Core–shell zeolite@Alg–Ca particles for removal of strontium from aqueous solutions

Abstract

A core–shell zeolite@Alg–Ca adsorbent was synthesized by a simple method of coaxial electrospinning and applied for the removal of Sr(II) ions from aqueous solution. The effects of various synthesis parameters, CaCl₂ concentration and voltage on the ability of the adsorbent to remove Sr(II) ions were studied. These parameters were found to have a significant influence on the adsorption capacity of the adsorbent for Sr(II) ions. The influence of several parameters such as pH, contact time, adsorbent dosage, initial strontium concentration, co-existing cation and temperature on the adsorption of Sr(II) ions were also investigated. The experimental data were analyzed using adsorption isotherm and adsorption kinetics. The adsorption isotherm was well described by the linear Freundlich isotherm model and the adsorption kinetics were well fitted by a linear pseudo-second-order model. The maximum adsorption capacity of the adsorbent for Sr(II) ions was 83.31 mg g⁻¹ at pH 4 and 328.15 K. The presence of Na(I) ions, Mg(II) ions, UO₂(II) ions, K(I) ions, and particularly Ca(II) ions, in the concentration range of 100–1000 mg L⁻¹ had a large negative impact on the removal of Sr(II) ions. The strontium adsorption process was feasible and spontaneous. The core–shell zeolite@Alg–Ca particles were more stable than zeolite in both acid and alkali media. The adsorption of Sr(II) ions on the adsorbent was realized via ion exchange and the adsorbent showed good reusability.