Competition adsorption characteristics of rice husk biochar for cadmium and lead

This study prepared rice husk biochar RHB700 using rice husks as raw materials under 700 ℃ conditions and investigated the adsorption characteristics of rice husk biochar for cadmium (Cd) and lead (Pb) in single-metal and dual-metal systems. The experimental results showed that under single conditions, the maximum adsorption capacity of rice husk biochar for Cd was 9.22 mg/g, and for Pb, it was 38.69 mg/g. Under competitive conditions, the maximum adsorption capacity for Cd decreased to 4.68 mg/g, while for Pb, it increased to 41.75 mg/g. Kinetic analysis indicated that the adsorption process of Cd 2+ is better described by a pseudo-second-order kinetic model, whereas the adsorption process of Pb 2+ is better described by the Elovich model, indicating that the adsorption of Cd 2+ and Pb 2+ on rice husk biochar is primarily chemical adsorption. Additionally, the study found that Pb 2+ inhibits the adsorption capacity of Cd 2+ on rice husk biochar under competitive conditions, while the presence of Cd 2+ has little effect on the adsorption of Pb 2+ on rice husk biochar, and may even slightly increase it.