In a recent study published in ACS Omega, Lopez et al., explored the effectiveness of biochars derived from banana leaves and coffee husks for removing phenol, a toxic pollutant, from aqueous solutions. Biochars, produced through the pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More of these agricultural wastes at 400°C and 500°C, were characterized to understand their structural and chemical properties and their capacity to adsorb phenol.  

The study revealed that biochars derived from both banana leaves and coffee husks can effectively adsorb phenol from water. The maximum adsorption capacities observed were 13.8 and 21.2 mg g-1 for banana leaf biochars, and 17.3 and 19.1 mg g-1 for coffee husk biochars. Higher pyrolysis temperatures generally led to increased graphitic structures and a more basic character in the biochars, influencing their adsorption capabilities.  

The adsorption process was primarily attributed to chemisorption involving π-π interactions, with the Freundlich model best describing the isotherm data, indicating a heterogeneous surface. The study also suggested that multilayer adsorption and pore filling contributed to phenol removal.  

These findings highlight the potential of utilizing agricultural residues like banana leaves and coffee husks to produce biochars for wastewater treatment, offering a sustainable approach to mitigate phenol pollution.  

SOURCE: Lopez, M. A. R., Ferreira, G. M. D., Figueiredo, M. T. D., Ferreira, G. M. D., Franca, J. R., Penido, E. S., Soares, J. R., Lobato, R. L. M., & Mageste, A. B. (2025). Mechanisms of Phenol Adsorption on Banana Leaves and Coffee Husk Biochars. ACS Omega.