Single and Competitive Adsorption Behaviors of Cu²⁺, Pb²⁺ and Zn²⁺ on the Biochar and Magnetic Biochar of Pomelo Peel in Aqueous Solution

As an environment-friendly material, biochar has been used to remove heavy metals from wastewater, and the development of cost-effective biochar has been an emerging trend. However, limited studies consider the competitive adsorption of co-existing metals and the separation efficiency of absorbent and solution after adsorption. In this study, pomelo peel was used to prepare biochar (BC) and magnetic biochar (MBC) at different temperatures. Then, the physicochemical properties of the biochars were characterized and the adsorption characteristics of Cu²⁺, Pb²⁺, and Zn²⁺ on the biochars in single, binary, and ternary metal systems were investigated. The results showed that both pyrolysis temperature and magnetization could affect the adsorption capacity of biochar. The adsorption kinetic and thermodynamic processes could be well described by the pseudo-second-order kinetic model and Langmuir model. The adsorption isotherm types of Pb²⁺ and Zn²⁺ changed in the binary metal condition. The competitive adsorption order of three heavy metal ions in ternary metal adsorption was Pb²⁺ > Cu²⁺ > Zn²⁺. The MBC of 500 °C showed a good adsorption capacity to Pb²⁺ in the co-existing environment, and the maximum adsorption capacity was 48.74 mmol g⁻¹. This study also provided technical support for the utilization of pomelo peel and the engineering application of biochar. View Full-Text