A comparative study of azo dye decolorization by electro‐Fenton in two common electrolytes

Abstract

BACKGROUND: This study compared the decolorization behaviors of a model azo dye of methyl red in Na 2 SO 4 and NaCl media by electro-Fenton process, in which FeSO 4 was added into the solution, while H 2 O 2 was efficiently generated on a graphite-polytetrafluoroethylene cathode. Parameters such as pH, cathodic potential, electrolyte concentration, and initial dye concentration as well as the treatment time were investigated to disclose different decolorization behaviour.

Removal of caffeine from aqueous solution by indirect electrochemical oxidation using a graphite-PVC composite electrode: A role of hypochlorite ion as an oxidising agent

“…At pH 3, the removal of caffeine was completed after 20 min which means acidic medium plays an important role to enhance the removal efficiency of caffeine may due to formation of HClO which is considered more active compared with ClO − as confirmed by [36]. It is also in agreement with early report [37].…”

pH-dependent degradation of acid orange II by zero-valent iron in presence of oxygen

“…The standard curve of Fe(II) was linear with a regression coefficient of 0.993 in the range of 0.05-1.0 mM. The concentration of H 2 O 2 was determined using potassium titanium (IV) oxalate colorimetry according to the method reported earlier [26,27] as follows. 4 mL of 0.01 M K 2 TiO(C 2 O 4 ) 2, 4 mL of 3.0 M H 2 SO 4 and 2 mL of sample containing H 2 O 2 were mixed for 15 min, then the obtained mixed solution was analyzed by UV-vis spectroscopy (UV-2501PC, Shimadzu) at a maximum wavelength of 400 nm (UV-2000, Shanghai, China).…”

Electrochemical reactivity of Ponceau 4R (food additive E124) in different electrolytes and batch cells

“…In contrast, the effect of electrolyte is much more controversial in Fenton-based EAOPs. For example, the use of Cl À was found to accelerate the decolorization of Acid Red 14 [33] and Methyl Red [42], but no significant enhancement [34] or even a detrimental effect [38] was reported for Allura Red AC and Orange II, respectively. More detailed studies are then needed to clarify this behavior.…”

“…Among the operating parameters that determine their performance, the supporting electrolyte is critical because different inorganic salts are present in real wastewater. This is often disregarded, but some studies are available for the treatment of organic pollutants [33][34][35][36][37][38][39][40][41][42][43][44][45][46]. Regarding the azo dyes, much is known about EO [35,36,44,46], whereas scarce information is available on EF and PEF [33,34,38,42].…”