Valorization of Water Hyacinth Biomass: Comprehensive Characterization and Production and Application of Activated Carbons

Abstract

This study explored a potential route for valorizing the entire biomass from water hyacinth. Initially, the biomass underwent complete characterization, revealing high contents of ash (35%), extractives (25%), and monosaccharides (41%), with glucose being predominant (21%). Lignin content was low (19%), with a monomeric composition rich in G- and H-units (3.6% and 3.4%, respectively). The biomass exhibited a low calorific value (11 MJ/kg) and high oxygen content (62%), contrasted with low carbon values (31%) and high H/C (14.9) and O/C (1.9) ratios. Subsequently, biochar production was conducted at two temperatures (500 and 800 °C), where a high yield was obtained at 500 °C (44%). Three types of activated carbon were produced using different activation processes: physical activation with CO₂ and chemical activation with K₂CO₃ and H₃PO₄. CO₂ activation yielded 34% but made almost no carbon or porosity (ABET = 9.4 m²/g). K₂CO₃ activation produced carbons with a low yield (21%) but a very high surface area (862 m²/g), featuring micropores and mesopores. In contrast, H₃PO₄ activation yielded 74%, resulting in primarily mesoporous material with minimal microporosity. The activated carbon produced with K₂CO₃ demonstrated high removal efficiency for all the tested pharmaceutical compounds.