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The Employment of a Removable Chitosan‐Derivatized Polymeric Sensitizer in the Photooxidation of Polyhydroxylated Water‐Pollutants
Author(s) -
Ferrari Gabriela V.,
Andrada María E.,
Natera José,
Muñoz Vanesa A.,
Paulina Montaña M.,
Gambetta Carolina,
Boiero María L.,
Montenegro Mariana A.,
Massad Walter A.,
García Norman A.
Publication year - 2014
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/php.12350
Subject(s) - photodegradation , chemistry , polymer , photochemistry , solvent , rose bengal , context (archaeology) , reaction rate constant , covalent bond , cationic polymerization , chitosan , photocatalysis , polymer chemistry , organic chemistry , catalysis , kinetics , paleontology , physics , quantum mechanics , biology
The known O 2 ( 1 ∆ g )‐sensitizer system Chitosan bounded Rose Bengal (CH‐RB), with Rose Bengal (RB) immobilized by irreversible covalent bonding to the polymer Chitosan (CH), soluble in aquous acidic medium, was employed in the photodegradation of three tri‐hydroxy benzene water‐contaminants (THBs). The system sensitizes the O 2 ( 1 ∆ g )‐mediated photodegradation of THBs by a process kinetically favored, as compared to that employing free RB dissolved in the same solvent. Additionally the free xanthene dye, degradable by O 2 ( 1 ∆ g ) through self‐sensitization upon prolonged light‐exposure, is considerably protected when bonded to CH‐polymer. The polymeric sensitizer, totally insoluble in neutral medium, can be removed from the solution after the photodegradative cycle by precipitation through a simple pH change. This fact constitutes an interesting aspect in the context of photoremediation of confined polluted waters. In other words, the sensitizing system could be useful for avoiding to dissolve dyestuffs in the polluted waters, in order to act as conventional sunlight‐absorbing dye‐sensitizers. In parallel the interaction CH ‐ O 2 ( 1 ∆ g ) in acidic solution was evaluated. The polymer quenches the oxidative species with a rate constant 2.4 × 10 8 M −1 s −1 being the process mostly attributable to a physical interaction. This fact promotes the photoprotection of the bonded dye in the CH‐RB polymer.