Extraction and characterization of nanocellulose crystals from cotton gin motes and cotton gin waste

Authors: Jordan, Jacobs; Easson, Michael; Dien, Bruce; Thompson, Stephanie; Condon, Brian

Submitted to: Cellulose
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/24/2019
Publication Date: 6/3/2019
Citation: Jordan, J.H., Easson, M.W., Dien, B., Thompson, S., Condon, B.D. 2019. Extraction and characterization of nanocellulose crystals from cotton gin motes and cotton gin waste. Cellulose. 26(10):5959-5979. https://doi.org/10.1007/s10570-019-02533-7.
DOI: https://doi.org/10.1007/s10570-019-02533-7

Interpretive Summary: The use of agricultural waste and residues from cotton in biocomposites and other materials is a potential high-value commercial application for underutilized renewable materials and provides alternative (non-textile) markets to the cotton agricultural industry. Cellulose nanocrystals (CNC) have attracted a great deal of attention as an environmentally-friendly biorenewable resource for use as reinforcing agents in nanocomposites, polymers, gels, and emulsions. The leading market-share for source material for production of nanocellulose materials is bleached wood-pulp, although extensive research is invested in developing lower cost alternatives needed to open up further markets. Other avenues of research focus on methods to isolate CNCs from commercial or industrial refuse and on developing new innovative applications. The use of cotton gin motes and cotton gin waste is an attractive low-value commodity for conversion to high-value CNC material because they are readily available and centrally located at cotton processing plants. With market demand for cellulose nanomaterials growing, expanding the sources of feedstocks is especially important. Cotton ginning by-products represent a huge potential but presently unexplored feedstock for cellulose nanocrystal (CNC) production. In the following, producing nanocellulose from cotton gin motes and cotton gin waste is investigated. Cellulose and subsequently CNCs were successfully extracted from these two post-process agroindustrial by-products using a combination alkali and bleaching chemical treatment followed by acid hydrolysis. Moreover, CNCs were extracted from gin motes without any chemical pretreatment while employing two subsequent post-extraction treatments. This work provides a method for producing a high value commodity from cotton gin motes and cotton gin waste, which represent new inexpensive source materials.

Technical Abstract: Cellulose nanocrystals (CNC) have attracted a great deal of attention as an environmentally-friendly biorenewable resource for use as reinforcing agents in nanocomposites, polymers, gels, and emulsions. CNCs are typically prepared from extracted cellulose or highly refined cellulose products. The chemical refining process can alter the chemical and physical properties of the cellulose fibers prior to extraction of CNCs. Moreover, the method of isolation can also insert various functional groups onto the nanocellulose, affecting thermal stability and imparting different physical properties. Herein, two byproducts of the cotton industry, cotton gin motes and cotton gin waste, are investigated for the preparation of nanocelluloses. Cellulose was purified from these two post-process agroindustrial by-products and CNCs subsequently produced by sulfuric acid hydrolysis. Additionally, two acid hydrolysis methods were utilized to successfully extract CNCs from gin motes without chemical pretreatment. CNCs were obtained with diameters <10 nm and lengths of ca. 100'300 nm resulting in high aspect ratios (12–33). Incorporating CNCs with these dimensions impart increased hydrophilicity to a substrate. The effect of post-extraction chemical treatments on crystallinity and morphology are discussed. The extracted nano-architectures were additionally characterized by FTIR, AFM, TGA, DLS, XRD and XPS. Differences in extraction method and chemical treatment resulted in different thermal properties and colloidal stability. Furthermore, this work provides a means of producing a high value commodity from inexpensive source materials such as cotton gin motes and cotton gin waste.