Surface energy characterization of different particulate silica gels at infinite dilution

Porous silica gels are the well-established adsorbent materials used in adsorption cooling, dehumidification, gas separation, and desalination applications. To understand the adsorption characteristics, morphological characterization of the adsorbent is widely used. However, the surface activities of the adsorbent material, which are the most influential parameters for the adsorption process, are still unknown. To determine the surface activities, surface energy analysis has been performed for four silica gel particulates (RD granular silica gel, Chromatorex, Home silica gel, and B-type silica gel) using inverse gas chromatography technique. Experiments have been conducted at infinite dilution (0.008 to 0.1 coverage) with a fixed flowrate (30 sccm) of helium gas. The results showed that RD granular silica gel has the highest value of total surface energy for all the coverages. A correlation between the dispersive component of surface energy and morphological characteristics (variation with specific surface area and pore size distribution) has been discussed. Comparative studies on surface energy components of the studied silica gels and activated carbons have also been presented, which will contribute to fulfilling the knowledge gap between morphological characterization and adsorption phenomenon.