• 대한화학회지
• /
• 제68권2호
• /
• pp.82-86
• /
• 2024

This paper presents the solid-state synthesis of insoluble Prussian blue (Fe₄[Fe(CN)₆]₃·xH₂O, PB) in a ball mill, utilizing the fundamental components of PB. Solid-state synthesis offers several advantages, such as being solvent-free, quantitative, and easily scalable for industrial production. Traditionally, the solid-state synthesis of PB has been limited to the reaction between iron(II/III) ions and hexacyanoferrate(II/III) complex ions, essentially an extension of the solution-based coprecipitation method to solid-state reaction. Taking a bottom-up approach, a reaction is designed where the reactants consist of the basic building blocks of PB: Fe²⁺ ions and CN^- ions. The reaction, with a molar ratio of Fe²⁺ and CN^- corresponding to 1:2.8, yields PB, while a ratio of 1:6.6 results in a mixture of potassium hexacyanoferrate(II) (K₄Fe(CN)₆), potassium chloride (KCl), and potassium cyanide (KCN). This synthetic approach holds promise for environmentally friendly methods to synthesize multimetallic PB with maximum entropy in nearly quantitative yield.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2001년도 하계학술대회 논문집
• /
• pp.1080-1083
• /
• 2001

Ultrafine NiO/YSZ composite powders were prepared by using a glycine nitrate process for anode material of solid oxide fuel cells. The specific surface areas of synthesized NiO/YSZ composite powders were examined with controlling pH of a precursor solution and the content of glycine. The characteristics of synthesized composite powders were examined with X-ray diffractometer, a BET method with N$_2$absorption, scanning and transmission electron microscopy. The strongly acid precursor solution increased the specific surface area of the synthesized composite powders. This is suggested to be caused by the increased binding of metal ions and glycine under a strong acid solution of pH=0.5 that lets glycine consist of mainly the amine group of NH$_3$$\^$+/. After sintering and reducing treatment of NiO/YSZ composite powders synthesized by GNP, the Ni/YSZ pellet showed ideal micro-structure very fine Ni parties of 3-5${\mu}$m were distributed uniformly and fine pores around Ni metal particles were formed, thes, leading to an increase of the triple phase boundary among gas Ni and YSZ.

• 한국환경과학회지
• /
• 제8권2호
• /
• pp.249-254
• /
• 1999

The biosorption and desorption of Cd were carried out using brown marine algae, known as the good biosorbent of heavy metals. The content of alginate bound to light metals could be changed by the physical and the chemical pretreatment of Sargassum fluitans biomass. The Cd uptake was independent of the alginate content. In case of protonated biomass, Cd uptake was the lowest because the alginic acid of biomass was dissolved to cadmium solution during the biosorption. The maximum Cd uptake of Sargassum biomass was ranged from 79 mg/g to 139 mg/g. In case of raw biomass, the higher the alginate content of biomass, the higher was the Cd uptake. 100% of Cd and light metals sorbed in the biomass were eluted at 0.1N HCI(pH 1.1). However, the elution efficiency in $CaCl_2$ and $Ca{(NO_3)}_2$solution was varied by the concentration, the solid to liquid ratio and the pH of calcium solution. The distribution coefficient between Cd and protons in the desorption solution at pH ranged from 1.6 to 2.9 was observed on the constant stoichometric coefficient(1.3).

• Bulletin of the Korean Chemical Society
• /
• 제29권3호
• /
• pp.623-626
• /
• 2008

Spin-coating electrostatic self-assembly (SCESA) is utilized to fabricate a single layer of carboxylic-acid-coated Pd nanoparticles (NPs) (D??5 nm) on an oppositely charged surface. The packing density of a NP monolayer formed on a rotating solid substrate (3000 rpm) was examined with regards to various parameters, including the particle concentration, the pH, and the ionic strength of the solution. Initially, the packing density grew exponentially with increases in the particle concentration, up to a maximum value (of 8.4 ´ 1011/cm2) at 1.2 wt%. The packing density was also found to increase drastically as the pH decreased and the ionic strength of the solution increased; these trends can be attributed to a reduction in the interparticle repulsions among the NPs in the solution and on the substrate. The best result of this study was achieved in a 1.2 wt% solution at pH 8; under these conditions, an NP monolayer with the highest density (namely, 1.6 ´ 1012/cm2) was obtained.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2001년도 추계학술발표대회
• /
• pp.197-203
• /
• 2001

A fusion protein, consisting of human epidermal growth factor as a recognition domain and human angiogenin as a toxin domain, can be used as a targeted therapeutic against breast cancer cells among others. The fusion protein was expressed as inclusion body in recombinant E. coli, and when the conventional, solution-phase refolding process was used the refolding yield was very low due to severe aggregation, probably due to the opposite surface charge due to vastly different pI values of each domain. Solid-phase refolding process exploiting ionic interactions between the solid matrix and the protein was tried, but the ionic binding yield was very low regardless of the resins and pH conditions used. To provide higher affinity toward the solid matrix, six lysine residues were tagged to the N -terminus of the hEGF domain When the cation exchange resins such as heparin- or CM-Sepharose were used as the matrix, the adsorption capacity increased 2.5-3 times and the subsequent refolding yield increased nearly IS times compared to the conventional process.

• Bulletin of the Korean Chemical Society
• /
• 제25권5호
• /
• pp.634-638
• /
• 2004

Titanium silicalite-1 (TS-1) molecular sieve was produced by microwave heating of amorphous titanium-containing solid precursors after impregnation with aqueous TPAOH solution. $SiO_2-TiO_2$ xerogel, sub-micron sized $SiO_2-TiO_2$ prepared by thermal plasma process, and Ti-containing mesoporous silica, Ti-HMS, were tested as the solid phase substrates. Highly crystalline product was obtained within 30 min. after microwave irradiation with yields over 90% using $SiO_2-TiO_2$ xerogel, which showed essentially identical physicochemical properties to TS-1 prepared by conventional hydrothermal method. Excellent catalytic activity was also obtained for 1-hexene epoxidation using $H_2O_2.\;SiO_2-TiO_2$ particles prepared by thermal plasma and Ti-HMS were found inferior as a substrate for TS-1, probably due to difficulties in wetting the surface uniformly with TPAOH.

• 동력기계공학회지
• /
• 제7권4호
• /
• pp.44-48
• /
• 2003

Alumium alloys casting are gaining increased acceptance in the automotive and electronic industeries and squeeze casting is the most efficient method of manufacturing such mass produced parts. This study has been investigated the microstructures and mechanical properties of Al-7.0Si-0.4Mg(AC4C)alloy fabricated by squeeze casting process for development of Engine Mountain Bracket. The microstructure of squeeze casted specimen were composed of eutectic structure Alumimim solid solution and $Mg_2Si$ precipitates. The tensile strength of as-solid solution treatment Al-7.0Si-0.4Mg alloy revealed 2985MPa. It was found that Al-7.0Si-0.4Mg alloy have good aging hardening effect results are presented to show the validity of the control method.

• 한국식품영양과학회지
• /
• 제30권1호
• /
• pp.25-31
• /
• 2001

가을무 품종별 깍두기 무의 절임 특성을 알아보기 위해, 절임염수의 소금 농도(10, 15 또는 20%)를 달리하여 절임염수를 제조한 후 $2{\times}2{\times}2\;cm$로 절단한 5품종('태백', '백자', '관동', '백광' 및 '백봉')의 가을무를 2배의 절임염수에 넣어 $15^{\circ}C$에서 절이면서 절임 중 깍두기 무의 염도, 중량, 수분함량, 가용성 고형물 함량, pH 및 조직감 특성(TPA)을 알아보았다. 5품종의 깍두기 무 모두 절임 염수의 염도가 높을수록, 절임 시간이 경과될수록 염도, 가용성 고형물 함량은 증가하였으며, 중량 및 수분함량은 강소하는 경향을 나타내었고, Texture Analyser에 의한 TPA값중 경도 및 파쇄성은 감소하는 경향을 나타내었다. 깍두기 무의 소금 농도가 3%에 달할 때까지의 절임 염수의 소금 농도에 따른 최적 절임 시간은 10% 절임 염수에서는 '태백'이 5시간, '백자'는 4시간, '관동' 및 '백봉'은 3시간, '백광'은 2시간이 적당하였으며, 15% 절임 염수에서는 '태백'이 2시간, '백자', '관동', '백봉' 및 '백광'은 1시간이 적당하였다. 절이는 동안 중량 감소율은 '백광' 및 '백봉'이 가장 컸고, '태백'이 가장 작았다. 절이는 동안 pH 감소 정도가 큰 품종은 '백광'이였고, pH 변화가 거의 없는 품종은 '백자'이었다. '태백'과 '백자'는 수분함량이 적고 가용성 고형물 함량이 많았으며 경도가 높았으며 '백광'은 수분함량이 많고 가용성 고형물 함량이 적였고 경도가 낮았으며, '관동'과 '백봉'은 '백자'과 '백광'의 중간 정도의 특성을 나타내었다.

• 대한화학회지
• /
• 제39권1호
• /
• pp.1-6
• /
• 1995

단결정 적층막을 제조하기 위해 사용되는 사파이어 기판에 대하여 황산과 인산의 혼합용액 화학적 에칭을 조사하였다. 여러가지 배향면의 사파이어에 대한 에칭정도는 황산과 인산의 3:1 조성과 $315{\pm}2^{\circ}C$에서 에칭시간에 의존하였다. 280~320$^{\circ}C$ 범위에서 30분간씩 산에칭시킨 후에 에칭속도(R)를 구하였고, log R에 대한 $1/T$ semilog plot로부터 활성화에너지$(E_a)$를 구하였으며, 그것은 $({\bar1}012) > (10{\bar1}0) > (11{\bar2}0) > (0001)$면 순서로 감소하였다. 한편 (0001), $({\bar1}012),\;(10{\bar1}0)$과 $(11{\bar2}0)$면의 표층 두께를 각각 64.6, 46.5, 16.2와 5.1 ${\mu}m$ 에칭시킨 후의 기판 표면을 SEM으로 관찰하였다.

• Bulletin of the Korean Chemical Society
• /
• 제25권4호
• /
• pp.549-552
• /
• 2004

A sensitive, selective and rapid method has been developed for the determination of mercury based on the rapid reaction of mercury(II) with p-sulfobenzylidenethiorhodanine (SBDTR) and the solid phase extraction of the colored chelate with $C_{18}$ disks. In the presence of pH 3.5 sodium acetate-acetic acid buffer solution and Emulsifier-OP medium, SBDTR reacts with mercury(II) to form a red chelate of a molar ratio 1 : 2 (mercury to SBDTR). This chelate was prconcentrated by solid phase extraction with $C_{18}$ disks. An enrichment factor of 50 was achieved. The molar absorptivity of the chelate is $1.28{\times}10^5 L{\cdot}mol^{-1}{\cdot}cm^{-1}$ at 545 nm in measured solution. Beer's law is obeyed in the range of 0.01-3 ${\mu}$g/mL. The relative standard deviation for eleven replicates sample of 0.01 ${\mu}$g/mL is 1.65%. This method was applied to the determination of mercury in tobacco and tobacco additive with good results.