Preparation of polyacrylic-acid/palygorskite composite particles via inverse-suspension polymerization for efficient separation of Ce from aqueous solution.

A novel granular composite adsorbent made from palygorskite (PGS) and polyacrylic acid (PAA) (PAA@PGS) was prepared successfully by inverse-suspension polymerization. Acrylic acid (AA) molecules present in the PGS pores form PAA chains passing through the PGS channels after in situ polymerization, and bond to each other through hydrogen bonds. PAA@PGS was characterized by X-ray diffraction (XRD), Thermogravimetric Analysis (TG/TGA), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). Ce was selected as a model to conduct the adsorption experiment, and the adsorption capacity reached 350 mg/g (initial concentration 500 mg/L, pH 6.0, 303.15 K). PAA@PGS performs well in the presence of interfering ions Na and has a high adsorption rate for about one hour. Moreover, PAA@PGS shows an excellent reusability, in the five cycle experiments, all the desorption rates are more than 95%, and when the fifth cycle time was completed, the adsorption capacity could still reach 87.20%.