Creating sustainable materials from waste – ScienceDaily

It’s no secret that we need more sustainable materials if we hope to help the planet. Bio-derived materials are a potential option, but they need to be economical if someone wants to use them.

For example, a better organic milk jug would be great. However, if the milk sells for $20 a gallon because the cost of the jug goes from $1 to $17, no one will buy it.

Led by Professor Thomas H. Epps, III, a team of University of Delaware researchers and CanmetENERGY collaborators has this type of economy in mind as they look for ways to recycle biomass into new products. . Take lignin, for example. Lignin is a component of plants and trees that provides strength and rigidity to help flora withstand what Mother Nature throws at it.

In the pulp and paper industry, however, lignin is a waste product from the manufacture of paper products. This type of lignin, known as technical lignin, is considered the dirtiest of the dirty, something that is not usable – except perhaps to burn for heat or to add to tires as filler.

The UD researchers say this widely available resource — about 100 million tons of technical lignin waste is generated each year in pulp and paper mills around the world — may be much more valuable.

The team demonstrated that industrially processed lignin can be efficiently transformed into high-performance plastics, such as bio-based 3D printing resins, and valuable chemicals. An economic and life-cycle analysis reveals that the approach can also be competitive with similar petroleum-based products.

An article describing the new method was published on Wednesday January 19 in Scientists progress. The work was supported primarily by funding from the National Science Foundation‘s Growing Convergence Research Program (NSF GCR), which aims to solve problems through multi-pronged, interdisciplinary collaboration.

“The ability to take something like technical lignin and not just break it down and turn it into a useful product, but do it at a lower cost and environmental impact than petroleum-based materials is something no one has. was really able to do.” show before,” said Epps, who leads NSF GCR efforts at UD and is the Allan and Myra Ferguson Professor Emeritus of Chemical and Biomolecular Engineering. He also holds a cross-appointment in the Department of Materials Science and Engineering.

An Everyday Ingredient Overcomes a High-Pressure Obstacle

One of the main problems with lignin beneficiation is that most of the processes to do so operate at very high pressures and are expensive and difficult to scale. The main disadvantages of current industrial techniques include safety issues, capital costs and energy consumption associated with traditional solvents, temperatures or pressures used in the process. To overcome these challenges, the research team replaced methanol, a traditional solvent used in lignin deconstruction, with glycerin so that the process could be carried out at normal atmospheric (ambient) pressure.

Glycerin is an inexpensive ingredient used in liquid cosmetics, soaps, shampoos, and lotions for its moisturizing abilities. But here, glycerin helps break down lignin into chemical building blocks that can be used to make a wide range of bio-based products, from 3D printing resins to different types of plastics, aromatic and fragrance compounds, antioxidants and more. again.

Using glycerin provided the same chemical functionality as methanol, but at a much lower vapor pressure, eliminating the need for a closed system. This change allowed researchers to perform the reaction and separation steps simultaneously, leading to a more cost-effective system.

Operation at atmospheric pressure is safer. Equally important, it also provides a simple path to scale beyond small batches and run the process continuously, creating more material with less labor in a cheaper, faster process.

Developing the process to be repeatable and consistent took about a year and involved input from undergraduate students, including Paula Pranda, co-lead author of the paper.

Pranda, now a doctoral student at the University of Colorado at Boulder, helped streamline the process. She also researched available datasets on the types of products the team could create and estimated the physical properties of those materials. This allowed co-author Yuqing Luo, a chemical engineering PhD student in Professor Marianthi Ierapetritou’s group, to model the system to see if it was economically feasible.

Luo’s work has shown that the UD team’s low-pressure method can reduce the cost of producing a bio-based pressure-sensitive adhesive from softwood Kraft lignin by up to 60% compared to the high-pressure process. pressure. The cost advantage was less pronounced for the other types of technical lignins used in the study, but softwood kraft lignin is among the most abundant types of technical lignin generated by the pulp and paper industry.

For Pranda, an experimenter, collaborating with student peers outside her area of ​​expertise like Luo, whose work focuses on modeling chemical processes to understand their cost, has been enlightening.

“I had never been part of a collaboration before, and I got a glimpse of how these other areas of chemical engineering work,” Pranda said.

According to Robert O’Dea, a PhD student at the Epps Lab and lead author of the paper, Luo’s contributions to economic modeling were key in determining whether to pursue this line of research.

“We knew we could do it physically, but we had to figure out if it made financial sense to do it at the scale of the chemical plant. Yuqing’s analysis showed yes,” O’Dea said.

The assessment of technical lignin waste from different types of pulping processes, obtained from the CanmetENERGY project collaborator in Canada, allowed Luo to examine how upstream costs such as price or feedstock yield would have an impact on the economy further downstream in the process.

Although the analysis demonstrated that yield plays a major role in plant economics, the operating cost of the new low-pressure process was significantly lower than the conventional process in all cases due to the lower costs. reduced investment and the generation of valuable co-products. . The researchers involved in the development of the process, from the Epps Group and colleagues from the research group of Professor UD Dionisios Vlachos, currently have a patent pending on the ambient pressure process.

Luo also carried out a life cycle assessment to understand the amount of greenhouse gas emissions (eg carbon dioxide) resulting from the production of materials. Having a good grasp of costs at every stage can help researchers explore ways to optimize the process and the infrastructure of the materials supply chain.

“We were trying to capture the big picture, not just the costs of the process, but also the environmental impacts on the whole operation,” Luo said.

The student collaboration grew out of meetings between faculty and students involved in materials lifecycle management work at UD, as part of the NSF GCR program.

“This naturally creates high-impact work because the NSF GCR program encourages us to address aspects such as materials science and environmental impacts at the same time. Thus, we simultaneously overcome multiple bottlenecks and obstacles through collaborative interdisciplinary,” Epps said.

And what about the potential of the method developed by UD to turn waste into valuable products?

“This shows that there is great potential for using renewable resources to make different types of plastics. You don’t have to use fossil fuels, plastics from renewable resources can also be economically feasible,” said Pranda said.

In addition to Epps, O’Dea, Pranda and Luo, other co-authors of the paper include UD alumni Alice Amitrano and Elvis Ebikade; postdoctoral researcher Eric Gottlieb; Olumoye Ajao and Marzouk Benali of Natural Resources Canada, CanmetENERGY; and Dionisios Vlachos, Unidel Dan Rich Chair in Energy, Professor of Chemical and Biomolecular Engineering and Director of the Catalysis Center for Energy Innovation; and Marianthi Ierapetritou, Bob and Jane Gore Centennial Chair in Chemical and Biomolecular Engineering.

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