서지주요정보
층상이중수산화물($Mg-Al-CO_3$ 체계)의 특성규명 및 소성생성물의 크롬산이온 수용액중에서 재수화반응에 관한 연구 = Characterization of layered double hydroxides ($Mg-Al-CO_3$ systems) and rehydration reaction of their calcined products in aqueous chromate solution
서명 / 저자 층상이중수산화물($Mg-Al-CO_3$ 체계)의 특성규명 및 소성생성물의 크롬산이온 수용액중에서 재수화반응에 관한 연구 = Characterization of layered double hydroxides ($Mg-Al-CO_3$ systems) and rehydration reaction of their calcined products in aqueous chromate solution / 이석우.
발행사항 [대전 : 한국과학기술원, 1995].
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등록번호

8005196

소장위치/청구기호

학술문화관(문화관) 보존서고

MCH 95023

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초록정보

Layered double hydroxides(LDHs), also called anionic clay minerals or hydrotalcite-like compounds(HTIcs), are a family of hydroxylated hydrate compounds of general formula; $[M(II)_{1-x}M(III)_x(OH)_2][X^{m-}_{x/m}\cdot{nH_2O}]$ In these compounds, the metal cations are located in $M(OH)_2$, brucite-like sheets that are positively charged when M(II) sites are occupied by M(Ⅲ) instead, then anions can be located in between the hydroxylated sheets in order to compensate for positive charge, and hydrated by water molecules. Several LDHs(Mg-Al-$CO_3$ systems) of varying $Mg^{2+}$/$Al^{3+}$ ratios were synthesized by a coprecipitation method, and were characterized by X-ray powder diffraction, FT-IR, $^{13}C$-CP MAS NMR, $^{27}AI$-MAS NMR, TGA/DSC, ICP-AES and other methods. X-ray powder patterns represent the products were layered structure materials. FT-IR and $^{13]C$-CP MAS NMR indicate that the carbonate anion was lied in a symmetrical site between two adjacent layers in parallel direction. $^{27}AI$-MAS NMR spectra show only single resonance due to octahedrally coordinated aluminum. According to TGA/DSC thermograms, LDHs were generally characterized by two endothermic transitions. The first transition was obserbed around 100-280℃ due to dehydration of interlayer water and the second around 280-500℃ due to dehydroxylation and decarbonation. Then the homogeneous mixed metal oxides formed. The rehydration reactions of calcined LDHs in aqueous chromate solution were investigated with various reaction conditions such as chromate concentration, calcination temperature and time, x value, competition of other anions, atmospheric conditions and pH at 298˚K. From the results, the mixed metal oxides, calcined at 340 - 760℃ were readily rehydratedin aqueous chromate solution to reconstruct original layered structure and optimum calcination temperature range were 560 - 600℃. The rehydration reaction of calcined LDHs were Langmuir type adsorption with single reaction site and not affected by calcination time. The maximum amount of adsorption was 2.5 mmol·$g^{-1}$ when x were 0.25 and 0.27. The adsorption of chromate anion was strongly affected by the anions which had high charge density and the inhibition of carbon dioxide in air was highly pH dependent. The rehydration reactions of calcined LDHs in aqueous salt solution are expected to apply for removal and fixation of toxic anions in industrial wastewater.

서지기타정보

서지기타정보
청구기호 {MCH 95023
형태사항 viii, 72 p. : 삽도 ; 26 cm
언어 한국어
일반주기 저자명의 영문표기 : Seog-Woo Rhee
지도교수의 한글표기 : 문희정
지도교수의 영문표기 : Hi-Chung Moon
학위논문 학위논문(석사) - 한국과학기술원 : 화학과,
서지주기 참고문헌 : p. 67-72
주제 Clay minerals.
Hydration.
Layer structure (Solids)
Hydroxide minerals.
점토 광물. --과학기술용어시소러스
수화 (화학) --과학기술용어시소러스
층상 조직. --과학기술용어시소러스
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