Adsorption of Methylene Blue from Aqueous Solutions on a Halloysite/Magnetite Composite: Experiment and Modeling

A halloysite/magnetite composite material is synthesized via the chemical coprecipitation of iron salts in halloysite pores. The efficiency of removing of a methylene blue thiazine dye from aqueous solutions is investigated using the obtained composite as an adsorbent. A unified model that combines the equilibrium and kinetics of adsorption is used to obtain a mathematical description of the adsorption process. It is shown that unlike standard models of adsorption kinetics (pseudo-first and -second order), the unified model allows us to determine the true rate constant of the process, which is independent of the initial concentration of the dye in a solution.