Multi‐phase electro‐chemical catalytic oxidation of wastewater

Abstract

The removal of organic pollutants from synthetic wash wastewater by a combined multi-phase electrocatalytic oxidation method was evaluated using porous graphite as anode and cathode, and CuO-Co 2 O 3 -PO 4 3− modified kaolin as catalyst. The synergic effect on COD removal was studied when integrating the electro-chemical reactor with the effective modified kaolin in a single undivided cell; the results showed that higher COD removal efficiency was obtained than those obtained using the individual processes. Under optimal conditions of pH 3, 30 mA cm −2 current density, very effective reduction of organic pollutants was achieved with this combined electrochemical method. High removal efficiency (90%) of the chemical oxygen demand (COD) was obtained in 60 min in the treatment of simulated wash wastewater (anionic surfactant, sodium dodecyl benzene sulfonate [DBS]). This method was also applied to treat wastewater form paper-making and resulted in a COD reduction of 84%. Based on the investigation, a possible mechanism of this combined electro-chemical process was proposed. The pollutants in wastewater could be decreased by the high reactive OH ž that were produced via the decomposition of electro-generated H 2 O 2 activated by the synergic effect of electro-field and catalyst. The results indicate that the multi-phase catalytic electro-chemical oxidation process is a promising technique for wastewater treatment.

Electro-Fenton Process and Related Electrochemical Technologies Based on Fenton’s Reaction Chemistry

“…A Chinese group 213,214 explored a combined multiple-phase electrochemical oxidation packed bed method using porous graphite as the anode and cathode, with a CuO-Co 2 O 3 -PO 4…”

“…A Chinese group , explored a combined multiple-phase electrochemical oxidation packed bed method using porous graphite as the anode and cathode, with a CuO−Co 2 O 3 −PO 4 3− modified kaolin catalyst packed near the electrodes. While H 2 O 2 was produced at the cathode, the degradation of organics was interpreted as a result of the adsorption of pollutants on the porous anode catalyst, followed by their oxidation by • OH produced from the oxidation/decomposition of H 2 O and H 2 O 2 at the modified kaolin.…”

“…The oxidation ability of several novel EF treatments introduced in section has been evaluated by degrading the anionic surfactant sodium dodecylbenzene sulfonate , and dimethylphtalate . The treatment of 150 mL of 750 mg L −1 of the former pollutant in 0.25 M Na 2 SO 4 was performed in a stirred tank reactor containing 19.2 cm 2 porous graphite as the anode and cathode, with a CuO−Co 2 O 3 −PO 4 3− modified kaolin catalyst packed between the electrodes.…”

“…(i) Environmental: Allowing the continuous in-situ electrogeneration of H 2 O 2 and catalytic regeneration of Fe 2+ to avoid the handling of chemical H 2 O 2 , its transport and storage, as well as the formation of sludge thanks to the controlled production of a small concentration of iron ions. (ii) Technological: Some challenges to enhance the performance and efficiency of future reactors include the combination of high surface area three-dimensional cathodes such as RVC, carbon felt, carbon fiber, or carbon nanotubes and GDEs to enhance both the continuous Fe 2+ regeneration and H 2 O 2 production, respectively, the use of novel advanced materials to develop new and high-performing anodes such as oxide nanotubes including TiO 2 for photoelectrocatalytic applications, as well as electrodeposited coatings of pure, doped, and composite materials with enhanced electrocatalytic properties, the development of more efficient multiple-phase oxidation , and three-dimensional electrode reactors to overcome the problems of mass transfer limitations inherent to electrode kinetics, and sunlight-assisted degradation for the destruction of persistent metallic complexes. (iii) Economical: Sunlight-driven systems based on solar panels and photovoltaic energy as a cheap source of electrical power.…”

Single and Coupled Electrochemical Processes and Reactors for the Abatement of Organic Water Pollutants: A Critical Review

“…203 In fact, the mineralization of organics in that side was higher than that found in the anodic compartment that contained a Ti/IrO 2 /RuO 2 anode. The oxidizing species • OH can also arise from the catalytic decomposition of H 2 O 2 on the surface of a heterogeneous catalyst in three-phase systems, 216 as well as from the oneelectron cathodic reduction of H 2 O 2 . For instance, the treatment of diethyl phthalate in an undivided cell equipped with a Pd-modified GDE as a cathode that favored the formation of H 2 O 2 and • OH and a DSA yielded 81% and 40% COD and phthalate removal after 9 h, respectively.…”