Effect of Dispersant on Transport of Nanoscale Iron Particles in Soils: Zeta Potential Measurements and Column Experiments

Abstract

Nanoscale iron particles (NIPs) have been studied during the last few years for their potential for remediation of groundwater and soils contaminated by chlorinated hydrocarbons, pesticides, heavy metals, and some inorganic anions. However, the effectiveness of in situ remediation largely depends on quick and uniform distribution of NIPs into the contaminated subsurface zones. Previous studies have shown that transport of bare NIPs in subsurface soils is very limited and surface modification by dispersants such as polymers and surfactants is necessary. The objective of this study was to investigate eight different dispersants at different concentrations to determine their ability to modify the surface characteristics and increase the stability of the NIP suspension, thereby minimizing agglomeration and sedimentation of the NIPs. The studied dispersants and their tested concentration ranges [as % of NIP suspension, weight-to-weight ratio (w/w)] were as follows: aluminum lactate (Al-lactate; 2–15%), sodium lactate (Na-lactate; 6–12%), ethyl lactate (EL; 6–12%), aspartic acid (ASP; 2–8%), polyacrylic acid (PAA; 2–8%), 2-hydroxypropyl-