Preparation of a novel carboxylate-rich palygorskite as an adsorbent for Ce3+ from aqueous solution

Abstract

A novel nanoscale adsorbing material, palygorskite (PGS) grafted polymethacrylic acid (PMAA) (PGS-g-PMAA), was successfully synthesized via atom-transfer radical-polymerization (ATRP). The grafting reaction was completed through a heterogeneous reaction in aqueous phase at normal temperature. Ce3+ was employed as a model to systematically investigate its adsorption performance. Meanwhile, the palygorskite was characterized by X-ray diffraction (XRD), Thermogravimetric Analysis (TGA), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscope (SEM). The results show that PGS-g-PMAA with abundant and highly accessible carboxyl groups demonstrated exceptional adsorption capacity to Ce3+. When pH is 7, temperature is 298.15 K, and the concentration of Ce3+ is 300 mg/g, the adsorption capacity reached the maximum (160.2 mg/g). PGS-g-PMAA shows a high adsorption rate, it reached adsorption equilibrium only after 40 min. In the premise of keeping the original structure of PGS, PMAA was bonded to its surface through the covalent bond, and the grafting ratio was only 15.4%. The adsorbability of PGS-g-PMAA indicated that the carboxylate-rich palygorskite composite is a promising adsorbent for removing the rare earth ions in aqueous solution. And this conclusion shows that ATRP method is an effective method for grafting functional polymer onto the surface of mineral in the aqueous phase.