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Greener Solutions 2020

Taking on PFAS in Carpets and Packaging

Four interdisciplinary student teams investigated safer alternatives to Per- and polyfluoroalkyl substances (PFASs) in carpets and packaging. Two carpet teams partnered with the California Department of Toxic Substances Control (DTSC), focusing on removal of PFAS from the carpet recycling stream and on formulations of aftermarket carpet treatments. Two packaging teams partnered with the commercial cleaning products company Method to tackle the challenge of PFAS in food and product packaging. 

The food packaging team identified alternatives to fluoropolymer mixtures in molded fiber such as rhamnolipids and pectin added to the existing paper system and nanocellulose and lignin sourced from within the paper system. The team thought creatively to identify how materials that would normally be wasted in the existing paper production system could be reused.

The product packaging researchers identified biopolymer films for product packaging for a range of Method Home products, including laundry powders, detergents, and soaps, with a range of moisture barrier needs. The team came up with strategies that fell into three categories: Biopolymer films derived from natural sources, including chitosan, pectin, and gelatin; chemical additive cross-linking film to improve barrier and mechanical properties, including with genipin and ferulic acid; and physical additive nanofillers to reinforce film’s barrier and mechanical properties, including with nanoclays and fibers.

The aftermarket carpet treatment team presented PFAS alternatives for aftermarket stain repellant treatments. Their proposed solutions included natural waxes and oils, biopolymers, and silicon-based materials, including silicon dioxide nanoparticles and silicon-containing small molecules and polymers. The team identified chitosan and cellulose nanocrystal as candidates for a biopolymer approach. The team noted the potential to combine multiple strategies to achieve optimal performance metrics.

The carpet recycling group presented innovative strategies to remove PFAS from carpet face fiber fluff during recycling. The team provided strategies with a range of timescales to implementation. The first strategy involved using base hydrolysis and granular activated carbon (GAC) adsorption to remove but not destroy PFAS. The second strategy built on the first, but proposed using reverse osmosis and plasma treatment to destroy the PFAS. The third strategy proposed the use of esterase (specifically pig liver esterase) as an alternative to using sodium hydroxide in the other proposed strategies. Finally, the fourth strategy focused on the potential for laccase to mediate PFAS removal. 

The team’s final findings were presented to the partners and the general public over Zoom on Tuesday December 3, 2020. All four reports can be viewed here.

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