Adsorptive removal of Cr(VI) from wastewater by α-FeOOH hierarchical structure: kinetics, equilibrium and thermodynamics

A novel hollow urchin-like alpha-FeOOH hierarchical structure was fabricated via a one-pot hydrothermal procedure without using any templates, surfactants or organic raw materials. An inside-out amorphous ripening mechanism was proposed to unravel its structural evolution. The kinetics, equilibrium and thermodynamics of its adsorptive removal of Cr(VI) from wastewater were comprehensively investigated. It was found that the adsorption process can be depicted using a pseudo-second-order model, and a high adsorption capacity of 58.97 mg g(-1) was obtained from the equilibrium adsorption isotherm. Also, the thermodynamic parameters (i.e., enthalpy, entropy and Gibbs free energy) at different temperatures were acquired to reveal a spontaneous adsorption process, with both physical and chemical characteristics.