Mesoporous SiO2–Prussian blue composite for high-efficiency cesium ion removal

Abstract

This research investigates the development of a mesoporous silica–Prussian blue (HOM-SiO₂-PB) composite adsorbent, created using a one-pot in situ sol–gel method. This technique integrates Prussian blue (PB) into the SiO₂ framework, enhancing its ability to capture cesium ions (Cs⁺) from contaminated water. The composite was thoroughly analyzed using various methods, including XRD, XPS, HR-TEM, SEM, and N₂ adsorption–desorption measurements. Results showed that HOM-SiO₂-PB has a high adsorption capacity of 92.5 mg g⁻¹ for Cs⁺ ions, with the adsorption process governed by ion exchange between Cs⁺ and K⁺ ions. Adsorption isotherms fit models such as the Langmuir model with R² values greater than 0.984, while kinetic data followed a pseudo-first-order model. The adsorbent demonstrated 98.3% removal efficiency, reducing Cs⁺ concentrations from 2.02 mg L⁻¹ to below 20 μg L⁻¹. The material also showed excellent selectivity for Cs⁺ over other ions like Na⁺, K⁺, Mg²⁺, and Ca²⁺, with a distribution coefficient (K_d) of 3.9 × 10³ L g⁻¹, and maintained high stability and reproducibility after seven regeneration cycles. This study underscores the potential of HOM-SiO₂-PB as an effective and sustainable solution for removing radioactive Cs⁺ ions from contaminated water.