A wet-synthetic method is described to obtain magnetic, air-stable, zero-valent iron nanoparticles coated with an alkanedioic acid. The particles can be immobilized in an amino-substituted polysiloxane matrix to provide materials capable of dechlorinating, debrominating, and deiodinating a wide variety of halogenated organic molecules dissolved initially in a highly polar medium. The methodology involves diffusion of the organic molecules into the polysiloxane matrix, their reaction with the embedded iron nanoparticles, and then diffusion of the dehalogenated products back into the polar medium or into the air. Thus, the abilities of the coated particles, as suspensions or within an amino-substituted polysiloxane matrix crosslinked with succinic acid, to dehalogenate various organic molecules (especially the model compounds, bromobenzene and chlorobenzene), have been assessed. Data from several spectroscopic methods demonstrate that the particles are in a crystalline α-Fe phase surrounded by the diacid shell. The effect of embedding 10 wt.% of the particles in amino-substituted polysiloxane-diacid matrices with different COOH/NH2 group ratios and the viscoelastic properties of the polymeric materials have been investigated as well. Potential uses of these gel-like materials to remove halogenated pollutants from various types of aquifers are mentioned.
Keywords:
zero-valent iron nanoparticles; amino-substituted polydimethylsiloxane; absorption; dehalogenation
