Efficacy of sumo fly ash as a filler material in plastic composite

Authors: BORDOLOI, SANANDAM - University Of Illinois; PRAJAPATI, RAVINDRA - University Of Illinois; ZHAO, LINDUO - University Of Illinois; Sharma, Brajendra - Bk; RAJAGOPALAN, NANDAKISHORE - University Of Illinois; BAROI, CHINMOY - University Of Illinois

Submitted to: ACS Sustainable Chemistry & Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/2/2024
Publication Date: 7/14/2024
Citation: Bordoloi, S., Prajapati, R., Zhao, L., Sharma, B.K., Rajagopalan, N., Baroi, C. 2024. Efficacy of sumo fly ash as a filler material in plastic composite. ACS Sustainable Chemistry & Engineering. https://doi.org/10.1016/j.conbuildmat.2024.137333.
DOI: https://doi.org/10.1016/j.conbuildmat.2024.137333

Interpretive Summary: The fly ash generated in coal power plants needs to be disposed of properly. Even proper landfill disposal poses environmental hazards due to the high leaching potential. Utilization of this fly ash currently is very low (16%), therefore it will be beneficial to increase the utilization not only to power plant operators, but also the general public in order to avoid surface and groundwater contamination. One of the ways for its utilization is as filler materials for polymers. This study evaluates the coating of fly ash using polymer made from vegetable oils and sulfur followed by their characterization, leaching potential, and filler in polymers. The results from this study will help identify the suitable coating of fly ash with modified vegetable oils to increase the compatibility with the polymer matrix and decrease the leaching potential for their use as a filler in polymers. This work will improve the economic value of waste cooking oil, and increase the utilization of vegetable oils, thereby increasing the demand for farm products. Further, this will help divert the fly ash from landfills and increase its beneficial usage.

Technical Abstract: Modifying fly ash (FA) for filler application can facilitate high volume and high value-application of FA. One of the major hurdles of utilizing unencapsulated FA as fillers is due to its hydrophilicity and tendency to leach out metals. The current study aims to develop a surface-modified FA (SuMo FA) as a suitable filler by coating it with a cross-linked polysulfide polymer from waste sulphur and oil derivatives. A Class F FA was coated with an in-house developed polysulfide polymer and was followed by a series of physicochemical analysis and 24-h batch leaching tests. This SuMo FA was compounded within PP and PE matrix and its thermo-mechanical properties were evaluated. The novel SuMo FA was ideal for filler application as it exhibited suitable spherical shape and size, hydrophobicity (contact angle '120°), and reduced leaching potential. Major contaminants (B, Cr, Pb, and Sr) in leachate of SuMo FA decreased by more than one order. Compounding the SuMo FA in polypropylene (PP) and polyethylene (PE) at 20% (by weight) increased the onset temperature as compared to virgin polymers as well as filler-based polymers (with uncoated FA and CaCO3). Similarly, the SuMo FA filled polymers exhibited the best overall mechanical properties (under flexural and tensile loading) as well as notch impact strength. The Shore D hardness implies that SuMo FA filled polymers were almost identical to the conventionally used CaCO3 filled polymers. The developed filler material from the SuMo FA can potentially reduce dependence on relatively costly CaCO3 fillers in polymer production thus adhering to the United Nations sustainable development goals (6 and 12).