A facile, cost-effective method for separation of free phase hydrocarbons and polycyclic aromatic hydrocarbons from aqueous mixtures would be a tremendous boon to the petroleum industry since it would expedite clean-up of contaminated waters, prevent environmental contamination, and could enhance oil recovery. In the proposed research project, magnetic extractants will be developed that are capable of absorbing the target organic species, thus allowing them to be rapidly separated by magnetic filtration. The magnetic extractants will be hybrid organic/inorganic materials that combine organic groups that have a high affinity for contaminant species with a magnetically-active core. They will be tested for their ability to absorb target compounds from aqueous mixtures and allow their rapid separation by magnetic filtration. The testing will be performed by use of aqueous mixtures of hexadecane, phenanthrene, crude oil, and actual industrial samples to which the magnetic extractants will be added. The mixture will be briefly shaken and then passed through an electromagnetic filter in order to remove the magnetically-active particles from the purified water. The aqueous effluent will be analyzed by gas chromatography/mass spectroscopy in order to determine the extent of hydrocarbon removal. Magnetic extractants that are successful in lowering contamination levels to extremely low levels (i.e. significantly less than drinking water standards) or undetectable levels will then be applied to actual contaminated waters from industrial operations. The potential application of the magnetic extractants in the breaking of oil-water emulsions will also be tested by addition of the extractants to an oil-in-water emulsion and determining the effect when such a mixture is passed through an electromagnetic filter. The recyclability of the extractants using a variety of stripping procedures followed by reuse will also be determined. The main technological advance of the proposed research is the development of magnetic extractants that are capable of transforming hydrocarbons into magnetically-active phases.
Progress Summary/Accomplishments:
X-ray powder diffraction showed that the resulting material contained nanocrystalline magnetite while infrared spectroscopy demonstrated the presence of an activated carbon phase. A similar procedure using a nickel gluconate/ iron gluconate mixture yielded a nickel-ferrite impregnated activated carbon. Magnetic testing of the powders with a strong bar magnet indicated that the magnetite and ferrite-containing powders were strongly and completely ferromagnetic. Furthermore, none of the powders demonstrated any remnant magnetization outside of a magnetic field, an important property so that the powder will not stick to non-magnetized steel. Also, in the case of the magnetite, the lack of a remnant magnetization means that we have achieved our goal of creating particles too small to become permanently magnetized.
A second material was prepared by coating a fine iron powder with poly-octadecyl methacrylate (average molecular weight of 170,000). The polymer was purchased as a toluene solution that was mixed with iron and allowed to evaporate yielding a waxy solid with imbedded iron particles. The proportions of the polymer and iron could be varied to provide a magnetic extractant that was neutrally buoyant (useful for removing soluble hydrocarbons) or which floats on water (useful for removing hydrocarbon slicks from water).
While the magnetic extractants were being synthesized, a magnetic filter was designed with the assistance of Eriez Magnetics. Working with this company, it was possible to design a moderate laboratory-scale filter that was similar to larger models currently used by industry.
Future Activities:
Future activities will include preparation of covalently-bound inorganic/organic composites for use as magnetic extractants, ordering of a magnetic filter (currently in the competitive bid process), and testing of the magnetic extractants.