Repurposing Cotton Gin Trash for Cellulose Nanofibril-Silver Hybrid and Ultralight Silver-Infused Aerogel

Authors: Nam, Sunghyun; Easson, Michael; Jordan, Jacobs; He, Zhongqi; Lima, Isabel; Hillyer, Matthew; ERNST, NICHOLAS - Purdue University Northwest- Hammond Campus; Fang, David; ISLAM, MD MUHAIMINUL - Tulane University

Submitted to: ACS Omega
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/26/2024
Publication Date: 8/28/2024
Citation: Nam, S., Easson, M.W., Jordan, J.H., He, Z., Lima, I.M., Hillyer, M.B., Ernst, N.E., Fang, D., Islam, M. 2024. Repurposing Cotton Gin Trash for Cellulose Nanofibril-Silver Hybrid and Ultralight Silver-Infused Aerogel. ACS Omega. 9(36):38195-38204. https://doi.org/10.1021/acsomega.4c05728?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as.
DOI: https://doi.org/10.1021/acsomega.4c05728?urlappend=%3Fref%3DPDF&jav=VoR&rel=cite-as

Interpretive Summary: This study has demonstrated the potential of cotton gin trash (CGT) as a sustainable and multifunctional material with diverse applications including the production of nanofibers and functional ultralight aerogels. The high shearing process employed in the study proved effective in fabricating CGT nanofibers, which served as a versatile nanotemplate for silver nanoparticle (Ag NP) synthesis. By functioning as a nucleation site, reducing agent, and stabilizing agent, the CGT nanofibers facilitated the production of a high concentration of Ag NPs both on the surface and within the nanofibers. The formation of Ag NPs was confirmed through the observation of surface plasmon resonance of the resulting CGT nanofiber-Ag hybrid. TEM images further validated the internal NP formation, revealing uniformly dispersed Ag NPs throughout the entire volume of the nanofibers. The fabrication of nanofibers and the synthesis of Ag NPs led to an increase in the crystallite size of CGT cellulose without significantly affecting its crystallinity. Moreover, the crystallite size of Ag NPs derived from CGT nanofiber was found to be slightly smaller than that from CGT. An aerogel fabricated from the CGT nanofiber-Ag hybrid exhibited ultralight characteristics. The infusion of Ag NPs into aerogel is expected to provide antimicrobial properties, and its performance will be the focus of future studies.

Technical Abstract: Nanofiber-silver hybrid and ultralight silver-infused aerogel were produced using cotton gin trash (CGT), an abundant agro-waste material. This repurposing of CGT was achieved by exploiting its potential for nanofiber extraction and the in situ synthesis of silver nanoparticles (Ag NPs). Nanofibers were extracted from CGT through a mechanical shearing process. These CGT nanofibers served as a multifunctional nanotemplate for controlled reduction of Ag ions, efficient nucleation, and stabilization of NPs, resulting in the production of a high concentration of Ag NPs (ca. 19 wt%) in the nanofibers. Transmission electron microscopy images of cross-sectioned nanofibers confirmed the uniform dispersion of NPs (ca. 18 nm diameter) inside the nanofibers. Rietveld refinement analysis of X-ray diffraction patterns revealed that CGT nanofibers produced smaller Ag crystallites compared to CGT microparticles. The CGT nanofiber-Ag hybrid was then fabricated into an aerogel using freeze-drying, with its weight being light enough to rest on a cotton flower’s stamen (0.01 g/cm3). The infusion of Ag NPs led to approximately 20% reductions in the surface area and pore volume of the aerogel.