Preparation of Fe₂O₃-coated vermiculite composite by hydrophobic agglomeration and its application in As/Cd co-contaminated soil

ABSTRACT

Exploring an economic and efficient method for simultaneous passivation of As and Cd in soils is of great current significance. In this study, a low-cost composite material, Fe₂O₃-vermiculite (Fe-V), for effectively passivating As/Cd was synthesized successfully based on hydrophobic aggregation method. The reaction products were characterized by XRD, SEM, EDS and FTIR, results showed that Fe₂O₃ was successfully loaded onto the surface of vermiculite by the connection with sodium stearate and employed this composite material to passivate the co-contaminated soil with As/Cd. All the percentage of toxicity reduction (P_d value) was higher than the control group, which indicated the passivation was effective. In soil A (As 45 mg/kg and Cd 6 mg/kg), the P_d of As were higher than 90%, the P_d of Cd were 80–100%. And in soil B (As 80 mg/kg and Cd 10 mg/kg), the P_d of As were more than 84.68%, the P_ds of Cd were about 99%. In the meantime, the application of Fe-V could apparently increase the residual fraction of As and Cd in soil A and soil B. Moreover, the passivation of As and Cd in soils by Fe-V composite materials was a combined physical and chemical action system. This research shows that Fe-V could play a good role in the passivation of As/Cd in different pollution levels of soils.

GRAPHICAL ABSTRACT

KEYWORDS:

• Vermiculite
• Fe₂O₃
• hydrophobic agglomeration
• As
• Cd

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This study was funded by the National Key R&D Program of China (2019YFC1805001), the National Natural Science Foundation of China (51874018) and Fundamental Research Funds for the Central Universities (FRF-TP-19-014B1).