Hydrothermal conversion of microalgae and its waste residue after biofuel extraction to acetic acid with CuO as solid oxidant

Abstract Production of chemicals from microalgae is a substantial way to contribute to the economic viability of a biorefinery. In this research, we report a new and green method for producing acetic acid from microalgae directly or from its waste residue after biofuel extraction using copper (II) oxide (CuO) as a solid oxidant. Results show that the CuO can significantly facilitate the oxidation of microalgae and its waste residue into acetic acid with the simultaneous reduction of CuO to Cu and Cu2O. The maximum acetic acid yield reached up to 35 % and 31 % from the microalgae and its waste residue, respectively, which are much higher than previous report (14.9 %) which is obtained with traditional liquid oxidants such as H2O2. The reduction of CuO to Cu(0) at a relatively low temperature (300 °C) offered an additional benefit of developing a sustainable method in copper metallurgy at mild conditions.