SLOW-RELEASE IRON-BASED BIOCHAR SOIL HEAVY METAL PASSIVATOR PREPARATION AND APPLICATION METHOD THEREOF

摘要

Disclosed are a slow-release iron-based biochar soil heavy metal passivator and a preparation and application method thereof. The passivator is prepared using a one-step process by mixing an iron-based biochar, a kaolinite and a biological starch in a specific ratio to obtain a core material; preparing, by reacting an acidic silica sol and a chitosan solution under an alkaline catalyst and an emulsifier, a chitosan-silica sol composite material as a coating material; and coating the core material with the coating material in a controlled mass/volume ratio of the core material to the coating material to obtain the passivator. The raw materials for the passivator are widely available. The preparation process is simple and convenient, allowing for industrial-scale production. The passivator can achieve highly efficient and long-lasting passivation of arsenic and cadmium contaminated soils and inhibits, with a sustained action lasting four consecutive growing seasons, absorption and accumulation of arsenic and cadmium in rice. Compared with a common iron-based biochar passivator, the invention provides higher efficiency and longer-lasting effectiveness, and can be widely used in remediation of a farmland suffering from combined arsenic and cadmium contamination.