Design of Molecular Sieving Carbon — Studies on Adsorption of Various Dyes in Liquid Phase—

Abstract

The adsorption isotherms of ten kinds of adsorbates (mainly dyes) in the liquid phase were measured on nine kinds of the fibrous activated carbons (ACF) which were prepared from the phenolic resin fabric. For comparison, the adsorption on five kinds of the granular activated carbons (ACG) prepared from the coconut shell were also studied. Each of ACF has a sharp pore distribution in the range of diameter less than ca. 4 nm. Each of ACG has transitional and macro pores besides micro pores. The dyes are different in their molecular shapes and sizes. The relation between the critical pore diameter (dc) and the critical molecular size of adsorbate was studied on the basis of the adsorption amount. Main results and informations obtained were as follows : (1) The adsorption of dyes in aqueous solutions proceeds within the micro pores of ACF and ACG, but does not proceed within the pores larger than ca. 20 nm-diameter on ACG. (2) The critical pore diameter (dc) for the molecular sieving adsorption is determined by a short-axis size of the adsorbate, and the relation between da and the critical short-axis size (Lc) was obtained as dc = 1.74 Lc. (3) The design concept for the preparation of ACF having the required critical pore diameter (∗fc) for the objective adsorbates was proposed. © 1987, The Chemical Society of Japan. All rights reserved.