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Kaolinite-urea complexes obtained by mechanochemical and aqueous suspension techniques--a comparative study
Eva Makó1, János Kristóf, Erzsébet Horváth
1Institute for Materials Engineering, University of Pannonia, H-8201 Veszprém, P.O. Box 158, Hungary. makoe@almos.vein.hu
Journal of Colloid and Interface Science
|November 21, 2008
Summary
Mechanochemical intercalation using urea fully expanded kaolinite clays, offering a faster method than aqueous solutions. This technique yields smaller crystallite sizes for kaolinite-urea intercalation compounds.
Area of Science:
- Materials Science
- Clay Science
- Nanotechnology
Background:
- Kaolinite clays are widely used in various industrial applications.
- Defect concentration in kaolinite influences its intercalation properties.
- Urea is a potential intercalant for modifying clay structures.
Purpose of the Study:
- To prepare and characterize kaolinite-urea intercalation compounds.
- To compare the efficiency of aqueous solution and mechanochemical intercalation methods.
- To elucidate the structural model of urea bonding to kaolinite.
Main Methods:
- Preparation of intercalation compounds via aqueous urea solution and mechanochemical grinding.
- Characterization using X-ray diffraction (XRD), thermal analysis, DRIFT spectroscopy, and scanning electron microscopy (SEM).
Main Results:
- Mechanochemical intercalation resulted in near-complete expansion of both low- and high-defect kaolinites within 1 hour.
- Aqueous intercalation yielded 77% and 65% intercalation for low- and high-defect kaolinites, respectively.
- DRIFT spectroscopy provided insights into urea's bonding to the siloxane surface, leading to a proposed structural model.
Conclusions:
- Mechanochemical intercalation is a highly efficient and rapid method for preparing kaolinite-urea intercalation compounds.
- The mechanochemical method produces compounds with smaller crystallite sizes compared to the aqueous method.
- The study proposes a structural model for urea intercalation in kaolinite, advancing the understanding of clay modification.
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