The MAJOR DIFFERENCE between Emulsified Zero-Valent Iron (eZVI) and other ZVI products is the physical structure of the eZVI product, which is a water-in-oil emulsion (see below images). This structure makes the eZVI product hydrophobic, and therefore it is fully miscible with source material in situ. The water contained in the interior of the eZVI emulsion provides the hydrogen for abiotic reductive dechlorination reactions to proceed. Without a hydrogen donor, abiotic reactions that occur on the surfaces of the ZVI particles will not proceed. If you are implementing a source area remediation and using the eZVI technology, make sure that your product supplier can document the micellular structure and hydrophobic chemistry of their EZVI product. Please note that a combination of ZVI and emulsified oil (oil in water emulsion) WILL NOTprovide the benefits that our eZVI product enables. The physical structure of the eZVI emulsion is the key to sustaining dramatic source area mass flux abatement and direct abiotic destruction of source mass, while simultaneously stimulating microbiological processes to destroy dissolved phase contaminants.
Due to the unique (patented) physical structure of eZVI, the ZVI component of the emulsion is protected inside of a hydrophobic membrane (see image above), and unlike any other ZVI products, this enables the ZVI to efficiently target the destruction of chlorinated hydrocarbons (e.g., contaminants that have the appropriate hydrophobic physical chemistry to pass through the vegetable oil membrane and contact the ZVI). Another significant difference between the technologies is the fact that eZVI takes advantage of the physical chemistry of the contaminant, and sequesters it within the vegetable oil membrane surrounding each micelle (see above images). The sequestering of contaminants into the vegetable oil membrane results in significantly reduced aqueous contaminant concentrations (~ 90% decrease), and therefore decreased mass flux from the source area. Contaminants that have phase partitioned into the vegetable oil layer then begin dissolving/diffusing into the aqueous interior of the micelle where they contact the ZVI and are destroyed (completely dechlorinated to ethane). A concentration gradient is established and the contamination is continually pulled toward the interior of the micelle where it abiotically dechlorinated. While both technologies utilize the same chemistries, eZVI is engineered to directly remediate source areas by taking advantage of the physical chemistry of the contaminant(s) and optimizing the role of abiotic reactions, which DO NOT create problematic daughter intermediates.
In addition to the above abiotic reactions, the vegetable oil membrane associated with the eZVI is a fermentable carbon source and therefore acts as an electron donor for biostimulation downgradient of the eZVI injection area(s). With eZVI you get a one-two punch; (1) optimized abiotic reactions along with (2) the polishing effects of anaerobic bioremediation processes. Target the use of your ZVI. Do not be fooled into thinking that injection of ZVI and a carbon substrate (e.g., vegetable oil, lactates, fatty acids, plant fibers) is the same as using eZVI. Our eZVI is the superior choice when remediating sites with source areas/DNAPL zones (residual or pooled).