Polyethyleneimine modified NH2-MIL-101(Fe) with high adsorption capacity towards hexavalent chromium and copper ion from solution

Metal-organic frameworks have unique structural, physical, and chemical properties, such as large specific surface area, high porosity, good crystalline structure, and thermal stability, and are thus found in broad applications in the field of water treatment.In this study, the facile synthesis of polyethyleneimine modified NH 2 -MIL-101(Fe) was performed in a single step, and the adsorption property toward hexavalent chromium and copper ions was carried out.MIL-101(Fe)@PEI (PEI -Polyethylenimine) has a higher adsorption capacity than NH 2 -MIL-101(Fe), indicating the composite is potential as an efficient adsorbent.The maximum adsorption capacity was 339 mg•g -1 for Cr(VI) (pH 5.5) and 32.9 mg•g -1 for Cu(II) (pH 5.0) from experimental results at 293 K, respectively.The process is a homogeneous physical and chemical adsorption, such as y ion exchange, surface complexation, and electrostatic attraction.For both Cr(VI) and Cu(II) adsorption, there is spontaneity and increasing entropy.Freundlich model is best suitable to fit the equilibrium data while pseudo-second-order kinetic model and double constant model can describe the kinetics of Cr(VI) and Cu(II), respectively.There is good property of spent adsorbent for regeneration and reuse.MIL-101(Fe)@PEI is promising as adsorbent for removal of some pollutants.