Potential of montmorillonite and humus-like substances modified montmorillonite for remediation of Pb and Zn-contaminated soils

Pb and Zn pollution for soil are becoming more and more serious, strengthening the treatment of contaminated soils is conducive to the sustainable development of soil. In this study, the humus-like substances modified montmorillonite (HLS-MMT) were synthesized to remediate the Pb and Zn-contaminated soils. The application of HLS-MMT in simulated and actual contaminated soil were carried, and the long-term stability of HLS-MMT was evaluated. The results showed that the mobility, bioavailability and leachability of heavy metals (HMs) significantly decreased after remediating by HLS-MMT. Compared with MMT, the TCLP leaching ratio (TLr) of Pb and Zn reduced by 9.27–13.96% and 10.3–13.18%, while the DTPA effectiveness (DEr) Pb and Zn reduced by 9.11% and 8.76% in simulated soil, respectively. Moreover, the aging experiments proved that HLS-MMT possessed a stability to resistance the freeze-thaw cycles, wet and dry alternation, and acid rain leaching. This article provides some theoretical basis for the soil remediation. [Display omitted] •HLS-MMT reduced greatly the mobility and chemical effectiveness of Pb and Zn.•HLS-MMT promoted obviously the formation of organic bond state Pb and Zn.•HLS-MMT possessed excellent long-term stability and practical application value.•The leachability of Pb reached environmental standards after HLS-MMT remediation.