Structure and properties of selected metal organic frameworks as adsorbent materials for edible oil purification

The scope of this study was to evaluate adsorbent material properties of some selected metal organic frameworks (MOFs) in comparison with natural clays (commercial bleaching earth-C.B.E., natural zeolite and sepiolite) for possible applications in edible oil purification. Seven MOFs were synthesised at gram level in the laboratory and the 3 clays were acid activated. Microstructural properties by scanning electrone miscoscopy (SEM), crystallinity properties by X-ray diffraction (X-RD), surface and pore properties by BET analysis, some spectral properties (NIR and 1H NMR), thermal properties by differential scanning calorimetry (DSC), and some adsorption properties were determined. It was shown that the synthesized MOFs represent morphologies like sphres, needles, cubic crystals, and amorphous masses. Their X-RD patterns indicated occurrence of different crystalline types. The largest surface area in aluminum-MOF (Al-MOF) and ZIF-8-MOF, largest pore volume in sepiolite and titanium-MOF (Ti-MOF), and largest pore radius in gamma-cyclodextrine-MOF (gamma-CD-MOF) were measured. Near infrared (NIR) and nuclear magnetic resonance (1H NMR) spectroscopy proved that coordination structures with metal nuclei and surrounding hydrogens were present. Thermal analysis indicated that except gamma-CD-MOF, all adsorbents were quite heat stable up to 450 degrees C temperatures. Finally, higher free fatty acid adsorption capacities in Ti-MOF, gamma-CD-MOF, Cr-MOF, and higher beta-carotene adsorption capacities in Ti-MOF and gamma-CD-MOF were measured. This study proved the great potential of the MOFs as adsorbents for various purification purposes in the edible oil industry.