Effect of alkali on methylene blue (C.I. Basic Blue 9) and other thiazine dyes

Mills, Andrew; Hazafy, David; Parkinson, John A.; Tuttle, Tell; Hutchings, Michael G.

doi:10.1016/j.dyepig.2010.05.015

Cited by 100 publications

(63 citation statements)

References 35 publications

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“…According to Mills et al [36] who reported acidic properties of MB, the first protonation of the phenothiazine dyes takes place at the heterocyclic nitrogen atom leading to a batochromic shift in λ max :…”

Section: Resultsmentioning

confidence: 98%

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Sulfuric acid controlled oxidative degradation of azure B and thionine dyes by cerium(IV)

Katafias

Fenska

2011

Int J of Chemical Kinetics

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Azure B (AB) and thionine (TH) cationic phenothiazyne dyes undergo an oxidative degradation by cerium(IV) in sulfuric acid media. TLC analysis of the reaction mixture containing an excess of the oxidant has shown the presence of thionine and/or methylene violet (Bernthsen) and other unidentified species. The kinetics of (i) two AB oxidation steps, namely the formation of a colored radical and its further decomposition, and (ii) the TH disappearance was studied using visible absorption spectroscopy combined with a stopped-flow method. Generation of the AB radical was confirmed by continuous flow electron paramagnetic resonance (EPR) spectroscopy. The reactions are first order in the total dye concentration, [S]. The kinetics of the studied systems is described by a common general rate law:

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Section: Resultsmentioning

confidence: 98%

“…Starting with MB, several very wellknown stains are produced, among them azure B and thionine dyes [35,36]. In our previous paper, the kinetics of two consecutive one-electron steps of MB oxidation by cerium(IV) in sulfuric acid media was described [13].…”

Section: Resultsmentioning

confidence: 99%

Sulfuric acid controlled oxidative degradation of azure B and thionine dyes by cerium(IV)

Katafias

Fenska

2011

Int J of Chemical Kinetics

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“…10,33 To prevent the aggregation of the BB9 molecules in solution with pH values above 10, the following experiments were carried out at pH 10. 34 However, an important amount of dye was adsorbed on the weakly acidic Purolite C107E at low pH values when the carboxylic groups were protonated so that the electrostatic interaction between the negative charge of the resin and the positive charge of the dye molecules could not be considered the unique mechanism of the adsorption. This suggested that other interactions contributed to the binding of dye molecule on the resin surface, most probably hydrogen bonding between the AOH of the carboxyl groups as hydrogen donors and the nitrogen atoms from BB9 dye as hydrogen acceptors.…”

Section: Article Wileyonlinelibrarycom/appmentioning

confidence: 99%

Macroporous polymeric ion exchangers as adsorbents for the removal of cationic dye basic blue 9 from aqueous solutions

Șuteu

Bı̂lbă

Coseri

2013

J of Applied Polymer Sci

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Two macroporous cation-exchange resins, Purolite C145, a strongly acidic cation macroporous resin, and Purolite C107E, a weakly acidic cation-exchange resin, were used to remove the dye Basic Blue 9 (BB9) from an aqueous medium. Batch adsorption experiments were carried out to analyze the effect of various parameters, such as the phase contact time, initial dye concentration, initial solution pH, resin dose, and temperature. The experimental equilibrium data were evaluated by the Langmuir, Freundlich, and Dubinin-Radushkevich (DR) adsorption models. The Freundlich model better described the adsorption processes of the BB9 dye onto both cation exchangers, and the monolayer adsorption capacities were established as 31.9846 mg/g (C145) and 27.77 mg/g (C107E) at 20C. The values of the mean free adsorption energy (E) obtained from the DR model suggested a porous structure of the adsorbents and proposed ion exchange at the main mechanism of the adsorption process. The values of the thermodynamic parameters showed that the retention of the cationic dye was a spontaneous and endothermic process. Environmental scanning electron microscopy and Fourier transform infrared spectroscopy were used to characterize the sorbent and also to validate the adsorption mechanism as ion-exchange ones. The desorption experiments by a batch method were performed with different solutions: 0.1 and 1 mol/L HCl, 2.5 mol/L H 2 SO 4 , CH 3 OH, and a mixture between 1 mol/L HCl and CH 3 OH. Desorption performed with sulfuric acid was shown to be most effective because more than 85% of the adsorbed dye was removed. V C 2013 Wiley Periodicals, Inc. J. Appl.Polym. Sci. 2014, 131, 39620.

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“…It is not initially obvious why TH should exhibit such a different behaviour when heat-treated, followed by exposure to high humidity. However, the absorption spectrum of the red-coloured, dry TH film (λmax = 510 nm) is very typical of that of the organo-soluble, water-insoluble, monomeric freebase form of TH (λmax = 487 nm in toluene [29]); and TH is the only thiazine dye in Table 2 to form such a species. Thus, heat treatment appears to promote the formation of the latter, red, monomeric freebase form (λmax = 510 nm), of the thiazine dye, TH, rather than the usual cationic, monomeric/dimeric blue-purple form (λmax = 602 nm [29]), and exposure to high humidity (>100 %) promotes the conversion of the red TH to its cationic form (λmax = 610 nm), which subsequently forms an extended aggregated species like all the other thiazine dyes tested.…”

Section: Other Thiazine / Hpc Humidity Indicator Filmsmentioning

confidence: 99%