• Title/Summary/Keyword: crystallization

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Synthesis and Characterization of Zeolite Using Water Treatment Sludge (정수슬러지를 이용한 제올라이트의 합성 및 특성연구)

  • Ko, Hyun Jin;Ko, Yong Sig
    • Clean Technology
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    • v.26 no.4
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    • pp.263-269
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    • 2020
  • Zeolite was synthesized hydrothermally using the water-treatment sludge, and the effects of various synthesis parameters like reaction temperature, reaction time, and Na2O/SiO2 molar ratio on the crystallization of zeolite were investigated. Crystal structure, physical property, and thermal stability of zeolite crystals were characterized by X-ray powder diffraction, FTIR spectroscopy, BET nitrogen adsorption, and TGA measurements. The removal efficiencies of nitrogen in ammonia, heavy metal ions, and TOC were calculated to evaluate zeolite's adsorption capacity. The primary chemical composition of water-treatment sludge was 28.79% Al2O3 and 27.06% SiO2. The zeolites were synthesized by merely employing the water-treatment sludge as silica and alumina sources without additional chemicals. Zeolite crystals synthesized through the water-treatment sludge were confirmed as an A-type zeolite structure. Zeolite A had the highest crystallinity obtained from a gel with the molar composition 2.1Na2O-Al2O3-1.6SiO2-65H2O after 5 h at a temperature of 90 ℃. The specific surface area of zeolite obtained was 55 ㎡ g-1, which was higher than commercial zeolite A. The removal efficiency of nitrogen in ammonia was 68% after 3 h of reaction time, while the removal efficiencies of Pb2+ and Cd2+ ions were 99.1% and 99.3%, respectively. These results indicate active ion exchange between Pb2+ or Cd2+ ion and Na+ ion in the zeolite framework. The adsorption experiments on the different zeolite addition conditions were performed for 3 h with 300 ppm humic acid. Based on the results, TOC's highest efficiency was 83% when 5 g of zeolite was added.

A Study on the Microstructure and Magnetic Properties of Fe83.2Si5.33-0.33xB10.67-0.67xPxCu0.8 Nanocrystalline Soft Magnetic Alloys with varying P Content (Fe83.2Si5.33-0.33xB10.67-0.67xPxCu0.8 나노결정질 연자성 합금의 P함량에 따른 미세구조 및 자기적 특성 변화 관찰에 관한 연구)

  • Im, Hyun Ah;Bae, Kyoung-Hoon;Nam, Yeong gyun;An, Subong;Yang, Sangsun;Kim, Yong-Jin;Lee, Jung Woo;Jeong, Jae Won
    • Journal of Powder Materials
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    • v.28 no.4
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    • pp.293-300
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    • 2021
  • We investigate the effect of phosphorous content on the microstructure and magnetic properties of Fe83.2Si5.33-0.33xB10.67-0.67xPxCu0.8 (x = 1-4 at.%) nanocrystalline soft magnetic alloys. The simultaneous addition of Cu and P to nanocrystalline alloys reportedly decreases the nanocrystalline size significantly, to 10-20 nm. In the P-containing nanocrystalline alloy, P atoms are distributed in an amorphous residual matrix, which suppresses grain growth, increases permeability, and decreases coercivity. In this study, nanocrystalline ribbons with a composition of Fe83.2Si5.33-0.33xB10.67-0.67xPxCu0.8 (x = 1-4 at.%) are fabricated by rapid quenching melt-spinning and thermal annealing. It is demonstrated that the addition of a small amount of P to the alloy improves the glass-forming ability and increases the resistance to undesirable Fex(B,P) crystallization. Among the alloys investigated in this work, an Fe83.2Si5B10P1Cu0.8 nanocrystalline ribbon annealed at 460℃ exhibits excellent soft-magnetic properties including low coercivity, low core loss, and high saturation magnetization. The uniform nanocrystallization of the Fe83.2Si5B10P1Cu0.8 alloy is confirmed by high-resolution transmission electron microscopy analysis.

Synthesis and Characterization of Collagen Peptide Based Copolymer from Shaving Scrap (셰이빙 스크랩으로부터 콜라겐 펩타이드계 공중합체 합성과 특성)

  • Park, Min Seok;Shin, Soo Beom;Kim, Ho Soo;Kim, Min Soo;Kim, Ha Sun;Jang, Jae Hyeok;Lee, Jin Kye;Lee, Dong Kuk
    • Applied Chemistry for Engineering
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    • v.33 no.6
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    • pp.581-587
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    • 2022
  • The leather industry generates a large amount of hazardous leather waste of various types every year. Among them, shaving scrap is difficult to recycle because it contains chromium ions. Many studies in recent years have shown that shaving scraps can be processed into various types of valuable products, such as adsorbent, filler, and poultry feed. In this study, collagen peptides were extracted from shaving scraps and structurally modified to be developed as new materials with improved physicochemical properties. First, the chromium ions contained in the shaving scraps were removed using a sodium hydroxide solution, and purified through concentration and low-temperature crystallization. The purified collagen peptide was used to prepare the powder using a spray dryer. The extracted collagen peptides were structurally modified by introducing double bonds by reacting with methacrylic anhydride (MAA), and the product was confirmed by 1H NMR spectroscopy. Next, a copolymer was prepared by redox polymerization of the modified collagen peptide (MCP) and 2-ethylhexyl acrylate (2-EHA). The structure of the copolymer was qualitatively confirmed by FT-IR. In conclusion, this study confirmed that collagen peptides can be extracted from shaving scrap and converted into new eco-friendly materials through certain treatments.

Zircon U-Pb and Rare Earth Elements Analyses on Banded Gneiss in Euiam Gneiss Complex, Central Gyeonggi Massif: Consideration for the Timing of Depositional Event and Metamorphism of the Basement Rocks in the Gyeonggi Massif (경기육괴 중부 의암 편마암 복합체 호상편마암의 저어콘 U-Pb 연령과 미량원소: 경기육괴 기반암의 퇴적 시기와 변성작용에 대한 고찰)

  • Lee, Byung Choon;Cho, Deung-Lyong
    • Korean Journal of Mineralogy and Petrology
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    • v.35 no.3
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    • pp.215-233
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    • 2022
  • The zircon U-Pb and trace element analyses were performed for banded gneiss in the Euiam gneiss complex, central Gyeonggi Massif. An age of detrital zircon shows predominant age peaks at ca. 2500-2480 Ma with numerous ages ranging from Siderian to Rhyacian period. The youngest age peak of detrital zircon constrains the maximum deposition age of protolith of banded gneiss at ca. 2070 Ma. Meanwhile, the zircon rim yielded metamorphic age of ca. 1966 ± 39 Ma ~ 1918 ± 13 Ma. Based on the error range, degree of discordancy, and value of mean squared weighted deviation, we considered that the age of 1918 ± 13 Ma is the most reasonable age indicating the timing of metamorphism for banded gneiss. The zircon rims yield Ti-in-zircon crystallization temperature of 690-740℃. Therefore, we suggested that there was a high-grade metamorphic event in the Gyeonggi Massif at ca. 1918 Ma which is older than the metamorphic event that occurred in the Gyeonggi Massif during ca. 1880-1860 Ma.

Analysis of carbonation characteristics on waste concrete (폐콘크리트의 탄산화 특성 분석)

  • Kim, Nam Il;Lee, Jong Tae;Chu, Yong Sik
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.32 no.4
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    • pp.151-158
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    • 2022
  • In this study, the waste concrete sample obtained as various particle size (0~2.36 mm) was carried out the basic measurements and carbonation for analyzing the possibility of its carbonation. It was then investigated some analysis such as crystallization (XRD pattern), microstructure (SEM), and the production of CaCO3 through the ignition loss (TG-DTA). The content of CaCO3 in the waste concrete sample before carbonation was found in 14.51 % and 28.52 % after carbonation in 24 hours. Moreover, the content of CaCO3 carbonated in 24 hours with fine grinded waste concrete sample was 32.73 %. The carbonation of the waste concrete sample was rapidly performed up to 6 hours, but gradually increased from 12 to 24 hours. Especially, the amount of CaCO3 between 12 and 24 hours was only produced 2.32 %. The calcite-shaped CaCO3 crystals after carbonation of the waste concrete sample were found in microstructure and their peaks were strongly detected on XRD pattern.

A Study on the Electrical Characteristics of Ge2Sb2Te5/Ti/W-Ge8Sb2Te11 Structure for Multi-Level Phase Change Memory (다중준위 상변환 메모리를 위한 Ge2Sb2Te5/Ti/W-Ge8Sb2Te11 구조의 전기적 특성 연구)

  • Oh, Woo-Young;Lee, Hyun-Yong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.35 no.1
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    • pp.44-49
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    • 2022
  • In this paper, we investigated current (I)- and voltage (V)-sweeping properties in a double-stack structure, Ge2Sb2Te5/Ti/W-doped Ge8Sb2Te11, a candidate medium for applications to multilevel phase-change memory. 200-nm-thick and W-doped Ge2Sb2Te5 and W-doped Ge8Sb2Te11 films were deposited on p-type Si(100) substrate using magnetron sputtering system, and the sheet resistance was measured using 4 point-probe method. The sheet resistance of amorphous-phase W-doped Ge8Sb2Te11 film was about 1 order larger than that of Ge2Sb2Te5 film. The I- and V-sweeping properties were measured using sourcemeter, pulse generator, and digital multimeter. The speed of amorphous-to-multilevel crystallization was evaluated from a graph of resistance vs. pulse duration (t) at a fixed applied voltage (12 V). All the double-stack cells exhibited a two-step phase change process with the multilevel memory states of high-middle-low resistance (HR-MR-LR). In particular, the stable MR state is required to guarantee the reliability of the multilevel phase-change memory. For the Ge2Sb2Te5 (150 nm)/Ti (20 nm)/W-Ge8Sb2Te11 (50 nm), the phase transformations of HR→MR and MR→LR were observed at t<30ns and t<65ns, respectively. We believe that a high speed and stable multilevel phase-change memory can be optimized by the double-stack structure of proper Ge-Sb-Te films separated by a barrier metal (Ti).

Development and Application of Cellulose Nanofiber Powder as a Nucleating Agent in Polylactic Acid (나노셀룰로오스 분말 개발과 폴리젖산 내 핵제 적용 연구)

  • Sanghyeon Ju;Ajeong Lee;Youngeun Shin;Teahoon Park
    • KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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    • v.29 no.1
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    • pp.51-57
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    • 2023
  • Because of the global pollution caused by plastic disposal, demand for eco-friendly transformation in the packaging industry is increased. As part of that, the utilization of polylactic acid (PLA) as a food packaging material is increased. However, it is necessary to improve the crystallinity of PLA by adding nucleating agents or to improve the modulus by adding fillers because of the excessive brittleness of the PLA matrix. Thus, the cellulose nanofiber (CNF) was fabricated and dried to obtain a powder form and applied to the CNF/PLA nanocomposite. The effect of CNF on the morphological, thermal, rheological, and dynamic mechanical properties of the composite was analyzed. We can confirm the impregnated CNF particle in the PLA matrix through the field emission scanning electron microscope (FE-SEM). Differential scanning calorimetry (DSC) analysis showed that the crystallinity of not annealed CNF/PLA nanocomposite was increased approximately 2 and 4 times in the 1st and 2nd cycle, respectively, with the shift to lower temperature of cold crystallization temperature (Tcc) in the 2nd cycle. Moreover, the crystallinity of annealed CNF/PLA nanocomposite increased by 13.4%, and shifted Tcc was confirmed.

Characterization of TMA-A zeolite incorporated by ZnO nanocrystals (ZnO 나노결정을 담지한 TMA-A 제올라이트의 특성분석)

  • Lee, Seok Ju;Lim, Chang Sung;Kim, Ik Jin
    • Analytical Science and Technology
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    • v.21 no.1
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    • pp.58-63
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    • 2008
  • Nano-sized ZnO crystals were successfully incorporated using ion exchange method in TMA-A zeolite synthesized by the hydrothermal method. The optimal composition for the synthesis of TMA-A zeolite was resulted in a solution of $Al(i-pro)_3$ : 2.2 TEOS : 2.4 TMAOH : 0.3 NaOH : 200 $H_2O$. 0.3 g of TMA-A zeolite and 5 mol of $ZnCl_2$ solution were employed for the preparation of ZnO incorporated TMA-A zeolite. The crystallization process of ZnO incorporated TMA-A zeolite was analyzed by X-ray diffraction (XRD). The incorporated nano-sized ZnO crystals and the crystallinity of TMA-A zeolite were evaluated by transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The size of the incorporated nano-sized ZnO crystals was 3~5 nm, while the TMA-A zeolite was 60~100 nm. The bonding structure and absorption of the ZnO incorporated TMA-A zeolite were compared with the ZnO and TMA-A zeolite by the FT-IR analysis. Subsequentlly, the ZnO incorporated TMA-A zeolite showed the photoluminescent characteristics on the wavelengths of 330~260 nm and 260~230 nm by measurement of UV spectrophotometer.

Preparation of cobalt oxide(Co3O4·CoO) ultra fine particles using cobalt(II) chloride hexahydrate and crystalline cellulose as a starting materials (Cobalt(II) chloride hexahydrate와 결정성 셀룰로오스를 출발물질로 사용한 산화코발트(Co3O4·CoO) 초미세입자의 합성)

  • Soo-Jong Kim
    • The Journal of the Convergence on Culture Technology
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    • v.9 no.3
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    • pp.587-592
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    • 2023
  • Cobalt oxide (Co3O4·CoO) ultra fine particles were synthesized by liquid phase precursor method. cobalt(II) chloride hexahydrate (CoCl2·6H2O) was as a starting material. A plant-derived crystalline cellulose was used as impregnating materials. A impregnated precursor was calcined at a temperature of 350 to 900℃ to obtain cobalt oxide particles having a particle size of 1 to 10㎛. The crystallization process and morphology according to the calcination temperature were examined, and the properties of the synthesized powder were evaluated using SEM and XRD. It was confirmed that a crystal phase of Co3O4 began to form around 350℃ and crystal growth occurred up to 900℃. At a temperature above 500℃, the Co3O4 crystal was changed to another crystal phase CoO.

1,3-Dioxolane-Based CO2 Selective Polymer Membranes for Gas Separation (1,3-Dioxolane 기반 CO2 선택성 고분자막의 개발)

  • Iqubal Hossain;Asmaul Husna;Ho Bum Park
    • Membrane Journal
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    • v.33 no.3
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    • pp.94-109
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    • 2023
  • 1,3-Dioxolane is an exciting material that has attracted widespread interest in the chemical, paint, and pharmaceutical industries as a solvent, electrolyte, and reagent because 1,3-dioxolane is not toxic, carcinogenic, explosive, auto-flammable, and multifunctional, and due to their excellent miscibility in most organic and aqueous solvent conditions. Recently, this material has received increasing attention as a CO2-selective polymer precursor to separating CO2 from flue gas and natural gas mixtures. Poly(1,3-dioxolane) (PDXL) possesses higher ether oxygen content than polyethylene oxide (PEO), which demonstrates superior membrane CO2/N2 separation properties owing to their polar ether oxygen groups exhibiting strong affinity toward CO2. Thus, PDXL-based membranes displayed an outstanding CO2 solubility selectivity over non-polar (N2, H2, and CH4) gases. However, the polar groups of PDXL, like PEO, promote chain packing efficiency and cause polymer crystallization, thereby reducing its gas permeability, which should be improved. In this short review, we discuss the recent advancement and limitations of PDXL membranes in gas separation applications. To conclude, we provide future perspectives for inhibiting the limits of 1,3-dioxolane-based polymers in the CO2 separation process.