Surface and bulk characterization of an ultrafine South African coal fly ash with reference to polymer applications

Show simple item record Van der Merwe, E.M. (Elizabet Margaretha) Prinsloo, Linda Charlotta Mathebula, Confidence Lethabo Swart, H.C. Coetsee, E. Doucet, F.J. 2014-10-10T05:27:32Z 2014-10-10T05:27:32Z 2014-10
dc.description.abstract South African coal-fired power stations produce about 25 million tons of fly ash per annum, of whichonly approximately 5% is currently reused. A growing concern about pollution and increasing landfillcosts stimulates research into new ways to utilize coal fly ash for economically beneficial applications.Fly ash particles may be used as inorganic filler in polymers, an application which generally requiresthe modification of their surface properties. In order to design experiments that will result in controlledchanges in surface chemistry and morphology, a detailed knowledge of the bulk chemical and miner-alogical compositions of untreated fly ash particles, as well as their morphology and surface properties,is needed. In this paper, a combination of complementary bulk and surface techniques was explored toassess the physicochemical properties of a classified, ultrafine coal fly ash sample, and the findings werediscussed in the context of polymer application as fillers. The sample was categorized as a Class F fly ash(XRF). Sixty-two percent of the sample was an amorphous glass phase, with mullite and quartz being themain identified crystalline phases (XRD, FTIR). Quantitative carbon and sulfur analysis reported a totalbulk carbon and sulfur content of 0.37% and 0.16% respectively. The spatial distribution of the phases wasdetermined by 2D mapping of Raman spectra, while TGA showed a very low weight loss for tempera-tures ranging between 25 and 1000◦C. Individual fly ash particles were characterized by a monomodalsize distribution (PSD) of spherical particles with smooth surfaces (SEM, TEM, AFM), and a mean par-ticle size of 4.6 m (PSD). The BET active surface area of this sample was 1.52 m2/g and the chemicalcomposition of the fly ash surface (AES, XPS) was significantly different from the bulk composition andvaried considerably between spheres. Many properties of the sample (e.g. spherical morphology, smallparticle size, thermal stability) appeared to be suitable for its applicability as filler in polymers, althoughthe wide variation in surface composition between individual particles may challenge the developmentof a suitable surface modification technique. The observation that the bulk and surface compositions ofthe particles were so intrinsically different, strongly suggested that surface characterization is importantwhen considering compatibility between matrices when applying fly ash as filler in polymers. en_US
dc.description.librarian hb2014 en_US
dc.description.sponsorship Ash Resources (Pty) Ltd (THRIP Grant number TP1207314696), the Ernst Oppenheimer Memorial Trust (Ref. 19632/01) and the National Research Foundation of South Africa (Grant num-ber TP1207314969). en_US
dc.description.uri en_US
dc.identifier.citation Van der Merwe, EM, Prinsloo, LC, Mathebula, CL, Swart, HC, Coetsee, E & Doucet, FJ 2014, 'Surface and bulk characterization of an ultrafine South African coal fly ash with reference to polymer applications', Applied Surface Science, vol. 317, pp. 73-83. en_US
dc.identifier.issn 0169-4332 (print)
dc.identifier.issn 1873-5584 (online)
dc.identifier.other 10.1016/j.apsusc.2014.08.080
dc.language.iso en en_US
dc.publisher Elsevier en_US
dc.rights © 2014 Elsevier B.V. All rights reserved. Notice : this is the author’s version of a work that was accepted for publication in Applied Surface Science. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Applied Surface Science, vol. 317, pp. 73-83, 2014. doi : 10.1016/j.apsusc.2014.08.080. en_US
dc.subject Fly ash (FA) en_US
dc.subject Bulk properties en_US
dc.subject Surface properties en_US
dc.subject Characterization en_US
dc.title Surface and bulk characterization of an ultrafine South African coal fly ash with reference to polymer applications en_US
dc.type Postprint Article en_US

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