Effective adsorption of quadrivalent cerium by synthesized laurylsulfonate green rust in a central composite design.

The layered laurylsulfonate intercalated green rust (lauryl-S GR) was synthesized to evaluate the influence of synthesis parameters and aqueous conditions on the adsorption of Ce. The maximum adsorption capacity of 305.58 mg/g by lauryl-S GR was predictably obtained. The pseudo-first-order kinetic model was appropriate in fitting the whole uptake process in a weak acid environment. Three isotherm models including Langmuir, Freundlich, and Tempkin were all reliable in depicting the isotherm adsorption process. The maximum monolayer adsorption capacity of lauryl-S GR towards Ce was 315.46 mg/g. Ce species including CeO and CeO besides CeO were matched in the XPS distribution, directly indicating the reduction reaction brought by Fe in the GR occurred to hydrated Ce ions during the adsorption. Nano-sized Ce particles attached to the lauryl-S GRs after the adsorption experiments were observed in the morphological characterization. Flocculated materials were formed on the surface of the lauryl-S GR at a pH of 7, which further reduced the active sites and disrupted the continuous uptake of Ce to the lauryl-S GR. This study expands the application of GRs and supplies an ideal iron-based material for the construction of the affiliated recovery pathway to the traditional separation of Ce.