IN-SITU CATALYTIC (Fe/Cu/Zn) HYDROTHERMAL LIQUEFACTION OF WATER HYACINTH

Abstract

Rising energy demands and global warming issues direct to opt for new alternative energy resources with a minimum carbon footprint. Moreover, the alarming concern of global temperature rise due to greenhouse gases and depletion of commercial conventional fossil fuels further limits their usage. Biomass, with abundant availability, meets all the requirements of renewable and carbon-neutral energy sources and has become a substitute for existing commercial fossil fuels. Lack of proper wastewater treatment facilities leads to nutrient-rich and metal-contaminated effluents, which are a threat to the environment. Agriculture residues, aquatic plants, wood wastes, and plant and animal wastes, including municipal waste, can be usually considered as potential carbon-rich biomass to generate gas, liquid, and solid fuels. Water hyacinth (Eichhornia crassipes) is a lignocellulosic biomass. It is identified as a potential source for bio-oil production as it is considered a harmful plant as it grows rapidly in stagnant water and extracts nutrients, oxygen, and heavy metals from water bodies, indirectly affecting flora and fauna's growth. It is a hyperaccumulator and can potentially absorb the metals and nutrients from the contaminated water for their growth. Hence, this noxious aquatic biomass can be utilized as it is inexpensive, easily available in abundance, and has no competition with food crops for its conversion to fuels, valuable compounds, and other applications, including bio-fertilizer, effluent treatment, polymers, and supercapacitor electrode. Hydrothermal liquefaction (HTL) can be a potential conversion process that can effectively handle wet biomass to produce bio-oil with low oxygen content. HTL process involves subjecting the biomass to high temperature and pressure in the presence of water, leading to biomass breakdown through thermal disintegration. This causes intricate reactions, driven by alterations in water's advantages and physical characteristics, such as density, solubility, and dielectric constant, under the specific operating temperature of 200 to 374 ⁰C and pressure range of 7-25 MPa. This research demonstrated the impregnation of iron (Fe), copper (Cu), and zinc (Zn) on water hyacinth at the pH of zero-point charge (PHZPC) and physio-chemical interactions during HTL experiments of water hyacinth for its conversion to bio-oil, carbon hybrids, and gas.