Preparation of a copper-substituted Prussian blue analogue-immobilized membrane suitable for efficient Cs removal in complex geothermal water

Abstract

Prussian blue analogue (PBA) membranes for efficient Cs removal via in situ synthesis have attracted much interest. Herein, copper-substituted PBA was developed and optimized on the surface of a substrate with the aid of tannic acid (TA). The fabricated Cu-PBA-TA membrane was systematically investigated for its Cs adsorption property in static and dynamic experiments. The as-prepared membrane showed a maximum adsorption capacity of 265.0 mg g⁻¹, which was the highest when compared to that of previously reported PBA membranes. Applied in geothermal water, the Cu-PBA-TA membrane showed favorable selectivity (K_d, 8680 mL g⁻¹) and the removal rate of Cs⁺ was about 90%. Its fast adsorption rate that reached equilibrium within 40 min and the benign reusability in the dynamic treatment of geothermal water confirmed the potential of the membrane for large-scale application.