Biomass Valorization Through Pyrolysis of Grape Peel Waste as Copper and Cadmium Adsorbent

Abstract

High concentrations of heavy metals in wastewater are commonly associated with industrialization, which require sustainable solutions for their removal. In this study, copper (Cu²⁺) and cadmium (Cd²⁺) adsorption through biochar (biomass pyrolyzed at high temperature) was selected as a suitable alternative to conventional methods. Grape peel residue was pyrolyzed at three different temperatures (400, 700, and 900 °C) and characterized by BET analysis.
Batch experiments were carried out to evaluate adsorption performance through kinetics and isotherm studies. The most effective biochar was selected and tested in a column experiment using a contaminated solution containing equal concentrations (10 mg/L) of Cu²⁺ and Cd²⁺ to simulate competitive adsorption conditions. The results showed that biochar produced at intermediate pyrolysis temperature displayed the highest adsorption capacities. The Freundlich model described isothermal data better than the Langmuir model (R²=0.974). Breakthrough curve analysis carried out over 13 h showed Cd²⁺ saturation, whereas Cu²⁺ removal was not completely saturated.