Field-Scale Transport and Transformation of Carboxymethylcellulose-Stabilized Nano Zero-Valent Iron

Abstract

The fate of nano zerovalent iron (nZVI) during subsurface injection was examined using carboxymethylcellulose (CMC) stabilized nZVI in a very large three-dimensional physical model aquifer with detailed monitoring using multiple, complementary detection methods. A fluorescein tracer test in the aquifer plus laboratory column data suggested that the very-aggressive flow conditions necessary to achieve 2.5 m of nZVI transport could be obtained using a hydraulically constrained flow path between injection and extraction wells. However, total unoxidized nZVI was transported only about 1 m and <2% of the injected nZVI concentration reached that distance. The experimental data also indicated that groundwater flow changed during injection, likely due to hydrogen bubble formation, which diverted the nZVI away from the targeted flow path. The leading edge of the iron plume became fully oxidized during transport. However, within the plume, oxidation of nZVI decreased in a fashion consistent with progressive depletion of aquifer "reductant demand". To directly quantify the extent of nZVI transport, a spectrophotometric method was developed, and the results indicated that deployment of unoxidized nZVI for groundwater remediation will likely be difficult.

Green Synthesis: Nanoparticles and Nanofibres Based on Tree Gums for Environmental Applications

“…Biopolymers (cellulose and its derivatives, chitosan and its derivatives, alginate, dextran, and tree gums) are another family of natural sources used as reducing and stabilizing agents for metal and metal oxide nanoparticle synthesis [39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58]. Vitamin B 1 , Vitamin B 2 (riboflavin), Vitamin C (ascorbic acid), coffee and tea extracts, beet juice, and grape pomace are well-known natural reducing agents or antioxidants used for the synthesis of stable nanoparticles and are comprehensively reported [59][60][61][62][63][64][65].…”

Characterization of preferential flow paths between boreholes in fractured rock using a nanoscale zero-valent iron tracer test

“…Previous studies indicated that nZVI particles can be transported at least 1-2.5 m in unconsolidated deposits Johnson et al 2013;Kocur et al 2014). This study intends to adopt nZVI slurry as a tracer for the direct detection of fracture flow paths.…”

Nanoremediation and International Environmental Restoration Markets

“…In the case of nZVI research based on laboratory studies and the fate of naturally occurring iron NPs indicates that the fate of manufactured nZVI in an aquifer will be conversion into larger particles of iron (II) and (III) oxides/hydroxides, similar to naturally occurring minerals (O'Carroll 2013, Johnson et al 2013, Reinsch et al 2010, Gilbert et al 2007). Transport of nZVI will be limited by processes of agglomeration and sorption, as well as its density, and the transport of unmodified nZVI will soon diminish as a result of processes of passivation (Reinsch et al 2010).…”