다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Surface modification of natural halloysite clay nanotubes with γ-aminopropyltriethoxysilane (APTES) was investigated. Untreated and modified samples were characterized by nitrogen adsorption, X-ray diffraction, elemental analysis, thermogravimetry, transmission electron microscopy, atomic force microscopy, MAS nuclear magnetic resonance (29Si, 13C, 29Al), and Fourier transform infrared spectroscopy. The modification mechanism was found to include not only the direct grafting of APTES onto the hydroxyl groups of the internal walls, edges and external surfaces of the nanotubes but other processes in which oligomerized APTES condensed with the directly grafted APTES to form a cross-linked structure. The thermal and evacuation pretreatment conditions were found to play an important role in controlling the extent and mechanism of the modification. The extent of modification is also strongly affected by the morphological parameters of the original clay samples. This study demonstrates that the surface chemistry...

Functionalization of Halloysite Clay Nanotubes by Grafting with γ-Aminopropyltriethoxysilane

Metakaolin as cementitious material: History, scours, production and composition – A comprehensive overview

Organo and inorgano-organo-modified clays in the remediation of aqueous solutions: An overview

Study on solids-to-liquid and alkaline activator ratios on kaolin-based geopolymers

Effects of calcination temperature of kaolinite clays on the properties of geopolymer cements

The effect of adding alumina-oxide to metakaolin and volcanic ash on geopolymer products: A comparative study

The present paper should be considered as a review of the application of Fourier Transform Infra-Red for surface clay characterization. The application of surface clay materials for water treatment, oil adsorption, excipients or as active in drugs has largely increased these recent years. The surface clay material presents hydroxyl groups, which can link very easily water molecules. These hydroxyl groups can react with organic groups and by their vibration in the infra-red region, FT-IR can be easily used as a technical method for surface clay characterization. In this paper, we focus on the determination of Lewis and Bronsted acid sites on the clay surface, a critical review of the sample preparation, the surface characterization of bulk clay and the modified surface clay samples using FT-IR spectroscopy.

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FT-IR Spectroscopy Applied for Surface Clays Characterization *

Potential of using granite waste as raw material for geopolymer synthesis

The surface properties of organosilane-modified smectite-type clays were examined by various physico-chemical techniques, including thermal gravimetric analysis (TGA), surface area measurements from N2 adsorption/desorption experiments (BET method), Fourier transform infrared spectroscopy (FTIR), chemical stability measurements in aqueous medium, and elemental analysis. The organically modified clays derived from the reaction of two natural Cameroonian smectites and one standard bentonite sample (for comparison purposes) with γ-aminopropyltriethoxysilane and 3-mercaptopropyltrimethoxysilane. Efficiency of the grafting process was demonstrated by comparing the physico-chemical characteristics of the clays before and after reaction with the organosilanes, which resulted in decreased porosity and decreased amounts of surface hydroxyl groups concomitantly to the presence of aminopropyl or mercaptopropyl groups attached to the aluminosilicate structure. The amine-bearing materials were subject to rather low chemical stability in neutral aqueous medium, which was improved with decreasing pH, while the thiol-containing ones were found to be stable over a wide pH range (2–10). Possible use of these materials as adsorbents for mercury(II) species was discussed and some preliminary experiments based on carbon paste electrodes modified with such grafted clays highlighted their interest for electroanalytical applications.

Functionalization of natural smectite-type clays by grafting with organosilanes: physico-chemical characterization and application to mercury(II) uptake

Daniel Njopwouo

Papers

Effects of calcination temperature of kaolinite clays on the properties of geopolymer cements

The effect of adding alumina-oxide to metakaolin and volcanic ash on geopolymer products: A comparative study

FT-IR Spectroscopy Applied for Surface Clays Characterization *

Potential of using granite waste as raw material for geopolymer synthesis

Functionalization of natural smectite-type clays by grafting with organosilanes: physico-chemical characterization and application to mercury(II) uptake