Research on Remediation of Cadmium-Contaminated Soil by Corn Stalk Biochar/C₃N₄ Composites

Biomass-activated carbon was prepared from agricultural waste wheat/corn straw, and then mixed with nitrogen (g-C₃N₄) in a certain proportion to synthesize carbon-based nanomaterials. Under different experimental conditions (calcination form, mixing ratio), the remediation effects of different types of carbon-based nanomaterials on cadmium (Cd) contaminated soil were investigated. The carbon-based nanomaterial system synthesized from corn biochar mixed nitrogen (g-C₃N₄) showed the best adsorption performance. On this basis, the static and dynamic adsorption properties of carbon-based nanomaterials on cadmium (Cd) in soil environment were studied through a series of characterization methods and adsorption models by changing the mixture ratio of corn straw and nitrogen (g-C₃N₄), temperature, time, substrate concentration and other background experimental conditions. The results showed that under the conditions of 35 ℃ and adsorption time ≥ 6 h, the calcined and remixed CN: YC = 2:8 samples had the best remediation effect on Cd²⁺ contaminated soil with a substrate concentration of 10 mg/L and pH value of 6. Langmuir and Freundlich’s adsorption isothermal models were used to investigate the adsorption mode of NC: YC series samples, which belong to the physical adsorption of a single molecular layer.