A new adsorption–desorption model for water adsorption in porous carbons

A new model is proposed to describe the adsorption and desorption branches of water adsorption in carefully synthesized mesoporous carbon materials. This model is an extension of a previous adsorption–desorption model proposed by Do et al. We prepared mesoporous resorcinol–formaldehyde carbon cryogels (RFCCs) by sol–gel polycondensation of resorcinol with formaldehyde in a slightly basic aqueous solution, followed by drying with freeze-drying and then carbonizing the RF cryogels at a high temperature under a nitrogen atmosphere. The resulting carbon materials have different surface and pore properties, which are valuable in the study of their effects on water vapor adsorption and desorption on RFCCs. The experimental data were used to test the model, and we have found that the model describes reasonably well all the data. We have also observed some interesting, but not unexpected, results in the analysis: the water cluster size in mesopore is larger than that in micropore, and the hysteresis loop of adsorption–desorption in mesopores is greater than that in micropores.

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► Water adsorption isotherms (at 298 K) on mesoporous carbon.
► Introducing a new water adsorption–desorption model.
► The water cluster size in mesopore is larger than that in micropore.