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Effects of Temperature and Concentration on the Rate of Photobleaching of Erythrosine in Water

Lookup NU author(s): Joshua Karlsson, Dr Owen Woodford, Roza Al-Aqar, Emeritus Professor Anthony Harriman



This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).


© 2017 American Chemical Society. Erythrosine, a popular food dye, undergoes fast O2-sensitive bleaching in water when subjected to visible light illumination. In dilute solution, erythrosine undergoes photobleaching via first-order kinetics, where the rate of bleaching depends critically on the rate of photon absorption and on the concentration of dissolved oxygen. Kinetic studies indicate that this inherent bleaching is augmented by self-catalysis at higher concentrations of erythrosine and on long exposure times. Under the conditions used, bleaching occurs by way of geminate attack of singlet molecular oxygen on the chromophore. Despite the complexity of the overall photobleaching process, the rate constants associated with both inherent and self-catalytic bleaching reactions follow Arrhenius-type behavior, allowing the activation parameters to be resolved. Bleaching remains reasonably efficient in the solid state, especially if the sample is damp, and provides a convenient means by which to construct a simple chemical actinometer.

Publication metadata

Author(s): Karlsson JKG, Woodford OJ, Al-Aqar R, Harriman A

Publication type: Article

Publication status: Published

Journal: Journal of Physical Chemistry A

Year: 2017

Volume: 121

Issue: 45

Pages: 8569-8576

Print publication date: 16/11/2017

Online publication date: 19/10/2017

Acceptance date: 02/04/2016

Date deposited: 18/12/2017

ISSN (print): 1089-5639

ISSN (electronic): 1520-5215

Publisher: American Chemical Society


DOI: 10.1021/acs.jpca.7b06440


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