The sonochemical decolorisation of textile azo dye CI Reactive Orange 127

Abstract

In the present study, Fenton and sono-Fenton processes were applied to the oxidative decolorisation of synthetic textile wastewater including CI Reactive Orange 127 and polyvinyl alcohol. Process optimisation [pH, ferrous ion (Fe 2+ ) and hydrogen peroxide (H 2 O 2 )], kinetic studies and their comparison were carried out for both of the processes. The sono-Fenton process was performed by indirect sonication in an ultrasonic water bath, which was operated at a fixed 35-kHz frequency and 80 W power. The optimum conditions were determined as [Fe 2+ ] = 20 mg l )1 , [H 2 O 2 ] = 15 mg l )1 and pH = 3 for the Fenton process and [Fe 2+ ] = 25 mg l )1 , [H 2 O 2 ] = 5 mg l )1 and pH = 3 for the sono-Fenton process. The colour removals were 89.9% and 91.8% by the Fenton and sono-Fenton processes, respectively. The highest decolorisation was achieved by the sono-Fenton process because of the production of some oxidising agents as a result of sonication. Consequently, ultrasonic irradiation in the sono-Fenton process slightly increased the colour removal to 91.8%, while decreasing the hydrogen peroxide dosage to one-third of that of the Fenton process.

COD and color removal from synthetic textile wastewater by ultrasound assisted electro-Fenton oxidation process

“…It was well known that pH is one of the most important factors limiting the oxidation efficiency of Fenton process in the treatment of wastewaters due to its role in controlling the speciation of iron (Fe 2+ /Fe 3+ ), the stability of hydrogen peroxide, and the oxidation ability of hydroxyl radical (OH ) generated in the reaction solution [10]. The influences of initial pH on COD and color removal were examined and results are demonstrated in Fig.…”

“…Furthermore, anaerobic processes are also not convenient for this kind of wastewater containing dye, because the degradation of azo dyes under anaerobic conditions results in the breakdown of azo bonds which leads to formation of toxic aromatic amines [4]. Therefore, many different chemical treatment processes have been proposed in order to treat the textile effluents containing azo dyes; adsorption [5], coagulation [6], electro-coagulation [7,8], Fenton oxidation methods [9,10], ozonation [11] and sonication [12]. Among these processes, the Fenton process is one of the most simple and cheap treatment methods for the textile wastewaters and has caught attention as an effective alternative for the treatment of textile wastewater.…”

Advanced treatment of coking wastewater by conventional and modified fenton processes

“…However, it can be degraded into H 2 O and O 2 by using catalyst MnO 2 . Thus, a 25 mL sample was added into a beaker containing MnO 2 for quenching the residual H 2 O 2 to prevent its interference on COD . The necessary amount of MnO 2 to degrade H 2 O 2 in the sample was calculated by taking the initial H 2 O 2 concentration into account.…”

“…Moreover, the oxidation potential of the process increases when ferric iron is transformed to ferrous iron, as shown in Eq. . After treatment, however, ZVI is easily separated by gravitational settling.…”

Azo Dye DB71 Degradation Using Ultrasonic-Assisted Fenton Process: Modeling and Process Optimization

“…The effects of the ultrasonic irradiation arise from acoustic cavitation. The synergetic effect of US irradiation reduces the Fenton reagents (H 2 O 2 and Fe 2+ ) requirement and then, it reduce the price and mentioned deficiencies by using low-concentration Fenton reagent [11][12][13].…”