Adsorption and mobility of water molecules and organic substances in carbon adsorbents Communication 3. Dependence of self-diffusion coefficients of adsorbed molecules of water and methanol on size of micropores in active carbons and on degree of pore filling

Conclusions

• 1. The self-diffusion coefficients (SDCs) of water and methanol molecules, measured by the pulse-gradient NMR method, are independent of the time of observation A. The previously noted dependence of the SDC on A is explained by the large error of SDC measurements at short observation times.

• 2. The SDC of adsorbed water and methanol molecules increases with increasing size of the micropores. In activated carbons with a mean half-width of the micropores smaller than 0.66 nm, the SDC of adsorbed methanol at 298°K is lower than the SDC of water, but in activated carbon with larger pores, the SDC of methanol is higher than that of water.