Dye adsorption and ζ-potential for activated carbon fibers obtained from metal complexes containing pitch

Abstract

The adsorption of acid and direct dyes (Acid Red 88 and Direct Yellow 11) on activated carbon fibers (Y-ACF, Al-ACF, and Ti-ACF) obtained from pitch containing metal complexes, viz., yttrium acetylacetonate, aluminumacetylacetonate, and titanium oxyacetylacetonate has been investigated in terms of pore size and ζ-potential. The ζ-potentials of Al-ACF, Ti-ACF, and Y-ACF possessed the isoelectric points at pH about 4.4, 4.4, and 6.7, respectively.The adsorption of Acid Red 88 on Y-ACF, Al-ACF, and Ti-ACF was lower than that on the metal-free ACF (A-20) in pH regions from 2 to 12. The adsorption of Direct Yellow 11 on Y-ACF with a large amount of mesopores was higherthan those on other microporous Al-ACF, Ti-ACF, and A-20 in acidic pH regions. On the other hand, the adsorbedamount of Direct Yellow 11 on Y-ACF decreased steeply withincreasing pH from the isoelectric point at pH 6.7. This suggests that the adsorption of dyes on ACF strongly depends on pore size of ACF and electrostatic interactionsbetween dye molecules and carbon surface.