Work

Co-pyrolyzed and valorized municipal solid wastes and coconut husks into biochar adsorbing methylene blue in aqueous solution

Year: 2025

Type: article

Abstract: The adsorption potential of biochar derived from municipal solid waste (MSW) and coconut husk (CH) for methylene blue (MB) removal was investigated in this study. Both produced biochars exhibited a pH PZC of 8.5 with no observed significant compositional changes (consistent with literature values). The integration of CH in the co-pyrolysis process altered the surface morphology of MSW-BC. Moreover, the post-adsorption images indicated MB deposition on the biochar surfaces. The MCH-BC had 559 m² g -1 specific surface area and about 29 mg g -1 adsorption capacity, and practically indicated superior adsorbent quality than MSW-BC (with corresponding lower values). Furthermore, the adsorption behaviors suggested that the phenomena were (1) potentially influenced by chemisorption from kinetic studies, (2) best fitted the Freundlich isotherm model, denoting a heterogeneous adsorption mechanism, and (3) endothermic and spontaneous from the thermodynamic analysis. The proposed adsorption mechanism was feasibly dominated by physisorption, as indicated by low ΔG° values (-1.234 kJ mol⁻¹ to -4.531 kJ mol⁻¹) and functional groups, likely facilitating hydrogen bonding, which perhaps followed by initially identified chemisorption from kinetic studies. Finally, the study highlighted the potential of co-pyrolyzed MSW and CH biochar as a competitive low-energy synthesis, producing an adsorbent for MB removal.

Source: Sustainable Chemistry for the Environment

DOI: 10.1016/j.scenv.2025.100284