EFFECT OF SURFACE-CHEMISTRY ON SORPTION OF WATER AND METHANOL ON ACTIVATED CARBONS

Two activated carbons from different sources were oxidized with nitric acid and hydrogen peroxide and the effects of this on their porous st ructure and sorption of water and methanol were studied. The microstru ctural properties were derived from analysis of N-2 isotherms. The sur face acidity was assessed. using Boehm titration and potentiometric ti tration. Changes in the surface chemistry were also monitored using di fference reflectance IR Fourier transform. From the potentiometric tit ration the pK(a) distributions were calculated and the surface density of acidic groups was evaluated. The structural and surface chemical r esults demonstrate that carbons derived IS crm different sources can h ave wide variation in their oxidation susceptibility. To further evalu ate the impact or the recorded changes due to oxidation in thf carbons studied, sorption uptake of water and methanol was measured and corre lated with the acidity of the carbon surfaces.