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

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. The present study examined the conversion of water hyacinth biomass into biochar and activated carbons to explore potential transformations into high-value products that could offset the significant costs associated with water hyacinth management. Various activation conditions were utilized to assess their impact on the properties of the carbon. As a proof of concept, the derived carbon materials were tested for their effectiveness in removing pharmaceutical compounds from water across different therapeutic categories, specifically antibiotics (tetracycline), analgesics (paracetamol), and antidepressants (fluoxetine). These emerging micropollutants pose a concern for living organisms, including humans, necessitating the development of effective mitigation strategies. To the authors’ knowledge, water hyacinth-derived carbons have not yet been studied to remove these pharmaceutical compounds. This will allow insights into their uptake capacity for these emerging organic water pollutants.