Nanoscale zero-valent iron (nZVI) has been widely applied to remediate heavy metal-contaminated soils and water. Its in situ treatment of combined heavy metal contaminated soil, followed by backfilling or other sustainable reutilizations, attracted attention to the treated soil’s deformation characteristics. In this study, soil samples were prepared using the modified slurry consolidation method to simulate the natural settling of backfilled soil and optimize the reactivity between nZVI and contaminants in soil. The deformation characteristics of natural soil, contaminated soil, and soil treated with varying dosages of nZVI (0.2%, 0.5%, 1%, 2%, and 5%) were investigated. Moreover, the plasticity indexes and particle-size distribution of the samples were examined through Atterberg limits and laser-diffraction particle-size analysis. After a 4 d slurry consolidation process, a typical result indicated the immobilization efficiency of all three heavy metal ions achieved over 90% with 2% nZVI. The presence of three heavy metal ions decreased the Atterberg limits and increased the compression index, permeability, and consolidation coefficient of the soil. Conversely, the introduction of nZVI increased plasticity and resulted in higher permeability, stable secondary consolidation, and less swell. Microscopically, with an increase in the dosage of nZVI, the soil aggregates transformed from a weak chemical bond with insoluble precipitates/iron oxides to larger aggregates consisting of nZVI/-soil aggregates, thereby enhancing the soil skeleton. This study shows improved permeability and deformation characteristics in nZVI-treated combined heavy metal-contaminated soil, offering valuable insights for practical nanomaterials’ in-situ treatment in engineering applications.

Nano zero-valent iron (nZVI) technologies have gained recognition for the remediation of heavily contaminated sites and reused as backfilling soil. The moisture environment at these sites not only impacts the reactions and reactivity of nZVI but also the dynamic responses of compacted backfilled soils. The research explored the effects of different nZVI dosages (0.2%, 0.5%, 1%, 2%, and 5%) on Lead-Zinc-Nickel ions contaminated soil under a controlled-moisture condition. Cyclic triaxial tests were performed to evaluate the dynamic responses of treated soil samples prepared using a consistent moisture compaction method. Particle size distribution and Atterberg limits tests assessed changes in particle size and plasticity. The study revealed a minor reduction in the particle size, liquid limit, plastic limit, and plasticity index of the contaminated soil. Notably, increasing nZVI dosages in treated soils led to growing Atterberg limits. An increase in the specific sand fraction of treated soils was observed with nZVI, suggesting nanoparticles–soil aggregations favoring existing larger particles. Stepwise loading cyclic triaxial tests indicated an optimal dynamic response of soil treated with 1% nZVI under the controlled-moisture condition, proven by notable enhancements in the maximum shear modulus, maximum shear stress, less shear strain, and higher damping ratio within the small strain range. It should be noted that moisture content in treated soils declined significantly with higher nZVI dosages during preparation, potentially impeding effective aggregation and the formation of a solid soil skeleton. These findings advance the importance of considering the balanced nZVI dosage and moisture content when employing the safety assessment of practical applications in both nano-remediation techniques and soil mechanics.

Advanced oxidation processes (AOPs) are increasingly used for the remediation of soils contaminated with petroleum hydrocarbons, as they rapidly mineralize recalcitrant fractions to CO₂ and H₂O. However, the effects of AOPs on the geotechnical properties of such soils remain not well understood. In this study, the influences of a combined oxidation system of sodium percarbonate (SPC), nanoscale zero-valent iron (nZVI), and sodium persulfate (PS) on the geotechnical behavior of petroleum hydrocarbon-contaminated soil were investigated. A series of tests, including basic geotechnical index, pH, Atterberg limits, particle size distribution, and consolidated undrained triaxial compression test, were conducted to explore the geotechnical responses and underlying mechanisms associated with the dual AOPs treatment. The results indicate that the diesel-contaminated soil exhibited slightly higher LL and PI compared with the natural soil. For the treated soils, LL and PI remained essentially unchanged with increasing SPC dosage. The particle-size distribution first migrated to finer fractions and then reverted to a coarser mode. The strongest fining was observed at 2% SPC, whereas higher SPC dosages induced aggregation and the formation of larger agglomerates. Consolidated undrained triaxial tests indicate that diesel contamination reduced undrained stiffness and strength. The nZVI–PS treatment without SPC produced a partial recovery in stiffness and a slight increase in the friction angle. With increasing SPC dosage, the soils exhibited a nonmonotonic response in stiffness and shear strength, where low SPC enhanced apparent cohesion and higher SPC weakened bonds while partially restoring frictional resistance. These findings suggest that advanced oxidation of petroleum hydrocarbon–contaminated soils requires a trade-off. This trade-off is between contaminant degradation efficiency and the preservation of geotechnical performance to ensure the reuse of the remediated soil.