This proposal is in response to the NSF's RAPID call for quick response research to the oil spill in the Gulf. The PIs have been involved in proprietary research on natural based plastics made from sorghum. It was shown that a powder made from certain sorghum varieties can be used effectively as an absorbent to remove organic based materials (e.g., car oils). The core of the proposed research is to combine the absorption properties of this natural based material with existing technology to shape it into a porous sponge-like material to be used to remove crude oil spilled in a seawater environment.
The goal of the proposed work is to develop an economically-viable, natural-based absorbent to clean up oil spills. The objective of proposed RAPID study is to identify and quantify the key parameters of the proposed natural based absorbent such that quick implementation can be realized to the current Gulf oil spill. The method to achieve the objective is to apply basic bench scale design of experiments that compare different parameters (loadings, size and structure, etc.) in a simulated system of crude oil and seawater. The experimental data will be used to assess the economic commercial viability of the method.
Intellectual Merit
Preliminary tests of the sorghum-based material in the shape of a foamy (sponge-like) absorbent have shown that it can absorb simulated crude oil as much as 12 to 20 times its own weight. By optimizing certain key parameters, the PIs can enhance this natural based absorbent potential to provide rapid and cost effective oil absorption levels. The material can be made at the site of the spill, thus eliminating storage and transportation cost associated with light weight substances. Moreover, there is the potential to recover a relative large portion (up to 80%) of the absorbed oil from the absorbent (not included in this study). Preliminary calculations show that the value of the recovered oil may be higher than the cost of the absorbent and the recovery operation.
Broader Impact
Without a doubt, an oil spill of the current magnitude threatens not only the human, animal and plant but also can cause irreparable damage to the environment. If the key parameters that affect the absorbent potential of the proposed natural-based, cost-effective solution can be identified and optimized, the resulting technique can be applied in other environments, for example, marshlands. This is because the absorbent material can be engineered in different sizes and physical structures (planar, cylindrical, etc.) and processing may provide for certain attractive properties for the application conditions. Both PIs have a track record of working with graduate and undergraduate students in their research programs. They also are active in the student chapter of several engineering professional societies and participate in high school programs that recruit underrepresented students to TTU. The outcomes of this study will be transmitted to the public in various forms including: peer-reviewed publication, to BP officials, DOE, and other appropriate forums.
This project was initiated in response to the Deepwater Horizon oil spill in the Gulf region on April 20, 2010 off the coast of Louisiana. The spill highlighted the need for effective cleanup methods for crude oil spills. The project investigated the use of a natural absorbent material to absorb the organic liquids. The disadvantage of other absorbents is that their absorptivity is low per unit mass thereby requiring large amounts in the case of large-scale applications. This work investigated the use of sorghum, a large volume grain crop, as an effective absorbent for organic liquids. Laboratory experiments were performed to determine the absorption capacity and the absorption rate of the crude oil by a foamy sorghum-based absorbent pellet. The foamy sorghum absorbent has a relatively low density of ~0.02 g/cm3 . The peanut-shaped pellets were provided by Milex Corp. They are approximately 5 cm in length with a diameter of 2 cm and with a weight of approximately 0.30 g. The absorptivity of the sorghum-based pellet was tested with synthetic oil (Soltrol 130®) as well as true crude oil (obtained from Midland, TX region). Tap water was used in order to simulate impurities that could be found in a given body of water. Outcomes: Intellectual Merit - In all experiments, the pellets were immersed in the solvent (synthetic oil, crude oil, a mixture of water and dispersant (soap) or a saline solution of water and salt), and withdrawn after some time. It was deduced that: The sorghum-based pellet absorbed 15 – 20 times its mass of crude oil and synthetic oil. When the sorghum-based pellet was tested in a crude oil/saline solution (water and Oceanic™ Natural Sea Salt Mix) mixture, the loading capacity also was found to be around 20 grams of crude oil per gram of sorghum-based pellet. From these experiments, it was deduced that the sorghum-based absorbent pellet is hydrophobic. When the sorghum-based pellet was immersed in both tap water and saline water, it lost its shape and dissociated. The investigation also revealed that 90% of the absorbed crude oil can be recovered mechanically by squeezing. Oil recovered via this means can then be processed and used to generate revenue. From an operational viewpoint, the foamy sorghum-based pellets can be produced at the site of the oil spill to minimize transportation costs. Outcomes: Broader Impact – Organic spills pose serious environmental effects especially when the scale of the spill is large. The sorghum-based absorbent is a natural product (biodegradable and thus eco-friendly) that is used mainly as feed for livestock. The U.S. is one of the top producers of sorghum in the world thus is it readily available and affordable. The foamy sorghum-based absorbent can be produced at the site of the spill thereby decreasing transportation costs and that over 91% of the oil can be recovered by squeezing. reliminary cost assessment shows that the cost of the sorghum-based absorbent is ~10% the capital gained from the recovered oil (based on $82/bbl and $0.90/kg of foamy sorghum-based absorbent).
