Selenium-rich slow-release cadmium inhibitor and preparation method thereof

The invention provides a preparation method of a selenium-rich slow-release cadmium blocking agent. The preparation method comprises the following steps: S1, preparing silicon dioxide microspheres with porous capillary structures; S2, soaking the silicon dioxide microspheres obtained in the step S1 in a saturated solution of inorganic selenium salt, performing filtering, and performing drying to obtain selenium-containing silicon dioxide microspheres; S3, preparing a wax wall water-absorbent resin microcapsule; S4, fully dry-mixing the selenium-containing silicon dioxide microspheres obtained in the step S2, the wax-wall water-absorbent resin microcapsules obtained in the step S3, starch, water glass and inorganic selenium salt, adding the water glass for granulation, and performing hot air drying in an environment of 30-35 DEG C to obtain an inner core; S5, spraying a coating agent on the surface of the inner core obtained in the step S4 for coating treatment, wherein the coating agent comprises modified sod