Preparation and characterization of a core–shell KNO3@alginate-Ca particle with uranium-removal and slow-release of KNO3

Abstract

A novel core–shell KNO₃@alginate-Ca particle with uranium-removal and slow-release of KNO₃ was prepared by a simple method of coaxial electrospinning. The feasibility of the core–shell KNO₃@alginate-Ca particle used for uranium removal and slow release of potassium was investigated. The main factors affecting the removal of uranium, including pH, initial concentration, temperature and contact time were investigated. The core–shell KNO₃@alginate-Ca particle displayed a high adsorption capacity of 0.825 mmol g⁻¹ at a pH of 5, initial concentration of 0.963 mmol L⁻¹ and a temperature of 318.15 K, and the maximum uranium absorption frequency was 91.143% at pH 5, 318.15 K and an initial concentration of 0.074 mmol L⁻¹. The adsorption data were fitted well with the non-linear Langmuir isotherms and non-linear pseudo-first-order kinetics. The presence of other cations like K(I) ions, Na(I) ions, Zn(II) ions and Mg(II) ions had almost no effect on the uranium adsorption. The uranium adsorption process was feasible and spontaneous. The adsorption of uranium on the core–shell KNO₃@alginate-Ca particle was mainly attributed to exchange between the calcium and uranium. The study of nutrient slow release revealed that the particle showed excellent slow-release properties. Thus, the core–shell KNO₃@alginate-Ca particle was a promising adsorbent for uranium removal and a slow-release material for potassium release.