Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 4

Number of results on page
first rewind previous Page / 1 next fast forward last

Search results

Search:
in the keywords:  gypsum
help Sort By:

help Limit search:
first rewind previous Page / 1 next fast forward last
1
Publication available in full text mode
Content available

CHITOSAN APPLIED FOR GYPSUM MODIFICATION

100%
Mucha M., Mróz P., Wrona D.
Progress on Chemistry and Application of Chitin and its Derivatives
|
2017
|
vol. 22
166 - 175
EN
In order to improve the properties of gypsum materials, including workability, mechanical strength and ability to retain water, various admixtures (also polymers), known as plasticisers, have been applied. These polymers can be soluble in water, such as cellulose and starch ethers, or unsoluble applied in a form of dispersion up to 5% of weight fraction. The admixtures are added into initial water and mixed with hemihydrate calcium sulphate in a proper ratio. In the hydration process of the hemihydrate into dehydrate, a crystallisation process leading to gypsum setting occurs. In the present work, a chitosan sample of DD=85% in two forms was applied: dissolved in 1% acetic acid and as a water dispersion in the weight fraction up to 1% of the gypsum matrix. The water to gypsum ratios of 0.6 or 0.74 was applied. The influence of chitosan on the rate of setting and kinetics of crystallisation of gypsum was investigated and discussed. The morphological structure of the resulting gypsum sample was examined using SEM microscopy. In the presented results, chitosan in the form of a 1% dispersion was a setting retardant and it changed the morphological structure of gypsum. However, mechanical tests showed a decrease of bending strength. When chitosan was applied as a biomaterial, the chitosan content in the composite was equal to 10%, and thus a compressing strength increased. The presence of PVA (polyvinyl alcohol) in the gypsum matrix caused a small effect on gypsum setting in contrast to PVAc (polyvinyl acetate), which is a good admixture for both cement and gypsum [2,3].
2
Content available remote

Preliminary studies of photocatalytic activity of gypsum plasters containing TiO2co-modified with nitrogen and carbon

100%
Janus M., Bubacz K., Zatorska J., Kusiak-Nejman E., Czyżewski A., Morawski A. W.
Polish Journal of Chemical Technology
|
2015
|
vol. 17
|
issue 2
96-102
EN
The conducted studies were focused on the development of the gypsum material exhibiting self-cleaning properties. To this end, the raw gypsum was mixed with unique TiO2-based photocatalysts, previously modified by nitrogen and/ or carbon doping. The photocatalytic activity of the obtained gypsum plasters was evaluated trough the degradation of model organic compound (Reactive Red 198) under UV-vis irradiation. The impact of the photocatalysts presence on the physicochemical properties of the obtained gypsum plasters was evaluated. Furthermore, the role of non-metals presence on the photocatalytic properties of the TiO2 was determined. It was confirmed that the addition of N,C co-modified titanium dioxide into gypsum bestows this material with self-cleaning properties. The highest dye removal rate was displayed by the gypsum plaster containing optimal amount (10 wt%) of co-modified TiO2/N,C photocatalyst, after 20 hours of UV-vis irradiation.
3
Content available remote

Utilization of waste gypsum in fertilizer production

86%
Malinowski P., Borowik M., Wantuch W., Urbańczyk L., Dawidowicz M., Biskupski A.
Polish Journal of Chemical Technology
|
2014
|
vol. 16
|
issue 1
45-47
EN
The results of the study regarding utilization of the waste gypsum formed as a by-product during the production of the magnesium sulphate from dolomite have been presented. The use of this waste have been proposed for the production of granulated multi-component fertilizers containing 25% N; 8% S; 14% CaO and 3.5% MgO. In the process of fertilizer production, the urea which will be bounded with the calcium and magnesium sulphate from the waste in the form of adducts of CaSO4 . 4CO(NH2)2 and MgSO4 . CO(NH2)2 . 3H2O will be the source of nitrogen in the fertilizer. It has been stated on the basis of the laboratory tests that the fertilizer with the assumed composition can be obtained by means of granulation of the raw material pulp, along with the dried and ground product return. The possibility of the production of the fertilizer with good physical properties according to the assumed concept has been confirmed in the pilot scale
4
Content available remote

Preparation methods of calcium sulphate and urea adduct

86%
Malinowski P., Biskupski A., Głowiński J.
Polish Journal of Chemical Technology
|
2007
|
vol. 9
|
issue 4
111-114
EN
The paper presents the results of laboratory studies on the preparation of calcium sulphate and urea adduct by: grinding, compacting and mixing in the presence of physical water. A method for the measurement of urea conversion into the adduct form, which is based on the difference in solubility of free urea and the adduct bound urea CaSO4·4CO(NH2)2 in n-butanol, was developed. Mixing the reagents in the presence of physical water produced the best results. High urea conversion into the adduct form, over 85%, in the prepared samples indicates that this method can be successfully used to get CaSO4·4CO(NH2)2 adduct.
first rewind previous Page / 1 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.