Casein-Hydroxyapatite Composite Microspheres for Strontium-Containing Wastewater Treatment

Inspired by the bone-seeking property of radioactive strontium (Sr) isotopes, we have prepared casein-hydroxyapatite-(aminomethyl)phosphonic acid (CS-HAP-AMPA) composite microspheres that share similar components with bone tissues and investigated their capacity to adsorb strontium ions (Sr2+) from contaminated water. These prepared microspheres are hollow with an orifice on the surface that can be easily manufactured by microfluidic technology. According to the experiments, the proper morphology of microspheres improves the adsorption capacity, and the maximum adsorption capacity is ≤231.22 mg/g compared with traditional adsorbents. In addition, the composite microspheres are capable of capturing the Sr2+ selectively and rapidly. The results reveal that the composite microspheres have great potential in capturing and immobilizing Sr2+ from contaminated water.