduced in the pretreatment process of the used cooking oil and rapeseed oil to enhance the conversion of the oil to the biodiesel by removing FFA(free fatty acid). More than 90% FFA was removed. Dry resins showed higher FFA removal efficiency than wet resins. Using transesterification the conversion of triglyceride into fatty acid methyl ester was raised up to 98%. These results can be applicable to the pretreatment of biodiesel feedstocks having high acidic value.

• Resources Recycling
• /
• v.25 no.5
• /
• pp.64-74
• /
• 2016

Titanium and iron are closely related in nature, although titanium is the ninth most abundant element in the Earth's crust. Iron in titanium ores must be removed for use as feedstocks in the manufacture of titanium dioxide pigments and pure $TiCl_4$ for metal titanium. In this study, various beneficiation processes of ilmenite for production of $TiO_2$ have been reviewed and compared. Most of these processes involve a combination of pyrometallurgy and hydrometallurgy. These beneficiation processes of ilmenite generate considerable quantities of wastes primarily in the form of iron salt, iron oxide and acidic effluents. Therefore, it is important that recovery of acid value from waste and conversion of iron bearing waste to useful materials for development of new beneficiation processes of ilmenite.