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Kinetics and Mechanism Study of Chemical Treatment of Methylene Green by Urea
Author(s) -
Ahmed Tehseen,
Uddin Fahim,
Azmat Rafia
Publication year - 2010
Publication title -
chinese journal of chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.28
H-Index - 41
eISSN - 1614-7065
pISSN - 1001-604X
DOI - 10.1002/cjoc.201090141
Subject(s) - chemistry , methylene blue , kinetics , urea , alkali metal , methylene , inorganic chemistry , ion , nuclear chemistry , reactive dye , base (topology) , medicinal chemistry , catalysis , organic chemistry , photocatalysis , mathematical analysis , physics , mathematics , quantum mechanics , dyeing
The kinetics and mechanism studies, for the reduction of methylene green (MG) by urea, in acidic and alkali media, were studied at λ max =652.8 nm by monitoring the depletion in MG concentration. The reaction was carried out by UV radiation, with variable dye concentration, reducing agent (urea), acid and base under different additive ions that are very common in dye waste water. The reduction followed pseudo first‐order kinetics with respect to different anions, cations, dye, reductant and OH − ion concentrations. It was found that most of the cations tested showed the inhibitory effect on dye decoloration, due to the formation of insoluble precipitate and followed the order K + >Na + >Al 3+ >Ca 2+ ≈Mg 2+ . Tested anions showed that the dye decoloration was significantly accelerated and followed the order Cl − >Br − >I − >NO − 3 >SO 2− 4 . A mechanistic model involving generation of a complex of dye with ions was proposed.