scholarly journals Theoretical investigation on the mechanism of the OH-initiated degradation process of reactive red 2 azo dye

RSC Advances ◽  
2017 ◽  
Vol 7 (66) ◽  
pp. 41799-41811 ◽  
Author(s):  
Cheng Luo ◽  
Hongjie Wang ◽  
Wenyi Dong ◽  
Xianbing Zhang
Keyword(s):  
Theoretical Investigation ◽  
Azo Dye ◽  
Degradation Process ◽  
Nucleophilic Attack ◽  
Dual Descriptor ◽  
Electrophilic Attack ◽  
Bond Lengths ◽  
Reactive Red 2 ◽  
Hydrazone Form

The dual descriptor (Δf) data of azo form (a, RR2) and hydrazone form (b, HRR2) of RR2 dianion. For Δf> 0 (green), the site is favorable for nucleophilic attack, for Δf< 0 (blue), the site is favorable for electrophilic attack. Key bond lengths in Å.

Catalysis by supported clusters: two examples of catalytic reactions that involve a molecular cluster frame

1982 ◽  
Vol 308 (1501) ◽  
pp. 115-124 ◽  
Keyword(s):  
Catalytic Reactions ◽  
Water Gas Shift ◽  
Nucleophilic Attack ◽  
Molecular Cluster ◽  
Molecular Water ◽  
Water Gas Shift Reaction ◽  
Electrophilic Attack ◽  
Supported Clusters ◽  
Shift Reaction ◽  
Water Gas

Two examples of catalysis by supported clusters are given that involve a molecular cluster frame during the catalytic cycle. (H)Os 3 (CO) 10 (OSi^) is able to hydrogenate ethylene between 343 and 373 K. The mechanism of this reaction, which involves the molecular cluster frame, requires the opening of the bridging three-electron oxygen ligand as the key step of the catalytic process. Rh 6 (CO) 16 adsorbed on alumina is a catalyst for the water-gas shift reaction carried out between 293 and 393 K. The mechanism of this reaction involves three steps: (i) electrophilic attack by surface protons on the metallic frame with formation of Rh I (CO) 2 and Rh III (H) (H) species; (ii) reductive elimination of H 2 favoured by CO coordination to the Rh III (H) (H) species; (iii) nucleophilic attack by molecular water on CO coordinated to Rh I with regeneration of the starting cluster, release of CO 2 and surface protons.

scholarly journals Photocatalytical Degradation of Congo Red Azo Dye Using Phosphono-Aminoacid-Cd(II) Pendant Groups Grafted on a Polymeric Support

2019 ◽  
Vol 70 (10) ◽  
pp. 3473-3476 ◽  
Author(s):  
Laura Cocheci ◽  
Lavinia Lupa ◽  
Aniela Pop ◽  
Aurelia Visa ◽  
Bianca Maranescu ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Congo Red ◽  
Azo Dye ◽  
Organic Dyes ◽  
Degradation Process ◽  
Polymer Support ◽  
Polymeric Support ◽  
Vis Spectroscopy ◽  
Red Dye ◽  
Scanning Electron

In the present study, a new compound was used for decontaminating water polluted by Congo Red dye. Phosphono-aminoacid-Cd(II) pendant groups grafted on a polymeric support was prepared using impregnation of a polymer support functionalized with phosphono-aminoacid groups with an aqueous solution of Cd(NO3)2x4H2O. The catalyst was characterized by Fourier transform infrared ray, scanning electron microscope, termogravimetric analysis UV-Vis spectroscopy. The results suggest that the studied material could efficiently be used as photocatalyst in the degradation process of waters containing organic dyes under UV-Vis light irradiation.

scholarly journals EFFECT OF RADICAL SCAVENGERS AND PROPOSED PATHWAYS FOR DEGRADATION OF AZO DYE IN AQUEOUS SOLUTION UNDER PRESENCE OF IRON(III) AND PERSULPHATE

2017 ◽  
Vol 60 (4) ◽  
pp. 88
Author(s):  
Heng Zhong ◽  
Hui Zhao ◽  
Jun Li ◽  
Lei Sun ◽  
Aihua Xu ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Carboxylic Acids ◽  
Azo Dye ◽  
Water Discharge ◽  
Radical Scavenging ◽  
Degradation Process ◽  
Ionization Mass ◽  
Radical Scavengers ◽  
Acid Orange 7 ◽  
Degradation Of Azo Dye

The degradation process of Acid Orange 7 (AO7) in aqueous solutions by iron(III) under activation by persulfate (PS, S2O82-) oxidation and Visible (Vis) light (≥420 nm) exposure has been studied. The radical scavenging effect was examined by using ethanol (EtOH), tert-butyl alcohol (TBA) and sodium azide to state that the hydroxyl radical (·OH) is regarded as the predominant reactive oxidant for the AO7 decolorization, while the sulfate radical (SO4·-) and singlet oxygen(1O2) are also make their contribution to dye's degradation. The reaction intermediates were determined by electrospray ionization-mass spectrometry (ESI-MS) analysis, and a probable degradation pathway mechanism has been proposed. It was suggested, that firstly an initial successive radical attacks the N atom of the dye, which decompose to p-phenolsulfonic acid and 1,2-naphthaquinone through the contemporaneous break of two C-N bonds. Afterwards, subsequent oxidation of these products and loss of the −SO3− group are observed. Finally, the acyclic carboxylic acids are formed from the central ring-opening, and then the further oxidation to simple carboxylic acids is evident. The work can provide a simple, effective and economic system for the treatment of non-biodegradable azo dye. The recommendations were proposed on organization of an effective quality control of technological water discharge and products of its processing at the local wastewater treatment facilities of industrial plants for prevention of the ingress of hazardous biological substances to the hydrosphere.Forcitation:Heng Zhong, Hui Zhao, Jun Li, Lei Sun, Aihua Xu, Dongsheng Xia, Nevsky A.V. Effect of radical scavengers and proposed pathways for degradation of azo dye in aqueous solution under presence of iron (III) and persulphate. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2017. V. 60. N 4. P. 88-94.

What happens to formamide during C—N bond rotation? Atomic and molecular energetics and molecular reactivity as a function of internal rotation

1993 ◽  
Vol 71 (6) ◽  
pp. 872-879 ◽  
Author(s):  
Keith E. Laidig ◽  
Lynn M. Cameron
Keyword(s):  
Electric Fields ◽  
Molecular Level ◽  
Enzymatic Catalysis ◽  
Nucleophilic Attack ◽  
Torsional Angle ◽  
Carbonyl Carbon ◽  
Electrophilic Attack ◽  
Bond Rotation ◽  
Planar Conformation ◽  
Molecular Reactivity

We investigate the energetics of rotation about the C—N bond in formamide at the molecular and atomic levels using the HF/6-31G**//HF/6-31G** level of theory. At the molecular level, the barrier to rotation results from a decrease in overall attractive energies upon rotation away from the planar conformation, primarily due to the lengthening of the C—N bond. At the atomic level, the barrier is due to the loss in interatomic attraction between the nitrogen and its bonded neighbors. We investigate the susceptibility of formamide to electrophilic attack at nitrogen and oxygen as well as nucleophilic attack at carbonyl carbon as a function of C—N bond rotation using the Laplacian model of reactivity. The model predicts the susceptibility to nucleophilic attack at carbonyl carbon to reach a maximum with a O—C—N—H torsional angle of 60°. As a mimic of solvent fields, we investigate the effect of solvation upon these predictions with the application of homogeneous electric fields. This geometry–reactivity relationship is related to proposed models of activation in the enzymatic catalysis of peptides.

Biodecolorization of the Azo Dye Reactive Red 2 by a Halotolerant Enrichment Culture

2007 ◽  
Vol 79 (12) ◽  
pp. 2446-2456 ◽  
Author(s):  
M. Inan Beydilli ◽  
Spyros G. Pavlostathis
Keyword(s):  
Azo Dye ◽  
Enrichment Culture ◽  
Reactive Red 2

Effects of oxidant concentration and temperature on decolorization of azo dye: comparisons of UV/Fenton and UV/Fenton-like systems

2012 ◽  
Vol 65 (11) ◽  
pp. 1970-1974 ◽  
Author(s):  
C. Y. Kuo ◽  
C. Y. Pai ◽  
C. H. Wu ◽  
M. Y. Jian
Keyword(s):  
Rate Constant ◽  
Rate Constants ◽  
Azo Dye ◽  
Activation Energies ◽  
First Order ◽  
First Order Kinetics ◽  
Oxidant Concentration ◽  
Decolorization Efficiency ◽  
Pseudo First Order ◽  
Reactive Red 2

This study applies photo-Fenton and photo-Fenton-like systems to decolorize C.I. Reactive Red 2 (RR2). The oxidants were H2O2 and Na2S2O8; Fe2+, Fe3+, and Co2+ were used to activate these two oxidants. The effects of oxidant concentration (0.3–2 mmol/L) and temperature (25–55 °C) on decolorization efficiency of the photo-Fenton and photo-Fenton-like systems were determined. The decolorization rate constants (k) of RR2 in the tested systems are consistent with pseudo-first-order kinetics. The rate constant increased as oxidant concentration and temperature increased. Activation energies of RR2 decolorization in the UV/H2O2/Fe2+, UV/H2O2/Fe3+, UV/Na2S2O8/Fe2+ and UV/Na2S2O8/Fe3+ systems were 32.20, 39.54, 35.54, and 51.75 kJ/mol, respectively.

Biological Decolorization of the Azo Dye Reactive Red 2 Under Various Oxidation-Reduction Conditions

2000 ◽  
Vol 72 (6) ◽  
pp. 698-705 ◽  
Author(s):  
M. Inan Beydilli ◽  
Spyros G. Pavlostathis ◽  
Wayne C. Tincher
Keyword(s):  
Azo Dye ◽  
Oxidation Reduction ◽  
Reactive Red 2
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