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 Preliminary but unpublished work has shown that this process works equally well with both oil-contaminated sand and the weathered and hardened polymeric hydrocarbons formed during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.
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.
Paul Painter and Bruce Miller, Penn State University This RAPID NSF award was a response to the Deepwater Horizon disaster (April 20, 2010), the largest accidental marine oil spill in history. It released close to 4.9 million barrels of crude oil into the Gulf of Mexico and fouled coastal areas. The project focused on using ionic liquids (ILs) to separate oil or tar from contaminated sand. The intellectual merit and driving force for the project was a demonstration of using these materials for large-scale operations by building a bench-top demonstration unit that would provide some of the data necessary for scale-up. ILs are liquids whose constituents are ions, like common table salt, except that they are liquids below 100?C. As a result of their ionic nature, they have unusual solvent properties. They have been widely studied only in the last few years but a number of practical applications have been identified, including the work completed in this project. Samples of oil contaminated sand in the form of tar balls were collected from beaches in the Gulf by the students involved in the project. The "light" fraction initially present in the oil had by then evaporated, leaving behind the "heavy" component and material that had partly polymerized as a result of exposure to elevated temperatures and ultra-violet light. This greatly complicates clean up by conventional detergent washing methods. Initial laboratory work was conducted to identify the most appropriate ionic liquid for separating tar from contaminated sand. As the research progressed, it became clear that although the ILs initially used did a very good job of cleaning the sand, their cost would severely limit practical applications. It was then found that deep eutectic ILs could also accomplish a separation. Deep eutectic mixtures are those where the melting point of the mixture is much less than the melting points of the pure components. A mixture of choline chloride, vitamin B4, an animal feed supplement produced in megaton quantities, and urea, a common fertilizer, is such a deep eutectic and has the properties of an ionic liquid at room temperature. These materials also gave a good separation of tar from sand (helped by an organic solvent to lower the viscosity of the tar and allow an ambient temperature separation). In addition to being readily available and cheap, these materials have the additional advantage of promoting plant life, so any residual IL left on the sand would actually help remediation efforts (e.g., through the growth of sand grasses). A bench-top separation was built and operated successfully in separating kilogram quantities of tar from sand using ILs. However, continuous operation was limited because of the ineffectiveness of hydrocyclones at the flow rates used. The hydrocyclones were included to separate the solids component from the liquids, but they clogged too easily at this scale of operation. This showed that decanting centrifuges are probably necessary and will be included as the process is scaled-up to accommodate larger flow rates and continuous operation. As a result of the work accomplished under this award, private investment has been attracted to help build a much larger demonstration unit. There are a number of broad impacts associated with the development of this technology, including the extraction of bitumen or heavy oil from U.S. deposits and the recovery of asphalt from waste materials such as roof shingles or drill cuttings that are now landfilled.
