Hydrogen peroxide electrogeneration from O electroreduction: A review focusing on carbon electrocatalysts and environmental applications.

Hydrogen peroxide (HO) stands as one of the foremost utilized oxidizing agents in modern times. The established method for its production involves the intricate and costly anthraquinone process. However, a promising alternative pathway is the electrochemical hydrogen peroxide production, accomplished through the oxygen reduction reaction via a 2-electron pathway.

A review on recent environmental electrochemistry approaches for the consolidation of a circular economy model.

Availability of raw materials in the chemical industry is related to the selection of the chemical processes in which they are used as well as to the efficiency, cost, and eventual evolution to more competitive dynamics of transformation technologies. In general terms however, any chemically transforming technology starts with the extraction, purification, design, manufacture, use, and disposal of materials. It is important to create a new paradigm towards green chemistry, sustainability, and circular economy in the chemical sciences that help to better employ, reuse, and recycle the materials used in every aspect of modern life.

A review of electro-Fenton and ultrasound processes: towards a novel integrated technology for wastewater treatment.

Nowadays, the presence of persistent dissolved pollutants in water has received increasing attention due to their toxic effects on living organisms. Considering the limitations of conventional wastewater treatment processes for the degradation of these compounds, advanced oxidation processes such as electro-Fenton and sono-chemical process, as well as their combination, appear as potentially effective options for the treatment of wastewater contaminated with bio-recalcitrant pollutants. In view of the importance of the development of processes using real effluents, this review aims to provide a comprehensive perspective of sono-electro-Fenton-related processes applied for real wastewater treatment.

Decontamination of wastewater containing contaminants of emerging concern by electrooxidation and Fenton-based processes - A review on the relevance of materials and methods.

In recent years, there has been an increasingly growing interest regarding the use of electrochemical advanced oxidation processes (EAOPs) which are considered highly promising alternative treatment techniques for addressing environmental issues related to pollutants of emerging concern. In EAOPs, electrogenerated oxidizing agents, such as hydroxyl radical (HO), can react non-selectively with a wide range of organic compounds, degrading and mineralizing their structures to unharmful molecules like CO, HO, and inorganic ions. To this date, a broad spectrum of advanced electrocatalysts have been developed and applied for the treatment of compounds of interest in different matrices, specifically aiming at enhancing the degradation performance.

Study of the performance of a cylindrical flow-through electro-Fenton reactor using different arrangements of carbon felt electrodes: effect of key operating parameters.

In this work, a cylindrical flow-through electro-Fenton reactor containing graphite felt electrodes and an Fe(II) loaded resin was evaluated for the production of the Fenton reaction mixture and for the degradation of amoxicillin (AMX) and fecal coliforms containing aqueous solutions. First, the influence of several factors such as treatment time, current intensity, flow rate, and electrode position was investigated for the electrogeneration of HO and the energetic consumption by means of a factorial design methodology using a 2 factorial matrix. Electric current and treatment time were found to be the pivotal parameters influencing the HO production with contributions of 40.

Experimental and Theoretical Insights on Methylene Blue Removal from Wastewater Using an Adsorbent Obtained from the Residues of the Orange Industry.

Chemical and thermochemical transformations were performed on orange peel to obtain materials that were characterized and further tested to explore their potential as adsorbents for the removal of methylene blue (MB) from aqueous solutions. The results show the high potential of some of these materials for MB adsorption not only due to the surface area of the resulting substrate but also to the chemistry of the corresponding surface functional groups. Fitting of the kinetic as well as the equilibrium experimental data to different models suggests that a variety of interactions are involved in MB adsorption.

Photo-assisted electrochemical advanced oxidation processes for the disinfection of aqueous solutions: A review.

Disinfection is usually the final step in water treatment and its effectiveness is of paramount importance in ensuring public health. Chlorination, ultraviolet (UV) irradiation and ozone (O) are currently the most common methods for water disinfection; however, the generation of toxic by-products and the non-remnant effect of UV and O still constitute major drawbacks. Photo-assisted electrochemical advanced oxidation processes (EAOPs) on the other hand, appear as a potentially effective option for water disinfection.

Study of polarized activated carbon filters as simultaneous adsorbent and 3D-type electrode materials for electro-Fenton reactors.

Electro-Fenton (EF) based water treatment processes using activated carbon (AC) packed beds constitute an attractive approach for the development of competitive degradation technology of persistent pollutants in aqueous effluents. In this work, the results of a study aimed to assess the effect on the EF performance of different parameters of the reactor's operation are presented. By means of a factorial experimental design, the influence of the AC source (lignitic or vegetal), AC acid pre-treatment, particle size distribution and the amount of Fe loaded resin in the reactor were analyzed.

Study of a coupled adsorption/electro-oxidation process as a tertiary treatment for tequila industry wastewater.

Vinasse wastewater from tequila industry that has been conventionally treated is usually characterized by a chemical oxygen demand (COD) above 150 mg L, which is the maximum content permitted for discharge by Mexican Regulation. In order to increase the wastewater quality, different processes were applied, and from the experimental results, the advantages and limitations were analyzed. In this way, although Fenton experiments showed acceptable COD removal efficiencies (79-90%), operation as well as cost limit its adoption as a viable technology.

Inactivation of helminth eggs in an electro-Fenton reactor: Towards full electrochemical disinfection of human waste using activated carbon.

The disinfection of helminth eggs and Escherichia coli contaminated aqueous solutions, was studied using an electro-Fenton reactor equipped with a polarized activated carbon (AC) packed bed and two chambers loaded with cation exchange resins. Experiments using different arrangements and operation conditions, revealed that effective elimination of Escherichia coli takes place in all electrochemical disinfection tests. For the more resistant helminth eggs however, adsorption, electro-oxidation and electro-Fenton experiments showed retention within the reactor and pathogen inactivation values of 0, 16, and 25%, respectively.

Electrochemical degradation of triclosan in aqueous solution. A study of the performance of an electro-Fenton reactor.

The electro-Fenton degradation of Triclosan in aqueous solution was studied using a cylindrical reactor in which polarized carbon cloth electrodes and a cation exchange resin were employed. Using a factorial design of experiments approach, the effect of four variables (considering two levels for each one), was measured on four response parameters that reflect the electrooxidation efficiency of the electrochemical reactor. The results revealed that in all cases triclosan degradation was very efficient (above 95%) and that while there is a reasonable effect of all variables and their interactions, the one with the strongest influence on the process is the nature and magnitude of the ionic strength of the electrolytic solution.

Optimization of the integral valorization process for orange peel waste using a design of experiments approach: Production of high-quality pectin and activated carbon.

The aim of this study was to optimize the integral valorization of orange peel waste by obtaining activated carbon after a process of pectin recovery in recycling of orange peel by transformation to value-added products of pectin extraction and activated carbon preparation. The study was supported by statistical analysis, and the significant factors and optimal conditions were obtained from the statistical analysis. Using a representative sample of orange peel waste, a yield of 29.

Novel arrangement for an electro-Fenton reactor that does not require addition of iron, acid and a final neutralization stage. Towards the development of a cost-effective technology for the treatment of wastewater.

A novel arrangement for an electro-Fenton reactor aimed to treat neutral wastewater is presented. The arrangement consists on three-compartments in series, two of them packed with a cation exchange resin and one positioned between these, containing a polarized activated carbon column where the electrochemical generation of the Fenton reagent takes place. While the hydroxyl radicals electrochemically produced in-situ, react with the pollutant species adsorbed on the activated carbon cathode, the resin compartments administrate and collect the iron cation and the hydrated proton species in alternating flow direction cycles.