0000000000131808
AUTHOR
A. Kurganov
Investigation of the porosity of silica and alumina with chemically bonded polystyrene
The effect of modification of porous silica and alumina with a copolymer of styrene and vinylsilane on the porosity of oxides have been investigated by means of low temperature nitrogen sorption. Only small changes of the specific surface area and of the specific pore volume were observed on modification of oxides with non-cross-linked copolymer. The specific surface area significantly increased after the cross-linking of the deposited polymeric layer while the specific pore volume remains almost unaffected. A broad hysteresis loop appears in the nitrogen sorption isotherm for the alumina modified with the cross-linked polymer. The porosity of oxides modified by chemisorption method differe…
Native and modified alumina, titania and zirconia in normal and reversed-phase high-performance liquid chromatography
Chromatographic properties of silica, alumina, titania and zirconia have been investigated in normal phase mode in the separation of test mixtures of basic, neutral and acidic compounds. In contrast to silica the chromatographic behaviour revealed the basic properties of the alumina, titania and zirconia surfaces. Therefore, separation of basic compounds on these packings seems very promising. Lypophilic packings have been synthesized by modification of titania, zirconia and alumina with organosilanes and polymers and tested for the separation of basic compounds and proteins. High hydrolytic stability of the modified packings was observed during separations with strong alkali and acidic elu…
Effect of solute association on the apparent adsorption isotherm. A model of the separation of non-racemic mixtures of enantiomers in achiral chromatographic systems
This article discusses the effect of solute association on the apparent adsorption isotherm and on the chromatographic peak profile. The modelling performed has shown that dimerization of a solute in a chromatographic system gives rise to an apparent adsorption isotherm of the non-linear type. This results first of all in peak broadening. Tailing or a fronting can be observed depending on the relative retention of the monomer and the dimer. Secondly, the retention of the solute depends on the amount of sample because of the non-linear character of the adsorption isotherm. As a result, an excess of one of two analytes with absolutely identical adsorption properties i.e. optical isomers, can …
Separation of polycyclic aromatic hydrocarbons under isocratic conditions by a column switching technique
A simple and efficient method of separating a 20-component PAH-mixture (RSM 1647 standard mixture +benzene, toluene, perylene and coronene) by RP-HPLC is described. Separation was by using two Superspher-100 RP-18 cartridges thermostatted at different temperatures under isocratic conditions with water-acetonitrile eluent. The analysis time with complete resolution of all components can be reduced to 15 min.
Effect of Size of Solvent Molecule on the Adsorption of p- and o-Xylene on ZSM-5 Type Zeolites and Mechanism of Adsorption
Summary The adsorption isotherms of p- and o-xylene have been studied on MFI-type zeolites of different alumina to silica ratios from solvents of different molecular sizes. The adsorption is mainly controlled by the shape and size of the pore opening relative to the size and shape of the sorbate and the solvent molecules. Aluminum containing zeolites formed colored π-complexes with p-xylene.