Effect of Potassium Dihydrogen Phosphate Combined with Thermally Activated Nano Serpentine and Thermally Activated Nano Zeolite on Cadmium in Soil

The combined application of potassium dihydrogen phosphate (KH2PO4) and thermally activated nano serpentine and KH2PO4 and thermally activated nano zeolite could immobilize cadmium (Cd) in contaminated soils by increasing soil pH value. The results showed that adding nPS700-2.0 (KH2PO4 and thermally activated nano serpentine activated at 700 °C, 2% addition) exhibited better performance under the same treatment condition; it reduced DTPA-Cd by 57.8% and exchangeable Cd by 48.76%. Adding nPF700 (KH2PO4 and thermally activated nano zeolite activated at 700 °C) reduced DTPA-Cd by 35.49–44.17% and exchangeable Cd by 35.89–42.57%, respectively. The increase of active adsorption points and the surface area of thermally activated nano serpentine reduced the bioavailability of Cd in soil, indicating that the combined application of phosphate and thermally activated nano serpentine has great potential for the immobilization of Cd in soil.