Silica gel

About: Silica gel is a research topic. Over the lifetime, 22313 publications have been published within this topic receiving 325516 citations. The topic is also known as: Amorphous silica & Precipitated amorphous silica.

Separation of lipid classes from plant tissues by high performance liquid chromatography on chemically bonded stationary phases

Abstract: The wide range of lipid classes found in plant tissues, including simple lipids, glycolipids, and phospholipids, have been resolved by gradient high performance liquid chromatography with evaporative light-scattering detection. The lipids from potato tubers were used to optimize the separations. Adsorption chromatography with silica gel gave disappointing results for the plant glycolipids. Much better separations were obtained with chemically bonded stationary phases, e.g. those with propionitrile or polymeric vinyl alcohol as the functional moiety. With careful calibration, good reproducibility was possible. Only highly acidic lipids such as phosphatidylserine still present some problems.

Synthesis and characterisation of ibuprofen-anchored MCM-41 silica and silica gel

Abstract: A non-steroidal anti-inflammatory drug (ibuprofen) has been anchored inside the mesoporous channels of MCM-41-type silica and on a silica gel surface. The relevant anchoring procedure through an ester function has been investigated. It uses the epoxide ring opening of 3-glycidoxypropylsilane grafted on the silica surface by the carboxylic-group-containing ibuprofen. The control of the surface modification and of the anchoring efficiency was achieved by comparison of spectroscopic data with those obtained using homogeneous counterparts. The use of nanostructured silica allowed an accurate verification of the different surface modifications and also a higher drug loading.

Pore structure evolution in silica gel during aging/drying II. Effect of pore fluids

Abstract: A two-step acid-base-catalyzed silica gel has been aged in a series of alcohol and water baths and some chemical and physical structures of the gel were measured using several techniques (low-field NMR, 29Si and 13C MAS-NMR, IR, Raman, nitrogen adsorption) on gels in wet and dry states. When the gel was placed in alcohol, the surface area increased as a result of esterification and depolymerization to 1500–2000 m2/g in the wet state which then decreased to 1000 m2/g after drying. In water, hydrolysis and condensation decreased surface area to 1000 m2/g (wet) and 500 m2/g (dry). This process was reversible. Alcohol-aging led to small pore size distributions (in much shorter times than previous studies of aging in the gel's mother liquor, ∼ 90% ethanol, 10% H2O). Surface areas calculated from 29Si MAS-NMR-derived Q distributions were in good agreement with adsorption-derived values for the samples dried from alcohol but water-dried samples appeared to contain some surface area which was inaccessible to adsorbing nitrogen after drying. These results indicate that the pore structure of silica gels may be dramatically altered during the aging process and that their wet gel features may be preserved (at least partially) upon drying.