Fast and High Amount of Uranyl Ion Uptake by p(Vinyl Phosphonic Acid) Microgels Prepared by UV Irradiation Technique

Micrometer-size poly(vinyl phosphonic acid) (p(VPA)) hydrogel was synthesized by employing UV irradiation of an emulsion containing vinyl phosphonic acid (VPA) and crosslinker, prepared using lecithin as surfactant and gasoline as solvent. The p(VPA) microgels were employed in absorption of UO22+ ions from aqueous environments and have very high and fast absorption capacity. In about 20 min, 670 mg UO22+ ions were absorbed per gram of p(VPA) microgel from the prepared UO22+ ion solution, and the absorption capacity increased up to 900 mg at pH 6. Various parameters affecting UO22+ absorption characteristics of p(VPA) were investigated. It was found that the Langmuir isotherm fitted the absorption characteristics of p(VPA) better than the Freundlich isotherm. Moreover, magnetic ferrite can be prepared within p(VPA) and used as a magnetically responsive p(VPA) microgel composite for externally controlled absorption of UO22+ ions with little decrease in the absorption capacity of the p(VPA) microgel.