SonoFenton degradation of an azo dye, Direct Red

Abstract

The degradation of a reactive azo dye, Direct Red 81 (DR81), by Fenton process and in conjunction with sonolysis (SonoFenton) was studied. The synergistic effect of Fenton process and sonolysis enhanced the degradation of Direct Red 81 in aqueous solutions and the reaction followed the mechanism of hydroxyl radical (HO) oxidation. The influence of the initial substrate concentration, pH and catalyst loading on the rate of decolorisation were studied. The dye decolorisation followed apparent first order kinetics. The optimum conditions for decolorisation were pH=3.0, [Fe(2+)]=0.2 g/l, [H2O2]=5.1×10(-3) mol/l and ultrasonic frequency=120 kHz, 60 W. These conditions yielded 99% decolorisation of DR81 within 75 min. The sonolytic degradation products of DR81 were identified using Electrospray Ionization-Mass Spectrometry (ESI-MS). The presence of CO3(2-), HCO3(-), Cl(-), NO3(-), and SO4(2-) ions in the dye solution did not have a considerable effect on the decolorisation efficiency. This study demonstrates that Fenton and SonoFenton methods can effectively decolorize DR81 dye in waste water. The dye concentration used in this study is higher compared to earlier studies illustrating the effective mineralization by the SonoFenton process. The mechanism of dye degradation is also proposed.

Fast preparation of RG-I enriched ultra-low molecular weight pectin by an ultrasound accelerated Fenton process

“…In the waste-water industry, advanced oxidation process has been widely used, as an efficacious and clean technology to treat polluted water by degradation organic wastes such as azo dye 26 , phenolic compound 27 and cellulose 28 through the HO∙ generated during the reaction 29–31 . As one of the most promising advanced oxidation processes, Fenton reaction particularly utilizes ferrous ion as the catalyst to generate HO∙ from H 2 O 2 30 (as shown in the reaction (1)).…”

Synthesis of Ce/SiO2 Composited Cross‐Linked Chitosan Flocculation Material and Its Application in Decolorization of Tartrazine Dye

“…Treating agent Treating conditions Removal rate/% [54] Cationic ethyl violet Carboxymethylated xylan flocculant Dosage = 100 mg/L, pH = 9 and time = 30 min 97.1 [55] Disperse yellow RGFL PFC-PDADMAC flocculant Dosage = 30 mg/L and time = 3 h 95.5 [56] Tartrazine Activated red mud adsorbents Dosage = 2.5 g/L, pH = 6 and time = 30 min 84.72 [57] Congo red Lawsone immobilized activated carbon adsorbents Dosage = 1 g/L, pH = 5-7 and time = 48 h 85 [58] Direct red Fenton reagent [Fe 2 + ] = 0.2 g/L, [H 2 O 2 ] = 5.1 × 10 À 3 mol/L, pH = 3.0 and time = 75 min 99 [59] Methyl orange Catalyst consisting of multi-walled carbon nanotubes and TiO 2 Dosage = 10 mg/50 mL, pH = 5.5 and time = 100 min 93…”

Multivariate Analysis of Digital Images as an Alternative to Monitor Dye Degradation by the Fenton Process

“…[10][11][12] The Fenton process has been applied in several dye degradation studies. [13][14][15][16][17][18][19][20] In the Fenton process, hydrogen peroxide (H 2 O 2 ) is decomposed by Fe 2+ species, producing hydroxyl radicals, following the Haber-Weiss mechanism presented in Equation 1.…”