Investigation of the Adsorption Capacity of H3PO4-Activated Biochar from Eucalyptus Harvest Waste for the Efficient Removal of Paracetamol in Water

The present study showed that it is possible add value to eucalyptus harvest waste, obtained in large quantities, from the cellulose industries, without known economic use, for the production of an activated biochar. The biochar, produced from the impregnation of eucalyptus harvest waste with H3PO4, and subsequently pyrolyzed at 600 °C for 1 h, was successfully used as a bioadsorbent in the removal of paracetamol, an emerging pollutant present in wastewater. The biochar showed a high specific surface area with micro- and mesopores and functionalized surface. The optimal conditions for the removal of paracetamol achieve an efficiency around 88–93%. The Langmuir and the pseudo-first-order models best fit the experimental data, with a maximum adsorption capacity of approximately 27.8 mg g−1, at 25 °C. The thermodynamic showed that adsorption occurred spontaneously, endothermally and randomly at the solid–liquid interface. In addition, the bioadsorbent showed excellent reusability and no significant difference in adsorption capacity was observed in more complex aqueous matrices. Thus, the activated biochar produced in this study proved to be an efficient, low-cost and environmentally friendly bioadsorbent, capable of removing paracetamol from contaminated water, with great potential for use in water treatment plants, on a large scale and economically, contributing to the improvement of water quality and minimizing residual biomass in the environment.