Cosorption of Sulfur Dioxide and Water on Cork

The cosorption of gaseous sulfur dioxide (SO2) and water vapor (H2O) on raw cork powder by using calorimetry coupled with manometry at 298 K was studied. Sorption isotherms of single components confirm the previous results obtained by thermogravimetry: SO2 is well chemisorbed on cork surface while H2O is only physisorbed. Moreover, the interaction of SO2 and H2O with cork appears more like an absorption process than an adsorption process. Competitive sorption of SO2 and H2O first occurs in favor of SO2 chemisorption. After all chemisorption sites are saturated by SO2, the cosorption process becomes selective for H2O. The amount of SO2 sorbed on cork is rather low compared to H2O. Results indicate that the sorption of SO2 on cork cannot explain the decrease in SO2 content observed during wine aging in bottle.