Sorption Kinetics of Copper Ions on Biochar and Zeolite

Abstract This study evaluates the sorption kinetics and adsorption isotherms of copper ions (Cu 2+ ) onto soil amended with biochar and natural zeolite. Biochar was produced from beech wood at pyrolysis temperatures of 400 °C and 500 °C, while clinoptilolite zeolite was used as a natural mineral sorbent. Sorption experiments assessed the efficiency and behaviour of Cu 2+ uptake, with data fitted to linear, Freundlich, and Langmuir isotherm models. The results showed that biochar produced at 400 °C had the highest adsorption capacity, with a maximum value S max of 172.58 mg/g, followed by zeolite at 162.52 mg/g and biochar at 500 °C with 158.86 mg/g. All sorbents exhibited strong linear adsorption behaviour, with correlation coefficients near or above 0.999, suggesting a uniform adsorption affinity. These findings demonstrate the effectiveness of biochar and zeolite as sustainable options for Cu 2+ removal from contaminated soils, providing insights into optimising sorbent selection and pyrolysis conditions for environmental remediation.