층상이중수산화물(Mg-Al-$CO_3$ 체계)의 물리 · 화학적 특성규명 및 소성된 시료의 크롬산이온 수용액에서 재수화반응

이석우,강문자,문희정,Rhee, Seog Woo,Kang, Mun-Ja,Moon, Hichung 대한화학회 1995 대한화학회지 Vol.39 No.8

Layered double hydroxides ($Mg-Al-CO_3$ systems, LDH), which are hydrotalcite-like anionic clay minerals, having different $Mg^{2+}\;to\;Al^{3+}$ ratio were synthesized by coprecipitation method. The subsequent products were characterized by the following methods; elemental analysis, X-ray powder diffraction, thermal analysis (DSC and TGA), FT-IR and $^{27}$Al-MAS NMR. X-ray powder patterns showed that the products formed were layered structure materials. Two heat absorption peaks were observed around 20 ∼280$^{\circ}C$ (surface water and interlayer water) and 280∼500$^{\circ}C$ (water from lattice hydroxide and carbon dioxide from interlayer carbonate) in DSC diagrams, and they were quantitatively analyzed by TGA diagrams (in case LDH4 16.2% and 28.6% respectively). FT-IR spectra indicate that the interlayer carbonate ions occupied symmetrical sites between two adjacent layers in a parallel direction. $^{27}$Al-MAS NMR spectra show only single resonance (8.6 ppm) of the octahedrally coordinated aluminum similar magnesium. When LDH4 was calcined at 560$^{\circ}C$ for 3 hours in air, its layered structure was destroyed giving a mixed metal oxide. However it readily became rehydrated in aqueous chromate solution to its original structure. 하이드로탈시이트류 음이온성 점토광물로 잘 알려진 증상이중수산화물($Mg-Al-CO_3$ 체계)을 마그네슘과 알루미늄의 비를 달리하면서 공침전법으로 합성하였다. 얻어진 생성물들의 특성을 원소조성분석, 분말 X-선회절분석, 열분석(시차주사열량분석과 열무게분석), FT-IR분광분석 및 $^{27}$/Al-MAS NMR분석등으로 규명하였다. 분말 X-선회절분석으로 생성물들이 층상구조를 이루고 있음을 확인하였다. 시차주사열량분석결과에서는 20-280$^{\circ}C$ 영역에서 표면수 및 층간수의 이탈로 인한 흡열피크가 관찰되며, 280-500$^{\circ}C$ 영역에서격자수 및 이산화탄소의 이탈로 일어나는 화학변화에 의한 강한 흡혈피크가 관찰되었다. 열무게분석결과에서는 두 영역의 질량감소량을 측정할 수 있었다(LDH4의 경우 각각 16.2%와 28.6%). FT-IR 분광분석결과층간의 탄산이온은 층과 평행하게 $D_{3h}$ 대칭구조로 존재하며, $^{27}$/Al-MAS NMR분석결과 층안의 알루미늄은 마그네슘과 마찬가지로 수산화이온에 의해 6배위환경으로 존재하였다. 공기분위기하의 560$^{\circ}C$에서 3시간 소성되어진 시료는 본래의 층상구조가 파괴된 균일한 혼합금속산화물로 변화하며, 이 물질은 크롬산이온 수용액에서 빠르게 재수화반응을 일으켜 본래의 층상구조를 회복하였다.

화학 물질의 안자극 시험용 세포 기반 미세유체 칩의 제작 및 응용

조수진(Sujin Cho),이석우(Seog Woo Rhee) 한국분석과학회 2021 분석과학 Vol.34 No.6

Alum 슬러지를 이용한 AlPO₄-계 다공성 물질의 합성

강광철,김용호,김진만,이철호,이석우,Kang, Kwang Cheol,Kim, Young Ho,Kim, Jin-man,Lee, Choul Ho,Rhee, Seog Woo 한국공업화학회 2011 공업화학 Vol.22 No.2

본 연구에서는 정수장의 alum 슬러지로부터 $AlPO_4$-계 다공성 물질의 합성과정을 규명하고자 가정용 세제, 휴믹산, 아미노산 등과 같은 유기물질을 틀로 사용하여 $Al(OH)_3$과 인산으로부터 $AlPO_4$-계 다공성 물질을 합성하였으며, $600^{\circ}C$의 공기 중에서 소성을 통하여 틀로 사용한 유기물질을 제거하였다. X-선 회절 분석 결과 합성된 물질은 $AlPO_4$-계 다공성 물질의 특징적인 패턴을 나타내었으며, 물질의 형태적인 특성은 주사전자현미경을 이용하여 관찰하였다. $^{27}Al$ MAS NMR 분석을 통하여 $Al^{3+}$ 이온 주변의 화학적 배위환경의 변화를 관찰하였다. 소성 전 물질에는 4배위와 6배위된 $Al^{3+}$ 이온이 함께 존재하지만, 소성 후 물질에서 $Al^{3+}$ 이온은 모두 4배위 환경에 존재하였다. 합성된 고체 내부에 형성된 기공은 BET 비표면적 측정으로 확인하였다. 최종적으로 합성된 물질의 응용으로 공기 중 유해 포름알데히드 제거 실험을 실시하였으며, 포름알데히드 분자가 물질에 존재하는 기공 표면에 흡착됨을 확인하였다. 결론적으로, alum 슬러지로부터 얻어진 $AlPO_4$-계 다공성 재료를 유해 기체의 흡착 및 제거에 활용할 수 있는 가능성을 제시하였다. In this study, the formation of $AlPO_4$-type porous materials from alum sludge was investigated. The materials were synthesized by the reaction of aluminum hydroxide and phosphoric acid with an organic template. Cationic surfactant, natural humic acid, and amino acids were used for the organic template. The residual organic templates were removed by calcination at $600^{\circ}C$ in the air. Powder X-ray diffraction patterns showed the charicteristic patterns of the $AlPO_4$-type porous materials. The morphology of the material was examined using a scanning electron microscopy. The coordination environment of $Al^{3+}$ ion was investigated by $^{27}Al$ MAS NMR technique. Both tetrahedrally and octahedrally coordinated$Al^{3+}$ ions were found in the as-synthesized samples while all $Al^{3+}$ ions were tetrahedrally coordinated in the calcined products. The development of mesopore in the solid material was confirmed by the measurement of BET specific surface area. Finally, they were used for removal of toxic formaldehyde from the air and the formaldehyde molecules were adsorbed on the surface of pores. In conclusion, $AlPO_4$-type porous materials from alum sludge might be applicable in the removal of toxic volatile organic compounds from the air.

이산화 티타늄/마이카 복합 재료의 적외선 광반사 특성

길현석 ( Hyun Suk Kil ),이석우 ( Seog Woo Rhee ) 한국공업화학회 2016 공업화학 Vol.27 No.1

In this work, we describe the synthesis and infrared light reflecting characteristics of TiO2/mica hybrid composites. TiO2/mica composite materials were obtained by the hydrolysis and condensation reaction of titanium isopropoxide in an aqueous solution of acetic acid in the presence of mica particles. Amorphous phase of TiO2 on the surface of mica was converted to the crystalline rutile phase via anatase phase by heat treatment (600-1000 ℃, 1-3 h) of TiO2/mica composite materials, and the size of crystals was controlled by heat treatment conditions. Physicochemical properties of mica and TiO2/mica composites were investigated using FE-SEM, ED-XRF, and PXRD. The solar reflectance of TiO2/mica composites in the near IR region (780∼2,500 nm) measured using a diffuse reflectance NIR spectrophotometer was 88.6%, which is rather higher than that of calcined pure mica (86.6%). Therefore, TiO2/mica composites can be used as NIR light reflective pigments.

표면처리된 AlPO₄에 대한 납 이온의 흡착 거동 분석

김용호,길현석,강광철,최석남,이석우,Kim, Young-Ho,Kil, Hyun-Suk,Kang, Kwang-Cheol,Choi, Suk-Nam,Rhee, Seog-Woo 한국분석과학회 2011 분석과학 Vol.24 No.4

세제 제조시설 폐수의 유기물을 틀로 하여 $Al(OH)_3$과 $H_3PO_4$의 반응으로 $AlPO_4$-계 물질을 합성하였다. 소성된 $AlPO_4$-계 물질을 APTMS, 석신산 무수물과 반응시켜 표면을 카르복실기로 바꾸었다. 분말 XRD 결과, 특징적인 $AlPO_4$-계 물질의 패턴을 얻었으며, 물질의 형태는 SEM으로 조사하였고, 작용기는 FT-IR 분석으로 확인하였다. 증류수에 분산시킨 고체의 표면 전위 측정 결과, $AlPO_4-NH_2$는 양의 표면 전하를 갖는 반면, $AlPO_4$-COOH는 음의 표면 전하를 갖는 것으로 나타났다. 합성된 $AlPO_4$-계 물질을 이용하여 수용액에서 유해 중금속의 제거 실험을 수행하였다. 납 이온은 표면에 존재하는 카르복실기와 착물을 형성하며 물질에 흡착되었고, 흡착 분배계수는 91.1 mL/g이었다. 결론적으로 본 연구에서 고찰한 $AlPO_4$-계 물질은 수환경에서 유해 중금속 이온의 제거에 활용될 수 있을 것이다. $AlPO_4$-type material was synthesized by a reaction of $Al(OH)_3$ and H3PO4 with organic templates from wastewater of detergent manufacturer. The surface of material was coated with carboxylate groups by the reaction of succinic anhydride with surface amino groups which were formed by treatment of the material with APTMS. Powder XRD patterns showed the characteristic patterns of $AlPO_4$. Morphology of the material was examined using a SEM and the functional groups were investigated by FT-IR analysis. The surface charge of a aqueous suspension was analyzed: $AlPO_4-NH_2$ has positively charged surface while $AlPO_4$-COOH has negatively charged one. They were used for the removal of toxic metals from aqueous solution. The lead ions were adsorbed on the surface by the formation of complexes with carboxylate of surface and $K_d$ was 91.1 mL/g. In conclusion, the $AlPO_4$-COOH might be applicable in the removal of toxic metal ions from aqueous system.

생물화공 , 에너지 / 환경 : 황철석 , 마그네슘 산화물과 Mg / Al LDH 에 대한 요오드 음이온의 흡착특성

강문자(Mun Ja Kang),이석우(Seog Woo Rhee),한필수(Pil Soo Hahn) 한국화학공학회 2001 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.39 No.4

To find out the materials having a high adsorption capacity for iodide anion, the adsorption characteristics of iodide on minerals, rock and oxide compounds were investigated and compared by batch experiments. Pyrite, magnesium oxide and calcined Mg/Al LDH are found as good adsorbents for iodide from literature survey and preliminary experiments. When the amount of pyrite or magnesium oxide was constant, the adsorbed amount was increased with initial iodide concentration. The adsorption characteristics of iodide on pyrite or magnesium oxide is represented by Freundlich adsorption isotherm. The adsorption experiments on calcined Mg/Al LDH were performed under the conditions excluding carbon dioxide. The adsorbed amount of iodide on the calcined LDH was higher than that on pyrite or magnesium oxide. The adsorption characteristics of iodide on the calcined LDH is described by Langmuir adsorption isotherm. The maximum adsorbed amount of iodide on the calcined LDH and K_(ads) of adsorption reaction, resulted from adsorption isotherm, are 3.8×10^(-3) ㏖/g and 7.1×10³, respectively. The adsorption of iodide on the calcined LDH is caused by the reconstruction reaction of the calcined LDH and this reaction includes a two-step ion-exchange process. The influence of carbonate anions of the aqueous solution in the adsorption of iodide on pyrite, magnesium oxide and calcined Mg/Al LDH was also investigated. The adsorbed percent of iodide on pyrite or magnesium oxide in the presence of HCO₃^- is similar to that in the absence of HCO₃^-. However, the adsorbed percent of iodide on the calcined LDH decreased sharply with the concentration of HCO₃^- .

약물 담지 다공성 중공 실리카 미세구 주위 세포의 주화성 이동

김해춘(Haechun Kim),강미선(Mi-Seon Kang),이석우(Seog Woo Rhee) 한국생물공학회 2010 KSBB Journal Vol.25 No.4

This paper demonstrates a microfluidic chip incorporating patterned hollow silica beads that can be effectively used for chemotaxis assay. The hollow silica bead has been exploited to develop a carrier for chemoattractant to induce cell migration. The microfluidic chip contains a patterned array of microfabricated docks which can hold only one bead per docking site. The hollow bead placed inside microfluidic chip releases chemotactic reagent (PDGF-BB) around its periphery in a controlled fashion which generates a signal for chemotatic migration of fibroblast cells. The number of cells migrated close to each bead has been assessed. On-chip cell migration assay showed a remarkable result proving the high efficiency and reliable accuracy in quantitative analysis. Therefore, the device could be extensively used in cell migration assay and other various studies related to cellular movements.

산화 아연 나노 입자로 도포된 마이카의 합성 및 특성 규명

김현석 ( Hyun Suk Kil ),김용호 ( Young Ho Kim ),박민영 ( Min Young Park ),이석우 ( Seog Woo Rhee ) 한국공업화학회 2012 공업화학 Vol.23 No.3

본 연구에서는 마이카와 산화 아연을 이용하여 복합 재료를 제조하고, 이를 자외선 차단 크림에 응용하는 연구를 수행 하였다. 먼저 마이카와 산화 아연을 각각 3-aminopropyltrimethoxysilane (APTMS)으로 처리하여 표면에 아민기를 생성 시켰다. 아민기가 붙은 마이카를 1,4-phenylenediisothiocyanate (PDC)와 반응시켜 표면에 -N=C=S 작용기를 활성화시킨 후, 아민기가 붙어있는 산화 아연과 결합시켜 산화 아연으로 덮인 마이카 복합 재료를 합성하였다. 원소 분석, EDS 분석, 열 중량 분석, SEM 이미지 분석, 형광 이미지 분석, 제타 전위 측정, X-선 회절 분석, DRS UV/Vis 분석을 통하여 고체 생성물의 특성을 규명하였다. 최종적으로 표준 프로토콜로 제조된 자외선 차단 크림의 파장에 따른 투과도를 280∼400 nm 범위에서 측정하여 자외선 차단 효과를 확인하였다. In this work, we have prepared the nanocomposite by the reaction of mica and zinc oxide, and investigated the application of nanocomposite to UV protecting creams. Mica treated with 3-aminopropyltrimethoxysilane (APTMS) reacted with 1,4-phenylenediisothiocyanate (PDC) to give -N=C=S functionalized surface, which was further reacted with zinc oxides coated with APTMS to give mica-zinc oxide nanocomposites. The composites were characterized by EA, EDS, TGA, SEM, zeta potential measurement, powder XRD, and DRS UV/Vis analyses. Finally, we measured transmittances of ultraviolet protection creams manufactured by using mica composite covered with zinc oxides in the range of 280∼400 nm. The nanocomposites developed in this work might be applicable as inorganic hybrid materials for UV protecting creams.

양이온 교환능을 갖는 K-Birnessite 콜로이드에 의한 수용성 우라늄(VI) 이온의 흡착 연구

강광철(Kwang Cheol Kang),김승수(Seung Soo Kim),백민훈(Min Hoon Baik),권수한(Soo Han Kwon),이석우(Seog Woo Rhee) 한국분석과학회 2010 분석과학 Vol.23 No.6

표면처리된 AlPO₄에 대한 납 이온의 흡착 거동 분석

김용호(Young Ho Kim),길현석(Hyun Suk Kil),강광철(Kwang Cheol Kang),최석남(Suk Nam Choi),이석우(Seog Woo Rhee) 한국분석과학회 2011 분석과학 Vol.24 No.4