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Aspects of solid-state chemistry of fly ash and ultramarine pigments
Thesis (PhD(Chemistry))--University of Pretoria, 2005.
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University of Pretoria
2013
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| _version_ | 1867613529852346368 |
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| access_status_str | Open Access |
| author2 | De Waal, Danita |
| author_browse | De Waal, Danita |
| author_facet | De Waal, Danita |
| collection | Thesis |
| dc_rights_str_mv | © 2006, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Thesis (PhD(Chemistry))--University of Pretoria, 2005. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/25229 |
| institution | University of Pretoria (South Africa) |
| last_indexed | 2026-06-10T12:37:36.202Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2013 |
| publishDateRange | 2013 |
| publishDateSort | 2013 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/25229 Aspects of solid-state chemistry of fly ash and ultramarine pigments De Waal, Danita alandman@postino.up.ac.za Landman, Andreas Adriaan Fly ash Solid-state Ultramarine Modelling UCTD Thesis (PhD(Chemistry))--University of Pretoria, 2005. Ultramarine pigments are aluminosilicate-based and contain sulphur-based chromophores. Several samples from two batches of fine fly ash, a predominantly aluminosilicate waste product of coal combustion, were used successfully to synthesise ultramarine blue. This was confirmed by infrared, Raman and X-ray diffraction results. Fly ash had the advantage of being amorphous, whereas the traditional starting reagent, kaolin, needed to be heat-treated before the ultramarine synthesis to weaken its structure. A comparison of the scanning electron micrographs of fly ash, fly ash treated at 1 000°C, fly ash reacted with sodium carbonate at 860°C and the ultramarine products showed that sulphur had a structure-directing effect. The sulphur clusters found in ultramarine pigments were studied by Self-Consistent-Field Hartree-Fock theory extended by Møller-Plesset second order perturbation theory at the minimum energy with the 6-311G** basis set to determine the relative stability of S2 , S2-• , S22-, and S3, S3-•, S32-. The singly charged species were the most stable in both sets, supporting the hypothesis that the exothermic transition from green to blue ultramarine was the transformation of the doubly charged species to the singly charged species. The open, C2v, isomer was most stable for the S3-• molecule - the blue ultramarine chromophore. The S4 molecule was a likely chromophore in ultramarine red. A Woodward-Hoffmann analysis supported the concerted formation of the puckered square S4 , pyramidal S4 , and gauche S4 chain isomers. Other possible species for the red chromophore were S4 -, S3 , S3 Cl, S3 Cl-, S2 Cl, S2 O, and S2 O-. On the basis of their calculated vibrational spectra most of the species could be discounted as possible red chromophores. The best candidate chromophore was the cis S4 chain based on the computed electronic spectrum. Chemistry unrestricted 2013-09-06T19:55:06Z 2004-09-30 2013-09-06T19:55:06Z 2006-06-04 2005-09-30 2004-06-04 Thesis Landman, A 2006, Aspects of solid-state chemistry of fly ash and ultramarine pigments, PhD(Chemistry) thesis, University of Pretoria, Pretoria, viewed yymmdd < http://hdl.handle.net/2263/25229 > http://hdl.handle.net/2263/25229 http://upetd.up.ac.za/thesis/available/etd-06042004-062900/ © 2006, University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf application/pdf University of Pretoria |
| spellingShingle | Fly ash Solid-state Ultramarine Modelling UCTD Aspects of solid-state chemistry of fly ash and ultramarine pigments |
| title | Aspects of solid-state chemistry of fly ash and ultramarine pigments |
| title_full | Aspects of solid-state chemistry of fly ash and ultramarine pigments |
| title_fullStr | Aspects of solid-state chemistry of fly ash and ultramarine pigments |
| title_full_unstemmed | Aspects of solid-state chemistry of fly ash and ultramarine pigments |
| title_short | Aspects of solid-state chemistry of fly ash and ultramarine pigments |
| title_sort | aspects of solid state chemistry of fly ash and ultramarine pigments |
| topic | Fly ash Solid-state Ultramarine Modelling UCTD |
| url | http://hdl.handle.net/2263/25229 http://upetd.up.ac.za/thesis/available/etd-06042004-062900/ |