Electrochemical Treatment of Dye Solution by Oxalate Catalyzed Photoelectro‐Fenton Process Using a Carbon Nanotube‐PTFE Cathode: Optimization by Central Composite Design

Abstract

Decolorization of C.I. Basic Blue 3 (BB3) by oxalate catalyzed photoelectro-Fenton process based on carbon nanotube-polytetrafluoroethylene (CNT-PTFE) electrode as cathode under visible light was studied. A comparison of electro-Fenton, photoelectro-Fenton, and photoelectro-Fenton/oxalate processes for decolorization of the solution containing BB3 has been performed. The results showed that color removal follows the decreasing order: photoelectro-Fenton/oxalate > photoelectro-Fenton > electro-Fenton. Response surface methodology (RSM) was employed to assess individual and interactive effects of the four main independent parameters on the decolorization efficiency. A central composite design (CCD) was employed for optimization of photoelectro-Fenton/oxalate treatment of BB3. The analysis of variance (ANOVA) showed a high coefficient of determination value (R 2 ¼ 0.958) and satisfactory prediction secondorder regression. This study clearly showed that RSM was one of the suitable methods to optimize the operating conditions. IntroductionDyeing and finishing operations produce large quantities of wastewater that contains organic dyestuff, surfactants, chelating agents, and other contaminants that can be characterized as high levels of total organic content and of color [1]. In recent years, advanced oxidation processes (AOPs) have received great attention for removal of hazardous organic pollutants from contaminated water. Among AOPs, Fenton-based processes, whose high performance relies on the great oxidation power of hydroxyl radicals (OH ) formed from Fenton's reaction (1), have been experiencing a remarkable development due to their promising results in combination with easy handling [11,12].Hydrogen peroxide and ferrous ions are simultaneously produced in an aqueous medium by the 2e À reduction of the dissolved molecular oxygen (Eq. (2)) and 1e À reduction of ferric ions which are initially introduced at a catalytic concentration (Eq. (3)) [13][14][15][16].Electrogeneration of hydrogen peroxide (Eq. (2)) usually occurs at carbon-felt [17][18][19][20][21][22] and carbon-polytetrafluoroethylene (PTFE) O 2 -diffusion [23,24] cathodes.The electro-Fenton method utilizes a Pt or a boron-doped diamond (BDD) anode in an undivided cell, while Fe(II) is added to the solution to permit degradation of pollutants by OH generated from reaction(1) in the medium. In case of the use of BDD anode supplementary OH are generated on the anode surface.In this paper, we studied the removal of Basic Blue 3 (BB3) as a model dye from aqueous solutions by oxalate catalyzed photoelectro-Fenton process with carbon nanotube-PTFE (CNT-PTFE) electrode as cathode under visible (VIS) light irradiation. The removal of BB3 has been studied by chitosan-based adsorbent [25], biosorption using biomass of Corynebacterium glutamicum [26,27], electro-Fenton process [28], and UV/peroxydisulfate oxidation [29]. However, to the best of our knowledge, the optimization of electrochemical decolorization

Comparative use of anodic oxidation, electro-Fenton and photoelectro-Fenton with Pt or boron-doped diamond anode to decolorize and mineralize Malachite Green oxalate dye

“…3a). Such enhancement of decolorization rate in PEF can be related to the acceleration of OH production from the higher Fe 2+ regeneration induced by photolytic reaction (5) and, mainly, by the photodecarboxylation of the complexes of Fe(III) with oxalate from the dye molecule via reaction (6) [38,39]. This surplus of OH can then attack preferentially the Malachite Green cation, with so little participation of Pt( OH) or BDD( OH) that the color is removed at analogous rate using either a Pt or BDD anode.…”

“…Fe 2+ (4) In our laboratory, we are also developing the photoelectroFenton (PEF) process, where the solution treated by EF is simultaneously illuminated with UVA light [34][35][36][37], yielding: (i) the photoreduction of Fe(OH) 2+ , the pre-eminent species at pH 3, to regenerate Fe 2+ ion with larger OH production by reaction (5), and (ii) the photolysis of generated Fe(III)-carboxylate intermediates via reaction (6). Recently, Khataee et al [38,39] reported that the addition of oxalate ion catalyzes the PEF process due to the enhancement of Fe 2+ regeneration via reaction (6).…”

“…The PEF process has been extensively applied to the treatment of azo dyes [24,[34][35][36][37][38][39], the most common pollutants in dyeing effluents, but no information on its viability to destroy dyes with a triphenylmethane group has been previously reported. To clarify the oxidation power of this method over dyes with this chromophore group, we have undertaken a study on the comparative degradation of Malachite Green by AO, EF and PEF.…”

Heterogeneous sono-Fenton-like process using nanostructured pyrite prepared by Ar glow discharge plasma for treatment of a textile dye

“…Moreover, other physical and chemical processes like adsorption and coagulation merely transfer contaminants to a secondary phase requires more treatment [4]. Hence, it is significant to find effective wastewater remediation methods like AOPs, which can not only degrade but also mineralize different contaminants without producing secondary waste [5]. Among AOPs, the Fenton and sonication processes are simple and efficient methods which are applied for the mineralization of various contaminants from polluted water sources [3].…”

Direct Blue 71 removal by electrocoagulation sludge recycling in photo-Fenton process: response surface modeling and optimization

“…It is mainly used to find a combination of values for factors by which the optimal value of response is obtained. By this technique, much more precise evaluation is provided with much less number of experimental runs in comparison with rather conventional, time-consuming one-factor-at-a-time methods [22]. In this study, effects of factors including initial pH, electrical current (mA)/current density (mA cm −2 ), and electrolysis time (min) on decolorization efficiency were evaluated using full central composite design (CCD) which is the most popular response surface design.…”