Synthesis of bimetallic Metal-Organic Frameworks composite for the removal of Copper(II), Chromium(VI), and Uranium(VI) from the aqueous solution using fixed-bed column adsorption

NiCo(BDC) bimetallic Metal-Organic Framework (MOF) is impregnated with MnO2 particles to synthesize a highly stable NiCo(BDC)@MnO2 composite. This MOF composite is applied for the removal of Copper (II), Chromium (VI), and Uranium (VI) heavy metal ions from aqueous solutions using batch adsorption and the fixed bed column method. The physicochemical properties of the composite were analyzed by Fourier transform infrared spectrometry (FTIR), powder X-ray Diffraction (PXRD), Scanning Electron Microscope (SEM), and Brunauer-Emmett-Teller (BET) analysis. TG-DTA analysis shown the composite MOF is thermally stable up to 450 degrees C. X-ray Photoelectron Spectroscopy (XPS) analysis confirms the presence of Nickel, Cobalt, and Mn. The fixed-bed column adsorption experiments on Cu(II), Cr(VI), and U(VI) were conducted to understand the effect of bed height, flow rate, and initial concentration on adsorption efficiency. NiCo(BDC)@MnO2 MOF composite showed a high adsorption capacity of 756.82 mg/g for Cu(II), 111.22 mg/g for Cr(VI), and 365.25 mg/g for U(VI) were examined by the Langmuir isotherm model. The equilibrium studies specified that Cu(II), Cr(VI), and U(VI) adsorption follows pseudo-second-order kinetics in the batch adsorption process and Thomas, Yoon-Nelson, Adam, and Bohart model in fixed-bed column adsorption, which indicates that chemisorption and surface complexation are maybe the primary mechanisms.