Progress 02/01/15 to 01/31/19
Outputs
Target Audience:The main target audience were scientists and engineers in academia and industry who work with membranes and/or fatty acids. The field of organic solvent nanofiltration (OSN) membranes is still an emerging field compared to the robust and commercially successful reverse osmosis membranes that are used to purify water. OSN membranes are used to separate organic chemicals dissolved in organic solvents, and this separation is complex and challenging. Several problems arise in this field including that the membranes are typically swollen by organic solvents which changes their ability to allow solvents and other chemicals to permeate. Also, organic chemicals have flexible structures so the differences in their sizes is often small. Finally, organic chemicals may interact strongly or weakly with the membranes depending on their functional groups present, and this will have a strong impact on their flux. New advances in OSN membranes are needed. Many opportunities to use OSN membranes exist if the challenge of developing membranes that separate closely related organic chemicals can be developed. The chemical industry produces many thousands of organic chemicals each year that are purified by distillation, column chromatography, crystallization, or other method. Membrane separations are highly desired because they use only low amounts of energy, do not require high temperatures that may degrade chemicals, and can be easily scaled to industrial levels. The main problem holding back this field is the lack of tunable, highly selective membranes that work in organic solvents and possess nm-sized pores. One particular problem that we are highly interested in solving is using OSN membranes to separate vegetable and fish oils and their fatty acids. Vegetable oils are the second largest natural products isolated worldwide (first is cellulose) and they represent safe, natural chemicals for the chemical industry. Vegetable oils are composed of three fatty acids linked by glycerol, and there are over a dozen major fatty acids found in vegetable oils. Scientists and engineers have developed commercial applications of vegetable oils and fatty acids, but they are limited in what can be developed due to unwanted fatty acids in the oils or mixtures of fatty acids. Simply, mixtures of fatty acids contain desired and undesired fatty acids. A major advance in this field would be to separate mixtures of fatty acids into components enriched in a single fatty acid. This is a highly challenging separation because fatty acids have similar molecular weights and sizes, separation of one fatty acid from another using a membrane is not possible. If developed, this membrane separation would allow the purification of fatty acids that can be developed into new products by the chemical industry. Similarly, separating mixtures of vegetable oils to remove vegetable oils with unwanted compositions is highly challenging. Yet, this separation would open up new opportunities to employ vegetable oils in industrial settings. Other target audiences are taxpayers and their children. We served this target audience by doing STEM outreach events at the Iowa State Fair, local schools, and a nursing home. These events were an opportunity to get children excited about science and talk about our efforts to develop nanometer-scale membranes for applications in agriculture. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?The training of graduate students and undergraduate students was very valuable. Undergraduates were integrated into every aspect of this project and one was an author on a publication. The graduate and undergraduate students received training in broad areas of organic chemistry, polymer chemistry, and materials science. They learned how to fabricate membranes, what the important challenges in membrane science were, how to navigate a project from conception to completion, how to think about OSN membranes, how to work with fatty acids and oils, and how to get past problems in scientific research. Several students who were supported by this grant received PhD's and numerous undergraduates received valuable research experience. How have the results been disseminated to communities of interest?We have disseminated our results in several publications, at seminars in other colleges, and a start-up company (Pure Oleochemicals). The publications were in high impact, widely read journals. The start-up company received a few rounds of funding, but it was ultimately unsuccessful. At the outreach events, I had a chance to talk to numerous fair goers about our research and the role the USDA plays in funding research to expand the use of corn and soybean oils. Most people I talked to had no idea that this happened and were excited to learn that new applications for corn and soybeans were being explored. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
Overall accomplishments: We developed the most selective OSN membranes reported in the chemical literature. These membranes were based on the reaction between di- and triepoxides and diamines to form cross-linked "epoxy" membranes. We designed these membranes from the molecular to the nanometer-size level to have high selectivities as membranes and, critically, to be easily varied. The membranes were fabricated from a wide range of epoxides and amines, and to change the nanometer-sized pores we rationally selected epoxides and amines with the desired properties. This method is unique in the field of OSN membranes, most OSN membranes have nanometer-sized pores that can only vary by a small amount, our membranes vary the pore size by large amounts yet are still highly selective. Another accomplishment was that our membranes had uniform levels of cross-links. We designed the monomers and synthesis to be self-correcting to allow for a high percentage of cross-links to form. This result meant that our membranes were uniform and did not have as many defects as other OSN membranes. The combination of these properties made our membranes the most selective in the field of OSN membranes. Objective #1: We will develop methods to purify oleic, linoleic, and linolenic acids (and their methyl esters) using nanoporous membranes and investigate many of the key parameters that affect their purification. 1) Major activities completed / experiments conducted: We fabricated OSN membranes using epoxides and amines, characterized their ability to separate chemicals with different sizes and molecular weights, and developed nm-thin membranes. 2) Data collected: We demonstrated that our membranes could separate mixtures of saturated fatty acids and their methyl esters. As the molecular weight of the fatty acids increased, the flux decreased. We fabricated nm-thin membranes and used modest pressure to demonstrate that we could get flux rates that are required for industrial properties. Furthermore, we demonstrated that we could optimize the separation efficiency by investigating how two membranes synthesized from different monomers functioned. We also demonstrated that we could separate EPA and DHA ethyl esters using our membranes. These fatty acid esters are the high value fish oil fatty acids that are highly desired for applications in human health. We choose to use these fatty acids because they are unsaturated similar to oleic, linoleic, and linolenic acids which are found in vegetable oils. 3) Summary statistics and discussion of results: We were the first to separate fatty acids and fatty acid esters using OSN membranes. This was an important and notable result because it demonstrated that OSN membranes could achieve this difficult separation. Most OSN membranes separate chemicals that have molecular weights greater than 400 g per mole and large differences in their molecular weights. In contrast, fatty acids had molecular weights less than 280 g per mole and differences in molecular weight of as little as 28 g per mole. These chemicals are typically viewed as too similar to separate, but our membranes were successful. In addition, we fabricated nm-thick membranes and used modest pressure to demonstrate that our membranes could separate these chemicals under industrially relevant conditions and at industrially important values for flux. We also demonstrated that our membranes could separate unsaturated fatty acids. This separation was unexpected and demonstrated that these chemicals could be separated using membranes. We had some success separating the unsaturated fatty acids derived from vegetable oils, but these results are still preliminary. We are still working on optimizing this separation using epoxy membranes. 4) Key outcomes or other accomplishments realized: We had several key outcomes based on this research. We reported the most selective OSN membranes in the literature; these membranes were made from a mixture of epoxides and amines. By varying the epoxides and amines, we were able to optimize the properties of the nm-sized pores of the membranes to separate a wide range of chemicals. These membranes were highly modular and were easily varied for a range of different separations. A second key accomplishment was that we were able to separate cis-fatty acids for the first time. These fatty acids had similar molecular weights and sizes, but our membranes were effective at separating them. This was the first time that membranes were shown to separate unsaturated cis-fatty acids. Third, we demonstrated that our membranes could be fabricated to be nm-thick and possessed high flux rates required for industrial applications. This was important because it demonstrated the potential for these membranes to be scaled to industrial levels. Finally, we also fabricated membranes with reversible cross-links that possessed two different nm-pore sizes depending on whether the cross-links were present or not. This allowed us to separate a three component mixture into streams enriched in each chemical. This was a new approach in OSN membranes that demonstrated how to control and vary the nm-sized pores using reversible cross-links. Objective #2: We will develop methods to purify corn, high oleic acid soybean, and linseed oils using nanoporous membranes and investigate many of the key parameters that affect their purification. Our OSN membranes were highly successful at separating fatty acids and fatty acid esters, but they were not successful at separating oils. The oils are much larger than the fatty acids, and our OSN membranes had nm-sized pores that were ideal to separate fatty acids but not the oils. We repeatedly attempted to separate the oils by expanding the pore sizes of the membranes, but we were unsuccessful. We tried several different approaches to achieve this separation by optimizing the monomers used in the synthesis of the OSN membranes. We were able to separate chemicals with molecular weights and sizes similar to the oils, but the oils had similar sizes and we could not separate them.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2017
Citation:
"Separation of saturated fatty acids and fatty acid methyl esters with epoxy nanofiltration membranes" Chad M. Gilmer, Christian Zvokel, Alexandra Vick, and Ned B. Bowden; RSC Advances, 2017, 7, 55626-55632
- Type:
Journal Articles
Status:
Published
Year Published:
2018
Citation:
"Reactive epoxy nanofiltration membranes with disulfide bonds for the separation of multicomponent chemical mixtures" Chad M. Gilmer, Ned B. Bowden; ACS Omega, 2018, 3, 10216-10224
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Progress 02/01/16 to 01/31/17
Outputs
Target Audience:One target audience of this grant was the taxpayers and their children. We served this audience by doing outreach events at the Iowa State Fair, the Sarah Harding nursing home, Hillside Christian School, and the Cedar Valley STEM fair. The Iowa State fair has approximately one million visitors each year out of a total population of three million in the state of Iowa. The University of Iowa runs a booth each year to showcase its accomplishments and to recruit new students. I ran a booth as a part of the larger University of Iowa booth to run chemistry experiments with children of all ages and to engage fairgoers on farming and the need for scientific research. For instance, I discussed with many of them our research efforts to separate and purify fatty acids to make them more accessible to the chemical industry. These conversations were interesting as many people I talked to did not understand why funding science was important although many were aware in a general way that science funding was a good idea. It was a pleasure to speak to so many people about how science can have a role in their lives and in agriculture. I also ran a booth at a STEM fair in Waterloo, Iowa where we did chemistry experiments with children up to 18 years old - and occasionally with their parents too. This event was meant to introduce children to careers in STEM fields, so we did chemistry experiments with them and talked to many of the high school students about careers in science and what to expect in college. It was a terrific experience to talk to young people and encourage them to pursue a career in STEM. I also did an outreach event at the Sarah Harding nursing home and at Hillside Christian School. Hillside serves students from K-8, so we had numerous hands on experiments and conducted a few experiments that needed to be done outside. The older students had excellent questions about chemistry and what chemists do, one of them asked to work in my lab in the summer of 2017 and I agreed to let her work with us. The nursing home visit was exciting because many of the people at the nursing home either grew up on a farm or in a small town that was surrounded by farms (Iowa has numerous farms). I did some science experiments with them and we talked about farming and the role of science in helping to advance farming. Everyone was excited about the possibilities for science to improve farming and the output of farms. Another target audience are scientists who work with membranes and/or fatty acids. We published a paper reporting new organic solvent nanofiltration membranes based on polyepoxies. These membranes are the most selective membranes reported for separating chemicals with molecular weights from 100 to 300 grams per mole. Our membranes had differences in flux up to 250/1, other membranes typically have differences of 10/1 or less. We applied these membranes to the separation of EPA and DHA (two of the key fatty acids in fish oil) and demonstrated a difference in flux of 1.4/1. Although a small difference in flux, these results demonstrate that the membranes can separate these fatty acids. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?The main training has been for graduate students, undergraduate students, and high school students. In the summer of 2016 my lab hosted a high school student who worked full time for 5 weeks on this project. She was a part of a program at the University of Iowa to give high school students research experience by working full time in a lab. She was a joy to have around and did a presentation and report on her project. A second high school student worked in my lab for 40 hours last summer to gain some experience about science. She was very helpful and was able to help us make and study membranes. I typically have four or more undergraduates working in my lab. In 2016 I had six different undergraduates from the University of Iowa working in my lab on various aspects of this project. One undergraduate was an incoming freshman, Basil, who repeatedly emailed me over the summer, so I took him into my group. He quickly learned what to do and then I gave him and another undergraduate, Jacob, their own project to fabricate membranes using nanoporous zeolites. They have had interesting results and are still working on that project. In addition to these two undergraduates a third undergraduate, Yulien, it writing a thesis based on her work so she can graduate with honors. The largest impact has been on the graduate students who have worked on this project. I currently have two four year and three first year graduate students working on this project. The two senior students will graduate within a year and are passing their expertise to the first year students. Both of the senior graduate students went to the Gordon Research Conference on membranes in August of 2016 and gave posters; one of them, Chad Gilmer, also gave a short seminar. Chad also went to the National Biodiesel Conference in San Diego in January of 2017 and presented a poster. In addition to these activities, the outreach activities that I ran in 2016 were done with graduate students who gained valuable experience working with the public and communicating excitement about science to them. They worked with me at each booth to interact with children and their parents to provide outreach to taxpayers. How have the results been disseminated to communities of interest?As described previously, I did outreach to a local school (K-8), at the Iowa State Fair, at a STEM event in Waterloo, and at the Sarah Harding Nursing home in Clinton. These events gave me and my students opportunities to interact with the public and talk to them about chemistry, nanoscience, and the importance of funding basic research. In each event we bring numerous hands on experiments that children of all ages can safely do. It is particularly fun to see many parents and grandparents doing the experiments with their children and watching their eyes light up when their experiment works. We work hard to encourage young students to pursue careers in the STEM fields by telling them about the opportunities to ask questions that no one has asked and then to try to answer them. The students find that description to be exciting and it gets them interested in science. We also have published a paper and attended two conferences. The paper was our first publication on polyepoxy membranes and describes exciting new membranes that are the most selective in this field. We applied these membranes to the separation of EPA and DHA and were able, for the first time, to separate these fatty acid esters. We expect that this paper will be the one that we and other regularly cite when referencing our work with these membranes. My graduate students and I also attended the Gordon Research Conference on membranes and presented our work. This conference gave us the opportunity to present our exciting new work on membranes to experts in the field and to learn what is the best work in membranes. It was a great learning experience for all three of us. Finally, Chad Gilmer attended the National Biodiesel Conference to talk about our efforts to separate fatty acid esters. His work was well received and many people were excited about its potential. What do you plan to do during the next reporting period to accomplish the goals?We are investigating numerous membranes for how they separate fatty acids and vegetable oils. The membranes that we are investigating most aggressively are based on the polyepoxy membranes that we recently developed. These membranes can be used to separate saturated fatty acids from each other and can separate EPA from DHA. We are investigating how to alter the structures of the membranes to better separate fatty acids. Furthermore, we are investigating how to expand the pore size to separate vegetable oils. Because we can alter the composition of the membranes, we can readily alter their nanopore sizes to reach the sizes of vegetable oils. We are also investigating membranes fabricated by a start-up company called Mattershift. These membranes are based on integrating carbon nanotubes into a polymeric backing such that chemicals pass through the nanotubes. These membranes are unique in the field, only two groups have reported membranes with nanotubes that span the length of the membrane and both groups are purifying water with them. We are investigating these membranes for the separation of fatty acids. This work may have a high impact because the membranes will be commercially available and easy to use by industry if we discover that they are effective to separate fatty acids.
Impacts
What was accomplished under these goals?
Farmers grow tremendous amounts of corn, soybeans, and other crops each year and from these crops are isolated vegetable oils that are used for cooking food, as animal feed, and as biodiesel. These oils are safe for the environment, inexpensive, and produced at large quantities. The oils can be chemically changed into smaller components called fatty acid esters that are used for animal feed and as biodiesel. Some of their characteristics of the esters make them highly desired starting materials for the chemical industry, but the esters are isolated as a mixture of five or more esters. The mixture of esters makes it hard to develop many downstream products, and the esters are expensive to separate from one another. Our research focuses on the development of membranes to separate esters from one another. We choose to use membranes because membrane separations are inexpensive and can be scaled up to industrial quantities, so any success has a path to being commercialized. If successful these membranes could be used to separate and purify esters for new applications in the chemical industry where green, biorenewable chemicals are needed. Objective #1: We will develop methods to purify oleic, linoleic, and linolenic acids (and their methyl esters) using nanoporous membranes and investigate many of the key parameters that affect their purification. We have developed new membranes based on polyepoxies that can separate fatty acids and fatty acid esters from each other. These membranes are highly selective for the separation of fatty acid esters based on both their molecular weights and degree of unsaturation. They were fabricated based on commercially available starting materials, and several dozen different membranes were fabricated and analyzed. A strength of this method is that the membrane can be optimized for each separation because the materials to make the membrane can be easily altered. These membranes were fabricated by mixing diamines and di- or triepoxides for 48 to 72 hours to allow the complete reaction between the amines and epoxides. We discovered that some diamines and diepoxides yielded membranes that worked better than others. A key component of the membranes was the molecular weight between cross-links; this value gave an estimate for the size of the nanopores that chemicals must permeate to pass through the membranes. We initially tested these membranes against a series of chemicals with well-defined nanometer sizes and shapes and discovered that they had separation efficiencies that were at least 10x better than other membranes. We applied these nanoporous membranes to the purification of fatty acids from fish oil and saturated fatty acids. EPA and DHA are the two important fatty acids found in fish oil, but they are only 30% of the total fatty acids found in fish oil. We demonstrated that our membranes could separate EPA and DHA from each other and from other fatty acids. We are working to optimize these separations so we can reach high purities for EPA and DHA. We also applied these membranes to the separation of saturated fatty acids. We optimized the membranes and discovered membranes that had over 60x difference in flux for saturated fatty acids. This work is being finished and written into a publication. Objective #2: We will develop methods to purify corn, high oleic acid soybean, and linseed oils using nanoporous membranes and investigate many of the key parameters that affect their purification. We are applying the nanoporous epoxy membranes to the purification of vegetable oils. Because the oils are much larger than the fatty acid esters, they have very slow flux through our membranes. We have discovered that by adding monoamines to the synthesis of the membranes produced membranes with larger pore sizes. We are currently investigating how these membranes separate the triacylglycerides found in vegetable oils.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2016
Citation:
"Highly cross-linked epoxy nanofiltration membranes for the separation of organic chemicals and fish oil ethyl esters" Chad M. Gilmer, Ned B. Bowden, ACS Applied Materials & Interfaces, 2016, 8, 24104-24111.
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Progress 02/01/15 to 01/31/16
Outputs
Target Audience:In 2015 the Bowden group completed numerous examples of outreach. In August of 2015 Professor Bowden took 7 graduate students to the Iowa State Fair for a day and ran a booth to expose fairgoers to chemistry. The booth was interactive so fairgoers could make slime (borax and glue), break nitrile gloves that were frozen in liquid nitrogen, observe how a polyacid salt adsorbed 100x its weight in water, and watched as a balloon disappeared when frozen in liquid nitrogen and then reappeared when it warmed up. The booth was very popular with fairgoers and was busy all day. This booth appealed to fairgoers of all ages from toddlers to grandparents, there were experiments and demos for everyone. At least 5,000 fairgoers visited this booth. Professor Bowden was present the entire time and engaged fairgoers in the experiments, discussions about his research with membranes, and the importance of funding fundamental research. Professor Bowden also ran a booth at a STEM fair for preteen and teenage students at the University of Northern Iowa in November of 2015. Many of the same experiments used in the state fair were employed and the results were very positive. The booth was very busy the entire time and some students came back multiple times. These booths are designed to be very interactive and to show elements of chemistry that are easy to understand and are entertaining. Professor Bowden also did outreach to a local school in Coralville, Iowa to work with K-8 students. He was at the school most of the day and engaged the students in discussions about science and the scientific method. He also did many experiments with the students. Professor Bowden also visited the Sarah Harding nursing home in Clinton, Iowa in June of 2015 to do outreach to the elderly residents. He did some science experiments and talked to the residents about what happens in chemistry departments and colleges. He discussed the importance of funding basic scientific research with the residents. Professor Bowden had several undergraduates who worked in his lab in 2015 and one high school student. The high school student came to the lab via a program run at the University of Iowa to encourage talented high school students work in a research lab for 5 weeks. The student was taught how to make membranes and was given a research project to work on. Professor Bowden gave four seminars at other universities and the Gordon Research Conference. These seminars covered the membranes that were synthesized in the Bowden group and how they functioned to separate fatty acids. Changes/Problems:We had significant challenges associated with changes in the dicyclopentadiene that altered the properties of our polydicyclopentadiene membranes. For five years we were able to make membranes from dicyclopentadiene that had the same properties, and over a dozen students were able to reproduce this work. The membranes were easy to fabricate and had exciting nanofiltration properties. Suddenly, we got a new batch of dicyclopentadiene that did not work as well; membranes made from it had poorer selectivities. Discovering the source of the problem was challenging because our membranes were very simple to make using only three chemicals: dicyclopentadiene, Grubbs catalyst, and 1,2-dichloroethane as a solvent for the Grubbs catalyst. We used each of these chemicals at their highest purities with success for years. After many experiments, we traced the problem to the dicyclopentadiene and determined that our problems were due to an impurity or impurities at ppm loadings. We took many routes to solving this problem. We had extensive conversations with Aldrich and Cymetech to learn what impurities were present in the different batches of dicyclopentadiene. From conversations with Cymetech, we learned that they switched from using heavy naphtha crude oil to fracking gas to make dicyclopentadiene. This switch changed the impurities in the dicyclopentadiene. We completed over a thousand experiments to try to find the right composition of dicyclopentadiene to produce polydicyclopentadiene membranes with our desired properties. Unfortunately, these experiments failed. We also asked approximately ten scientists in the U.S. if they would send us an old bottle of dicyclopentadiene and many were willing to do so. The dicyclopentadiene we received was partly decomposed and none of these batches yielded membranes that we needed for this project. We are still working to recover our old technology; Professor Bowden is scheduling a visit to the Cymetech factory to talk to the people who produce high purity dicyclopentadiene. Because of these problems with dicyclopentadiene, we developed a new set of nanofiltration membranes based on polyepoxies. We understood many of the key parameters that we needed in nanofiltration membranes, so we designed a series of membranes based on polyepoxies that are better in some regards to the polydicyclopentadiene membranes. We are preparing our first paper on our new polyepoxy nanofiltration membranes and are applying them to all of the separations in our original grant proposal. What opportunities for training and professional development has the project provided?The main training and professional development has been the training received by two graduate students, a high school student, and two undergradutes who worked on this project. The graduate students completed most of the experiments and developed new nanofiltration membranes based on polyepoxies that can separate fatty acids and triacylglycerides. They are both making progress towards their PhDs. In addition, these graduate students supervised undergraduates and a high school student in the lab and gained experience as research supervisors. The undergraduate students and high school student gained experience doing research in nanofiltration and assisted in many of the key experiments that were completed. How have the results been disseminated to communities of interest?In 2015 the Bowden group completed numerous examples of outreach. In August of 2015 Professor Bowden took 7 graduate students to the Iowa State Fair for a day and ran a booth to expose fairgoers to chemistry. The booth was interactive so fairgoers could make slime (borax and glue), break nitrile gloves that were frozen in liquid nitrogen, observe how a polyacid salt adsorbed 100x its weight in water, and watched as a balloon disappeared when frozen in liquid nitrogen and then reappeared when it warmed up. The booth was very popular with fairgoers and was busy all day. This booth appealed to fairgoers of all ages from toddlers to grandparents, there were experiments and demos for everyone. At least 5,000 fairgoers visited this booth. Professor Bowden was present the entire time and engaged fairgoers in the experiments, discussions about his research with membranes, and the importance of funding fundamental research. Professor Bowden also ran a booth at a STEM fair for preteen and teenage students at the University of Northern Iowa in November of 2015. Many of the same experiments used in the state fair were employed and the results were very positive. The booth was very busy the entire time and some students came back multiple times. These booths are designed to be very interactive and to show elements of chemistry that are easy to understand and are entertaining. Professor Bowden also did outreach to a local school in Coralville, Iowa to work with K-8 students. He was at the school most of the day and engaged the students in discussions about science and the scientific method. He also did many experiments with the students. Professor Bowden also visited the Sarah Harding nursing home in Clinton, Iowa in June of 2015 to do outreach to the elderly residents. He did some science experiments and talked to the residents about what happens in chemistry departments and colleges. He discussed the importance of funding basic scientific research with the residents. What do you plan to do during the next reporting period to accomplish the goals?We are using our new polyepoxy membranes to separate fatty acids, fatty acid esters, and triacylglycerides. These membranes are versatile and can complete many separations that the polydicyclopentadiene membranes were successful at. In addition, our new polyepoxy membranes can complete separations where our polydicyclopentadiene membranes failed. We intend to concentrate mostly on the polyepoxy membranes but devote a small, limited effort to learning how to make the polydicyclopentadiene membranes function properly again.
Impacts
What was accomplished under these goals?
We had to overcome some significant initial problems. Our old polymeric membranes were based on polydicyclopentadiene, and we were able to make these membranes for years without any trouble. We always used high purity dicyclopentadiene and the Grubbs catalyst that were purchased from Aldrich. Aldrich did not produce dicyclopentadiene, they purchased it from Cymetech and repackaged and sold it. The dicyclopentadiene was at approximately 99% purity and over 5 years at least a dozen different students made membranes with it. The dicyclopentadiene changed and the membranes had different properties. We completed over a thousand experiments to try to find the cause of the problem and learned that the problem was with the dicyclopentadiene rather than the Grubbs catalyst. Around the time we had trouble with dicyclopentadiene, the feedstock that was used to make it changed from heavy naphtha crude oil to lighter crude oil. In other words, the feedstock to make dicyclopentadiene changed from heavy crude oil to more inexpensive fracking gas. Our experiments indicate that an impurity or impurities at ppm loadings in the old dicyclopentadiene were important to the cross-linking of the final polymer and the properties of dicyclopentadiene as a membrane. Although we are still working on solving the problems with polydicyclopentadiene, we developed new nanofiltration membranes based on polyepoxies. These membranes are formed by the reactions of epoxides and amines to yield highly cross-linked nanofiltration membranes. We developed a series of membranes based on commercially available starting materials that have different nanometer-sized pores and selectivities. These new membranes are very exciting for several reasons. First, we can separate fatty acids (and fatty acid esters) from each other. In fact, we are about to submit our first paper describing these membranes and the separations that are possible. Second, the size-selectivities are easily varied by changing the monomers used in their synthesis. We can rationally alter the membranes by mixing together different monomers. Third, because we can vary the size-selectivity, we can also separate triacylglycerides. Fourth, the membranes are very stable and have potential applications in industry because they are inexpensive and stable. We started a collaboration with the USDA facility in Peoria, Illinois to work on projects together. By combining their expertise and knowledge with our nanofiltration membranes, we believe we can do some exciting science to separate and purify fatty acids, triacylglycerides, and other agriculturally important chemicals.
Publications
- Type:
Journal Articles
Status:
Other
Year Published:
2016
Citation:
Highly-crosslinked Epoxy Membranes for Separation of Organic Molecules and Fish Oil Ethyl Esters
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