Efficient ZIF-67 alginate composite hydrogel material and its application to enhanced copper (II) adsorption from aqueous solutions

Metal-organic framework materials(ZIF-67) were loaded on Sodium alginate/polyvinyl(PVA/SA) hydrogel by in situ growth method for adsorption of heavy metal Cu (II). The structure of hydrogels composited with MOFs and polymers was designed to improve the poor mechanical properties of natural polymer gel materials and the inconvenience of powdered MOFs materials in practical applications. Synthesized hydrogel spheres were characterized by FT-IR, SEM, XRD, XPS, etc. The adsorption results showed that the optimum adsorption process of Cu (II) pH was 5.0. The adsorption kinetics and isotherm suggest that the adsorption process follows the Freundlich isotherm and the pseudo-second-order models. The experimental maximum adsorption capacity was 128.4 mg/g, 3.3 times and 1.8 times higher than ordinary SA and PVA/SA hydrogel spheres. The selectively experimental results show that PVA/SA@ZIF-67 exhibits better adsorption performance (especially for ion Cu(II), Pb(II) ) and it also indicates that PVA/SA@ZIF-67 has application potential when applied in some specific fields of wastewater treatment. More importantly, PVA/SA@ZIF-67 exhibited exceptional mechanical stability and showed excellent recycling capability in the cyclic adsorption process.