Scholarly Work - Mechanical & Industrial Engineering
Permanent URI for this collectionhttps://scholarworks.montana.edu/handle/1/8878
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Item Role of sodium sulfate in electrical conductivity and structure of lignin-derived carbons(Elsevier BV, 2024-08) Kane, Seth; Hodge, David B.; Saulnier, Brian; Bécsy-Jakab, Villő Enikő; Dülger, Dilara N.; Ryan, CecilyLignin is a promising renewable alternative to fossil fuels for producing carbon materials such as carbon fibers, activated carbons, or carbon black. Despite extensive research, lignin-derived carbon materials show limited graphitization relative to comparable petroleum-derived carbons. Further, lignin-derived carbons show high variation in graphitization and electrical conductivity depending on the source of the lignin. Herein, nine lignins, derived from various feedstocks and isolation procedures, are pyrolyzed to produce biochar at 1100∘C. These lignins have a range of chemical compositions, carbon structures, and particle sizes. As a result, the pyrolysis behavior of these lignins varies, with powdered, clumped powder, and “foam” biochar morphologies resulting from finely powdered lignin. The produced biochars vary widely in both electrical conductivity, from 0.19 to 19 S/cm, and in-plane graphitic crystallite size, from 3.4 to 41.2Å. A significant decrease in electrical conductivity is identified when Na2SO4 is removed from lignin, accompanied by an increase in graphitic crystallite size. Based on this finding, a quadratic relationship between biochar graphitic crystallite aspect ratio and electrical conductivity is proposed that builds on established quasi-percolation models for biochar electrical conductivity.Item Evaluation of the bonding properties between low-value plastic fibers treated with microbially-induced calcium carbonate precipitation and cement mortar(Elsevier BV, 2022-11) Espinal, Michael; Kane, Seth; Ryan, Cecily; Phillips, Adrienne J.; Heveran, ChelseaPlastic fiber reinforced cementitious materials offer the potential to increase the reusability of plastic waste and create lower-CO2 cementitious composites. However, the bonding properties of many plastic types with ordinary Portland cement (OPC) are largely unknown. This work employs single fiber pullout (SFPO) tests to quantify the interfacial bonding properties of polyvinyl chloride, low-density polyethylene, polypropylene, polystyrene, and acrylonitrile butadiene styrene embedded in OPC mortar. The interfacial bonding properties were compared for fibers either treated with microbially-induced calcium carbonate precipitation (MICP) or left untreated. SFPO tests revealed that plastic type had a large influence over bonding properties. Specifically, the fiber surface energy, as estimated from water contact angle measurements, was found to be the driving factor of bond strength. ABS had the highest surface energy and demonstrated the strongest bonding out of all plastic types studied. However, MICP treatment of fibers did not increase the interfacial bond strength for any of the plastics studied. The thick and inconsistent coverage of biomineral over the fiber surface from MICP is likely attributed to preventing an increase in bond strength. These results contribute to the design and application of plastic-reinforced mortars by comparing bonding properties for a range of typically low-value, unrecycled plastic types.Item Biochar as a Renewable Substitute for Carbon Black in Lithium-Ion Battery Electrodes(American Chemical Society, 2022-09) Kane, Seth; Storer, Aksiin; Xu, Wei; Ryan, Cecily; Stadie, Nicholas P.Lignin-derived biochar was prepared and characterized toward potential applications as a conductive electrode additive and active lithium host material within lithium-ion batteries (LIBs). This biochar was specifically selected for its high electrical conductivity, which is comparable to that of common conductive carbon black standards (e.g., Super P). Owing to its high electrical conductivity, this biochar serves as an effective conductive additive within electrodes comprising graphite as the active material, demonstrating slightly improved cell efficiency and rate capability over those of electrodes using carbon black as the additive. Despite its effectiveness as a conductive additive in LIB anodes, preliminary results show that the biochar developed in this work is not suitable as a direct replacement for carbon black as a conductive additive in LiFePO4 cathodes. This latter insufficiency may be due to differences in particle geometry between biochar and carbon black; further optimization is necessary to permit the application of biochar as a general-purpose conductive additive in LIBs. Nevertheless, these investigations combined with an assessment of greenhouse gas emissions from biochar production show that replacing carbon black with biochar can be an effective method to improve the sustainability of LIBs.Item Biochar as a Renewable Substitute for Carbon Black in Lithium-Ion Battery Electrodes(American Chemical Society, 2022-09) Kane, Seth; Storer, Aksiin; Xu, Wei; Ryan, Cecily; Stadie, Nicholas P.Lignin-derived biochar was prepared and characterized towards potential applications as a conductive electrode additive and active lithium host material within lithium-ion batteries (LIBs). This biochar was specifically selected for its high electrical conductivity, which is comparable to that of common conductive carbon black standards (e.g., Super P). Owing to its high electrical conductivity, this biochar serves as an effective conductive additive within electrodes comprised of graphite as the active material, demonstrating slightly improved cell efficiency and rate capability over electrodes using carbon black as the additive. Despite its effectiveness as a conductive additive in LIB anodes, preliminary results show that the biochar developed in this work is not suitable as a direct replacement for carbon black as a conductive additive in LiFePO4 (LFP) cathodes. This latter insufficiency may be due to differences in particle 2 geometry between biochar and carbon black; further optimization is necessary to permit the application of biochar as a general-purpose conductive additive in LIBs. Nevertheless, these investigations combined with an assessment of greenhouse gas emissions from biochar production show that replacing carbon black with biochar can be an effective method to improve the sustainability of LIBs.Item Physical and chemical mechanisms that influence the electrical conductivity of lignin-derived biochar(2021-10) Kane, Seth; Ulrich, Rachel; Harrington, Abigail; Stadie, Nicholas P.; Ryan, Cecily A.Lignin-derived biochar is a promising, sustainable alternative to petroleum-based carbon powders (e.g., carbon black) for polymer composite and energy storage applications. Prior studies of these biochars demonstrate that high electrical conductivity and good capacitive behavior are achievable. However, these studies also show high variability in electrical conductivity between biochars (– S/cm). The underlying mechanisms that lead to desirable electrical properties in these lignin-derived biochars are poorly understood. In this work, we examine the causes of the variation in conductivity of lignin-derived biochar to optimize the electrical conductivity of lignin-derived biochars. To this end, we produced biochar from three different lignins, a whole biomass source (wheat stem), and cellulose at two pyrolysis temperatures (900 °C, 1100 °C). These biochars have a similar range of conductivities (0.002 to 18.51 S/cm) to what has been reported in the literature. Results from examining the relationship between chemical and physical biochar properties and electrical conductivity indicate that decreases in oxygen content and changes in particle size are associated with increases in electrical conductivity. Importantly, high variation in electrical conductivity is seen between biochars produced from lignins isolated with similar processes, demonstrating the importance of the lignin’s properties on biochar electrical conductivity. These findings indicate how lignin composition and processing may be further selected and optimized to target specific applications of lignin-derived biochars.Item Biomineralization of Plastic Waste to Improve the Strength of Plastic-Reinforced Cement Mortar(2021-04) Kane, Seth; Thane, Abby; Espinal, Michael; Lunday, Kendra; Armagan, Hakan; Phillips, Adrienne J.; Heveran, Chelsea M.; Ryan, Cecily A.The development of methods to reuse large volumes of plastic waste is essential to curb the environmental impact of plastic pollution. Plastic-reinforced cementitious materials (PRCs), such as plastic-reinforced mortar (PRM), may be potential avenues to productively use large quantities of low-value plastic waste. However, poor bonding between the plastic and cement matrix reduces the strength of PRCs, limiting its viable applications. In this study, calcium carbonate biomineralization techniques were applied to coat plastic waste and improved the compressive strength of PRM. Two biomineralization treatments were examined: enzymatically induced calcium carbonate precipitation (EICP) and microbially induced calcium carbonate precipitation (MICP). MICP treatment of polyethylene terephthalate (PET) resulted in PRMs with compressive strengths similar to that of plastic-free mortar and higher than the compressive strengths of PRMs with untreated or EICP-treated PET. Based on the results of this study, MICP was used to treat hard-to-recycle types 3–7 plastic waste. No plastics investigated in this study inhibited the MICP process. PRM samples with 5% MICP-treated polyvinyl chloride (PVC) and mixed type 3–7 plastic had compressive strengths similar to plastic-free mortar. These results indicate that MICP treatment can improve PRM strength and that MICP-treated PRM shows promise as a method to reuse plastic waste.