Novel reductive extraction process to convert the bio-oil aqueous acid fraction into fuels with the recovery of iron from wastes

In this work, bio-oil waste AAF (aqueous acid fraction) was used to recover iron from red mud (RM) waste by a reductive extraction process. In this process, extraction of iron from RM with AAF is followed by thermal treatment of AAF-Feextracted mixture, leading to the reduction of the Feextracted with the production of Fe/C composites, a valuable feedstock for the steel industry, and a gas fuel fraction. Analyses by IR, UV-vis, ESI-MS, CHN, potentiometric titration, TG, TG-MS, TOC and 1H NMR showed AAF can efficiently extract Fe3+ present in RM waste. After extraction, the mixture AAF-Feextracted was treated at 400, 600 and 800 °C to decompose mainly into two fractions: solid (30-40 wt%) and gas (60-70 wt%). Mössbauer and XRD analyses of the solid fraction showed the presence of reduced iron phases, e.g. Fe2+, Fe0 and iron carbide, with 76% of carbon. TG-MS analyses of gas fraction showed the production of H2 (58 mol%), C1-C4 (19 mol%) and COx (23 mol%), with potential application as a fuel.