Correlation between PSD and adsorption of anionic dyes with different molecular weigths on activated carbon

Abstract

The correlation between the adsorption capacity of commercial activated carbons and the pore size distributions in the removal of anionic dyes was investigated. We performed experimental adsorption isotherms measurements of the anionic dyes reactive red 120 (RR120), procion red MX-5B (PRMX-5B) and acid blue 25 (AB-25) in the activated carbons WV1050, Norit R1 and Maxsorb. The activated carbons were carefully characterized by N2 adsorption at 77K and molecular simulation methods to obtain the PSDs and retention capacity of selected pores (8.9, 18.5 and 30.9Å). Batch experiments were carried out in order to obtain single component dye isotherms. We found that the proposed selected pores of the PSD directly correlates with adsorption capacity when the size of the dye molecule is compatible with the carbon pore size. Between RR120 and PRMX-5B we noted that dye chemistry strongly affect the retention capacity. Based on our results, the use of N2 derived PSD and molecular simulation of dye retention in selected pores can be a useful tool to guide to the optimization of carbon-based adsorbents for dye removal.