title: Oil-in-water emulsions for encapsulated delivery of reactive iron particles.
abstract: Treatment of dense nonaqueous phase liquid (DNAPL) source zones using suspensions of reactive iron particles relies upon effective transport of the nano- to submicrometer scale iron particles within the subsurface. Recognition that poor subsurface transport of iron particles results from particle-particle and particle-soil interactions permits development of strategies which increase transport. In this work, experiments were conducted to assess a novel approach for encapsulated delivery of iron particles within porous media using oil-in-water emulsions. Objectives of this study included feasibility demonstration of producing kinetically stable, iron-containing, oil-in-water emulsions and evaluating the transport of these iron-containing, oil-in-water emulsions within water-saturated porous media. Emulsions developed in this study have mean droplet diameters between 1 and 2 microm, remain kinetically stable for > 1.5 h, and possess densities (0.996-1.00 g/mL at 22 degrees C) and dynamic viscosities (2.4-9.3 mPa x s at 22 degrees C and 20 s(-1)) that are favorable to transport within DNAPL source zones. Breakthrough curves and post-experiment extractions from column experiments conducted with medium and fine sands suggest little emulsion retention (< 0.20% wt) at a Darcy velocity of 0.4 m/day. These findings demonstrate that emulsion encapsulation is a promising method for delivery of iron particles and warrants further investigation.
authors: Department of Civil and Environmental Engineering, Tufts University, 200 College Avenue, Room 113, Anderson Hall, Medford, Massachusetts 02155, USA.
authors: Nicole D
authors: ND
authors: Berge
authors: C Andrew
authors: CA
authors: Ramsburg
mesh_terms: D002627:Chemistry, Physical; D004655:Emulsions; D007501:Iron / Q000032:analysis* / Q000737:chemistry; D007700:Kinetics; D008855:Microscopy, Electron, Scanning / Q000379:methods; D009821:Oils / Q000737:chemistry*; D010316:Particle Size; D016062:Porosity; D012995:Solubility; D012996:Solutions; D013997:Time Factors; D014867:Water / Q000737:chemistry*; D018508:Water Purification / Q000379:methods
chemical_list: D004655:Emulsions; D009821:Oils; D012996:Solutions; D014867:Water; D007501:Iron