ADSORPTION OF ALCOHOL ON SILICA GEL

The effects of ageing and different temperatures of evacuation on silica gel have been studied in respect of adsorption of anhydrous alcohol. There was little change in adsorption isotherms as long as the temperature of evacuation did not exceed a certain limit. Beyond this the adsorption improved at all pressures for the samples of gel used. Ageing improved adsorption at higher pressures but depressed it at lower ones. A fresh gel did not show hysteresis unless the temperature of evacuation was about 300º. Older gels or those evacuated at higher temperatures showed permanent hysteresis in adsorption. but the hyatersis region was nor alike for different samples of the gel. About 2% of the adsorbed liquid could not be pumped out even at elevated temperatures. The gel had sometimes to be flushed a number of times to obtain reproducible adsorption branches.