Degradation Of Reactive Orange Research Articles

Process Development for Photocatalytic Degradation of Reactive Dyes in Wastewater

Advanced oxidation processes (AOPs) are widely used for the removal of recalcitrant organic constituents from industrial and municipal wastewater. This study mainly focused the use of TiO2 and ZnO catalysts for removal of textile dyes. Synthesis of TiO2 and ZnO photo catalysts was done by sol-gel method. These catalysts were used to obtain enhanced photo catalytic action and were coated on glass beads to improve the photo catalytic activity. The synthesized beads were examined using SEM, FTIR and XRD. Synthesized photocatalysts were examined extensively for their photocatalytic activities with Reactive Orange(RO), Reactive Blue(RB), Textile industry Effluent (TIE) and mixture of dyes (RO+RB, RO+RB +TIE) at various concentrations (50ppm, 100ppm). The photocatalytic degradation of RO, RB, TIE, RO+RB and RO+RB +TIE dyes solution (100mg/L and 50mg/L) using TiO2 and ZnO were investigated under UV light irradiation (λ=254nm). Photocatalytic studies revealed that the TiO2 has shown much higher photocatalytic activity than the ZnO catalyst. The photocatalytic activity of the TiO2 catalyst follows the order: Reactive Orange of 50 ppm (80.98%) > Reactive Blue dye of 50 ppm (77.17%)> Reactive Orange dye of 100 ppm (74.98)>Reactive blue of 100 ppm (72%). The photocatalytic activity of the ZnO catalyst follows the order: Reactive Orange of 50 ppm (75.12%) > Reactive Blue dye of 50 ppm (73.98%)> Reactive Blue dye of 100 ppm (71%)>Reactive Orange of 100 ppm (70%).

Application of central composite design for electrochemical oxidation of reactive dye on Ti/MWCNT electrode

In the present study, degradation of Reactive Orange 7 dye was investigated using a new designed titanium electrode, in which a plate of Ti was coated with multi-walled carbon nanotubes (Ti/MWCNT) via electrophoretic deposition technique. A series of characterizations including field scanning electron microscopy, X-ray diffraction, cyclic voltammetry, scanning electrochemical impedance spectroscopy and chronoamperometric analysis were performed to investigate MWCNT impact on the microstructure and electrochemical properties of Ti electrode. Furthermore, the effect of main operating parameters as independent variables (current density, electrolyte concentration, initial pH, and electrolysis time) on color removal efficiency as response variable were investigated and optimized by central composite design under response surface methodology. The maximum color removal efficiency of 89.1% and chemical oxygen demand removal efficiency of 55% were obtained, under the optimum condition. These results indicate that the presence of MWCNT on the Ti substrate noticeably promoted the electrochemical activity and the electrodes’ property for treatment of dye in aqueous solution.

Degradation of reactive orange 4 dye using hydrodynamic cavitation based hybrid techniques

In the present work, degradation of reactive orange 4 dye (RO4) has been investigated using hydrodynamic cavitation (HC) and in combination with other AOP’s. In the hybrid techniques, combination of hydrodynamic cavitation and other oxidizing agents such as H2O2 and ozone have been used to get the enhanced degradation efficiency through HC device. The hydrodynamic cavitation was first optimized in terms of different operating parameters such as operating inlet pressure, cavitation number and pH of the operating medium to get the maximum degradation of RO4. Following the optimization of HC parameters, the degradation of RO4 was carried out using the combination of HC with H2O2 and ozone. It has been found that the efficiency of the HC can be improved significantly by combining it with H2O2 and ozone. The mineralization rate of RO4 increases considerably with 14.67% mineralization taking place using HC alone increases to 31.90% by combining it with H2O2 and further increases to 76.25% through the combination of HC and ozone. The synergetic coefficient of greater than one for the hybrid processes of HC+H2O2 and HC+Ozone has suggested that the combination of HC with other oxidizing agents is better than the individual processes for the degradation of dye effluent containing RO4. The combination of HC with ozone proves to be the most energy efficient method for the degradation of RO4 as compared to HC alone and the hybrid process of HC and H2O2.

Photocatalytic activity of surface fluorinated TiO 2-P25 in the degradation of Reactive Orange 4

Photocatalytic activity of surface fluorinated TiO 2-P25 (F-TiO 2-P25) in the degradation of a chlorotriazine azo dye Reactive Orange 4 (RO 4) under ambient conditions was investigated in this study. Characterization of F-TiO 2-P25 reveals that the catalyst has a strong absorption in the UV range and the presence of F atom in the catalyst. The degradation rate of RO 4 with surface fluorinated TiO 2-P25 is three times faster than bare TiO 2-P25. The quantum yield of UV/TiO 2-P25 process is largely decreased by the increase of initial dye concentration, whereas in UV/F-TiO 2-P25 process, the influence of initial dye concentration is less. Surface fluorination of TiO 2-P25 enhanced the adsorption of RO 4 dye, while improving overall degradation rate. The optimum operating conditions of UV/F-TiO 2-P25 process for efficient degradation are reported.

RETRACTED ARTICLE: Kinetic and anion degradation products study on photocatalytic degradation of reactive orange 5 solution with phosphotungstic acid

Abstract Increasing environmental pollution caused by toxic dyes is a matter of great concern due to their hazardous nature. So it is crucial to develop processes which can destroy these dyes effectively. It has been generally agreed that reactive orange 5 (KGN) can be effectively degraded in aerated phosphotungstic acid (HPA) in a homogeneous reaction system using near-UV irradiation. In this paper, photocatalytic degradation of reactive orange 5 solutions with phosphotungstic acid was investigated, especially more attention was paid to the kinetic model and the anion degradation products. The results revealed that the photocatalytic degradation reaction of KGN with HPA in a homogenous solution can be described by Langmuir-Hinshelwood equation and Langmuir-Hinshewood kinetic model described it well. The reaction manifested the first order with lower concentration(⩽30 mg L−1) with the limiting rate constant and the adsorption constant in this case being 0.8098 mg L−1 min−1 and 4.359 10−2 L mg−1, respectively. The degradation mechanism of KGN with HPA is different from that with TiO2, the anion products of the two reaction systems are the same. The difference in degradation mechanism of KGN with HPA from that with TiO2 is caused by the nature of the photocatalyst.

RETRACTED: Kinetic study on photocatalytic degradation of reactive orange 5 solution with phosphotungstic acid

This article has been retracted at the request of the Editor-in-Chief and Authors. Please see Elsevier Policy on Article Withdrawal ( http://www.elsevier.com/locate/withdrawalpolicy ). Reason: The authors have plagiarized the Masters thesis of Min Zhu, Dalian Jiaotong University, 2004. They have also duplicated significant parts of a paper published in Central European Journal of Chemistry 6 (2008) 99–105, doi: 10.2478/s11532-007-0064-2 . One of the conditions of submission of a paper for publication is that authors declare explicitly that their work is original and has not appeared in a publication elsewhere. Re-use of any data should be appropriately cited. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and we apologize to readers of the journal that this was not detected during the submission process. We thank Professor Xiuhua Zhu (Dalian Jiaotong University) for bringing the thesis plagiarism to our attention.

Photocatalytic decolourisation and degradation of Reactive Orange 4 by TiO 2-UV process

The photocatalytic decolourisation and degradation of an azo dye Reactive Orange 4 (RO4) in aqueous solution with TiO 2-P25 (Degussa) as photocatalyst in slurry form has been carried out using UV-A light (365 nm). There is a significant difference in adsorption of dye on TiO 2 surface with the change in the solution pH. The effect of various parameters such as catalyst loading, pH and initial concentration of the dye on decolourisation and degradation have been determined. The dye is decolourised in 80 min and completely degraded in 180 min under optimum conditions. The degradation was strongly enhanced in the presence of electron acceptors such as H 2O 2, (NH 4) 2S 2O 8 and KBrO 3. The photodecolourisation and degradation kinetics are discussed in terms of Langmuir–Hinshelwood kinetic model. The degradation intermediates were analysed by GC–MS technique.