The influence of thermal treatment on properties of kaolin
The kinetics of dehydroxylation of South African kaolin revealed that both the inner and the surface hydroxyl groups disappear according to first order kinetics, however, the surface group disappeared faster than the inner groups, showing that diffusion control kinetics is also important. T...
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| Format: | Article |
| Language: | English |
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Association of Chemical Engineers of Serbia
2016-01-01
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| Series: | Hemijska Industrija |
| Subjects: | |
| Online Access: | http://www.doiserbia.nb.rs/img/doi/0367-598X/2016/0367-598X1500066E.pdf |
| _version_ | 1828887806936612864 |
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| author | Erasmus Elizabeth |
| author_facet | Erasmus Elizabeth |
| author_sort | Erasmus Elizabeth |
| collection | DOAJ |
| description | The kinetics of dehydroxylation of South African kaolin revealed that both
the inner and the surface hydroxyl groups disappear according to first order
kinetics, however, the surface group disappeared faster than the inner
groups, showing that diffusion control kinetics is also important. The
temperature dependent transformations of the kaolin was measure by means of
fractional conversion of the ratios between AlO6:AlO4 and Si-O-Al:Si-O-Si,
which showed kobs values 0.0168 s-1 and 0.0089 s-1 for the transformation to
the spinel phase and values of 0.0165 s-1 and 0.0156 s-1 for the
transformation to mullite respectively. The pozzolanic activities of the
kaolin calcined at different temperatures showed a maximum pozzolanic
activity when the kaolin is calcined at 650°C and the pozzolanic activity for
mullite is even less than for the uncalcined kaolin. XPS revealed that the
atomic ratio between Si and Al did not change from kaolin to metakaolin
(Si:Al = ca. 1.2) however the mullite showed a atomic ratio of Si:Al = 1.52,
implying that some deallumination occurred during calcination at high
temperatures. |
| first_indexed | 2024-12-13T12:11:16Z |
| format | Article |
| id | doaj.art-272852c332da49a28e8a5d4442922383 |
| institution | Directory Open Access Journal |
| issn | 0367-598X 2217-7426 |
| language | English |
| last_indexed | 2024-12-13T12:11:16Z |
| publishDate | 2016-01-01 |
| publisher | Association of Chemical Engineers of Serbia |
| record_format | Article |
| series | Hemijska Industrija |
| spelling | doaj.art-272852c332da49a28e8a5d44429223832022-12-21T23:46:49ZengAssociation of Chemical Engineers of SerbiaHemijska Industrija0367-598X2217-74262016-01-0170559560110.2298/HEMIND150720066E0367-598X1500066EThe influence of thermal treatment on properties of kaolinErasmus Elizabeth0University of the Free State, Department of Chemistry, Bloemfontein, Republic of South AfricaThe kinetics of dehydroxylation of South African kaolin revealed that both the inner and the surface hydroxyl groups disappear according to first order kinetics, however, the surface group disappeared faster than the inner groups, showing that diffusion control kinetics is also important. The temperature dependent transformations of the kaolin was measure by means of fractional conversion of the ratios between AlO6:AlO4 and Si-O-Al:Si-O-Si, which showed kobs values 0.0168 s-1 and 0.0089 s-1 for the transformation to the spinel phase and values of 0.0165 s-1 and 0.0156 s-1 for the transformation to mullite respectively. The pozzolanic activities of the kaolin calcined at different temperatures showed a maximum pozzolanic activity when the kaolin is calcined at 650°C and the pozzolanic activity for mullite is even less than for the uncalcined kaolin. XPS revealed that the atomic ratio between Si and Al did not change from kaolin to metakaolin (Si:Al = ca. 1.2) however the mullite showed a atomic ratio of Si:Al = 1.52, implying that some deallumination occurred during calcination at high temperatures.http://www.doiserbia.nb.rs/img/doi/0367-598X/2016/0367-598X1500066E.pdfdehydroxylationkaolinmetakaolininfra-redpozzolanic activitymullite |
| spellingShingle | Erasmus Elizabeth The influence of thermal treatment on properties of kaolin Hemijska Industrija dehydroxylation kaolin metakaolin infra-red pozzolanic activity mullite |
| title | The influence of thermal treatment on properties of kaolin |
| title_full | The influence of thermal treatment on properties of kaolin |
| title_fullStr | The influence of thermal treatment on properties of kaolin |
| title_full_unstemmed | The influence of thermal treatment on properties of kaolin |
| title_short | The influence of thermal treatment on properties of kaolin |
| title_sort | influence of thermal treatment on properties of kaolin |
| topic | dehydroxylation kaolin metakaolin infra-red pozzolanic activity mullite |
| url | http://www.doiserbia.nb.rs/img/doi/0367-598X/2016/0367-598X1500066E.pdf |
| work_keys_str_mv | AT erasmuselizabeth theinfluenceofthermaltreatmentonpropertiesofkaolin AT erasmuselizabeth influenceofthermaltreatmentonpropertiesofkaolin |