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Zastosowanie modyfikowanej mezoporowatej krzemionki SBA-15 w procesie adsorpcji 4-chlorofenolu

Moritz M.

Przemysł Chemiczny

2015

T. 94, nr 6

872-875

Przedstawiono wpływ funkcjonalizacji materiału SBA-15 na proces adsorpcji 4-chlorofenolu. Modyfikację powierzchni mezoporowatej krzemionki przeprowadzono metodą graftingu z użyciem 3-aminopropylotrietoksysilanu. Określono charakterystykę strukturalną adsorbentów z użyciem techniki XRD oraz sorptometrii azotu. Wykazano znaczący wzrost pojemności adsorpcyjnej modyfikowanego adsorbentu względem 4-chlorofenolu w porównaniu z czystą krzemionką SBA-15. Wykazano, że proces adsorpcji 4-chlorofenolu na badanych sorbentach przebiega zgodnie z zależnością Langmuira.

Mesoporous SiO₂ was modified by grafting with NH₂(CH₂)Si(OEt)₃ and used for adsorption of p-ClC₆H₄OH. The SiO₂ samples were characterized by X-ray diffraction and N₂ sorption anal. Adsorption capacity of modified/ unmodified SiO₂ was detd. at 25°C for p-ClC₆H₄OH concn. 5.0⋅10⁻⁴–4.2⋅10⁻² mol/L. More than 2.5 times higher adsorption capacity was achieved on modified SiO₂.

Nanostruktury krzemionkowo-metaliczne. I. Otrzymywanie i modyfikacja nanocząstek krzemionkowych

Jankiewicz B.J., Choma J., Jamioła D., Jaroniec M.

Wiadomości Chemiczne

2010

[Z] 64, 11-12

913-942

Silica-metal nanostructures consisting of siliceous cores and metal nanoshells attract recently a lot of attention because of their unique properties, mainly catalytic and spectroscopic. The core of these nanostructures is coated with a thin layer (nanoshell) of another material, often being a noble metal, of a thickness between 1 and 20 nm. The silica-metal nanostructures are highly functional materials of properties different from those of the siliceous core and the metal nanoshell. Already nowadays these nanostructures have found various applications such as for an exaltation of chemical stability of colloids, for an enhancement of luminescence properties of materials, for biosensing, drug delivery and other medical applications. The main goal of this two-part review is the presentation of various methods for the preparation of silica-metal nanostructures, description of the most important physicochemical properties of these materials, and presentation of their potential applications. The first part is focused on the main preparation methods of silica particles being used as cores for the aforementioned core-shell nanostructures and methods for their surface modification. A special emphasis is given on the Stöber method, which is relatively simple, effective and well verified for the synthesis of large silica particles (with diameters from 100 nm to several microns). A typical preparation of silica particles is based on mixing ethanol, ammonia (as a catalyst), and often small amount of water, followed by rapid or gradual addition of tetraethyl orthosilicate (TEOS) under vigorous stirring. This article reviews numerous studies reporting the effects of various factors on the structural properties of silica particles, especially the steps required for controlling their size, assuring narrow particle size distribution and high uniformity of the resulting particles. The surface chemistry of siliceous cores is essential in the process of metal nanoshells formation. Therefore, in this work the main methods for modification of the silica surface are presented in details in order to prepare this surface for the formation of metal nanoshells. This modification is often based on the replacement of silanols with specific organic groups (often aminopropyl and mercaptopropyl groups), which interact strongly with metal nanoparticles. In 1998 Halas and co-workers elaborated a simple method for the preparation of core-shell nanostructures involving attachment of specific organic groups to the silica surface followed by deposition of gold nanoparticles and subsequent reduction of tetrachloroauric acid in order to obtain continuous gold nanoshells. The first modifier of the silica surface was 3-aminopropyltriethoxysilane. Later, several other modifiers have been tested. The aforementioned modification of the silica surface can be singleor two-step process. The single-step process involves hydrolysis and condensation of TEOS in the presence of functional organosilane, which results in silica particles with desired organic groups attached. The two-step process involves the synthesis of silica particles in the first step and their surface modification with organosilanes in the second step. The presented literature survey shows that the proper modification of the surface of silica particles is a necessary condition for the formation of uniform metal nanoshells.