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[en] Highlights: ► Dosing strategies for a photo-Fenton process were evaluated. ► The dosing strategy had no effect of on the decolorization. ► The type of strategy influenced SUVA index, toxicity reduction and biodegradability. ► A continuous reagents supply was found to be the most adequate strategy. ► Decolorization as well as a less toxic and biodegradable effluent was produced. - Abstract: Three reagent dosing strategies used in the solar photo-assisted decolorization of a mixture of sulfonated dyes consisting of acid blue 113, acid orange 7 and acid red 151 were evaluated. Results demonstrated that the dosing strategy influenced both reagent consumption and the biodegradability and toxicity of the effluent. In one strategy (E1), the Fenton's reactants were dosed in a punctual mode, while in the other two strategies (E2 an E3), the reactants were dosed continuously. In the E2 strategy the reactants were dosed by varying the duration of the injection time. In the E3 strategy, the reactants were dosed during 60 min at a constant rate, but with different concentrations. All cases showed that feeding the reactor between 40% and 60% of the maximal dose was sufficient to decolorize more than 90% of the mixture of azo dyes. The E1 strategy was less effective for aromatic content reduction. Conversely, the continuous addition of the reagents (E2 and E3 strategies) improved the aromatic content removal. E3 strategy was substantially more appropriate than E1 strategy due to improved the effluent quality in two key areas: toxicity and biodegradability.
[en] The studies of any possibility that heavy metals such as copper (Cu), lead (Pb), cadmium (Cd), chromium (Cr), iron (Fe), zinc (Zn), manganese (Mn) and nickel (Ni) and other azo dyes such as Reactive Orange 16, Red 106 and Yellow 42 will interfere the measurement of RB5 using the differential pulse cathodic stripping voltammetry (DPCSV) technique are described. This study is a part of method development for voltammetric determination of RB5 which will be used to analyze wastewaters from batik industry. A 2 mg/L RB5 was firstly scanned under the optimum parameters, followed by addition of a series of concentration from 2 to 5 mg/L of each metals and other reactive azo dyes standard solutions into voltammetric cell containing 2 mg/L RB5. Results show that the present of 2 mg/L Fe, 3 mg/L Cu and more than 3 mg/L Ni, Mn, Pb, Cd, Zn and Cr have interfered the measurement of 2 mg/L RB5. All azo dyes at 2 mg/L level interfered the measurement of RB5. (author)
[en] One of three diazo dyes with the same fundamental structure have been used in most studies of DNAPL behavior in porous media to stain the NAPL: Sudan III, Sudan IV, or Oil-Red-O. The dyes are generally implicitly assumed to not influence DNAPL behavior. That assumption was tested using simple entry pressure experiments
[en] A new mechanism controlling the molecular motion in thin azo-containing films during a photoinduced change in the surface nanorelief is found. It is shown experimentally that exposure of a solid AD-1 azo dye, deposited on a glass substrate, to incoherent linearly polarised light leads to formation of nanostructures with a characteristic size of 200 nm, which are similar to droplets of melt of this dye on the same substrate. It is shown that photoinduced mass transport in a solid AD-1 azo dye film can be explained by the mobility of molecules related to their trans-cis-photoisomerisation, which leads to film softening with subsequent formation of spherical protrusions under surface tension forces.
[en] To identify the enzymes potentially useful for the decolorization of azo dyes, the secretome of the ascomycetous fungus Myrothecium roridum IM6482 was studied by using a bottom-up proteomic approach. Among the identified proteins, the most promising for dye removal was laccase, which decolorized respectively, 66, 91, 79, and 80% of Acid Blue 113 (AB 113), Acid Red 27 (AR 27), Direct Blue 14 (DB 14), and Acid Orange 7 (AO 7). The degradation of dyes was enhanced at the wide range of pH from 4 to 8. The addition of redox mediators allowed eliminating AB 113 in concentrations up to 400 mg/L and decolorization of the simulated textile effluent. Microbial toxicity and phytotoxicity tests indicated that dyes are converted into low-toxicity metabolites. This is the first insight into the M. roridum secretome, its identification and its application for removal of select azo dyes. Obtained results extended knowledge concerning biodegradative potential of ascomycetous, ligninolytic fungi and will contribute to the improvement of dye removal by fungi.
[en] A microstructured hollow core negative curvature fibre containing photoaligned layers of SD1 azo dye has been proposed and fabricated. The presence of SD1 azo dye in the fibre structure leads to a spectral shift of photonic bandgaps to longer wavelengths in accordance with the numerical results. After irradiation by external UV light the fibre exhibits a dependence of spectral shift of photonic bandgaps and amplitude change on guided light polarisation. (letter)
[en] Two new series of azo reactive dyes containing labile chlorine atoms have been synthesized. The synthetic methodology involved the diazotization of 4-nitro-2-aminophenol (2) and 4-aminobenzene sulfonic acid (7), followed by azo coupling in alkaline medium with 1-amino-8-naphthol-3,6-disulphonic acid (3) and 7-amino-1-hydroxy naphthalene-3-sulfonic acid (8) respectively. The latter on condensation of key intermediates 4 and 9 with 1,3,5-trichlorotriazine afforded the cyanurated dyes (5, 10). A number of separately synthesized novel bis aromatic diamines (1a-i) were coupled with (5 and 10) at room temperature to achieve the targeted dyes 6a-h and 11a-h, respectively. Structures of newly synthesized compounds were confirmed by the spectral and elemental analysis. The dyes were applied on cotton fibers to assess their application properties, and were shown to possess high values of light fastness, wash fastness and rubbing fastness. (author)
[en] Interaction of toluidine blue (TB), a biologically potent cationic phenothiazinium dye, with anionic surfactant, sodium bis(2-ethylhexyl) sulfosuccinate (AOT) have been thoroughly studied employing absorption and emission spectroscopy. A completely distinct spectral behavior of TB has been observed corresponding to pre-micellar and post-micellar region of AOT. Steady-state fluorescence anisotropy measurement has been carefully undertaken to rationalize the spectroscopic results. Effect of γ-cyclodextrin (γ-CD) on the spectral properties of TB has also been encountered for understanding of binding interaction between them. Molecular docking study has been accomplished to enlighten the probable orientation of TB inside the γ-CD core. Here particular interest has been focused on a mixed system, composed of AOT pre-micelles and γ-CD. A remarkable diminution of both absorption and emission intensities of TB has been observed in AOT pre-micelle with a simultaneous colorimetric change of TB solution from dark blue to lavender, and subsequent addition of γ-CD results in enhancement of intensities with dramatic reversal of the lavender colored solution to the original dark blue color. The emission characteristics of TB in the presence of AOT and γ-CD may prove as promising for an ‘IMPLICATION’ logic gate which may perform a significant role in the field of molecular electronics.