Study of synthesis of mordenite zeolite/MIL-101 (Cr) metal–organic framework compounds with various methods as bi-functional adsorbent

Abstract

In the present study, for the first time the preparation of mordenite zeolite/MIL-101(Cr) metal – organic framework (MOF) samples (MOR/MIL-101(Cr)) with different methods was suggested. The preparation of compounds was performed via hydrothermal (H), solvothermal (S) and refluxing methods. The properties of synthesized compounds and individual MOF and MOR zeolite were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption–desorption measurement and thermo gravimetric analysis (TGA). The XRD results indicated diffraction peaks for each two compounds (MOR and MIL-101) in synthesized samples. The SEM and TEM images showed mixture of MOF and mordenite zeolite via refluxing and solvothermal method. In hydrothermal method, a new composite were fabricated by diffuse of MIL-101 particles with octahedral and spherical morphology in plate shaped MOR zeolite. The nitrogen sorption isotherms characterized microporous cages in MOR/MIL-101 samples and individual samples. The BET results showed the surface areas of all synthesized compounds were smaller than individual MOF and MOR zeolite. Based on TGA plots, synthesized MOR/MOF compounds were more thermally stable compared to the isolated MIL-101(Cr). All prepared compounds were tested as bi-functional adsorbent in removal of acidic/anionic methyl orange (MO) and cationic methylene blue (MB) dyes simultaneously. The acidity from framework Al-O(H)-Si sites in MOR and basicity from amine groups in MIL-101 obtained by post-synthetic modification. Among the synthesized compounds, MOR/MIL-101 composite by solvothermal method were selected as the best bi-functional adsorbent.