Biochar production from Manilkara zapota seeds, activation and characterization for effective removal of Cu2+ ions in polluted drinking water

Over years of human evolution and industrialization, water pollution due to heavy metal ions has become a significant consequence, especially with drinking water being unnoticed with very low concentrations. Any heavy metal concentration above this permissible limit is toxic and needs immediate mitigation. Adsorption using activated biochar is an effective method to do so. In this study, biochar was produced from Manilkara zapota through pyrolysis at 700 °C and ball-mill activation was done. Functional analysis of the biochar was done by Boehm titration and point of zero charge and further characterized by FTIR, XRD, and FESEM. The effect of parameters and initial optimization was carried out, and their isotherm, kinetic, and thermodynamic studies were done accordingly. The results show effective removal of copper ions with a maximum removal efficiency of 94% and a maximum equilibrium adsorption capacity of 18.27 mg/g. Batch adsorption study reveals the mechanism of adsorption involved, which tends to be monolayer, homogenous chemisorption exerting spontaneous, endothermic reaction with an increased affinity towards Cu²⁺ ions. Furthermore, activated sapota seed biochar can be improvised to commercialize the product and make it economically viable in polluted drinking water purification.