• Title/Summary/Keyword: purity

Search Result 2,418, Processing Time 0.028 seconds

High-Purity Purification of 2,6-Dimethylnaphthalene (2,6-DMN) in Light Cycle Oil - Purification of 2,6-DMN from Concentrate of DMN Isomers by Crystallization - (접촉분해경유 중의 2,6-dimethylnaphthalene (2,6-DMN)의 고순도 정제 - 결정화에 의한 DMN 이성체 농축액 중의 2,6-DMN의 정제 -)

  • Kim, Su Jin;Jeong, Hwa Jin
    • Applied Chemistry for Engineering
    • /
    • v.19 no.1
    • /
    • pp.105-110
    • /
    • 2008
  • The high-purity purification of 2,6-dimethylnaphthalene (2,6-DMN, 10.43 wt%) from the concentrate of DMN isomers recovered from light cycle oil (LCO) through distillation-extraction combination was examined by a crystallization operation. To select the most suitable crystallization solvent for purification of 2,6-DMN, several conventional solvents, which have been employed commercially as crystallization solvents for high-purity performance, were tested, through measurement of purity and yield of 2,6-DMN. The solvents used were acetone, cyclohexanone, ethanol, ethyl ether, ethyl acetate, isopropyl ether, methanol, n-hexane, n-heptane, pyridine, THF, toluene, and a mixture of methanol and acetone. The mixture of 60 vol% methanol and 40 vol% acetone (M/A = 1.5) was found to be suitable for purification of 2,6-DMN in the concentrate of DMN isomers based on purity and yield. Increasing the operation temperature and the volume ratio of solvent (M/A = 1.5) to feed (concentrate of DMN) resulted in improving the purity of 2,6-DMN, whereas the yield decreased. The crystal recovered by crystallization run using the concentrate of DMN isomers contained about 76 wt% 2,6-DMN. Furthermore, for recovery of high-purity 2,6-DMN, crystal containing 76 wt% 2,6-DMN was crystallized. As a result, crystal with 99.7 wt% 2,6-DMN was recovered with 40% yield.

Development of analytical method for the isotope purity of pure D2 gas using high-precision magnetic sector mass spectrometer

  • Chang, Jinwoo;Lee, Jin Bok;Kim, Jin Seog;Lee, Jin-Hong;Hong, Kiryong
    • Analytical Science and Technology
    • /
    • v.35 no.5
    • /
    • pp.205-211
    • /
    • 2022
  • Deuterium (D) is an isotope with one more neutron number than hydrogen (H). Heavy elements rarely change their chemical properties with little effect even if the number of neutrons increases, but low-mass elements change their vibration energy, diffusion rate, and reaction rate because the effect cannot be ignored, which is called an isotope effect. Recently, in the semiconductor and display industries, there is a trend to replace hydrogen gas (H2) with deuterium gas (D2) in order to improve process stability and product quality by using the isotope effect. In addition, as the demand for D2 in industries increases, domestic gas producers are making efforts to produce and supply D2 on their own. In the case of high purity D2, most of them are produced by electrolysis of heavy water (D2O), and among D2, hydrogen deuteride (HD) molecules are present as isotope impurities. Therefore, in order to maximize the isotope effect of hydrogen in the electronic industry, HD, which is an isotope impurity of D2 used in the process, should be small amount. To this end, purity analysis of D2 for industrial processing is essential. In this study, HD quantitative analysis of D2 for high purity D2 purity analysis was established and hydrogen isotope RM (Reference material) was developed. Since hydrogen isotopes are difficult to analyze with general gas analysis instrument, they were analyzed using a high-precision mass spectrometer (Gas/MS, Finnigan MAT271). High purity HD gas was injected into Gas/MS, sensitivity was determined by a signal according to pressure, and HD concentrations in two bottles of D2 were quantified using the corresponding sensitivity. The amount fraction of HD in each D2 was (4518 ± 275) μmol/mol, (2282 ± 144) μmol/mol. D2, which quantifies HD amount using the developed quantitative analysis method, will be manufactured with hydrogen isotope RM and distributed for quality management and maintenance of electronic industries and gas producers in the future.

Effect of the Si-C Powder Prepared by Mechanical Alloying on the Densification of Silicon Carbide Powder

  • Yoon, Bola;Lee, Sea-Hoon;Lee, Heesoo;Hwang, Geumchan;Kim, Byungsook
    • Journal of the Korean Ceramic Society
    • /
    • v.53 no.1
    • /
    • pp.99-104
    • /
    • 2016
  • High purity Si-C (99.999%) powder prepared by mechanical alloying was added to a commercial SiC powder as a sintering additive. Reaction bonded silicon carbide balls and jars with high purity (99.98%) were used for the mechanical alloying. As a result, the purity of the sintered Si-C was higher than 99.99%. When sintered at $2200^{\circ}C$ under 50 MPa pressure for 1 h, SiC containing 10 wt% of high purity Si-C showed a relative density of 95.3%, similar to the relative density of commercial SiC (95%). However, the relative density of SiC decreased to 90.6% without the additive when the applied pressure decreased to 40 MPa. In contrast, the relative density was nearly unaffected by the decrease of the pressure when using the Si-C additive. Therefore, the addition of Si-C powder promoted the densification of SiC above $2000^{\circ}C$ under 40 MPa pressure.

Recovery of High Purity Tin from Waste Solution of the Tin Plating by Ion-exchange and Cyclone-electrowinning (주석도금폐액으로부터 이온교환 및 사이클론 전해채취를 이용한 고순도 주석의 회수)

  • Kang, Yong-Ho;Shin, Gi-Wung;Ahn, Jae-Woo
    • Resources Recycling
    • /
    • v.25 no.4
    • /
    • pp.42-48
    • /
    • 2016
  • A research for the recovery of the metal with high purity from the waste tin plating solution was carried out. First, tin plating waste solution was tested to remove the organic substances and metallic impurities such as Fe, Zn, Na etc. using ion exchange resin having iminodiacetic functional groups (Lewatit TP 207). Second, the tin solution was purified to obtain the high purity tin solution using ion exchange resin having ethylhexyl-phosphate functional groups (Lewatit VPOC 1026). Finally, 99.98% of the high purity of tin metal can be recovered from the purified solution by cyclone type electrowinning method.

1Determination of optical purity of N-acetyl-1-naphthylethylamine by chiral chromatography and NMR spectroscopy (키랄 크로마토그래피와 NMR 분광법에 의한 N-acetyl-1-naphthylethylamine의 광학순도 측정)

  • Jeong, Young-Han;Ryoo, Jae-Jeong
    • Analytical Science and Technology
    • /
    • v.23 no.1
    • /
    • pp.97-101
    • /
    • 2010
  • (R)-N-3,5-dinitrobenzoyl (DNB) phenylglycinol derived chiral selector was used as a HPLC chiral stationary phase (CSP) for the resolution of racemic N-acylnaphthylalkylamines. In this study, determination of optical purity was performed by both chiral chromatography and NMR spectroscopy by using the (R)-phenylglycinol derived chiral selector. The data of accuracy and precision of each optical purity value are calculated from the results of NMR and HPLC experiments by comparing with true value. Average error of the NMR method was +2.2% with average RSD of 4.54%, while that of HPLC method was -3.5% with average RSD of 3.23%.

A Novel Method for Production of Concentrated Purity Maltose Using Swollen Extruded Starch (Extrusion시킨 팽윤 전분을 기질로 한 새로운 Maltose 생산법)

  • Lee, Yong-Hyun;Kim, Dong-Sun;Shin, Hyun-Dong;Park, Jin-Seo
    • Microbiology and Biotechnology Letters
    • /
    • v.22 no.1
    • /
    • pp.106-113
    • /
    • 1994
  • A novel method for production of concentrated purity maltose using swollen extruded corn starch was investigated. Degree of gelatinization of extruded starch suitable for maltose formation was found to be around 70%. The optimal amiunt of enzyme was 400 unit fungal $\alpha $-amylase per g of starch, and the reaction time was 12 hours. At extruded starch concentration of 300 g/l(w/v), maltose concentration and content were reached up to 220 g/l(w/v) and 77%(w/w), respectively. The maltose forming reaction was also successfully proceeded at high starch concentration of 700 g/l(w/v), however, the conversion yield and content were decreased. By the addition of extruded starch by fed-batch wise, the maltose concentration, purity, and conversion yield could be improved up to 465 g/l(w/v), 70%(w/w), and 0.63, respectively. The investigated maltose production process seems to have many potential advantages over the conventional process utilizing liquefied starch, and the feasibility for industrial application needs to be evaluated.

  • PDF