Chemically modified kaolinite. Grafting of methoxy groups on the interlamellar aluminol surface of kaolinite

Tunney, James J.; Detellier, Christian

doi:10.1039/jm9960601679

Cited by 144 publications

(123 citation statements)

References 44 publications

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“…can be attributed to the decomposition of methoxy groups together with dehydroxylation of kaolinite [7,15,41]. Similarly to previous reports, there is a small decrease in the dehydroxylation peak temperature (as compared to that of the untreated kaolin), which indicates the modification of the kaolinite structure with methoxy groups.…”

Section: Thermal Analysissupporting

confidence: 61%

“…After drying the wet kaolinite-Me complexes at room temperature, the (001) reflections of the expanded phase decreased to 0.86 nm (ZK-U-Me(air-dry) sample), which is close to the value (d 001 = 0.88 nm) reported by Cheng et al [38] for similar air-dried complex prepared from kaolinite-U pre-intercalate. According to the literature [7,15,35,41], the formation of the 0.86-nm complex from the 1.11-nm one can be attributed to the partial release of mobile Me and/or water molecules from the interlayer spaces during the air-drying process. After treating the wet kaolinite-Me intercalation complex with CTAC, the (001), (002), (003), (004), and (005) reflections of the kaolinite-CTAC intercalation complex [30,35,40] appeared at 3.82, 1.91, 1.27, 0.95, and 0.76 nm, respectively (ZK-U-Me-CTAC(unwashed) sample).…”

Section: Xrd Analysismentioning

confidence: 99%

“…From the DMSO and NMF pre-intercalates, the formation of a kaolinite-Me complex with basal spacing of 1.11-1.13 nm was established in methanol-wet state [10,12,15,19,29,30,[33][34][35][36]41], but on air-drying, a contraction down to 0.93-0.86 nm was observed [12,15,19,38,41]. Using elemental and thermal analysis results, Tunney and Detellier [7], Komori et al [15], and Matusik and Klapyta [36] calculated the values of x=0.87, x=0.36, and x=0.48, respectively, for the supposed chemical formula of In spite of the more eco-friendly behavior of U, there are only two studies reported in the literature [34,41], where the kaolinite-U pre-intercalate was used to synthesize kaoliniteMe complexes. In our previous work with U [41], we obtained the same methanol-wet state (with the basal spacing of 1.12 nm) as prepared earlier in the literature using the kaolinite-DMSO and kaolinite-NMF pre-intercalates [10,12,15,19,29,30,[33][34][35][36].…”

Section: Introductionmentioning

confidence: 99%

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Characterization of kaolinite-cetyltrimethylammonium chloride intercalation complex synthesized through eco-friend kaolinite-urea pre-intercalation complex

Makó

Kovács

Katona

et al. 2016

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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Because of its suitability for producing kaolinite nanoscrolls, the kaolinitecetyltrimethylammonium chloride intercalation complex is of interest in the research area of kaolinite nanocomposites. Experimental and molecular simulation analyses are used to investigate this intercalation complex, revealing its real structure formed through partially methoxy-modified kaolinite. Cost-efficient homogenization method is applied to synthesize the eco-friend kaolinite-urea pre-intercalation complex, which was found to be favorable to intercalate cetyltrimethylammonium chloride into the interlayer space of kaolinite. The influence of the pre-intercalated urea molecules, the partial modification of kaolinite structure with methoxy groups, and the presence of methanol molecules in the interlayer space of kaolinite on the intercalation of cetyltrimethylammonium chloride is characterized experimentally by X-ray diffraction, thermal analysis, Fourier transform infrared spectroscopy, and electron microscopy. The kaolinite-cetyltrimethylammonium chloride complex is identified at the basal spacing of 3.82 nm with the chemical formula of Al 2 Si 2 O 5 (OH) 3.7 (OCH 3 ) 0.3 (CTAC) 1.6 (Me) 1.6 . Our molecular simulations predict methanolcontaining structures between methoxy-functionalized kaolinite layers with diffuse guest molecular arrangements. ________________________________________________________________

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Section: Thermal Analysissupporting

confidence: 61%

Section: Xrd Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Characterization of kaolinite-cetyltrimethylammonium chloride intercalation complex synthesized through eco-friend kaolinite-urea pre-intercalation complex

Makó

Kovács

Katona

et al. 2016

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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“…Embora no presente caso o metanol tenha sido utilizado no processo de lavagem, a mesma fase hidratada pode ser obtida através da lavagem com água da fase intercalada com uréia 21 descartando-se, desta forma, a funcionalização com grupamentos metóxido. Outra evidência da não existência do grupamento metóxido é a não observação de bandas características através de FTIR 36 . A Figura 4 apresenta os difratogramas de raios-X da caulinita hidratada seca ao ar (K-ar) e após aquecimento a varias temperaturas (Tabela 1).…”

Section: Figura 2 Difratogramas De Raios-x Da Fase Hidratada Seca Aounclassified

Comportamento térmico da caulinita hidratada

Gardolinski

Filho

2003

Quím. Nova

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Recebido em 23/11/01; aceito em 28/5/02 THERMAL BEHAVIOR OF HYDRATED KAOLINITE. Well-ordered kaolinite from the Brazilian Amazon Region (State of Pará) was initially reacted at 60 °C with a water dimethylsulfoxide mixture. After washing and characterisation, the resulting material was washed several times with methanol and in the final step with water. The water molecules displace the previously dimethylsulfoxide intercalated molecules and two different hydrated kaolinites were obtained. An unstable phase characterized by an interplanar basal distance of 0,996 nm that after drying collapse to the stable 0,844 nm hydrated kaolinite. The dehydration of the sample to disordered kaolinite was accompanied by Powder X-ray Diffractometry, thermal analysis (simultaneous TG and DSC) and FTIR spectroscopy.Keywords: kaolinite; clay minerals; intercalation compounds. INTRODUÇÃOOs argilominerais do grupo da caulinita envolvem quatro variedades politípicas polimórficas, a Nacrita (JCPDS:16-606), Diquita (JCPDS:10-446), Caulinita (JCPDS:14-164 e 29-1488) e Haloisita 0,7 nm ou metahaloisita (JCPDS:29-1487), todos com a fórmula Al 2 Si 2 O 5 (OH) 4 , além da Haloisita 1,0 nm ou endelita (JCPDS:1489) com a fórmula Al 2 Si 2 O 5 (OH) 4 .2H 2 O 1,2 . Tipicamente os argilominerais nacrita, diquita, caulinita e haloisita 0,7 nm ocorrem na forma de cristais tabulares e a haloisita 1,0 nm na forma de tubos ou cilindros, que ocorrem pelo enrolamento das lamelas da caulinita.Dependendo da sua gênese, a caulinita pode se apresentar com elevada, média e alta ordem estrutural ao longo do eixo "b" da estrutura triclínica (ou monoclínica), sendo baixo o teor de substituintes isomórficos (normalmente Fe +3,+2 no sítio do alumínio), sendo considerada eletricamente neutra. Minerais do grupo da caulinita e outros argilominerais são formados pela decomposição de feldspatos por processos geológicos, tendo provavelmente sericita como intermediário (Eq. 1). A formulação da caulinita pode ser descrita como resultante da deposição de 2 moles de gibbsita (variedade polimórfica do Al(OH) 3 ) sobre dois moles de sílica, mantendo-se as estruturas dos dois compostos (tipo 1:1). A Figura 1 apresenta a estrutura da gibbsita (a), sílica (b), o processo de montagem da estrutura ideal da caulinita (c) e a estrutura final da caulinita (d).Na estrutura da gibbsita os átomos de alumínio estão posicionados nos centros dos octaedros e, nos vértices, estão posicionados os grupamentos hidroxila. Somente 2/3 dos octaedros são ocupados e os octaedros são ligados pelas arestas, o que caracteriza a caulinita como dioctaédrica 1,2 . Na estrutura da sílica, os átomos de silício estão posicionados nos centros dos tetraedros, nos quais os vértices são ocupados por átomos de oxigênio. Devido a forma com que os tetraedros são coordenados uns aos outros, cria-se um buraco na lamela que expõe a hidroxila interna para eventuais reações (Figura 1b). Exemplos de intercalação de caulinitas envolvem o uso de pequenas moléculas polares (tipicamente dimetilsulfóxido e Nmetilformamida) 3-...

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“…This result shows that the methoxy modification makes the interlayer space of kaolinite available for 5FU loading. The molecular dimensions of 5FU are approximately 0.49 nm × 0.53 nm (Datt et al, 2013), and the d 001 value of dry Kaol-MeOH is 0.82 nm (Komori et al, 2000;Tunney and Detellier, 1996), suggesting that 5FU might be arranged as a roughly vertical monolayer in the interlayer space of kaolinite (Fig. 1e).…”

Section: Xrd Tem and Elemental Analysismentioning

confidence: 99%