Adsorption of cationic dye onto fly ash-based geopolymer: Batch and fixed bed column studies

Mohammed V University in Rabat, Centre des Sciences des Matériaux (CSM), (LPCMIO), Ecole Normale Supérieure Rabat, Morocco

Abstract

Cationic dye adsorption from aqueous solution onto synthesized geopolymer was investigated by batch and fixed bed column experiments. The geopolymer material was elaborated by alkali solution and fly ash supplied by Jorf Lasfar power plant of Morocco. Physical and chemical characteristics of samples were determined by FX, DRX, SEM, ²⁹Si MAS NMR and Zeta potential methods. The Brunauer, Emmett and Teller (BET) technique is used to determine the surface area. The Barrett-Joyner-Halenda (BJH) method was performed to obtain pore size distribution curves and average pore diameter. Kinetics data were analyzed using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. To predict the breakthrough curves and determine the main fixed bed column parameters, three kinetic models; Tomas, Bohart–Adams and Yoon-Nelson models are applied to fitting the experimental data. The kinetic study showed that the pseudo-second-order can be used to describe the methylene blue (MB) adsorption process on the geopolymer matrix. The kinetic models of the adsorption in dynamic column are suitable to describe the continuous adsorption process of dyestuff by the geopolymer. The results of this study indicated that geopolymer derived from fly ash can be used as a low cost effective adsorbent for cationic dye removal from industrial aqueous effluent.