Kaolinite: NMF Intercalates

Uwins, Philippa J.R.; Thompson, John; Yago, Anya

doi:10.1346/ccmn.1993.0410609

Cited by 35 publications

(26 citation statements)

References 25 publications

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“…Georgia kaolinite (KGa-1, available from the Source Clay Mineral Repository of The Clay Minerals Society) was selected for detailed investigations because it intercalates very well and consists mainly of euhedral platey crystals with no halloysite tubes or other rolled particles. Georgia kaolinite has also been studied in similar intercalation experiments by other workers (Costanzo and Giese 1985;Uwins et al 1993;Wada 1961 About 3 g of kaolinite are thoroughly mixed with 25 ml of saturated solution of KAc in centrifuge tubes and allowed to intercalate for 2 d at 80 ~ The progress of intercalation is monitored by periodic X-ray diffraction (XRD) of the intercalates. After maximum intercalation has occurred, based upon a maximum ratio of 14 to 7 A peak intensity, the suspensions are centrifuged, and supernatant KAc solution is removed.…”

Section: Methodsmentioning

confidence: 95%

“…Several kaolinites described by Uwins et al (1993) have been initially tested in this study. Georgia kaolinite (KGa-1, available from the Source Clay Mineral Repository of The Clay Minerals Society) was selected for detailed investigations because it intercalates very well and consists mainly of euhedral platey crystals with no halloysite tubes or other rolled particles.…”

Section: Methodsmentioning

confidence: 99%

“…The Georgia kaolinite intercalated readily with a saturated solution of KAc (Figure 1), More than 80% intercalation, indicated by a reduction in the intensity of the 7.2-A reflection and appearance of a reflection at 14 ,~, was achieved in about 2 d. Rigorous methods of intercalation, such as grinding of salt with clay (Wada 1961;Uwins et al 1993) were avoided, as these procedures may severely deform the structure and morphology of kaolinite.…”

Section: Bulk Properties Of Intercalates and Hydratesmentioning

confidence: 99%

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Experimental Transformation of Kaolinite to Halloysite

Singh

Mackinnon

1996

Clays and clay miner.

111

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Abstract--A well-characterized kaolinite has been hydrated in order to test the hypothesis that platey kaolinite will roll upon hydration. Kaolinite hydrates are prepared by repeated intercalation of kaolinite with potassium acetate and subsequent washing with water. On hydration, kaolinite plates roll along the major crystallographic directions to form tubes identical to proper tubular halloysite. Most tubes are elongated along the b crystallographic axis, while some are elongated along the a axis. Overall, the tubes exhibit a range of crystallinity. Well-ordered examples show a 2-layer structure, while poorly ordered tubes show little o1 no 3-dimensional order. Cross-sectional views of the formed tubes show both smoothly curved layers and planar faces. These characteristics of the experimentally formed tubes are shared by natural halloysites. Therefore, it is proposed that planar kaolinite can transform to tubular halloysite.

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Section: Methodsmentioning

confidence: 95%

Section: Methodsmentioning

confidence: 99%

Section: Bulk Properties Of Intercalates and Hydratesmentioning

confidence: 99%

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Experimental Transformation of Kaolinite to Halloysite

Singh

Mackinnon

1996

Clays and clay miner.

111

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“…Exemplos de intercalação de caulinitas envolvem o uso de pequenas moléculas polares (tipicamente dimetilsulfóxido e Nmetilformamida) [3][4][5][6][7][8][9] , fenômeno este associado ao processo de solvatação dos grupamentos hidroxila externos. A intercalação de algumas moléculas particulares somente é possível através do deslocamento de outras moléculas previamente intercaladas [10][11][12][13][14][15][16] .…”

Section: Introductionunclassified

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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“…The existence of overlapping euhedral pseudo hexagonal platelets exhibiting dense-tight-thick layers was observed in the beneficiated kaolinite ( Figures 3 and 4), a feature which is typical to most kaolinite minerals [53]. Following chemical treatment with salt solution this stacking sequence was observed to change to vermiform shaped particles mixed with skinny stacked euhedral pseudo hexagonal platelets ( Figure 5).…”

Section: Sem-edax Analysismentioning

confidence: 89%

Dynamics of Kaolinite-Urea Nanocomposites via Coupled DMSO-Hydroxyaluminum Oligomeric Intermediates

Sempeho

Kim

Mubofu

et al. 2015

Indian Journal of Materials Science

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Kaolinite-urea nanocomposites were prepared via intercalation reactions in an attempt to investigate the dynamic nature of kaolinite morphology for advanced applications in controlled release systems (CRS). Characterization was done using SEM-EDX, XRF, ATR-FTIR, XRD, and DT/DTG; Andreasen pipette sedimentation technique was used to determine the grain size distribution of the raw kaolinite. The X-ray diffraction pattern revealed the existence of an FCC Bravais lattice where the intercalation ratios attained were 51.2%, 32.4%, 7.0%, and 38.4% for hydroxyaluminum oligomeric intercalated kaolinite, substituted urea intercalated kaolinite, calcined DMSO intercalated kaolinite, and hydroxyaluminum reintercalated kaolinite, respectively, along with their respective crystallite sizes of 33.51-31.73 nm, 41.92-39.69 nm, 22.31-21.13 nm, and 41.86-39.63 nm. The outcomes demonstrated that the employed intercalation routes require improvements as the intercalation reactions were in average only ≈32.3%. The observations unveiled that it is possible to manipulate kaolinite structure into various morphologies including dense-tightly packed overlapping euhedral pseudo hexagonal platelets, stacked vermiform morphologies, postulated forms, and unique patterns exhibiting self-assembled curled glomeruli-like morphologies. Such a diversity of kaolinite morphologies expedites its advanced applications in the controlled release systems (CRS) such as drug delivery systems and controlled release fertilizers (CRFs).

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Kaolinite: NMF Intercalates

Cited by 35 publications

References 25 publications

Experimental Transformation of Kaolinite to Halloysite

Experimental Transformation of Kaolinite to Halloysite

Comportamento térmico da caulinita hidratada

Dynamics of Kaolinite-Urea Nanocomposites via Coupled DMSO-Hydroxyaluminum Oligomeric Intermediates

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