Surface Modifications Enhance Nanoiron Transport and NAPL Targeting in Saturated Porous Media

Abstract

Rapid in situ degradation of chlorinated solvents present as nonaqueous phase liquids (NAPL) can be accomplished using reactive zerovalent nanoiron particles. Prior studies have shown that nanoiron transport in the subsurface is limited, and successful delivery of the nanoiron is essential for effective remediation. Here, the physical properties of bare and modified nanoiron are measured, and laboratory column reactors are used to compare the transport of three types of surface-modified nanoiron; triblock polymer-modified, surfactant-modified, and a commercially available polymer-modified nanoiron. The effect of particle concentration and solution ionic strength on the transport of each modified nanoiron is evaluated, and the filtration mechanisms for bare and modified particles are determined in microfluidic flow cells and quartz crystal microbalance (QCM) experiments that probe the particle-collector grain interaction. The effect of surface modification on nanoiron reactivity is evaluated in batch experiments. Transport of modified nanoiron does not directly correlate with-potential or colloidal stability, but rather correlates to particle-grain interactions. Filtration of bare nanoiron is caused by straining and subsequent clogging rather than by deposition to clean sand grains, suggesting that filter ripening models rather than clean bed filtration models should be used to describe nanoiron transport at high particle concentrations. Surface modification decreased nanoiron reactivity by two to four times, but as high as a factor of nine depending on the modifier used. Amphiphilic triblock copolymer modified nanoiron with a high hydrophobe/hydrophile ratio shows promise for in situ targeting of NAPL, but requires further optimization.

Homogeneously Dispersed Zerovalent Iron Nanoparticles Supported on Hydrochar-Derived Porous Carbon: Simple, in Situ Synthesis and Use for Dechlorination of PCBs

“…In addition, yields of H 2 and CO first increased from 200 to 400°C, then decreased within the temperature range of 400 to 700°C, and again increased at temperatures above 700°C. The highest yields of H 2 and CO were achieved at a treatment temperature of 900°C, while the yields of CH 4 were relatively constant over the entire temperature range of 200 to 900°C.…”

Transport and deposition of functionalized CdTe nanoparticles in saturated porous media

“…To date, a limited number of studies have been conducted to investigate the mobility and deposition of engineered NPs (e.g. carbon nanotubes, iron NPs, Fullerene) in the subsurface environment (Jaisi et al, 2008;Kanel et al, 2007;Pelley and Tufenkji, 2008;Saleh et al, 2007). To the best of our knowledge, none have investigated transport of functionalized QDs in porous media.…”

Recent Advances in Solid Waste Minimization using Nanotechnology

“…It enables the high precipitation of contaminants, by generating non-toxic iron oxide end product without losing the reactivity [27] (Li 2006). Although the properties of nZVI gives promising solution for solid waste remediation but the biocompatibility and safety from the disposal of these highly reactive compounds are uncertain in that regards the study have been made to intentionally modifying the surface of these nZVI particle to ensure the safe utilization and remediation [28][29] (Saleh 2007), ( Hydutsky 2007). Besides inorganic nanoparticles scientist have been exploring the use of biological inspired organic polymers and dendrimers for solid waste treatments.…”