Hydrothermal Liquefaction of Metals (Zn, Cu-Zn, Fe-Cu-Zn) Loaded Water Hyacinth to Bio-Oil
摘要
Water hyacinth is a hyperaccumulator that extracts nutrients, oxygen, and heavy metals from water bodies and has been identified as a potential source for bio-oil production. During hydrothermal liquefaction, transition metals catalyze the reactions and enhance the bio-oil yield. In the present article, the mono, bi and tri-metallic combination of transition metals such as Zn, Fe/Zn, Cu/Zn, and Fe/Cu/Zn are used as catalysts for hydrothermal liquefaction of water hyacinth to understand the synergistic effect of different transition metals on the bio-oil yield by varying operating parameters namely temperature, residence time, and biomass-to-water ratio. The Zn-impregnated water hyacinth has resulted in a bio-oil yield of 33.2 ± 0.9% and a water-soluble fraction of 45.4 ± 1.4%. The chemical composition of bio-oil samples was characterized by GC-MS and NMR spectroscopy indicating the formation of alkanes and alcohols majorly. The bio-oil samples (Zn-impregnated) analyzed by NMR spectroscopy show higher alkanes and alcohols content. XRD and XPS confirmed the carbothermal reduction of Zn2+ to Zn0 nanoparticles during hydrothermal liquefaction. The addition of Fe, Cu, and Zn simultaneously showed the synergetic effect in promoting the maximum total bio-oil yield of 37.6 ± 1.1% with HHV of heavy oil as 26.79 (MJ/kg) and light oil of 25.96 (MJ/kg).