Preparation of Tetra Pak-Based Hydrochars for Cleaning Water Polluted by Heavy Metal Ions: Physicochemical Properties and Removal Mechanism

This paper addresses the analysis of hydrothermal carbonization of Tetra Pak residues using diluted sulfuric acid to obtain hydrochars for cleaning water polluted by heavy metal ions. The hydrochar samples were prepared under different carbonization conditions, and a detailed study of their composition, textural parameters, and surface functionalities was performed. It was found that the hydrothermal carbonization and dwell time of the Tetra Pak wastes significantly affected the composition of the hydrochars. These hydrochar samples contained oxygenated functional groups and aluminum-silicon moieties that were responsible for the Pb2+, Zn2+, and Hg2+ adsorption. The removal of these heavy metal ions using Tetra Pak hydrochars was an endothermic and multi-ionic process. Hydrothermal carbonization is a promising approach to improve Tetra Pak waste management, generating materials with interesting properties for addressing the problem of wastewater and industrial effluent depollution.