Preparation of Potassium Copper (II) Ferrocyanide Anchoring Hydrogel Composites for Rubidium Recovery

Potassium copper ferrocyanide (KCuFC) is considered promising for rubidium resource recovery with high adsorption capacity and excellent selectivity. However, its microcrystalline powder structure restricts the recycling. In this work, a useful ternary hydrogel was prepared using graphene/polyvinyl alcohol/chitosan/tetracarboxylic acid (RPCT) by via hydrogen bond reaction. In which graphene makes the improved stability, tetracarboxylic acid offers many chelating sites for Cu 2+ . Further, potassium copper (II) ferrocyanide anchoring hydrogel composites (RPCT-KCuFC) could be formed in situ in 40 mmol L −1 K 4 Fe(CN) 6 by coprecipitation. Various FE-SEM, EDS, XRD, IR, and other technologies proved the structure, composition, and physical properties. The recovery of Rb + was investigated using RPCT-KCuFC from solution in detail. The adsorption process fits pseudo-second-order model with three-stage intraparticle diffusion process, and the Langmuir isotherm model could explain the adsorption behavior. The adsorption capacity is about 262.48 mg g −1 (45°C, 4 h, pH 7, [Rb + ] initial = 10 mg L −1 ). Over 95% of Rb + could be desorbed from the RPCT-KCuFC (Rb + ) in 0.5 mol L −1 of HCl/NH 4 Cl with 4 h. Moreover, RPCT-KCuFC was applied to recover Rb + from simulative brine. The present work provided effective immobilization strategies of KCuFC for separating Rb + .