산성 수열반응을 통한 키토산으로부터 레불린산의 생산

정귀택 한국화학공학회 2014 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.52 No.3

최근 목질계, 미세조류, 해양 거대조류 등의 재생가능한 자원으로부터 생산된 많은 화학물질들이 화학산업에 도입되고 있다. 키틴/키토산은 지구상에서 두 번째로 풍부한 자원이며, 게, 새우, 곤충과 같은 갑각류의 껍질로부터 얻을 수있다. 본 연구에서는 키토산으로부터 levulinic acid의 생산을 위하여 고온 산 가수분해와 실험계획법을 적용하여 반응온도, 촉매량, 반응시간의 반응조건을 최적화 하였다. 결과적으로 반응온도와 촉매농도는 높을수록 levulinic acid의 생성이 증가하였고, 반응시간은 일정시간 이후에는 크게 영향을 미치지 못하였다. 최적 반응조건을 조사한 결과, 반응온도 175 oC, 촉매농도 2.4%, 그리고 반응시간 40.7분의 조건에서 2.7 g/L의 levulinic acid를 얻었다. Recently, many chemicals produced from renewable resources such as lignocellulosics, micro-algae andmarine macro-algae, were introduced to chemical industry. Chitin/chitosan is secondly abundant feedstock on Earth. It iseasily obtained from crusraceans’ shells such as crab, shrimp and insects. In this work, we performed the acidic-hydrothermalhydrolysis to produce levulinic acid from chitosan using statistical approach. By design of response surfacemethodology, the effect of reaction temperature, catalyst amount, and reaction time and their reciprocal interactions wereinvestigated. As a result, higher reaction temperature and catalyst amount increased the higher concentration of levulinicacid. However, reaction time did not caused large increase of levulinic acid after some reaction period. Levulinic acid of2.7 g/L produced from chitosan in the optimized condition of reaction temperature of 175 oC, sulfuric acid of 2.4% andreaction time of 40.7 min.

Platform chemicals production from lipid-extracted Chlorella vulgaris through an eco-friendly catalyst

정귀택,김성구 한국화학공학회 2021 Korean Journal of Chemical Engineering Vol.38 No.5

Microalgae are a widely available, renewable, and sustainable resource for bioenergy which may be used as a carbon-neutral alternative. We conducted hydrothermal conversion with MSA to obtain levulinic (LA) and formic acids (FA) from the lipid-extracted Chlorella vulgaris. Based on our analysis of reciprocal interactions between reaction conditions, maximum LA yields were obtained at high temperature, mid-range catalyst concentration, and mid-/longrange reaction time. Maximum FA yields were obtained at high temperature, high-range acid concentration, and short-/ mid-range time. Using the Box-Behnken method to optimize the reaction, yields of 39.17% for LA and 20.19% for FA were obtained with 5% biomass, 0.5M MSA at 195 oC for 35 min. Moreover, the effect of CSF on yield of LA and FA could be suitably represented by Sigmoidal equations with high R2. Overall, the application of lipid-extracted microalgae residue and eco-friendly MSA may prove useful for platform chemicals production.

Methanesulfonic acid-mediated conversion of microalgae Scenedesmus obliquus biomass into levulinic acid

정귀택,김성구 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.104 No.-

In this study, we produced levulinic acid (LA) from green microalgae Scenedesmus obliquus under amethanesulfonic acid (MSA)-mediated conversion. To optimize reaction condition and evaluate theirreciprocal interactions of reaction factors, a statistical experimental approach with central compositedesign was used. By optimizing the reaction conditions, LA was formed at a yield of 40.74% based on totalcarbohydrate at 180 C, 12.5% biomass, 1.875 M MSA (0.15 M MSA/1% biomass), and 40 min. The combinedseverity factor (CSF) evaluation showed that glucose formation matched the non-linear sigmoidalequation with high regression. However, the LA formation was matched to the non-linear model (exponentialdecay) with high regression. The highest LA was observed at CSF > 3.5. The availability of microalgaeas biomass and MSA as a catalyst was proven for producing sugar and platform chemicals.

폐수처리 탈질 공정에 미치는 인자 연구

정귀택,박석환,박재희,방성훈,임은태,박돈희 한국생물공학회 2008 KSBB Journal Vol.23 No.6

In this study, the effects of several factors such as initial nitrate concentration, C/N ratio, biomass amount and external carbon source on denitrification process were investigated using synthetic wastewater and sludge obtained from wastewater treatment facility. As a result, the condition of lower initial nitrate concentration was increased to the removal rate of nitrate than that of high concentration. The increases of C/N ratio and initial biomass amount were linearly enhanced the removal rate. The use of ethanol as external carbon source was shown the highest removal yield than that of others.

Optimization of lipid extraction from marine green macro-algae as biofuel resources

정귀택,박돈희 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.12

The extraction of lipid from Enteromorpha intestinalis was investigated. Among 13 types of organic solvent, the chloroform/methanol (2 : 1, v/v) system obtained the highest content. Considering the lipid extraction procedure and extracted amount, the optimal solid/liquid ratio was 1 : 50 (w/v). With increasing extraction temperature, the content was enhanced until 45 oC, after which it increased only slightly. Correspondingly, with increasing extraction time, the content linearly increased until 2.5 hr, after which it held steady. From a fatty acid compositional analysis of the lipid extracted from E. intestinalis, the content of palmitic acid and stearic acid was 39.85±1.19% and 14.61±0.80%, respectively. The unsaturated fatty acids (C18:1, C18:2 and C18:3) concentrations, meanwhile, were 0.3-3.2%.

Efficient conversion of glucosamine to ethyl levulinate catalyzed by methanesulfonic acid

정귀택,김성규 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.10

This study is focused on the possibility of using crustacean waste shells for sustainable biofuels and chemical production. We investigated the synthesis of ethyl levulinate (EL) from glucosamine by the methanesulfonic acidcatalyzed hydrothermal reaction using Box-Behnken design. In the ethyl levulinate synthesis, higher water content highly inhibited the formation of EL. Among the reaction factors, reaction temperature, catalyst concentration, and reaction time positively affected the outcome more than substrate concentration. The optimized reaction conditions were 200 oC reaction temperature, 60 g/L substrate concentration, 0.75M catalyst concentration, and 44.9min. Under these conditions, a 22.76mol% EL yield was achieved. These results suggest that crustacean waste shells can be used for renewable feedstocks to produce valuable chemicals and biofuels.

Detoxification of Hydrolysate by Reactive-extraction for Generating Biofuels

정귀택,김성구,박돈희 한국생물공학회 2013 Biotechnology and Bioprocess Engineering Vol.18 No.1

We introduce a reactive extraction to detoxify hydrolysate before fermentation to biofuels. In the selection of diluents, n-octanol showed the highest removal yield of 5-hydroxymethylfurfural (5-HMF) and levulinic acid. The removal yields of inhibitors were normalized to 30-min reactions. In treatments with pure extractant or diluents,only 2 ~ 4.1% of the formic acid was removed. Tri-noctylamine (extractant) removed levulinic acid and acetic acid more efficiently, and furfural was removed more efficiently than formic acid or 5-HMF. n-Octanol (polar diluent) removed levulinic acid and acetic acid, furfural,and 5-HMF at 21.2, 33.7, and 65.7%, respectively. In contrast, kerosene (inert diluent) only removed the furfural by 27.6%. Based on these results, the optimum reactiveextraction system comprised tri-n-octylamine as the extractant, n-octanol as the polar diluent, and kerosene as the inert diluent. The optimal proportion of complex extractant was 20% trialkylamine, 70% n-octanol, and 10% kerosene. By detoxification, 63.9% of acetic acid and levulinic acid, 24.4% of 5-HMF, 63.9% of formic acid, and 64.0% of furfural could be removed.

Enhancement of Growth and Secondary Metabolite Biosynthesis: Effect of Elicitors Derived from Plants and Insects

정귀택,박돈희 한국생물공학회 2005 Biotechnology and Bioprocess Engineering Vol.10 No.1

Plant-derived natural products have been and will continue to be valuable sources. Elicitors have been employed to modify cell metabolism in order to enhance the productivity of useful metabolites in plant cell/tissue cultures. In this study, several elicitors were used to improve the productivity of useful metabolites and to reduce culture time for archiving high concentration in P. ginseng hairy root cultures. The addition of chitosan, chitosan oligosaccharide and alginate oligosaccharide to the culture of P. ginseng hairy roots caused growth to be inhibited with the increase in elicitor concentration. The usage of the chitosan elicitor and D-glucosamine caused a slight decrease in hairy root growth, whereas total ginseng saponin accumulated slightly with the increase in elicitor concentration. When gel beads were added to the culture medium at the initial period, hairy root growth was enhanced. The maximum growth was 1.35 times higher than that of the control at 1% (w/v). Total ginseng saponin content decreased due to the addition of alginate beads. This would result in consistent diffusion of lower levels of calcium ions during the culture period that promotes biomass growth.

Estimating and Improving Cold Filter Plugging Points by Blending Biodiesels with Different Fatty Acid Contents

정귀택,박재희,박석환,박돈희 한국생물공학회 2008 Biotechnology and Bioprocess Engineering Vol.13 No.4

Biodiesels are alkyl esters produced by transesterification of higher fatty acids (aliphatic chains composed of 14 to 22 carbon units) from animal fats and/or vegetable oils. The cold filter plugging points (CFPP) of biodiesels are not only higher than that of petro-diesel, but they also differ from the melting point of the raw (unesterified) materials. In this study, we empirically derived equations that estimated the CFPP of a biodiesel based on its fatty acid content, using various biodiesel blends containing four methyl esters with different fatty acid compositions: soybean (SME), palm (PME), rapeseed (RME), and lard (LME). These blending ratio experiments yielded three equations that described the correlation between CFPP and fatty acid content: Y (CFPP, ℃) = -3.1X (blending ratio) - 12.7 (PME/SME); Y = 2.2X - 10.7 (LME/SME); and Y = -4.0X - 13.0 (PME/RME). We also obtained the correlation between CFPP and total saturated fatty acid methyl ester content in the biodiesels: Y (CFPP, ℃) = 0.449X (total saturated fatty acid methyl ester content, wt%) - 9.198. These empirical equations accurately predicted CFPP values of biodiesel compounds with known fatty acid compositions, facilitating the use of diverse biodiesels in industrial fields.

Chitosan으로부터 균일 산 촉매를 이용한 Ethyl Levulinate의 합성

정귀택,김성구,Jeong, Gwi-Taek,Kim, Sung-Koo 한국화학공학회 2020 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.58 No.2

In this study, the production of ethyl levulinate from chitosan using successive acid-catalyzed hydrolysis and esterification was investigated. To optimize and analysis the reaction factors and heir reciprocal interaction, response surface methodology was introduced. In the effect of water content in ethanol solvent, the production yield of ethyl levulinate was high at 5% water content (or 95% ethanol). As a result of optimization of reaction factors, 30.1% ethyl levulinate yield was obtained under the condition of 200 ℃, 3.19% chitosan, 0.49M sulfuric acid, 5% water content, and 58 min. Finally, the formation yield of ethyl levulinate was tended to enhance by increase of combined severity factor. This result indicated that the potential of chitosan as feedstock for production of chemicals and fuels. 본 연구에서는 갑각류의 껍질로부터 추출한 chitosan으로부터 황산을 촉매로 사용하여 가수분해 및 에스테르화 반응과 반응표면분석 실험계획법을 적용하여 화학 원료 및 연료로 사용 가능한 ethyl levulinate의 생산 가능성을 조사하였다. 반응물 중 수분함량의 영향을 조사한 결과, chitosan의 가수분해와 동시에 탈수반응과 ethyl levulinate로의 에스테르화와 반응은 5% 수분함량에서 가장 높았다. 반응표면분석 실험계획법을 이용하여 반응인자를 최적화한 결과, 200 ℃, 3.19% chitosan, 0.49M 황산 촉매, 5% 수분함량(95% 에탄올 용매), 그리고 58분의 반응조건에서 30.1%의 ethyl levulinate의 생성 수율을 얻었다. 또한, ethyl levulinate의 생성 수율은 반응의 가혹도가 증가할수록 증가하는 경향을 나타내었다. 이러한 결과는 chitosan이 화학 원료 및 연료의 생산에 사용될 수 있는 바이오매스로서의 잠재력이 있다고 판단된다.