• Korean Chemical Engineering Research
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• 제52권3호
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• pp.355-359
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• 2014

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 수 있다. 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 $175^{\circ}C$, 촉매농도 2.4%, 그리고 반응시간 40.7분의 조건에서 2.7 g/L의 levulinic acid를 얻었다.

• 한국결정성장학회지
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• 제11권1호
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• pp.33-37
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• 2001

$213^{\circ}C$에서 깁사이트와 pseudoboehmite를 출발물질로 하여 산성도를 변화시켜 수열합성법에 의해서 카올리나이트를 합성하였다. 합성된 카올리나이트는 X-선회절 분석기와 적외선 분광광도계를 이용하여 결정화 과정을 조사하였으며 Hinckley 지수를 계산하였다. 산을 이용한 카올리나이트 합성은 출발물질의 용해를 촉진시켜 결정화하였다. 결정화 속도와 적층결함은 음이온의 종류, 산성도와 출발물질에 의존하였다.

• 한국세라믹학회지
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• 제31권11호
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• pp.1401-1413
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• 1994

The synthesis of kaolinite mineral from domestic diatomite for silica resource, commercial vailable gibbsite or alumina for alumina resource were made under various hydrothermal treatment, and the sythetic effect of acidic mineralizers, temperature treatment with time duration, particle size of alumina on formation of kaolinite mineral and the plastic properties of synthesized kaolinite were investigated. The various acidic mineralizers which are HCl, HNO3, H2SO4 and Oxalic acid were employed for hydrothermal reaction in the range of 0.01 mol/ι to 2 mol/ι concentration of each mineralizers. It was found that HCl in the level of 1 mol/ι solution produced highly yields of well-crystallized and platy form kaolinite mineral and gave the most effective extraction of iron oxide, compared to that of others, that HNO3 produced highly yield of kaolinite but lower extraction of iron oxide, that H2SO4 produced low yield of kaolinite and formed alunite mineral, and that oxialic acid formed spherical crystalline kaolinite and gave low extraction of iron oxide. Moreover, it showed that kaolinite minerals were well synthesized in a wide range of less than 2 mol/ι acids, but were poorly synthesized at more than 2 mol/ι acids. However, boehmite and kaolinite were coexistently formed in the temperature range of 18$0^{\circ}C$ and 20$0^{\circ}C$ when the calcined diatomite and gibbsite were involved. The well-ordered kaolinite mineral as a platy form was highly synthesized in the temperature range of 220 and 24$0^{\circ}C$, when the same marterials as above were used with treatment of 1 mol/ι HCl solution. The results also revealed that the size of crystalline platy form kaolinite, synthesized from alumina and calcined diatomite with treatment in 1 mol/ιHCl solution at 24$0^{\circ}C$, was much larger than that of gibbsite and calcined diatomite shown previously, and that kaolinite and corundum minerals were coexistently formed under any hydrothermal treatment conditions. The plasticity of synthesized kaolinite from under 2 ${\mu}{\textrm}{m}$ alumina and calcined diatomite was very poor, and that of the synthesized kaolinite from raw diatomite and gibbsite gave higher than that of calcined diatomite and gibbsite.

• 한국식품영양과학회지
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• 제27권1호
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• pp.93-101
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• 1998

In order to improve the functional properties of several fish meat extracts as an alternate protein source, theri basic plastein reactions were evaluated. The UV absorption at 270 and 290 nm indicated that plasteins had higher amount of hydrophobic peptide or amino acid than the fish meat extracts. The water solubilities of the extracts were reduced at acidic pH. Values for the emulsifying capacity of the extracts and plasteins were over 30% although the latter showed the higher ones than the former. The osmolalities of the extracts at 1.0% concentration were 39(loach), 33(bastard halibut), 30(jacopever) and 24(crucan carp) milliosmole. Generally the slightly higher osmolalities were noted in the plasteins to be compared with the extracts. Both the extracts and plasteins exhibited a higher antioxidative effect than tocopherol. The hydrophobic amino acid which had been introduced at plastein reaction attributed the stronger antionxidative effect of its product than the extracts.

• Nano
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• 제13권11호
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• pp.1850132.1-1850132.14
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• 2018

The direct synthesis of metal-organic frameworks (MOFs) with acidic and basic active sites is challenging due to the introduction of functional groups by post-functionalization method often jeopardize the framework integrity. Herein, we report the direct synthesis of acid-base bifunctional MOFs with tuning acid-base strength. Employing modulated hydrothermal (MHT) approach, microporous MOFs named $UiO-66-NH_2$ was prepared. Through the ring-opening reaction of 1,3-propanesultone with amino group, $UiO-66-NH_2-SO_3H-type$ catalysts can be obtained. The synthesized catalysts were well characterized and their catalytic performances were evaluated in one-pot glucose to 5-HMF conversion. Results revealed the acid-base bi-functional catalyst possessed high activity and excellent stability. This work provides a general and economically viable approach for the large-scale synthesis of acid-base bi-functional MOFs for their potential use in catalysis field.

• 자원환경지질
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• 제21권3호
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• pp.209-221
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• 1988

The ore deposit of the Ohtani mine is one of repesentatives of plutonic tungsten-tin veins related genetically to acidic magmatism of Late Cretaceous in the Inner zone of Southwest Japan. Based on macrostructures of vein filling on the order of ore body, three major mineralization stages, called stage I, stage II, and stage ill from earliest to latest, are distinguished by major tectonic breaks. The alteration zories are characterized by specific mineral associations in pseudomorphs after biotite. The alteration zones can be divided into two parts, i. e. a chlorite zone and a muscovite zone, each repesenting mineralogical and chemical changes produced by the hydrothermal alteration. The chloritic alteration took place at the beginning of mineralization, and muscovite alteration in additions to chloritic alteration took place at stage II and ill. The alteration zones are considered to be formed by either of two alteration mechanism. 1) The zones are formed by reaction of the rock with successive flows of solution of different composition and different stage. 2) The zones are formed contemporaneously as the solution move outward. Reaction between the solution and the wall-rock results in a continuous change in solution chemistry. The migration of the successive replacement of the fresh zone$\rightarrow$the chlorite zone$\rightarrow$the muscovite zone may have transgressed slowly veinward, leaving metasomatic borders between the different zones.

• Korean Chemical Engineering Research
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• 제57권1호
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• pp.133-141
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• 2019

침전법으로 환류방법 또는 수열합성법을 이용하여 산 염기점을 갖는 고비표면적 지르코니아를 합성하였다. 제조된 지르코니아는 침전제로 수산화암모늄 수용액을 사용하여 Zr 용액의 pH를 2에서 10 범위 내에서 조절하였으며 질소흡착분석, X-선 회절분석(XRD), 이소프로판올 승온탈착법(IPA-TPD), 주사전자현미경 분석, X-선 광전자분광분석, 산-염기점 분석을 통해 IPA 분해반응의 촉매활성과 연관하여 특성분석을 수행하였다. 환류방법을 사용할 시, tetragonal 상이 높은 지르코니아를 얻기 위해서는 Zr 용액의 pH가 높아야 하며, pH 9 이상에서는 순수한 tetragonal 상의 지르코니아 합성이 가능하였다. 또한, 비표면적이 큰 지르코니아를 얻기 위해서는 높은 pH가 요구되었으며, pH 10에서 합성한 경우에는 $600^{\circ}C$에서 소성 후에도 $260m^2g^{-1}$의 높은 비표면적이 얻어졌다. 하지만 같은 조건 하에서 고압이 수반되는 수열합성에는 $40m^2g^{-1}$ 이하의 매우 낮은 비표면적을 보였으며, monoclinic 상의 지르코니아가 합성되었다. 고 비표면적 tetragonal 상의 지르코니아를 얻기 위해서는 용액의 pH가 가장 큰 영향을 미쳤으며, 용액의 pH와 무관하게 높은 압력이 필요한 수열합성에서는 monoclinic 지르코니아가 생성되었으며 상대적으로 비표면적이 낮게 나타났다. 높은 비표면적과 tetragonal 상을 갖는 지르코니아는 염기점에 비해 산점이 우세하여 IPA 분해반응에서 선택적 탈수반응만 진행되는 프로필렌만 생성되었다.

• 청정기술
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• 제23권1호
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• pp.104-112
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• 2017

해조류로부터 수열 액화 반응을 통해 생성된 원료를 이용하여 수소가스를 생산하기 위해 개질 반응용 상용화 촉매와 $K_2Ti_xO_y$가 첨가된 니켈(Ni) 제조 촉매를 사용하여 반응온도에 따른 수증기 개질 반응을 수행하였다. 반응원료는 해조류 바이오매스를 503 K의 반응온도에서 2시간 동안 수열 액화를 통해 생성된 액화 원료를 사용하였으며, 상용화 촉매(FCR-4-02)와 제조 촉매($Ni/K_2Ti_xO_y-Al_2O_3$, $Ni/K_2Ti_xO_y-SiO_2$, $Ni/K_2Ti_xO_y-ZrO_2/CeO_2$, Ni/$K_2Ti_xO_y$-MgO) 및 반응온도에 따른 수증기 개질 반응의 활성을 비교 연구하였다. 실험결과 제조 촉매 4종 모두 상용화 촉매와 비교하여 반응활성이 높게 나타나는 것이 확인되었으며, 제조 촉매의 지지체에 따라 생성되는 가스의 조성이 달라지는 것이 확인되었다. 특히, 산성이나 염기성을 띄는 $Al_2O_3$와 MgO의 지지체와 중성을 띄는 $SiO_2$의 지지체에서는 CO가 선택적으로 높게 생성이 되었으며 환원성을 띄는 $CeO_2$를 포함하는 지지체에서는 수성가스 전환 반응이 일어나 $CO_2$가 높게 생성됨을 보였다.

• 자원환경지질
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• 제17권4호
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• pp.299-314
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• 1984

The Yeongdo Island in Busan City is a remnant of the latest Cretaceous volcano, and consists geologically of andesites, rhyolite tuff, pelitic and psammitic hornfelses, lapilli rhyodacite tuff of the Yucheon Group, felsite and felsite porphyry of the Bulgugsa intrusives, and Holocene sediments in ascending order. The hornfelses are bound to the Taejongdae Formation. The stratigraphic position of the Formation is determined definitely into the Yucheon Group, thus the geologic age is approximately the same with the volcanic rocks of the Group. The sediments had been thermally metamorphosed to make pelitic and psammitic hornfelses of the albite epidote hornfels facies by the effects of active hydrothermal circulation, vaporization, and hybridization of andesitic solution, or of basification of acidic intrusives. Thus, on occasion, those hornfelses are not used to be distinguished from the andesitic rocks in the southeastern part of the Korean peninsula. The paleocurrent direction determined from several cross-beddings of the Taejongdae Formation is suggested to be from southwest to northeast. Orbicular rocks occur in hornfelsed rhyolite tuff, pelitic- and psammitic-hornfelses, and felsite porphyry at a lot of outcrops in the area of southwestern shoreline of the Yeongdo Island. Orbicules in rhyolite tuff and hornfels in the island might have originated from diffusion processes of metasomatic metamorphism carried out by hydrothermal solution rised from the intrusive adamellite which may be emplaced deeply under the Yeongdo volcanics. Those orbicules are due to metasomatic, secondary, and epigenetic origin. Proto-, multi-shelled, and multi-cored orbicules are described in the orbicular tuff. But multi-cored orbicules are not found in the orbicular fornfels. 250 tuff-orbicules numbered sporadically are in $20,000m^2$ area of the locality of orbicular tuff. About 60 hornfels-orbicules occurred sporadically are in $1,700m^2$ area of the locality of orbicular hornfels in the Taejongdae Formation. Orbicules in felsite porphyry might have originated by diffusion reaction between xenoliths and a quiescent zone in felsite porphyry magma. Those are of igneous, primary, and syngenetic origin.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.90.1-90.1
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• 2010

Due to the rapidly diminishing energy sources and higher energy production cost, the interest in dye-sensitized solar cells (DSSCs) has been increasing dramatically in recent years. A typical DSSC is constructed of wide band gap semiconductor electrode such as $TiO_2$ or ZnO that are anchored by light-harvesting sensitizer dyes and surrounded by a liquid electrolyte with a iodide ion/triiodide ion redox couple. DSSCs based on one-dimensional nano-structures, such as ZnO nanorods, have been recently attracting increasing attention due to their excellent electrical conductivity, high optical transmittance, diverse and abundant configurations, direct band gap, absence of toxicity, large exiton binding energy, etc. However, solar-to-electrical conversion performances of DSSCs composed of ZnO n-type photo electrode compared with that of $TiO_2$ are not satisfactory. An important reason for the low photovoltaic performance is the dissolution of $Zn^{2+}$ by the adsorption of acidic dye followed by the formation of agglomerates with dye molecules which could block the I-diffusion pathway into the dye molecule on the ZnO surface. In this paper, we prepared the DSSC with the ZnO electrode using the chemical bath deposition (CBD) method under low temperature condition (< $100^{\circ}C$). It was demonstrated that the ZnO seed layers played an important role on the formation of the ZnO nanostructures using CBD. To achieve truly low-temperature growth of the ZnO nanostructures on the substrates, a two-step method was developed and optimized in the present work. Firstly, ZnO seed layer was prepared on the FTO substrate through the spin-coating method. Secondly, the deposited ZnO seed substrate was immersed into an aqueous solution of 0.25M zinc nitrate hexahydrate and 0.25M hexamethylenetetramine at $90^{\circ}C$ for hydrothermal reaction several times.