Novel Materials for Facile Separation of Petroleum Products from Aqueous Mixtures Via Magnetic Filtration

EPA Grant Number: R827015-01-0
Title: Novel Materials for Facile Separation of Petroleum Products from Aqueous Mixtures Via Magnetic Filtration
Investigators: Allen W. Apblett
Institutions: Oklahoma State University
EPA Project Officer: Bala Krishnan
Project Period: August 1, 2000 to January 31, 2001 (N/C Ext. to July 31, 2001)
Project Amount: $20,000
Research Category: Separations

Description:

The major objective of this research is to develop magnetic extractants that can be used in conjunction with a magnetic filter to efficiently and economically remove petroleum products from aqueous solutions and mixtures. The project will synthesize three types of magnetically-active materials that are capable of absorption of hydrocarbons so that the latter can be rapidly and efficiently removed from water using magnetic filtration technology. Initial tests will be performed with mixtures of hexadecane, a typical alkane, and phenanthrene, a typical polynuclear hydrocarbon. These compound will allow testing of the performance of the magnetic extraction process on pure compounds in a manner that is conducive to a better theoretical assessment of the process. At the same time, a more practical assessment will be made using crude oil/water and crude oil/brine mixtures. The primary investigator (P.I.) will also obtain at least two actual contaminated water samples from the petroleum industry (e.g. drill cuttings, produced water, etc.). Oklahoma State University has a close research interaction with Halliburton that will provide a vector for obtaining these samples. The ability to purify such "real-life" samples in the laboratory will provide the necessary proof of the applicability of magnetic filtration to the petroleum industry. A second goal of the research is to test whether the magnetic extractants in conjunction with an applied magnetic field would be useful for breaking emulsions.

This proof of concept research will demonstrate the feasibility of a magnetic extraction process and determine the parameters that will allow an assessment of the potential economic benefit to the petroleum industry. Ultimately, achievement of these goals is expected to benefit the petroleum industry through a reduction in the cost of compliance with U.S. environmental regulations. Furthermore, the research will involve both a graduate student and an undergraduate student and will thus contribute to the human resource needs of the petroleum industry in the very important area of environmental compliance.

The deliverables of the proposed research are the following. First, three types of potential magnetic extractants, each with two different types of binding groups (a 18-carbon alkane and biphenyl) will be synthesized. "Magnetic" adsorption isotherms for two test petroleum products, an alkane and a PAH will be measured. The three magnetic extractants that exhibit the best extraction behavior will be tested for removal of crude oil from water and brine by magnetic filtration. The two most successful extractants at this stage will be tested in the separation of hydrocarbons from at least two actual industrial samples and for the breaking of an oil in water emulsion. The regeneration and reuse of the magnetic extractants using a magnetically-assisted washing step with petroleum ether will also be demonstrated using crude oil-loaded extractants.

Progress Summary/Accomplishments:

The main task for this period was the binding of anchoring sites for organic molecules to magnetically active sites. The materials chosen for this purpose were magnetite and iron while maleic acid was used as the anchoring agent. It was found that the addition of an aqueous maleic acid solution to an iron powder resulted in a reaction that proceeded rapidly at room temperature to givie sufficiently thick films of iron maleate that the iron surface became green in color. After washing with an excess of water and drying in vacuo, the infrared spectrum of the resulting powder demonstrated an adherant film of ferric maleate on the surface of the iron particles.

The magnetite used in this study was an actual mineral sample. Chunks of this material were ground to a fine powder within an alumina rotary mill. Next, a maleic acid solution was added to the magnetite and the mixture was allowed to stir for 24 hours. After washing with an excess of water and drying in vacuo, the infrared spectrum of the resulting powder demonstrated the uptake of maleic acid onto the surface of the iron particles. However, thermal gravimetric analysis demonstrated that only a small amount of maleate was present. Therefore, we are currently using a reaction between molten maleic acid with magnetite in order to maximize the incorporation of the organic anchoring agent.

The maleic acid-coated particles are being converted to polymer composites that will be used as magnetic extractants. Maleic acid is polymerizable due to its alkene residue and initiation of this reaction by a radical initiator results in a polymer that not only conforms to the surface morphology but is extremely well-anchored at a multitude of sites on the inorganic particles. Furthermore, when the polymerization reaction is performed, binding groups for organic compounds can be introduced by including them as compounds with vinyl residues that are incorporated directly into the backbone of the polymer. Thus, particles that bear residues for binding of organic contaminants are readily attached to the magnetically-active particles. In this investigation, vinyl stearate, and vinyl biphenyl are being used to introduce straight-chain alkyl or aryl groups.

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. The magnetic filter was ordered and received and is now ready for testing of the magnetic extractants.

Future Activities:

Future activities will include preparation and characterization of additional covalently-bound inorganic/organic composites for use as magnetic extractants, and testing of the magnetic extractants.