Preparation, characterization and adsorption evaluation of spherical mesoporous Al-MCM-41 from coal fly ash

The present study offers an economic synthesis of Al-containing spherical mesoporous Al-MCM-41 material from coal fly ash by one step. The texture and composition of the samples were characterized by XRD, N2 adsorption, FE-SEM, TEM, FT-IR, and 27Al MAS NMR. As a catalyst, the effects of ethyl acetate to the diameter and sphericity of the samples have also been investigated. The results show that the sample Al-MCM-41-10 prepared at the amount of ethyl acetate value of 10 mL displays the largest BET surface area (525.0 m2/g) and pore volume (0.71 cm3/g). Using this material as adsorbent for methylene blue (MB) removal, the adsorption capacity reaches 277.78 mg/g. The effects of pH, contact time, initial adsorbate concentration and temperature were evaluated by batch of adsorption experiments. Adsorption kinetics and isothermal adsorption studies showed that the pseudo-first-order model and the Langmuir isotherm fitted the experimental data quite well, indicating that the MB adsorption onto Al-MCM-41-10 adsorbent should be monolayer and chemical adsorption with the surface reaction. Thermodynamic analysis indicated an exothermic nature of adsorption and a spontaneous and favorable process. Our present study shows an economic way to treat MB using the industrial solid waste of coal fly ash.