Simultaneous Galvanic Generation of Fe2+ Catalyst and Spontaneous Energy Release in the Galvano-Fenton Technique: A Numerical Investigation of Phenol’s Oxidation and Energy Production and Saving

Abstract

The present paper investigates the potential of the Galvano-Fenton process as an advanced technique in terms of the simultaneous oxidation of a model pollutant, phenol, and the energy release and saving as compared to conventional electrochemical techniques, namely, Fenton, Fenton-like, and Electro-Fenton. A numerical model describing the electrochemical, electrolytic, and phenol’s mineralization reactions is presented. Simulations are conducted to predict the kinetics of ferrous and ferric ions, radicals’ formation, and phenol degradation along with released power. Parametric analysis and comparisons are also performed between the basic configuration of the Galvano-Fenton process and its upgraded version integrating a pre-immersion stage of the electrodes in the electrolyte equivalent to 25% of the total experiment’s duration. The ratio of the initial concentration of H2O2 to the concentration of the released/added Fe2+ catalyst is varied from 10 to 30. The effect of phenol concentration is inspected over the range of 0.188 to 10 mg/L as well. Compared to conventional Fenton-based techniques, the Galvano-Fenton process demonstrated a higher performance by reaching 1.34% of degradation efficiency per released J. This is associated with the generation of hydroxyl radicals of 0.047 nM/released J with initial concentrations of hydrogen peroxide and phenol of 0.187 mM and 2 µM, respectively. Moreover, the integration of the pre-immersion stage allowed the overcoming the barrier of the null degradation rate at the initial instant.

Electrocatalysts for Inorganic and Organic Waste Nitrogen Conversion

“…While an effective approach, the main drawbacks of Fenton-based treatment procedures are the dependence on large volumes of reagents and the formation of an Fe-based sludge. These issues can be minimized by using electrochemical techniques such as the electro-Fenton approach (Figure f), where the H 2 O 2 is produced in situ and the Fe 3+ is regenerated into Fe 2+ , or the electrochemical Fenton (also called Galvano-Fenton) approach (Figure g), where the Fe 2+ is generated in situ through the use of a sacrificial anode . An emerging approach, electro-Fenton with sacrificial anode, looks to produce both reagents in situ .…”

“…Organic species oxidation mechanisms. ,− Direct oxidation mechanism on (a) an active electrode and (b) a nonactive electrode. (c) Indirect oxidation mechanism mediated by active chlorine species.…”

Water Remediation from Recalcitrant Pollution Using the Galvano-Fenton Process: A Modeling Approach of the Hydroxyl Radical Generation and the Energy Efficiency

“…The initial latency, due to the absence of the Fenton catalyst when the process is started, is probably the reason for the delay observed in terms of the performance of the Galvano-Fenton process for the degradation of phenol. The mechanism of phenol degradation, which has been adopted in a previous work of our research group (Kerboua et al 2021), is closely dependent on the release of free radicals in the electrolyte; hence, in Fig. 5, we examine the evolution of the concentration of the intermediate species formed during phenol degradation using Galvano Fenton process, as described in Table 2.…”

Galvano-Fenton Engineering Solution with Spontaneous Catalyst’s Generation from Waste: Experimental Efficiency, Parametric Analysis and Modeling Interpretation Applied to a Clean Technology for Dyes Degradation in Water

“…This Galvanic process is based on the spontaneous corrosion of iron without any external current to generate in situ the Fenton catalyst. The study was performed in blank electrolyte [22] as well as in the presence of Acid Orange 7 and phenol as model pollutants [23,24] in order to figure out the pathways of formation and regeneration of the ferrous ion catalyst and the mechanistic aspects that characterize this technique (as compared to classic Fenton and electro-Fenton). Whilst classic Fenton requires stoichiometric yields of added ferrous catalyst in the form of ferrous salt, the Galvano-Fenton process produces the ferrous catalyst in situ by the spontaneous galvanic corrosion of the iron wastes.…”

“…Thus, the Galvano-Fenton process does not require any external current and, on the contrary, produces energy along with the oxidation of target pollutants. From a technological point of view, the energetic outcomes of the Galvano-Fenton process have been recently studied as a novel approach for energy from waste [25], and estimations have been made in terms of energy production and saving, using the basic configuration as well as an upgraded one relying on a pre-immersion stage of the electrodes in the electrolyte [24]. Economically speaking, a direct comparison with the classic Fenton process clearly shows that the Galvano-Fenton eliminates the need for ferrous salt addition, which prevents at least an additional operation cost related to the use of ferrous sulfate heptahydrate salt as a catalyst source [26].…”