During coffee cultivation, coffee cherries are harvested and the fruit is subsequently disposed of during bean preparation. Through this process, 85% of cultivated mass is lost with the discarded fruit; which is substantial considering over 10 bill. kg of beans are produced annually. Disposal of the coffee fruit poses numerous complications depending on disposal method including fermenting compost that requires costly management and harmful pesticide application, air pollution from burning, and water pollution if dumped. Thus there is intrinsic value in the circular recapture of coffee biomass through diverted waste and mitigated environmental harm. In the last 10 years, a fiber spinning method based on ionic liquids (ILs) as a cellulose solvent has been explored. The IL medium presents a new, versatile, and potentially greener means of fiber production compared to conventional methods, as well as a direct method for processing raw biomass. ILs are tunable organic salts notable for having low melting temperatures (Tm&lt;100°C), good thermal stability, and a negligible vapor pressure. ILs have been shown to be excellent cellulose solvents with feedstocks ranging from processed woodpulp, woody biomasses, and cotton-like fibers, however, it is proposed that leveraging of this technology towards low value biomass waste streams may be both economically and environmentally valuable. Using the superbase derived IL, 1,8-diazabicyclo-undec7-enium acetate ([DBUH][OAc]), we have produced fiber isolates from coffee fruit biomass with minimal purification. Thermophysical properties of [DBUH][OAc] were analyzed using differential scanning calorimeter (DSC) and rheometry and compared against incomplete literature data . Fiber isolates were also imaged using optical and scanning electron microscopy. Using this hand-drawing method, smooth fibers with diameters on the scale of ~50-300 um have been produced. Fibers were observed to have dark pigmentation due to retention of pigmented residues of the raw biomass. The precipitated isolates swell substantially in the aqueous coagulation bath, demonstrating volumetric increases as high as 190% over the dried volume. Further work is underway to characterize the fiber isolates in terms of crystallinity and how the molecular composition affects fiber properties and the overall drawing process itself.

Coffee break: High volume agriculture waste as fiber feedstocks using ionic liquid processing

ACS Fall 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.