Discipline: Technology and Engineering
Subcategory: Materials Science
Room: Park Tower 8216
Shardai Johnson - Tuskege University
Co-Author(s): Vijay Rangari, Tuskegee University, Tuskegee, AL; Shaik Jeelani,Tuskegee University, Tuskegee, AL
The second-most globally traded commodity is by fare coffee. Spent coffee grounds, once utilized for soil enrichment, biofuels, and bioactive compounds, is also responsible for 11 million metric tons of biomass waste a year. Due to nutrient blocking activity of the tannins in coffee, ecology near landfills can be greatly altered after large quantities are dumped, of which methane (landfill gas) develops. Reducing and reusing the waste associated with coffee consumption will limit its negative ecological and atmospheric effects. According to literature, our protocol should result in activated carbon, but closure analysis of our data presented a compiled species of biochar, specifically Turbostractic carbon (TC), which resulted from pyritization of spent coffee grounds under high autogenic pressure. Instead of a porous structure, a heterogeneous carbon species with a mix of ordered and disordered regions formed. To synthesize our TC, locally sourced SCG was dehydrated at 90? for 70 hours to remove moisture. The SCG was then separated into 5.0g specimens and carbonized, starting at 4 MPa, in N2, with a MTI GSL-1100X-RC Hydrothermal Reactor at 15?/min to 1000? with three-hour isotherms. Samples were removed, weighed, and then characterized by Scanning Electron Microscopy (JOEL6510LV), Transmission Electron Microscopy, X-ray Diffraction, and Raman Spectroscopy. At the max temperature and isotherm, the sample mass was reduced by 70.9%. The bulk particles observed were 35?m in diameter with pore sizes ranging from 400 to 900nm. TEM micrographs showed the mixed species of the TC for particles less than 50 nm in diameter. The peaks observed in X-ray diffraction, confirm the presence of TC. Once produced, the TC and matrix polymers for the filaments were exposed to O2 low Temperature Plasma (LTP) at different times, from 30 secs to 60 minutes to modify the morphology at the surface and to determine which the best treatment time to develop composite filaments with improved mechanical properties. Treated samples were characterized with XPS after each exposure interval. Increased exposure demonstrates an increase in carbonates and adventitious carbon available for bonding. The explored technique delivers a secondary use for the SEG and reduces the ecological effects of the coffee waste. Going forward, polypropylene and poly methyl methacrylate will be used as matrix materials for the composite filaments. We will also look at the mechanical properties, hydrophobicity, and the feasibility of using the TC in additive manufacturing techniques. There will be consideration for additional applications as the project expands.
Funder Acknowledgement(s): Thank you to Dr. Shaik Jeelani and Vijaya Rangari for their continued guidance. This work is supported by Centers of Research Excellence in Science and Technology (CREST), the NSF EPSCoR RII-Track-1 Cooperative Agreement OIA-1655280 and Alabama Graduate Research Scholars Program (GRSP) funded through the Alabama Commission for Higher Education and administered by the Alabama EPSCoR. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation.
Faculty Advisor: Vijay Rangari, email@example.com
Role: I conducted all of the research described in the abstract.