The Synthesis of Metal–Organic-Framework-Based Ternary Nanocomposite for the Adsorption of Organic Dyes from Aqueous Solutions

Abstract

In the present study, a ternary magnetic nanocomposite (SiO2/MnFe2O4/ZIF-8) was synthesized via the embedding of the SiO2/MnFe2O4 nanocomposite within the metal–organic framework (ZIF-8). The synthesized nanocomposite was characterized using suitable techniques including FT-IR, XRD, SEM, TEM, VSM, and BET. The nanocomposite showed a high surface area (SBET = 831 m2·g−1) and superparamagnetic behavior (23.7 emu·g−1). All characterization techniques confirmed the successful combination of three nanocomposite parts (MnFe2O4, SiO2, and ZIF-8). The nanocomposite was examined for the adsorption of organic dyes, malachite green (MG) and methyl red (MR), from aqueous solutions. The adsorption conditions including ionic strength, contact time, pH, and adsorbent dosage were optimized by studying their change effect. The SiO2/MnFe2O4/ZIF-8 nanocomposite showed high adsorption capacities (1000.03 and 1111.12 mg/g) for the removal of MG and MR, respectively, from water. The isotherm and kinetics studies indicated that the adsorption of MG and MR dyes on the surface of the SiO2/MnFe2O4/ZIF-8 nanocomposite followed the Langmuir isotherm model and pseudo-second-order kinetic model, suggesting the monolayer chemisorption mechanism. The reusability study of up to five successive cycles indicated the successful reuse of the SiO2/MnFe2O4/ZIF-8 adsorbent for dye removal from wastewater. The comparison of the present adsorbent to the previously reported adsorbents indicated that it is a promising adsorbent for dye adsorption from wastewater and must be investigated in the future for the removal of additional pollutants.