The Separation of Hydrocarbons from Contaminated Sand Using Ionic Liquids

TECHNICAL ABSTRACT:

This award is funded under the Rapid Research Response program. The proposed research is aimed at developing a process to separate oil and tar from contaminated sand using ionic liquids (ILs). The catastrophe now unfolding in the Gulf of Mexico will have a disastrous effect on many beaches. In addition, sand berms and barriers are being built to protect fragile wetlands. There will be large quantities of contaminated sand that will need to be treated. Initial plans appear to involve storage in designated landfills and lagoons. Treating this material and cleaning contaminated sand is both an urgent, immediate need and long-term problem that requires a timely response.

In preliminary work at Penn State it has been shown very recently that ILs can be used to separate bitumen from tar or oil sands. Bitumen is a complex material consisting of molecules that range in size from small to polymeric. Oil that is washed onto beaches has usually lost its 'light' or volatile fraction, leaving a sludge of heavy oil or tar balls that largely consist of oligomeric and polymeric hydrocarbons. Present methods used to separate oil, bitumen or tar from sand are expensive or environmentally challenging (e.g., the hot or warm water process used to obtain bitumen from Canadian tar sands).

Bitumen can be extracted from tar sands using ILs alone or in conjunction with a non-polar solvent. The separation occurs at room temperature and does not require the use of water in the initial separation process (the disposal of waste process water is a big problem in the oil or tar sands industry). Essentially all of the bitumen is recovered in a very clean form. The minerals (sand) are also recovered in an uncontaminated form after removing residual IL with small amounts of (cold) water. Preliminary but unpublished work has shown that this process works equally well with both oil-contaminated sand and the weathered and hardened polymeric hydrocarbons formed during 'ageing'.

The proposed research will establish the appropriate choice of IL, proportions of co-solvent (to lower the viscosity of the sludge and tar to facilitate separation), kinetics of separation, etc., necessary to obtain a clean separation of hydrocarbons from sand, such that the former is in a state suitable for delivery to a refinery and the latter can be used for environmental remediation. A bench-top separation unit will be built in order to determine the operating parameters necessary for a large-scale process. Although the proposed work is application-motivated, it is anticipated that a technology demonstration will lead to new fundamental science such as an understanding of the interactions between ILs, minerals, and hydrocarbons, and how this affects phase behavior and separation processes. Obtaining an insight into these processes forms the intellectual merit of the proposal.

NON-TECHNICAL ABSTRACT:

This award is funded under the Rapid Research Response program. The proposed research is aimed at developing a process to separate oil and tar from contaminated sand using ionic liquids (ILs). The catastrophe now unfolding in the Gulf of Mexico will have a disastrous effect on many beaches. In addition, sand berms and barriers are being built to protect fragile wetlands. There will be large quantities of contaminated sand that will need to be treated. Initial plans appear to involve storage in designated landfills and lagoons. Treating this material and cleaning contaminated sand is both an urgent, immediate need and long-term problem that requires a timely response. In very recent preliminary work at Penn State it has been shown that ILs can be used to separate bitumen from tar or oil sands.

In addition to the immediate potential impact on the Gulf beaches if this project is successful and adopted, there also will be broader impacts, in that the separation of oil from sand or other minerals is not only a novel and potentially extremely effective way of cleaning sand and soils after an environmental disaster, but also important in other areas. Examples of these are extracting bitumen and asphalt from Utah tar sands; cleaning sand that is part of the product stream obtained in oil well operations; separating oil from drilling muds; and treating the large amounts of so-called oily sludge generated in refinery operations.