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: The laminated structure of graphene oxide (GO) confers unique interactions with water molecules which may be utilised in a range of applications that require materials with tuneable hygroscopic properties.
Abstract: The laminated structure of graphene oxide (GO) confers unique interactions with water molecules which may be utilised in a range of applications that require materials with tuneable hygroscopic properties. The precise role of the expandable interlayer spacing and functional groups in GO laminates has not completely been understood to date. Herein, we report the experimental and theoretical investigations on the adsorption and desorption behaviour of water in GO laminates as a function of relative pressure. We observed that GO imparts high water uptake capacity of up to 0.58 gram of water per gram of GO (g g−1), which is significantly higher than silica gel as a conventional desiccant material. More interestingly, the adsorption and desorption kinetics of GO is five times higher than silica gel. The observed extraordinary adsorption/desorption rate can be attributed to the high capillary pressure in GO laminates as well as micro meter sized tunnel-like wrinkles located at the surface.
81 citations
TL;DR: An improved crown ether-based chiral stationary phase (CSP) was prepared by dynamic coating of a reversed-phase silica gel with a new chiral crown ether which was designed to have more lipophilicity than the previously used one, while preserving the basic structure responsible for chiral recognition.
81 citations
TL;DR: In this paper, the authors used a Ru 2+ (bipy) 3 dichloride solution for impregnation of the zeolite surface, which was characterized by X-ray diffraction and the loading with ruthenium ions determined photometrically.
Abstract: Zeolite Y was ion-exchanged with ruthenium(III) chloride, and the respective ruthenium(II) bipyridyl complex (Ru 2+ (bpy) 3 ), which is an excellent fluorescent oxygen probe, was prepared inside the zeolite supercages. In addition, a Ru 2+ (bipy) 3 dichloride solution was used for impregnation of the zeolite surface. Both materials were characterized by X-ray diffraction and the loading with ruthenium ions determined photometrically. In order to obtain sensor materials, they were incorporated into silicone polymers and spread, as a thin layer, onto a polyester mechanical support. The resulting sensor membranes were tested with respect to luminescence intensity, quenching by molecular oxygen, response time to oxygen and long-term stability under various conditions. Oxygen can be measured over the 0–760 Torr range, with very good resolution between 0 and 200 Torr. Both the quenching efficiency and the long-term stability of the Stern-Volmer quenching constant are tremendously improved when compared to sensors where the fluorophore is absorbed onto the surface of either a zeolite or silica gel. When spread onto glass rather than polyester, the sensors lend themselves to operation at temperatures as high as 200 °C.
81 citations
TL;DR: In this article, a procedure was developed for the separation and identification of nitrogenous compounds in used tire-derived oil, which were partially produced by pyrolysis of tire accelerants.
81 citations
01 Aug 1990
TL;DR: In this article, it was shown that after the adsorption of individual “gaseous” surfactant molecules which probably constitute nucleation sites, there is the formation of interfacial micelles.
Abstract: The search for the origins of the macroscopic interfacial phenomena, the adsorption layer structure, and the nature of interactions between solid and surfactant molecules and between molecules at adsorbed states has led us to a calorimetric investigation of adsorption. The adsorption of nonionic surfactants onto the hydrophilic surfaces of silica gel has been studied by batch microcalorimetry for a wide range of coverages. Differential molar enthalpies of adsorption corresponding to the adsorption processes have been obtained. The microcalorimetric method for the investigation of adsorption from solution is shown to be a very sensitive tool for the elucidation of the adsorption mechanism. The calorimetric results indicate that there are at least two kinds of interactions between nonionic surfactant molecules and the silica surface, the first one being due to a direct interaction between the polar parts of molecules and the surface (exothermic effect) and the second resulting from lateral interactions between the hydrophobic chains, leading to the formation of interfacial aggregates (endothermic effect). The principal conclusion resulting from the present investigation is that after the adsorption of individual “gaseous” surfactant molecules which probably constitute nucleation sites, there is the formation of interfacial micelles. The main driving forces for the formation of aggregates are of the same nature as those for the formation of micelles in the bulk solution.
81 citations