Modified Mofs-Coal Fly Ash Composites for Enhanced Efficiency in the Removal of Heavy Metal Ions from Aqueous Matrix

Abstract

Metal Organic Frameworks (MOFs) and Na-modified Coal Fly Ash (CFA) composites were prepared by solvo-hydrothermal method to enhance the toxic heavy metal ion removal from aqueous matrix as against their pristine forms. Al, Cu, Zr and Ga-BTC based MOFs were recognized as potential and efficient and adsorbents in the removal of Pb(II), Hg(II) and Cd(II) and among them Ga showed higher adsorption efficiency. Hence, Ga-amino terephthalic acid (Ga-ATP) MOF is synthesized and tested for these metal ions removal. Further, MOF-CFA composites and Ga-ATP MOF were well characterized by XRD, SEM-EDX, FT-IR, Raman, UV-DRS, N₂ sorption and XPS. The metal ion removal was estimated by ICPOES and SEM-EDX analyses. All the four BTC MOFs composites with CFA have shown enhanced adsorption for the heavy metal ion removal and among them Ga BTC MOF-CFA composite showed exceptionally high adsorption capacity for Pb(II) ions of about 1983 mg/g from aqueous matrix. Ga-ATP MOF also exhibited high removal efficiency for Pb(II) ions of 1560 mg/g. Ga BTC MOF-CFA composite was found to be stable and regenerable for 5 runs of adsorption cycles.