Cellulose nanomaterials from cotton gin byproducts: processing and applications

Authors: Jordan, Jacobs; Easson, Michael

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 8/10/2022
Publication Date: N/A
Citation: N/A

Interpretive Summary: Due to the acute toxicity and persistent environmental factors associated with petroleum-based additives, biopolymers such as cellulose, lignin and cottonseed protein are being looked at more closely as replacement additives in the manufacturing industry. Biopolymers are natural, biodegradable compounds produced by the cells of living organisms. Cellulose is the most abundant biopolymer on earth and is the chief structural component of woody and non-woody plants. Cellulose is primarily used in the production of paper and paperboard, as well as a variety of other derivative applications including various nanomaterials. The two primary sources of cellulose are wood and cotton, which may contain other biopolymers such as lignin, which are usually removed prior to, for example, pulping and paper manufacturing. Cottonseed protein is a biopolymer that has been used in films, coatings, adhesives and as a reinforcement for paper products. Biopolymers like cellulose and cottonseed protein represent a sustainable alternative to petroleum-based additives in the manufacturing industry. Cotton gin motes and cotton gin trash are renewable agricultural by-products from cotton gin operations, which represent an underutilized source of cellulose. Herein the process methods whereby these two feedstocks are converted into nanomaterial products composed of fibers or crystals is discussed. Further, the fibers and crystals may be modified or obtained at different stages of processing to meet specific end-use applications. The fibers and crystals were then used with cottonseed protein as a paper-reinforcement additive. Improved strength and toughness of the paper was observed. This effect was improved when fibers were used that were not processed to remove lignin. This indicates a potential cost-savings compared to using nano fibers and crystals from cotton gin motes and cotton gin trash (or wood sources) which have been heavily purified to remove lignin.

Technical Abstract: The recent trend away from petroleum-based products and additives is due to a shift towards green and sustainable chemistry, where petroleum-based additives suffer from acute toxicity and persistent environmental concerns. Biopolymers as replacements, on the other hand, are abundantly available, renewable, and sustainable. Cottonseed protein is a biopolymer used in films, adhesives, and paper products as a reinforcement additive. Cellulose is the most abundant biopolymer on earth and is the chief structural component of the primary cell walls of plants, and can be chemically, enzymatically, and mechanically processed into cellulose nanofibers (CNFs) and nanocrystals (CNCs). However, the production of CNFs and CNCs is often from highly purified cellulose which has been oxidatively bleached to remove lignin and other components. To meet the needs of reduced cost, CNFs and CNCs were prepared through a variety of chemical processes from cotton gin motes (CGM) and cotton gin trash (CGT). Given the millions of tons of CGT and the hundreds of thousands of tons of CGM available, these two agricultural by-products are promising biomass feedstocks for further value-added applications and offer an enormous, but presently undeveloped, biomass feedstock for production of nanocellulose. CNCs and CNFs were applied as performance additives tested with cottonseed protein as a paper strength modifier. Improved tensile strength, modulus, and elongation at break were observed when the cottonseed protein was used at 10% giving improvements of 87% (modulus) and 97% (tensile strength). When 2% or 10% additive of CNFs or CNCs, respectively, were used the modulus improved 117–122% and the tensile strength improved 127–141%. Furthermore, when lignin-containing CNFs (LCNFs) were used the improvement in modulus and tensile strength were 130% and 167% respectively. These LCNFs have a longer degree of polymerization and were not oxidatively bleached, both reducing cost and eliminating waste products.