In-situ synthesis of potassium copper hexacyanoferrate−expanded graphite for effective removal of strontium from water

Abstract

Radiostronium remediation is highly demanded for ecological conservation, nuclear energy sustainability, and human health. However, industrial applications of 90Sr removal adsorbents remain challenging due to the issues of efficient adsorbent exploitation and costly synthesis processes. Herein, we report a low-cost adsorbent for the removal of Sr2+ ions from water by in-situ synthesis and immobilization of potassium copper hexacyanoferrate (KCuHCF) onto expanded graphite (EG). The XRD, FTIR, SEM, and TEM results indicated that the nanoscale KCuHCF granules were homogenously distributed on EG interlayers. It showed excellent Sr2+ adsorption capacities of 6.05 mg·g−1 in water with ultralow Sr2+ concentrations and high selectivity even in the presence of various disturbing ions, including K+, Na+, Mg2+, and Ca2+ ions. The adsorption data were well-fitted by the pseudo-second-order kinetic model and the Langmuir isotherm model, suggesting the nature of heterogeneous monolayer chemisorption. Ion exchange between Sr2+ and lattice Fe2+ dominated the adsorption process. Compared with other state-of-the-art adsorbents that suffer the issues of complex and expensive synthesis processes, this work offers a facile and economical KCuHCF−EG adsorbent for the efficient removal of Sr2+ ions from radioactive wastewater.