ABSTRACT
Recently, nanoscale Zero-Valent Iron (nZVI) has been extensively applied in treatments of contaminated sites and as key materials of permeable reactive barriers (PRBs), due to its excellent remediation efficiency in both heavy metal and organic contaminants and its environmental friendliness. However, the macro-micro-structural mechanism of nZVI-soil interactions is still unclear. By which, the uncertainty of remediation efficiency and the instability of site engineering properties should be noticed, especially the relationship between “Nanomaterial’s blockage effect” and permeability of target soil. The main objective of this article is to address the key issues in pore characteristics and permeability of nZVI treated soil through a series of macroscopic to microscopic experimental analysis. A modified slurry consolidation method was applied for the sample preparation of treated soil, as for the special water-oxygen requirement of nZVI reactions. Based on the calculated permeability coefficient by oedometer tests, it indicated that the permeability of nZVI treated soil increased with the increase in nZVI dosage. By mercury intrusion pore measurement (MIP), more intra-particle pore distribution and a larger percentage of connectivity pore could prove that the nZVI treatment by the slurry consolidation procedure led to better permeability instead of a “blockage effect” by injection-type treatment. Thus, the article provides an important theoretical and scientific basis for further understanding the macro-microscopic interaction mechanisms of nano-remediation technology on soils and for efficient applications of in-situ nano-remediation engineering.
