The role of ethanol proportion on pore structure construction and adsorption stability in MTMS based aerogels

Using MTMS as the silicon source, silica aerogels were synthesized via the sol-gel method followed by ambient pressure drying. The effect of the ethanol ratio in the precursor on the gelation process, skeleton structure and adsorption durability was investigated. As the ratio of ethanol increased, the gelation time of aerogels was prolonged, accompanied by a reduction in density. The skeleton underwent a transformation from micrometer scale to nanometer scale. The specific surface area of the aerogel increased from 31.033 m ² /g to 695.02 m ² /g. Increasing the specific surface area of the aerogel enhances its adsorption capacity for organic solvents, and E ₄ sample exhibiting a saturated dichloromethane adsorption capacity of 10.56 times its own mass. The adsorption-desorption process results in the structural damage to aerogel frameworks, characterized by framework fracture and particle fragmentation. This phenomenon is pronounced in aerogels with smaller framework diameters. When ethanol is employed as the adsorption solvent, the aerogel demonstrates exceptional cyclic stability, maintaining over 90.1% of its original adsorption capacity after 50 adsorption-desorption cycles. This work reveled the mechanism of capacity decay of aerogels during organic solvent adsorption-desorption process, providing theoretical foundations for understanding the adsorption capacity decline.