Comparative study of the adsorption of micropollutant contained in aqueous phase using coal fly ash and activated coal fly ash: Kinetic and isotherm studies

Abstract

Abstract The removal of methylene blue (MB) from aqueous solution with the help of fly ash (FA) and activated FA was investigated by kinetics and isotherms modeling studies. The results of physical and chemical analyses of the FA after activation process indicate the formation of new geo-adsorbent. The adsorption kinetics behavior of MB onto fly ash and activated fly ash were studied and compeered using pseudo-first-order, pseudo-second-order and intra-particle diffusion models. The equilibrium adsorption data were evaluated by Langmuir, Freundlich and Temkin isotherm equations. The investigation of adsorption isotherms data were fitted well to Langmuir isotherm model and the adsorption kinetic was better expressed by pseudo-second-order equation. Based on the Langmuir model, the maximum monolayer adsorption capacity of MB using FA and activated fly ash were 2.88 and 37.08 mg/g, respectively. The results indicate that the activated FA is an efficient and low-cost adsorbent for decontamination of dye containing water. In addition, the other results suggested that the formation of new stable material for encapsulation of aqueous solution contaminated by high concentration of methylene blue.