Topic
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.
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TL;DR: In this article, a mixture of lard and restaurant grease was used to synthesize tallow-methyl esters, which were then converted to esters by alkali-catalyzed methanolysis.
Abstract: Methyl or ethyl esters were produced from lard and restaurant grease by lipase- or base-catalyzed reactions. Before esterifying, some renewable substrates (lard and restaurant grease) should be manipulated through acetone fractionation or on a chromatography column packed with an adsorbent to obtain maximal reaction rate. Because lipase activity was hindered by excess amounts (more than 1 mol) of methanol, each 1 M methanol was added sequentially after 24 h of reaction. Through a three-step reaction, 74% conversion to tallow-methyl ester was obtained. However, a porous substance, such as silica gel, improved the conversion when more than 1 M methanol was used as reaction substrate. When a 1∶3 (fractionated lard/methanol, mole ratio) substrate was used, the conversion rates (i.e., extent of conversion) were 2.7 (24 h) and 2.8% (48 h). However, with 10% silica gel in the reaction mixture, the conversion rates increased to 25 and 58%, respectively. Regenerated restaurant grease (FFA removed through column chromatography) was further converted to esters by alkali-catalyzed methanolysis. After 24 h of reaction, 96% conversion was obtained, while only 25% conversion was observed from crude grease. Alkyl esters produced in this study could be used for fuels, potentially as biodiesel.
148 citations
TL;DR: A rapid and efficient high-performance liquid chromatography procedure for the separation of phospholipids using isocratic elution and UV detection at 203 nm, which is suitable for the analysis of phosphotidylcholine in tissue extracts.
148 citations
TL;DR: Optically active (+)-poly(triphenylmethyl methacrylate) (PTrMA) which has the chirality due to only helicity has been used as two different types of chiral stationary phases for resolving enantiomers by HPLC as mentioned in this paper.
Abstract: Optically active (+)-poly(triphenylmethyl methacrylate) (PTrMA) which has the chirality due to only helicity has been used as two different types of chiral stationary phases for resolving enantiomers by HPLC. One was prepared with the insoluble (+)-PTrMA ground to small particles and the other by adsorbing the soluble polymer on macroporous silica gel. These stationary phases, particulary the latter, resolved a wide variety of enantiomers including hydrocarbons, esters, amides, halides, phosphoric compounds and so on by using a polar eluent like methanol.
148 citations
TL;DR: In this paper, the physical and chemical structures of gels dried from aprotic solvents were studied by a series of techniques (29 Si MAS-NMR, nitrogen adsorption, SAXS, elemental analysis, TGA).
Abstract: A two-step acid/base-catalyzed silica gel has been aged in alcohol and water baths followed by various aprotic solvents with a wide range of surface tensions. Low temperature (CO 2 ) and high temperature (ethanol) aerogels were also prepared. The physical and chemical structures of gels dried from aprotic solvents were studied by a series of techniques ( 29 Si MAS-NMR, nitrogen adsorption, SAXS, elemental analysis, TGA). The aprotic solvents isolated the effects of pore fluid surface tension during drying since they do not participate in condensation and other reactions. For aprotic solvents, a linear decrease in xerogel surface area was observed with increasing surface tension. Pore volume and pore size distribution followed a similar trend. Depending upon whether the gel had been washed in ethanol or water prior to the aprotic solvent, the final pore volume was changed significantly for a given surface tension. This indicates that both surface area and pore volume may be independently controlled.
147 citations
TL;DR: In this article, a simple strategy for the construction of an electrochemical interface with a tunable kinetic barrier by self-assembling organically modified silica gel and gold nanoparticles is presented.
Abstract: A simple strategy is presented for the construction of an electrochemical interface with a tunable kinetic barrier by self-assembling organically modified silica gel and gold nanoparticles. Self-assembly of an organically modified silica layer is carried out from the hydrolyzed sol of the precursor mercaptopropyltrimethoxysilane. The kinetic barrier of this self-assembled silicate film is modified by gold nanoparticles that are self-assembled into the silicate network. The electrochemistry of ferricyanide redox reaction is used as a marker to probe the interface.
147 citations