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Methoxy-modified kaolinite as a novel carrier for high-capacity loading and controlled-release of the herbicide amitrole.

Tan D, Yuan P, Annabi-Bergaya F, Liu D, He H - Sci Rep (2015)

Bottom Line: Due to the diffusional restriction of the intercalated AMT by the lamellar structure of the kaolinite and the strong electrostatic attraction between the intercalated AMT and the kaolinite, a slow release of AMT from the methoxy-modified kaolinite was achieved.These results show that the methoxy-modification is a facile method to make the interlayer space of kaolinite available for hosting other guest molecules.The methoxy-modified kaolinite is a promising candidate for high-capacity loading and controlled-release of other molecules such as drugs, agrochemicals, and biochemicals.

View Article: PubMed Central - PubMed

Affiliation: 1] CAS Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China [2] Key Laboratory of Solid Waste Treatment and the Resource Recycle (SWUST, Ministry of Education), Mianyang 621010, China.

ABSTRACT
Methoxy-modified kaolinite was used as a novel carrier for loading and release of the herbicide 3-amino-1,2,4-triazole, known as amitrole (abbreviated here as AMT). The methoxy modification made the interlayer space of the kaolinite available for AMT intercalation. The AMT loading content in methoxy-modified kaolinite reached up to 20.8 mass% (twice the loading content by unmodified kaolinite). About 48% of this amount is located in the interlayer space. The release profiles of the AMT fit with the modified Korsmeyer-Peppas model. Due to the diffusional restriction of the intercalated AMT by the lamellar structure of the kaolinite and the strong electrostatic attraction between the intercalated AMT and the kaolinite, a slow release of AMT from the methoxy-modified kaolinite was achieved. These results show that the methoxy-modification is a facile method to make the interlayer space of kaolinite available for hosting other guest molecules. The methoxy-modified kaolinite is a promising candidate for high-capacity loading and controlled-release of other molecules such as drugs, agrochemicals, and biochemicals.

No MeSH data available.


XRD patterns of the kaolinite samples.
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f1: XRD patterns of the kaolinite samples.

Mentions: The raw kaolinite (Kaol) shows a typical diffraction pattern with a characteristic d001 value of 0.71 nm (Fig. 1a). Grafting of methoxy groups in the interlayer space of kaolinite12 shows a d001 value in methoxy-modified kaolinite (KaolMeOH) of 0.85 nm (Fig. 1b). The remaining reflection at 0.71 nm in KaolMeOH is due to a residual unintercalated kaolinite. In the case of AMT-loaded unmodified kaolinite (AMT-Kaol), the d001 value of kaolinite remains unchanged (Fig. 1c), indicating that AMT cannot intercalate into the interlayer space of the unmodified kaolinite. In the case of the AMT-loaded modified kaolinite (AMT-KaolMeOH) (Fig. 1d), the d001 value increased to 1.15 nm. Compared to the d001 value of 0.85 nm observed for KaolMeOH, this increase of 0.30 nm suggests the intercalation of AMT in the interlayer space. The intercalation of AMT is a fast process, a maximum intercalation was achieved in approximately 10 minutes (see details from the Supporting Information, Fig. S1). Although the intercalated AMT increased the interlayer distance of kaolinite, the methoxy modification and AMT loading did not appear to affect the porosity of kaolinite (Table S1, Fig. S2) because the increase of the interlayer distance of kaolinite was not sufficiently large to accommodate the adsorption of N2 molecules (0.364 nm) in the interlayer space. However, due to the intercalation of AMT in the interlayer space of the methoxy-modified kaolinite, the AMT loading content in AMT-KaolMeOH, calculated from the percentage of N, reached up to 20.8 mass%, which is twice the loading content of AMT-Kaol (10.3 mass%).


Methoxy-modified kaolinite as a novel carrier for high-capacity loading and controlled-release of the herbicide amitrole.

Tan D, Yuan P, Annabi-Bergaya F, Liu D, He H - Sci Rep (2015)

XRD patterns of the kaolinite samples.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4352846&req=5

f1: XRD patterns of the kaolinite samples.
Mentions: The raw kaolinite (Kaol) shows a typical diffraction pattern with a characteristic d001 value of 0.71 nm (Fig. 1a). Grafting of methoxy groups in the interlayer space of kaolinite12 shows a d001 value in methoxy-modified kaolinite (KaolMeOH) of 0.85 nm (Fig. 1b). The remaining reflection at 0.71 nm in KaolMeOH is due to a residual unintercalated kaolinite. In the case of AMT-loaded unmodified kaolinite (AMT-Kaol), the d001 value of kaolinite remains unchanged (Fig. 1c), indicating that AMT cannot intercalate into the interlayer space of the unmodified kaolinite. In the case of the AMT-loaded modified kaolinite (AMT-KaolMeOH) (Fig. 1d), the d001 value increased to 1.15 nm. Compared to the d001 value of 0.85 nm observed for KaolMeOH, this increase of 0.30 nm suggests the intercalation of AMT in the interlayer space. The intercalation of AMT is a fast process, a maximum intercalation was achieved in approximately 10 minutes (see details from the Supporting Information, Fig. S1). Although the intercalated AMT increased the interlayer distance of kaolinite, the methoxy modification and AMT loading did not appear to affect the porosity of kaolinite (Table S1, Fig. S2) because the increase of the interlayer distance of kaolinite was not sufficiently large to accommodate the adsorption of N2 molecules (0.364 nm) in the interlayer space. However, due to the intercalation of AMT in the interlayer space of the methoxy-modified kaolinite, the AMT loading content in AMT-KaolMeOH, calculated from the percentage of N, reached up to 20.8 mass%, which is twice the loading content of AMT-Kaol (10.3 mass%).

Bottom Line: Due to the diffusional restriction of the intercalated AMT by the lamellar structure of the kaolinite and the strong electrostatic attraction between the intercalated AMT and the kaolinite, a slow release of AMT from the methoxy-modified kaolinite was achieved.These results show that the methoxy-modification is a facile method to make the interlayer space of kaolinite available for hosting other guest molecules.The methoxy-modified kaolinite is a promising candidate for high-capacity loading and controlled-release of other molecules such as drugs, agrochemicals, and biochemicals.

View Article: PubMed Central - PubMed

Affiliation: 1] CAS Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China [2] Key Laboratory of Solid Waste Treatment and the Resource Recycle (SWUST, Ministry of Education), Mianyang 621010, China.

ABSTRACT
Methoxy-modified kaolinite was used as a novel carrier for loading and release of the herbicide 3-amino-1,2,4-triazole, known as amitrole (abbreviated here as AMT). The methoxy modification made the interlayer space of the kaolinite available for AMT intercalation. The AMT loading content in methoxy-modified kaolinite reached up to 20.8 mass% (twice the loading content by unmodified kaolinite). About 48% of this amount is located in the interlayer space. The release profiles of the AMT fit with the modified Korsmeyer-Peppas model. Due to the diffusional restriction of the intercalated AMT by the lamellar structure of the kaolinite and the strong electrostatic attraction between the intercalated AMT and the kaolinite, a slow release of AMT from the methoxy-modified kaolinite was achieved. These results show that the methoxy-modification is a facile method to make the interlayer space of kaolinite available for hosting other guest molecules. The methoxy-modified kaolinite is a promising candidate for high-capacity loading and controlled-release of other molecules such as drugs, agrochemicals, and biochemicals.

No MeSH data available.