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The Reaction Mechanisms and Kinetics of Removing Azo Reactive Dye by Indirect Photolysis Approaches
Author(s) -
Tsui S. M.,
Chu W.
Publication year - 2002
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143002x140288
Subject(s) - photodissociation , kinetics , chemistry , photochemistry , degradation (telecommunications) , chemical kinetics , reactive dye , organic chemistry , computer science , physics , quantum mechanics , telecommunications , dyeing
The photodegradation of azo reactive dye (RR2) in the presence of acetone (ACE) or triethylamine (TEA) via indirect photolysis was investigated. Photolytic experiments were conducted in a merry‐goround photoreactor with 253.7‐nm monochromatic UV lamps. The photodegradation of RR2 in aqueous ACE or TEA solution was found to be kinetically controlled by pseudo‐first‐ and zero‐order kinetics, respectively. Typically, the photodegradation reaction is more favorable at higher pH. In the presence of TEA, the rate enhancement primarily is a result of the electron transfer from TEA to RR2 and results in the photoreduction of dye chromophore. Photosensitization is likely the dominant mechanism in the presence of ACE. With respect to the decoloration rate, ACE proved to be a promising rate enhancer at elevated concentrations, and the solution color faded rapidly within 5 minutes of retention time. The photodecoloration of RR2 was found to co‐occur with photodechlorination and was followed by photodesulfonation at a later stage in which the mineralized end products, including hydrogen, chloride, and sulphorate ions, were detected in approximately stoichiometric amounts.