Functionalized Charcoal as a Buffering Matrix of Copper and Zinc Availability
High copper (Cu) and zinc (Zn) contents in soil can cause phytotoxicity to plants and contaminate surface and groundwater, with negative effects on agriculture and the environment. Functionalized charcoal (OCh) has high cation exchange capacity (CEC) and the ability to adsorb Cu and Zn and control their availability in the soil and water. An adsorption study at two pH levels was carried out to evaluate increasing Cu and Zn sorption capacity provided by the functionalization process of a charcoal. In addition, a kinetics study of competitive and non-competitive adsorption-desorption of Cu and Zn in OCh was also evaluated. The results showed that functionalized charcoal (Ch) increased CEC 8.7 times due to an increase in carboxyl and phenolic groups, without changing its specific surface area. The Cu and Zn kinetics study showed higher interaction of Cu with the OCh, with total adsorption capacity of 53.1 mg g−1. From this amount, only 74.9 % was desorbed. However, competitive adsorption with Zn reduced the total amount of Cu adsorbed and decreased the Cu affinity for organic matter. This study shows the potential use of functionalized charcoal for control of Cu and Zn availability in the soil solution.