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Experimental results for the wicking process in a solid thin porous layer by liquids of different polarity with defined surface free energy components and viscosity has been considered theoretically. The method was used for determination of the solid surface free energy of the adsorbents used in thin layer chromatography. Experiments were performed on commercial glass plates precoated with silica, CN-silica, diol-silica, NH 2 -silica, and silanized silica with n -alkanes, diiodomethane, water, and formamide as mobile phases. Surface free energy components determined for investigated adsorbents were used for characterization and comparison of their surface properties.

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Abstract  

The results of dynamic and quasi-isothermal thermodesorption of water from a silica gel surface at low furnace heating rates in the temperature range 20–125° are presented. From the experimental results, the water film pressure π on silica gel surface, the activation energy ΔE and the evaporation heat ΔH were calculated. An interpretation of π changes in relation to the film thickness and wetting process has been proposed. It is concluded that the characteristic film pressure values correspond to the work of spreading, and immersional, adhesional and adhesional-cohesional wetting. From the determined film pressure values, the average value of the silica gel polar component, γ s P , was calculated to be 114.67 mJ/m2.

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