Acidic and Basic Functionalized Biochar from Licuri Nutshell for Methylene Blue Removal: A More Sustainable Solution for Wastewater Treatment

The right to clean water is one of the Sustainable Development Goals from the United Nations Agenda 2030. Industrial activity produces several tons of wastewater daily contaminated with dyes that must be treated. In this sense, the adsorption employing carbon-based materials as adsorbents is one of the most used and efficient processes. In this study, we developed a more sustainable biochar derived from a licuri nutshell (LN), a typical Brazilian lignocellulosic residue, for methylene blue (MB) removal. The chemical treatment of this biochar with sulfuric acid and sodium hydroxide created a functional structure with acid and basic sites. The licuri nutshell modified biochar (LNMB) presented a maximum adsorption capacity of MB of 826.45 mg g-1, while the non-modified biochar and the commercial activated carbon presented only 5.27 and 142.86 mg g-1, respectively. The recyclability of the adsorbents was evaluated, and there was a loss of efficiency in each cycle for every material. However, it is remarkable that LNMB presented in only one adsorption cycle almost six times more MB removal than the commercial material, thus proving its promising feature as a greener adsorbent derived from lignocellulosic waste.