Passivator for repairing cadmium, lead and arsenic contaminated soil of saline-alkali soil, and preparation method of passivator

The invention provides a preparation method of a passivator for remediation of cadmium, lead and arsenic contaminated soil of saline-alkali soil. The method comprises the following steps: 1) pre-treating clay minerals to remove bound water on the surfaces of the clay minerals, improve the pore structure of the clay minerals and enhance the adsorptive property of the clay minerals; and 2) fully anduniformly mixing the pretreated clay minerals, phosphate, organic silicon and a soluble iron salt to obtain the passivator. The invention further provides a passivator for repairing cadmium, lead andarsenic contaminated soil of saline-alkali soil, wherein the passivator comprises the following components in percentage by mass: 40-60% of clay minerals, 20-30% of phosphate, 10-20% of organic silicon and 10% of a soluble ferric salt, can be applied to remediation of farmland soil, reduces the effective state content of cadmium, lead and arsenic in contaminated soil, is low in cost, efficient, safe and environment-friend