This study was conducted on the reduction reaction of the azo dye Reactive Black 5 by means of the Mn85Al15 particles prepared by melt-spinning and ball-milling processes. The morphology, the surface elementary composition and the phase structure of the powders were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. The degradation efficiency of the ball milled powder was measured by using an ultraviolet-visible absorption spectrophotometer and the collected powder was analyzed by means of Fourier transform infrared spectroscopy technique to characterize the functional groups in the extract. The degradation of Reactive Black 5 and the analysis of the aromatic by-products were investigated by high performance liquid chromatography coupled with tandem mass spectrometry. The ball-milled powder shows higher degradation efficiency and the Reactive Black 5 solution was completely decolorized after 30 min. The degradation kinetics and the formation by-products depend on the pH and temperature of the solution. The analyses of the extracted product confirmed the cleavage of the (–N[double bond, length as m-dash]N–) bonds. Our findings are expected to pave the way for a new opportunity with regard to the functional applications of nanostructured metallic particle

The use of metallic particles has been shown to be an effective, low-cost method for degradation of many contaminating compounds. In this work, we analyze the efficiency of MnAl metallic powders for degrading azo dyes, which are the class of colorant compounds most utilized by the textile industry. We used different routes to produce the metallic particles obtaining different internal structures as characterized by X-ray diffraction and electronic microscopy. The ability to act as discoloration materials was assessed by decolorization experiments of Reactive Black 5 and Orange II azo dyes aqueous solutions. The degradation reaction of the dye molecules was monitored by ultraviolet-visible (UV) spectrophotometry showing fast kinetics, with reaction times among the shortest found in literature. The effect of the different production methods on their performance as decolorizing materials was studied as function as various parameters such as initial pH, dye concentration and temperature. The electrochemical and corrosion properties of the MnAl compounds seem to be the key factors explaining the high decolorization efficiency of these materials. *Manuscript-revised Click here to view linked References

This work studies the degradation of azo dye Reactive Black 5 by Ca-Al metallic particles prepared by melt-spinning and ball-milling. The morphology and the phase structure of the metallic powders were characterized and the decolorization efficiency of Reactive Black 5 solutions were assessed by monitoring the dye degradation by ultraviolet-visible absorption spectrophotometry. The decolorization process using the Ca-Al powders showed fast kinetics and high efficiency. 40 mg L-1 dye solution was successfully decolorized in 1 min using 0.1 g/100 mL of Ca65Al35 powder, suggesting it as an effective, low-cost means for degradation of azo-compounds.Peer ReviewedPostprint (author's final draft

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Azo compounds are used in the textile and leather industry. A significant step during the azo dyes treatment of water is the degradation by breaking the N=N bonds. This break produces the decolorization of water. In this research work, 10% atomic of Fe or Co was added to produce ternary Mn-Al-rich, nanostructured, mechanically alloyed powders in order to improve the decolorization of Reactive Black 5 solutions and to check Fe and Co addition’s influence. The microstructure was followed by X-ray diffraction, the morphology and composition by electronic microscopy and energy-dispersive X-ray spectroscopy (EDS) microanalysis. The dye degradation was monitored with ultraviolet/visible absorption spectrophotometry. After degradation, the remaining organic compound was checked by high-performance liquid chromatography (HPLC) and the functional groups of the powdered alloys by infrared spectroscopy. Fe addition to Mn-Al displayed faster kinetics and a higher efficiency than the Co addition. The Mn-Al-Fe solution (0.25 g/100 mL) was fully decolorized in 5 min. On the other side, Mn-Al-Co powders were able to successfully decolorize the dyed solution in 10 min under the same conditions. Thus, nanocrystalline Fe-doped Mn-Al alloys are good candidates for use in the decolorization process, in comparison with Co-doped and other intermetallic particles.