Adsorption of Cd(II) on mesoporous Al2O3 prepared from high-aluminum fly ash

Abstract

Abstract Cadmium (Cd) pollution has increased in water bodies due to an increase in industrial and agricultural activities, threatening human health and ecosystem stability. In this study, high-alumina fly ash (HAFA) was used as a low-cost raw material to prepare mesoporous alumina (MA) adsorbents to remove Cd(II) from water. The adsorption performance of the synthesized MA for Cd(II) was investigated at different pH values, initial Cd(II) concentrations, and contact times. The results showed that MA was successfully prepared from HAFA, and showed a specific surface area of 318.7 m2 g−1 and average pore size of 4.5 nm. The adsorption of Cd(II) on the synthesized MA had the best adsorption environment at pH 7, and the contact time to reach the dynamic adsorption equilibrium was 60 min. The pseudo-second-order and Langmuir models accurately described chemisorption and monolayer adsorption of Cd(II) on the surface of the synthesized MA, respectively. The fitting results of the Intra-particle diffusion model show that the intraparticle diffusion of particles is not the only step controlling the rate during the adsorption of Cd(II) by synthetic materials. The maximum adsorption capacity of the synthesized MA for Cd(II) was calculated to be 88.26 mg g−1 using the Langmuir isotherm.