Microemulsion and solution approaches to nanoparticle iron production for degradation of trichloroethylene

In this study, nanoscale iron particles were synthesized using the microemulsion method and the properties were compared with the particles produced by the solution method. The nanoparticles were characterized by using the transmission electron microscope (TEM) and powder X-ray diffraction (XRD). The water-in-oil (w/o) microemulsion system was made up of n-octane, cetyltrimethyl-ammonium bromide (CTAB), butanol and water, and was characterized by measuring the conductivity of the solution and interfacial tension between the surfactant solution and the n-octane. The conductivity of the microemulsion system increased from about 10 μs cm−1 to over thousands of μs cm−1 with the addition of water. Interfacial tension between the n-octane and the CTAB aqueous solution was reduced to less than 6 dyn cm−1 with the addition of butanol, a co-surfactant used in this study. The average diameter of synthesized iron nanoparticles using the microemulsion method was less than 10 nm, which was much smaller than the particles produced by the solution method. The performance of the nanoiron produced in the laboratory was studied by dechlorinating trichloroethylene (TCE), a dense non-aqueous phase liquid (DNAPL) and listed as a priority pollutant by the US EPA. The degradation rate of TCE by the nano iron particles produced in the laboratory was quantified and compared with a commercially available nano iron product.