The National Academies Press

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From page 165... ... Besides providing technical expertise and leadership in various areas of the circular economy, chemical engineers have opportunities to address challenges in the following four more specific technology areas:  purification of materials with a large volume and a high rate of collection, such as paper, cardboard, polyethylene terephthalate (PET) , glass, and steel;  recycling of polymers with a large volume and a low rate of collection;  utilization of by-products of manufacturing processes, such as used concrete, CO2, and food waste; and  development of materials with high value that currently have a small volume and a low rate of collection, such as 3-D printing materials and biobased ma terials. Read the entire page →
From page 166... ...  Dispose of the plastic in the product and/or package in a managed landfill. FIGURE 6-4 Global production, use, and fate of polymer resins, synthetic fibers, and additives, 1950–2019, in millions of metric tons. Read the entire page →
From page 167... ... and using renewable energy in the production of fossil-derived plastics are some alternative options for reducing the carbon footprint of plastics. Chemical engineers have an opportunity to apply quantitative, systems-level thinking to this problem through the application of TEA and LCA to determine which options optimize emissions reductions while considering other trade-offs, such as water consumption, cost, and environmental justice. Read the entire page →
From page 168... ... . The main unit operations that chemical engineers can further develop, optimize, scale up, and commercialize are polymer dissolution, extraction, processing, layer separation, filtration, contaminant migration, and solvent diffusion and recycling (Pappa et al., 2001; Walker et al., 2020; Zhao et al., 2018) Read the entire page →
From page 169... ... Other potential solutions to the plastics disposal problem beyond the recycling technologies discussed above include the following:  Use of biodegradable plastics and various enzymes and biodegrading organ isms for plastics -- LCAs are necessary to determine whether in some envi ronments, the negative effects of the uncontrolled release of the biodegrada tion products into the atmosphere outweigh the benefits of using biodegradable plastics.  Closed-loop recycling of polymers synthesized with in-chain functional groups that act as break points -- For example, Häuβler and colleagues (2021) Read the entire page →
From page 170... ... and the development of monomaterial solutions that achieve the same performance as multimaterial solutions are two key areas in which chemical engineers will continue to contribute. Regeneration of Natural Systems A biobased economy includes both biobased materials and biobased fuels (fuel uses are discussed in Chapter 3) Read the entire page →
From page 171... ...  Pyrolysis oil -- Biomass pyrolysis produces pyrolysis oil, which can then be upgraded to different chemicals. Biobased plastics are also part of the circular economy of plastics. Read the entire page →
From page 172... ... , biobased plastics can potentially have a lower carbon footprint and additional end-of-life options, such as composting. The global production of biobased plastics was 2.1 million metric tons in 2020, representing less than 1 percent of total plastics production. Read the entire page →
From page 173... ... More specifically, challenges and opportunities for chemical engineers in this domain include  scalable and economical processes for producing biobased plastics (e.g., PEF and PBS) and biobased monomers (e.g., biobased terephthalic acid; Collias et al., 2014) Read the entire page →
From page 174... ... In the transition from a linear to a circular economy, specific opportunities for chemical engineers include redesigning processes and products to reduce or eliminate pollution (e.g., Shi et al., 2021) , developing new ways to reduce and utilize waste, designing products to be used longer, and designing processes and products using sustainable feedstocks. Read the entire page →
From page 175... ... Flexible Manufacturing and the Circular Economy 175 cused on pilot- and demonstration-scale projects in advanced manufacturing, including scaled-down and scaled-out processes; process intensification; and the transition from fossil-based organic feedstocks and virgin-extracted inorganic feedstocks to new, more sustainable feedstocks for chemical and materials manufacturing. Read the entire page →
From page 176... ... For example, materials research in academic chemical engineering departments will include work in polymer science, rheology, catalysis, biomaterials, nanomaterials, electronic materials, self-assembly, and soft matter; several of these subjects have been discussed in earlier, application-focused chapters of this report. Chemical engineers have been responsible for many advances in materials design and development. Read the entire page →
From page 177... ... . This chapter explores four areas of materials research, design, and production in which chemical engineers are particularly active: polymer science and engineering, complex fluids and soft matter, biomaterials, and electronic materials. Read the entire page →
From page 178... ... . Chemical engineers' backgrounds in polymer chemistry, thermodynamics, and kinetics have been especially well suited to designing and understanding the interplay between thermodynamic and kinetic driving forces acting through the atomic- (monomer) Read the entire page →
From page 179... ... Within the next 20 years, the capability to design polymers from the bottom up for target applications will likely advance to a point at which the desired properties and behavior of a polymer can be specified and, using a combination of multiscale simulation and artificial intelligence (AI) , the building blocks and the processing strategy can be designed to make it. Read the entire page →
From page 180... ... Similarly, chemical engineers are well poised to develop alternative, scalable plastics with properties equal to or better than those of current commodity plastics and with a greener life cycle. COMPLEX FLUIDS AND SOFT MATTER Traditionally, chemical engineers have designed and formulated functional fluids that are exploited in fields ranging from food, personal care, and pharmaceuticals to active braking fluids and bulletproof vests. Read the entire page →
From page 181... ... . The design of such scalable functional structures is an area in which chemical engineers can contribute in new ways to functional materials for energy management. Read the entire page →
From page 182... ... . Chemical engineers have addressed these issues by understanding droplet and bubble dynamics and have developed paradigms with which to understand the nonlinear dependence of interface mobility and surfactant concentration (Stebe et al., 1991) Read the entire page →
From page 183... ... Chemical engineers are likely to continue to be at the forefront of this work. Nanoparticles Among the most exciting developments in soft matter in the last 20 years is the design, synthesis, and assembly of nanoparticles -- colloidal particles ranging in size from Read the entire page →
From page 184... ... , polymethylmethacrylate (PMMA) , or silica colloidal particles long studied by chemical engineers, today's nanoparticles can be made from a variety of materials (e.g., gold, silver, CdTe/S/Se, PbS/Se) Read the entire page →
From page 185... ... Theory and computer simulation are essential for finding the "sweet spots" in the vast design spaces available for patchy particles. Data science, and in particular deep learning with neural networks, has an important role to play in nanoparticle design for self-assembly. Read the entire page →
From page 186... ... By combining assembly engineering with active nanoparticles, chemical engineers are well positioned to create novel materials and material machines with robotic function at the nanoscale. BIOMATERIALS The design of biomaterials has seen strong growth in chemical engineering as a large number of advances have led to clinical translation that leverages degradable and biologically derived polymer systems. Read the entire page →

From page 165...

... Besides providing technical expertise and leadership in various areas of the circular economy, chemical engineers have opportunities to address challenges in the following four more specific technology areas:  purification of materials with a large volume and a high rate of collection, such as paper, cardboard, polyethylene terephthalate (PET) , glass, and steel;  recycling of polymers with a large volume and a low rate of collection;  utilization of by-products of manufacturing processes, such as used concrete, CO2, and food waste; and  development of materials with high value that currently have a small volume and a low rate of collection, such as 3-D printing materials and biobased ma terials.