Significantly enhanced alkaline stability and cyanide suppression of Prussian blue analogues using montmorillonite for high-performance cesium removal

Radiocesium (Cs+) treatment is getting more attention as Japan plans to dump wastewater from Fukushima nuclear meltdown into the Pacific Ocean. Prussian blue is a star material and medicine for intracellular and extracellular therapy of Cs+. However, it and its analogues are essentially unstable in alkali-solution and seawater due to break down easily into the hazardous cyanide substance. In this study, copper ferrocyanide/magnetic montmorillonite composites (KCuFC/M-MT) were prepared using an in-situ synthetic method. This method can inhibit the decomposition of Prussian blue analogues (PBAs) and the production of toxic cyanide. The 5KCuFC/M-MT composites exhibit excellent Cs+ adsorption properties (204.48 mg/g), good material chemical stable over a wide pH region (2 ≤ pH ≤ 12), safe amount of cyanide release (< 0.2 mg/L, EPA, USA), and low-toxic to human hepatocytes (HepG2 cells), which are promising for the application in radioactive wastewater treatment. The adsorption mechanism and stabilization mechanism were systematically studied. This study provides a reference for the control radioactive Cs+ hazards by using clay material stabilized ferrocyanide material and provides a new direction for the research of cesium-control materials. This research solves the problem of basic instability of PBAs and expands new application fields for PBAs, especially decorporation agent for internal contamination by radiocesium.