Synthesis of iron-based metal–organic frameworks and carbon derivatives via unconventional synthetic methods and waste precursors with potential for gas storage

Abstract

Metal–organic frameworks (MOFs) have remarkable characteristics including high porosity as well as large internal surface areas. However, these materials have found very limited use industrially due to their high cost of production. The use of waste materials and industrial by-products to generate cheaper and environmentally friendly precursors could potentially open doors for industrial production of MOFs. Two types of Fe-based MOFs (Fe-MIL-53 and Fe-MIL-88B) were prepared using acid mine drainage (AMD) waters as a metal precursor source and waste polyethylene terephthalate-derived terephthalic acid (PET-BDC) as a linker via microwave-assisted and sonochemical-assisted synthesis procedures. Additionally, a carbonization strategy was utilized to enhance the porosity and surface area of these MOF materials. Upon carbonization, surface areas were drastically improved to above 600 m² g⁻¹ for both MIL-53 and MIL-88B prepared using the two unconventional methods. The obtained carbons also exhibited reasonable gas uptake capacities, with MIL-53 derived carbons having a higher hydrogen capacity of 1.32 wt% (at 77 K and 1 bar) and a carbon dioxide capacity of 2.09 mmol g⁻¹ (at 298 K and 1 bar). The gas uptake capacities of MIL-88B derived carbons were found to be relatively low.