Adsorption of whitening agents on cellulose fibers — Monitored by streaming potential measurements,calorimetry and fluorescence |
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| Authors: | K K Stana C Pohar V Ribitsch |
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| Institution: | (1) Institute of Textile Chemistry, University Maribor, Slovenia;(2) Department of Chemistry and Chemical Technology, University Ljubljana, Slovenia;(3) Department of Physical Chemistry, University Graz, Heinrichstraße 28, 8010 Graz, Austria |
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| Abstract: | Fluorescent whitening agents (FWA) are used to improve the whiteness of cellulose fabrics. It is well known but not completely understood that the fluorescence decreases (chemical and physical mechanisms of distinguishing) above a certain FWA concentrationc
crit. This reduction of fluorescence correlates very well with the alteration of the adsorption process studied by calorimetry and zeta potential measurements. The results obtained by these methods indicate that the adsorption mechanism is different at concentrations below and abovec
crit. The reduction of the intensity of fluorescence, the degree of whiteness and the zeta potential are caused by the adsorption of a second layer of fluorescent whitening agents. This second layer reduces the zeta potential due to a shielding effect and reduces the whiteness and fluorescence by a bathochromic shift of the reflection curves. The final effect is a reduction of the total reflection. |
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| Keywords: | Cotton fibers dye adsorption calorimetry zeta potential fluorescence degree of whiteness |
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