“Soil for Soil Remediation” Strategy Driven on Converting Natural Soils into Fe₂O₃-CAN-Type Zeolite Composites for Dual Ionic Heavy Metal-Contaminated Soil Remediation: Universality, Synergistic Effects, and Mechanism

Abstract

Herein, we developed a universal "soil for soil remediation" strategy to utilize soil resources for cation-/aniontype heavy-metal-contaminated soil remediation. The representative natural soils fetched from 12 different areas in China have been universally converted into Fe 2 O 3 -CAN (hydroxycancrinite) zeolite composite materials. Furthermore, we discover that due to the presence of exchangeable Na + and OH − in CAN channels together with the intrinsic surface adsorption function of Fe 2 O 3 -CAN, Fe 2 O 3 -CAN holds distinctive cation/anion dual ion-exchange functions and strong adsorption capacity, which could synergistically remediate cation-/anion-type HM-contaminated soil. When 25 g/kg Fe 2 O 3 -CAN is added into Cd/As polluted soil (100−200 ppm), Cd 2+ and AsO 2 − in soil could be immobilized simultaneously and the Cd/As bioaccumulation in the harvested vegetables is dramatically suppressed with reduction ratios of 48.1−67.0%, effectively reducing the HM enrichment in the phytosphere. Overall, this work confirms the high universality of Fe 2 O 3 -CAN synthesis using different types of natural soils and demonstrates that the as-synthesized Fe 2 O 3 -CAN composite material can be further effectively used for soil remediation. The "soil for soil remediation" strategy developed here could improve the flexibility and economy of soil remediation, which can be extended to a broad range of locations worldwide.