Synthesis of iron-based adsorbents and their application in the adsorption of molybdenum ions in nitric acid solution

A series of “easy-to-prepare” powders was synthesized and their application in the adsorption of Mo ions in 3 mol/L nitric acid solution was investigated. The powders were also calcinated at various temperatures, which effect was investigated as a function of the dissolved Fe concentration in the solution. In addition, the equilibrium sorption isotherm of Mo onto Fe-based adsorbent was analyzed by the Langmuir, Freundlich and Redlich-Peterson sorption models, whereas the adsorption kinetic was analyzed using the intraparticle diffusion model and the pseudo-second order kinetic model. The overall adsorption process was described well by the pseudo-second order kinetic model. It was found that the amount of Mo(VI) ion sorbed at equilibrium was 8.3126 mg/g, with 83% of Mo adsorption occurring the first 10 min and attaining equilibrium was at ca. 150 min. This behavior suggests that the sorption takes place rapidly on the external surface of the adsorbent where the binding may be through interaction with the functional groups located on the surface of the adsorbent.