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Metachromasy as an indicator of photostabilization of methylene blue adsorbed to clays and minerals.
J Photochem Photobiol B
; 121: 23-6, 2013 Apr 05.
Article
in English
| MEDLINE
| ID: mdl-23474529
ABSTRACT
The influence of methylene blue adsorption to different clays on its photodegradation was studied. Methylene blue in solution was decomposed by sunlight in a zero-order process. Adsorption to some clay minerals (sepiolite and vermiculite) and a zeolite (clinoptilolite) accelerated the degradation process, and converted it to a first-order reaction. On the other hand, adsorption to other clay minerals (palygorskite and montmorillonite) stabilized the dye and prevented its degradation. Interestingly, in the clay-dye complexes that exhibited stability, clear metachromasy of the adsorbed methylene blue occurred, whereas the effect was not observed in the clay-dye complexes that underwent photodegradation.