Bio Inspired Preparation of Clay Hexacyanoferrate Composite Hydrogels as Super Adsorbents for Cs.
A facile and low cost fabrication route, inspired by the adhesive proteins secreted by mussels, has been developed to prepare a clay based composite hydrogel (DHG(Cu) containing hexacyanoferrate (HCF) nanoparticles for the selective removal of Cs+ from contaminated water. Initially, montmorillonite was exfoliated prior to coating with a thin layer of polydopamine (PDOPA) via the self polymerization of dopamine. Mixing the composite (D clay) with HCF precursor, followed by addition of copper ions, led to self assembly of the polymer coated exfoliated clay nanosheets into a three dimensional network and in situ growth of KCuHCF nanoparticles embedded within the gel structure. Analytical characterization verified the fabrication route and KCuHCF immobilization by a copper ligand complexation. Rheology testing revealed the composite hydrogel to be elastic under low strain and exhibited reversible, self healing behavior following high strain deformation, providing good retention of KCuHCF nanoparticles in the membrane. The adsorbent DHG(Cu) showed superior Cs+ adsorption capacity ~173 mg/g) with performance maintained over a wide pH range, and excellent selectivity for Cs+ when dispersed in seawater at low concentration, 0.2 ppm. Based on its excellent mechanico chemical properties, the fabricated hydrogel was tested as a membrane in column filtration, showing excellent removal of Cs+ from Milli Q water and seawater, with performance only limited by the fluid residence time. For comparison, the study also considered other composite hydrogels, fabricated as intermediates of DHG(Cu) or fabricated with Fe3+ as the crosslinker and reactant for HCF nanoparticle synthesis.
ACS applied materials interfaces