Blue Degradation Reaction Research Articles

Electro-Fenton Process Catalyzed by Fe3O4 Magnetic Nanoparticles for Degradation of C.I. Reactive Blue 19 in Aqueous Solution: Operating Conditions, Influence, and Mechanism

Fe3O4 magnetic nanoparticles (MNPs) were employed for electro-Fenton (Fe3O4–electro-Fenton) degradation of C.I. Reactive Blue 19 (RB19) in an undivided electrochemical reactor with an activated carbon fiber felt cathode and a platinum anode. On the basis of physicochemical characterization of the Fe3O4 MNPs as well as quantitative measurements of iron leaching and H2O2 generation, it is concluded that the Fe3O4 MNPs facilitated the decomposition of H2O2 to generate hydroxyl radicals (•OH). Moreover, the cathodic electro-Fenton facilitated electro-regeneration of ferrous ion and maintained continuous supply of H2O2. The effect of several operational parameters such as pH, current density, amount of added Fe3O4 MNPs, initial RB19 concentration, and temperature on the removal of total organic carbon was investigated. It was found that the Fe3O4–electro-Fenton degradation of RB19 followed two-stage first-order kinetics with an induction period and a rapid degradation stage. Mineralization of RB19 proceeded rapidly only at pH 3.0. Increasing the current density and the dosage of Fe3O4 MNPs enhanced the rate of RB19 degradation. However, higher current densities and Fe3O4 dosages inhibited the reaction. The rate of RB19 degradation decreased with the increase in initial RB19 concentration and increased with the increase in temperature. The removal efficiency of total organic carbon reached 87.0% after 120 min of electrolysis at an initial pH of 3.0, current density of 3.0 mA/cm2, 1.0 g/L concentration of added Fe3O4 MNPs, 100 mg/L initial dye concentration, and 35 °C temperature. On the basis of the analytical results for the intermediate products and the assumption that •OH radicals are the major reactive species, we propose a possible pathway of RB19 degradation during the cathodic electro-Fenton process using Fe3O4 MNPs as iron source.

Synthesis of bismuth (III) oxide films based anodes for electrochemical degradation of reactive blue 19 and crystal violet

The Bi2O3 films-based anodes were synthesized by electrodeposition of Bi on stainless steel substrate at constant current density and during different deposition times, fallowed by calcination, forming Bi2O3. The thickness of the films was determined by two methods: the observation under the microscope and by calculation from mass difference. Electrochemical proceses at the anodes were ivestigated by linear sweep voltammetry. At the anodes obtained within 2, 5, 10 and 15 minutes of deposition, two dyes, namely: Reactive Blue 19 and Crystal Violet, were decolorized by oxidation with ?OH radical, generated from H2O2 decomposition at the anodes. Decoloration times of the anodes varied, and the shortest one was achieved with the anode obtained during 5 minutes of deposition, with the film thickness of 2.5?0.3 ?m. The optimal H2O2 concentration for the dyes degradation was found to be 10 mmol dm-3.

Synthesis and catalytic properties of La or Ce doped hydroxy-FeAl intercalated montmorillonite used as heterogeneous photo Fenton catalysts under sunlight irradiation

A series of La and Ce doped hydroxyl FeAl intercalated montmorillonite (FeAl-Mt) were prepared by a co-intercalation method for catalytic oxidation of Reactive Blue 19 (RB19) by a heterogeneous photo Fenton process under natural sunlight irradiation. The physicochemical properties of the obtained catalysts were deciphered by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray absorption fine structure (XAFS) and UV-vis diffuse reflectance spectroscopy (DRS). The results showed that Ce or La doped FeAl Keggin polyoxocations were intercalated into the gallery of montmorillonite and the physicochemical properties of intercalated FeAl Keggin polyoxocations were mildly changed after Ce or La doping, resulting in defects and lattice vacancies. The doping of Ce or La could effectively improve the catalytic performance of FeAl-Mt measured by heterogeneous photo Fenton degradation of RB19 catalyzed by the obtained products. The synergistic effect between the doped element and FeAl intercalated montmorillonite played a crucial role in the enhancement of heterogeneous catalytic activity under natural sunlight irradiation.

Application of in situ electrochemically generated ozone for degradation of anthraquninone dye Reactive Blue 19

Degradation of anthraquninone dye C.I. Reactive Blue 19 (RB19) via generated ozone by electrochemical oxidation process was investigated in this research. Ti/Sn–Sb–Ni electrode was used as an anode for ozone generation. The anode electrode was characterized electrochemically by cyclic voltammetry and characterized morphologically by scanning electron microscopy and X-ray diffraction. The amount of ozone concentration and RB19 degradation increased with increasing of applied voltage, electrolysis time, and in 1 M HClO4 at room temperature. The results of UV/Vis spectroscopy showed that the anthraquinone structure was degraded by dissolved generated ozone and also intermediate compounds were detected by integrated gas chromatography–mass spectrometry (GC/MS). Removal of color and COD were 100 % after 3 min and 48.2 % after 15 min reaction time, respectively.

Electrochemical degradation of Reactive Blue 19 in chloride medium for the treatment of textile dyeing wastewater with identification of intermediate compounds

In the present study, electrochemical degradation experiments were conducted to degrade a textile dye namely Reactive Blue 19 (RB-19). A laboratory scale bench-top reactor was used to investigate the effect of various operating parameters using titanium based dimensionally stable anode (DSA). The oxidation of RB-19 takes place in the bulk solution with electrolytically generated chlorine/hypochlorite. Increasing the initial pH and increasing the reaction temperature decreases the de-colorization efficiency. At the same time, increasing the chloride concentration and increasing the current density showed an increase in the color removal. The complete removal of color was achieved within a short period of electrolysis for different concentrations of RB-19. However, the removal of chemical oxygen demand (COD) and total organic carbon (TOC) was 55.8% and 15.6%, respectively, for 400 mg/L RB-19 with 1.5 g/L sodium chloride concentration. The intermediate compounds formed during the degradation were identified using a gas chromatography coupled with mass spectrometry (GC/MS). In the present study, no chlorinated organic compounds were detected during the course of electrolysis. The major compounds identified were benzene, 2-hydroxy, 4,4-napthaquinoine (C.I. Natural orange 6), 1-aminoanthraquinone (C.I. Diazo fast red AL), benzyl alcohol, benzaldehyde, benzoic acid, phthalic anhydride, phthalide, phthaldehyde and 1,3-indanone.