Adsorption Properties Of Silica Gel Research Articles

A facile process for the preparation of organic gel-assisted silica microsphere material for multi-mode liquid chromatography.

Organic gel (OG) has excellent characteristics, including a large surface area, adjustable pore/channel size, and good chemical stability, and has attracted great attention in the field of materials. However, the OG packed column is difficult to pack due to the weak mechanical strength and poor monodispersity. Herein, 1-allyl-3-methyl imidazolium hexafluorophosphate-co-1-dodecanethiol ([AMIm]PF6-co-TDDM) was prepared on the silica microsphere for chromatographic packing available in multimode liquid chromatography (LC) mode with the good mechanical properties of silica microspheres through a simple OG synthesis method. [AMIm]PF6-co-TDDM@SiO2 hybrid microspheres with uniform particles and narrow particle size distribution are used as stationary phases of LC. These microspheres are used in anion-exchange (IEC), reversed-phase (RP), and hydrophilic interaction (HILIC) mode for the separation of different analytes. Such microspheres can also be used for the preliminary qualitative analysis of active ingredients in actual samples in addition to organic acids, alkylbenzenes, and nucleoside bases. The [AMIm]PF6-co-TDDM@SiO2 chromatography packing also has good reproducibility and stability. The adhesive properties of organogels and the adsorption properties of silica gel simplify the synthesis of stationary phase materials. This simple and effective strategy for preparing [AMIm]PF6-co-TDDM@SiO2 composite microspheres by one-pot method can expand the application of OG as a functional additive on silica microspheres in LC.

Adsorption properties of silica gel <em>in situ</em> modified with copolymers of 4-vinylpyridine and styrene towards ions of toxic metals

Adsorption properties of silica gel <em>in situ</em> modified with copolymers of 4-vinylpyridine and styrene towards ions of toxic metals

Preparation of Poly(allylamine)-Silica Composites and Adsorption Performance for Heavy Metal Ions

Poly (allylamine)-silica composites (PAA/SiO2) was prepared via CPTCS as coupling agent and PAA as modifier. The structure and adsorption properties of silica gel, CPTCS-SiO2 and PAA/SiO2 were determinated by FTIR, structural analysis, TG analysis and adsorption test. The results show that PAA/SiO2 had excellent adsorption capacities for Cu (II), Pb (II) and Ni (II) in aqueous solutions. Its adsorption capacities can reach 0.972mmol/g for copper ion at experimental conditions. Besides, PAA/SiO2 also possessed excellent stability in the flow tests.

Effect of Heat on the Adsorption Properties of Silica Gel

Published version of an article in the journal: International Journal of Engineering and Technology. Also available from the publisher at: http://www.ijetch.org/papers/416-T886.pdf Open access.

Effect of Hydrothermal Treatment on Adsorption Properties of Silica Gel

It has been proven by coupling near infared spectroscopy to second derivative processing of the spectra that the free and hydrogen bonded silanol groups attached to water molecules absorb at 5314 and 5270 cm−1, respectively. The same method was employed to probe the surface of the hydrothermally treated silica gel samples after pretreatment and evacuation at three different temperatures. The chemical and physical properties of silica gel depend on the nature of the surface silanol groups. Free silanol groups and hydrogen bonded silanol groups play an important role in adsorption of water molecules. Any change or variation in the silanol groups is expected to change the adsorption properties of any silica gel. Two silica gel samples with varying surface characteristics were used in this study. After heating and evacuating at 200, 750, and 1100 °C, the samples were hydrothermally treated in steel bombs and their surface functionalities were probed using near-infrared spectroscopy. The same samples were also dehydroxylated at 450 and 650 °C and analyzed by near-infrared spectroscopy. Furthermore, effectiveness of the treated samples in adsorbing water molecules was followed by monitoring the mass of water adsorbed by silica gel. These investigations form the basis for understanding the relationship between adsorption effeciveness and types of silanol groups on silica gel surface. The results clearly indicate that the hydrothermal treatment of silica gel pretreated at temperatures up to 750 °C increases the concentration of hydrogen bonded silanol groups on the silica gel surface. The sample treated at 1100 °C did not undergo any change under hydrothermal treatment. The concentration of free silanol groups increases in the dehydroxylated samples. The results also show that the adsorption rates of water molecules on the surface decrease significantly after pretreatment of these samples at a particular humidity.

The Influence of Fullerene on Adsorption Properties of Silica Gel with Respect to Medium‐molecular‐mass Peptides

Adsorption properties of silica gels modified with fullerene were studied with respect to medium‐molecular‐mass peptides. Two techniques were used for the introduction of fullerene into silica: solid‐phase and liquid‐phase. On the basis of optical density spectra and mass spectra, the parameters of adsorption were determined and some conclusions were reached concerning the character of adsorption.

Adsorption properties of silica gel prepared from a decationized sol

In accordance with the IUPAC classification, the shape of the capillary condensation hysteresis and type of the sorption isotherms of the vapors of water and tetrachloromethane by silica gel are identified, the latter being prepared from a decationized silica sol in the presence of aluminum chloride. It is found that the adsorption and structural properties of the silica gel depend on the concentration of silicon(IV) oxide and Al/Si molar ratio, as well as on the type of the adsorbate used. It is shown that the effect of aluminum chloride is manifested mainly in the spatial rearrangement of the particles of silicon(IV) oxide into dense agglomerates followed by their aggregation with the conservation of internal porosity. This leads to the appearance of narrow slitlike mesopores and to a decrease in or the stabilization of the average pore radius.

Influence of manufacturing variables on surface properties and dynamic adsorption properties of silica gels

The surface properties of silica gel such as surface area, pore volume, and average pore diameter are affected by the manufacturing variables including pH values, gelling and dehydration temperatures. The dynamic adsorption properties of silica gel are also affected by their preparation conditions. The mass transfer zone and the amount of adsorption were discussed using the experimental data of breakthrough curve. The influence of the manufacturing variables on the trends of breakthrough curves is important in most of the adsorbent modification. It was found in this study that the manufacturing variables affected the adsorption performance significantly. Therefore, the relationship between the manufacturing variables and the corresponding adsorbent properties conducted by the dynamic adsorption apparatus was examined in this study. This discussion is rare in most of the studies of preparing silica gels, which are usually focused on the relationship between the manufacturing variables and the surface properties of silica gels only. However, it is not necessary that a silica gel with larger surface area will give a smaller mass transfer zone or mass transfer resistance. The modification of adsorbents should consider not only the improvement of their surface properties but also their adsorption performance.

The influence of grafted functional groups on the adsorption properties of silica

The adsorption properties of silica gel with grafted aminopropyl and guanidinoethanethiol (GET) groups were studied by the techniques of adsorption under static conditions and gas chromatography. It was shown that molecules capable of forming hydrogen bonds are adsorbed on all modified samples more weakly than on the initial silica gel. The grafting of GET radicals on the surface results in a noticiable increase in the dispersion interaction with adsorbed molecules. Calculation of the contributions of molecular groups to the constant of adsorption equilibrium showed that the thermodynamic characteristics of adsorption on aminosilochromes and aminosilicas with a polymeric layer of the modifying agent have similar values. Such adsorbents can be used for investigation of polar compounds, including organic bases.

Investigation of the adsorption properties of silica gel by using electron paramagnetic resonance

Investigation of the adsorption properties of silica gel by using electron paramagnetic resonance