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Naringenin (NRG), a flavanone compound present in citrus fruits, has a variety of beneficial physiological active functions such as antioxidant, anti-inflammatory, and hypoglycaemic. In this study, an sensor was constructed by electrodeposition and used for the electrochemical study of NRG. Reduced graphene oxide (rGO) and glutathione (GSH) showed the ability to synergistically amplify NRG signals and possessed good linearity in the concentration range of 10.00–1200.00 μ mol l−1. The linear equation is Ip = 0.0776logc + 0.9353 (R2 = 0.9901), and the limit of detection is 3.33 μ mol l−1. The sensor performed well in terms of reproducibility, stability, and selectivity, which in turn enabled the detection of NRG in tomatoes. The average recovery of the sensor is 95.68% to 111.92%, with RSD less than 11.89%. The results were also verified by Ultraviolet–visible spectroscopy(UV-vis). Furthermore, density-functional theory was employed to analyse the front track of the NRG, speculating that the NRG underwent a transfer of two electrons and two protons. [ABSTRACT FROM AUTHOR]

Florfenicol (FLO) is the most widely used veterinary antibiotic and has been detected frequently in various animal products and water bodies. Electrooxidation and electroreduction are effective strategies to eliminate halogenated environmental pollutants in water. In this work, SnO 2 -Sb 2 O 3 /Ti felt electrode and Pd/Ni foam electrode were used to treat FLO in water. The influence of water quality parameters on the removal efficiency of the two technologies was investigated, and the suitability of the two technologies was evaluated from the perspectives of energy consumption, stability, microbial inhibition and product toxicity. The experimental data show that both technologies can effectively remove FLO within 60 min, the energy consumption of oxidative degradation is 8.6 times that of reduction dehalogenation, and more toxic intermediate products are produced during the oxidation process. However, oxidative degradation process can realize the removal of microbial inhibition faster than the reduction dehalogenation process. Combined with UHPLC-Q EXACTIVE, the destruction of FLO main molecular structure and the substitution of F atoms are the key that weaken the antimicrobial properties of the degradation products. This work provides theoretical basis for the controllable treatment of halogenated antibiotics in water. [Display omitted] • FLO in water was treated by electrooxidation and electroreduction respectively. • The efficiency and interference factors of the two strategies were studied. • Both approaches can eliminate the antibacterial activity of FLO. • The potential antibacterial sites of FLO were identified via mass spectrometry. [ABSTRACT FROM AUTHOR]

Nowadays, the excessive utilization of fossil-based chemicals has caused serious environmental problems, especially due to the negative carbon footprints. Addressing this issue by substituting fossil resources with environmentally friendly biomass is imperative. This study focuses on the electrooxidation of 5-hydroxymethyl-2-furaldehyde (HMF), a biomass-derived chemical, into 2,5-furandicarboxylic acid (FDCA) in alkaline solutions, a crucial feedstock, for the chemical industry. Given the acknowledged instability of HMF in an alkaline environment, this research investigated the kinetic approximation of HMF degradation under varying concentrations of KOH solutions (0.1 M and 1 M KOH) over 12 hours. Then, the electrooxidation of HMF to FDCA over cobalt-iron-based catalysts was investigated. As a result, the FDCA was successfully produced in 0.1 M KOH solution with a remarkable yield of up to 94 %, while a higher concentration (1 M KOH solution) accelerated the electrooxidation process. However, the yield and Faradaic efficiency could be greatly dropped after 12 hours of storing time due to the effects of HMF degradation reactions (Cannizaro and polymerization reactions). Therefore, this degradation phenomenon should be considered on an industrial scale, particularly when HMF may be stored for an extended period before utilization. [Display omitted] • Humins and Cannizzaro products can be rapidly formed in strong alkali environments. • Direct electrooxidation of HMF in the fresh solution showed satisfying results. • The prepared optimum CoFe-based electrocatalyst exhibited exceptional stability. • Electrooxidation of degraded HMF resulted in lower FDCA yield as well as FE. [ABSTRACT FROM AUTHOR]

In this study, the treatment of nanofiltration (NF) concentrate from a landfill leachate treatment plant through the electrooxidation (EO) process was investigated. Experimental studies were conducted in a batch reactor equipped with multi-metal oxide/TiO2 doped Ti anode and Pt doped Ti cathode. Persulfate was added as the oxidant and the performance of Fe0, Fe2+, and Fe3+ species as catalysts for persulfate activation was compared. Kinetic studies were carried out for chemical oxygen demand (COD) removal from leachate NF concentrate. Maximum COD removal efficiency was obtained by the EO process in which persulfate was added as the oxidant and Fe2+ was used as the catalyst for persulfate activation. Optimum values of the process variables (pH 5, current 2 A, Fe2+ dose 12 mM and persulfate dose: 60 mM) were determined. The COD removal was 77.1% under optimum conditions. The overall COD removal mechanism is well fitted with the pseudo-first-order and second-order kinetic models with R2 values of > 0.80 under all applied current values. Specific energy consumption calculated for optimum conditions were 73.4 kWh/m3 and 14.3 kWh/kg COD. The EO process assisted with Fe2+ activated persulfate can be evaluated as an efficient treatment method for leachate NF concentrate treatment. Article Highlights: SO4−. was produced by electrochemically activation. Fe0, Fe2+, and Fe3+ species as catalysts were compared. Multi-metal oxide/TiO2 anode and Pt/Ti cathode were used in batch processes. 77.1% COD removal was achieved with electrooxidation—Fe2+ activated persulfate. Kinetic models with R2 values of > 0.80 under all applied current values. [ABSTRACT FROM AUTHOR]

The direct urea fuel cell (DUFC) functions as a dual-purpose technology, serving as both a renewable energy production system and a means to degrade urea in wastewater. Herein, Ni-P nanosheets are synthesized using a chemical nickel-plating technique and applied to the urea oxidation reaction (UOR). The reaction time, plating solution pH, and reaction temperature play crucial roles in facilitating UOR kinetics. The optimized Ni-P nanosheets display good catalytic performance and the voltage difference between the 9000th and the first cycle is only 28 mV at 10 mA cm−2. Additionally, it maintains outstanding long-term stability at 1.52 V versus reversible hydrogen electrode (RHE) for 70 hours and Ni-P nanosheets deactivates by less than 1% compared to the initial current density, further confirming the high stability of Ni-P nanosheets for the UOR. This research not only offers a rapid and effective approach for developing advanced UOR catalysts but also introduces a conceptual framework for designing catalysts for various catalytic reactions. [Display omitted] [ABSTRACT FROM AUTHOR]

• Shape-controlled Pd 3 Sn electrocatalysts transitioned from nanonetwork to nanostrips and nanodots were synthesized. • Pd 3 Sn-dots catalyst due to the ultra-small size and uniform dispersion leads to a large electrochemically active area. • Pd 3 Sn-dots catalyst presents excellent performance towards ethanol and ethylene glycol oxidation reactions. At present, it is still a great challenge to control the morphology and size of nanoparticles for obtaining more efficient and stable catalysts for direct fuel cell reactions. Herein, we have synthesized a series of Pd 3 Sn bimetallic catalysts with different morphologies that transitioned from nanonetwork to nanostrips and then to nanodots by altering the varieties of reducing agents and the amount of surfactant. And the formation mechanisms of nanocatalysts were also investigated. It is worth noting that Pd 3 Sn-dots, due to the unique structure, uniform dispersion and ultra-small size, exhibit excellent electrocatalytic activity for ethanol oxidation reaction and ethylene glycol oxidation reaction, which distinctly higher than the other Pd 3 Sn catalysts and commercial Pd/C catalysts. Moreover, the as-prepared Pd 3 Sn catalysts also performed greater long-term durability due to the electronic and synergistic effects. This work provides guidance on the morphology-dependent nanocrystals, which will show a great potential as anodic catalysts in direct fuel cell applications. [ABSTRACT FROM AUTHOR]

Highlights • The Au-NPs have average size of around 7 nm was obtained by a simple green synthesis method using H. sabdariffa L. extract which act as reductant and stabilizer. • The Au-NPs modified electrodes have acceptable stability, repeatability and reproducibility towards determination of nitrite. • The Au-NPs modified electrodes hold possible applications for evaluating specific concentration range of nitrite ions in water. Abstract In this study, gold nanoparticles (Au-NPs) were synthesized through green biosynthetic route using water extract of Hibiscus sabdariffa leaves (H. sabdariffa L.) which acted as both reductant and stabilizer agents. The synthesized Au-NPs were characterized by UV–vis spectroscopy, XRD, TEM, FESEM, EDX, zeta potential, and FTIR spectroscopy. By analyzing the UV–vis, FTIR and HPLC data, and comparing with previous studies, the presence of chlorogenic acid in H. sabdariffa L. was identified as the major antioxidant compound involved in the reduction of Au3+ ions. The FESEM micrograph and TEM images visualized that Au-NPs were formed with a narrow distribution and an average particle size of 7 ± 2 nm at stirring time of 80 min. As for application, the electrooxidation of nitrite was studied with Au-NPs. The electrocatalytic activity of bare GCE and Au-NPs/GCE towards the electrooxidation of nitrite was examined and compared via cyclic voltammetry. Higher electrooxidation of nitrite ions for the synthesized Au-NPs was observed at a stirring time of 80 min. The prepared material showed a linearity of 0.37–10 mM towards nitrite electrooxidation, with the limit of detection (LOD) of 0.11 mM (S/N = 3). Moreover, the prepared electrode presented acceptable stability, repeatability and reproducibility. Graphical abstract Image, graphical abstract [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Degradation of paracetamol (>90%) by electrooxidation process using graphite electrode. • Total degradation and mineralization (>82% COD removal & >65% TOC removal) at the end of 240 min of electrolysis. • Effect of initial pH, electrolyte concentration (Na 2 SO 4) and current density was a crucial parameters. • Idendification of transformation products of paracetamol by HPLC. • A pathway for paracetamol degrdation by hydroxyl radicals (OH) based on reaction intermediates. Abstract Paracetamol is one of the micropollutant in water and most frequently used drugs as moderate pain reliever. These micropollutants are serious threat to human and environment. In the present investigation, we made attempt to degrade the electrochemical oxidation of paracetamol in water by graphite as anode. Electrooxidation behavior of paracetamol at graphite anode was tested by cyclic voltammetry technique performed in the potential range of -1.0 to +1.0 V versus Ag/AgCl. The optimized conditions were obtained by varying different factors, such as electrolyte concentration (0.02-0.1 M), current density (3.1–7.1 mA/cm2), initial pH (4–8) and paracetamol concentration (20 mg L−1). The results showed that the maximum removal of paracetamol concentration, chemical oxygen demand (COD) and total organic carbon (TOC) reached >90%, >82% and >65% after 240 min electrolysis at an initial pH 4, having paracetamol concentration of 20 mg L−1 at a constant current density of 5.1 mA/cm2 with 0.1 M Na 2 SO 4 supporting electrolyte. Different SO 4 2- concentrations in water promoted the electro generation of strong mediator oxidant species, such as OH, SO 4 - and S 2 O 8 2- increasing the removal efficiency of paracetamol. The degradation of paracetamol and its mineralization trend were monitored by UV–vis spectrophotometric method and total organic carbon (TOC) analyzer, respectively. FT-IR spectra confirmed that the functional group changes after electrolysis of paracetamol. HPLC studies revealed the byproduct (hydroquinone, benzoquinone and carboxylic acid) formation during the electrolysis process. On the other hand, researchers are actively involved in ozonation, photocatalysis, activated charcoal and biological treatments etc., to remove/degrade micropollutant, which are major drawbacks for the implications. [ABSTRACT FROM AUTHOR]

Abstract Thousands of compounds are used and disposed of every day and many of them are not degraded in conventional treatment plants. It is necessary an alternative to eliminate these compounds. This can be done through electrooxidation technology, which was applied in this work to a mixture of pharmaceutical compounds including alprazolam (ALP), clonazepam (CLP), diazepam (DZP), lorazepam (LZP) and carbamazepine (CBZ) at 100 µg.L-1. The mixture was studied with different types of electrolytes and the neurotoxic effect of the treatment was evaluated. The best result was obtained with NaCl (0.5 g.L-1), leading to complete degradation of CLP, LZP and CBZ. [ABSTRACT FROM AUTHOR]

Abstract Thousands of compounds are used and disposed of every day and many of them are not degraded in conventional treatment plants. It is necessary an alternative to eliminate these compounds. This can be done through electrooxidation technology, which was applied in this work to a mixture of pharmaceutical compounds including alprazolam (ALP), clonazepam (CLP), diazepam (DZP), lorazepam (LZP) and carbamazepine (CBZ) at 100 µg.L-1. The mixture was studied with different types of electrolytes and the neurotoxic effect of the treatment was evaluated. The best result was obtained with NaCl (0.5 g.L-1), leading to complete degradation of CLP, LZP and CBZ. [ABSTRACT FROM AUTHOR]

The electrocoagulation (EC) and electrooxidation (EO) processes are employed widely as treatment processes for industrial, agricultural, and domestic wastewater. In the present study, EC, EO, and a combination of EC + EO were evaluated as methods of removing pollutants from shrimp aquaculture wastewater. Process parameters for electrochemical processes, including current density, pH, and operation time were studied, and response surface methodology was employed to determine the optimum condition for the treatment. The effectiveness of the combined EC + EO process was assessed by measuring the reduction of targeted pollutants, including dissolved inorganic nitrogen species, total dissolved nitrogen (TDN), phosphate, and soluble chemical oxygen demand (sCOD). Using EC + EO process, more than 87% reduction was achieved for inorganic nitrogen, TDN, and phosphate, while 76.2% reduction was achieved for sCOD. These results demonstrated that the combined EC + EO process provided better treatment performance in removing the pollutants from shrimp wastewater. The kinetic results suggested that the effects of pH, current density, and operation time were significant on the degradation process when using iron and aluminum electrodes. Comparatively, iron electrodes were effective at reducing the half-life (t 1/2) of each of the pollutants in the samples. The application of the optimized process parameters on shrimp wastewater could be used for large-scale treatment in aquaculture. [Display omitted] • Shrimp metabolism contaminates the surrounding water system. • Shrimp wastewater contains a considerable amount of nitrogen and phosphate. • Electrochemical processes are effective to treat shrimp wastewater effluent. • Optimized parameters are effective for resource recovery of aquaculture effluent. [ABSTRACT FROM AUTHOR]

The presence of toxic pollutants in wastewater discharge can affect the environment negatively due to presence of the organic and inorganic contaminants. The application of the electrochemical process in wastewater treatment is promising, specifically in treating these harmful pollutants from the aquatic environment. This review focused on recent applications of the electrochemical process for the remediation of such harmful pollutants from aquatic environments. Furthermore, the process conditions that affect the electrochemical process performance are evaluated, and the appropriate treatment processes are suggested according to the presence of organic and inorganic contaminants. Electrocoagulation, electrooxidation, and electro-Fenton applications in wastewater have shown effective performance with high removal rates. The disadvantages of these processes are the formation of toxic intermediate metabolites, high energy consumption, and sludge generation. To overcome such disadvantages combined ecotechnologies can be applied in large-scale wastewater pollutants removal. The combination of electrochemical and biological treatment has gained importance, increased removal performance remarkably, and decreased operational costs. The critical discussion with depth information in this review could be beneficial for wastewater treatment plant operators throughout the world. [Display omitted] • Inclusive explanations of electrochemical processes have been discussed. • Electrochemical processes degrade a wide variety of chemicals in wastewater. • Combination of electrochemical-biological processes enhances pollutants removal. • Pre-electrochemical processes enhance the degradation of pollutants. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate the removal efficiencies of the electrochemical treatment systems as an alternative for the treatment of cardboard plant wastewater (CPW). In accordance with this purpose, CPW was treated by electrocoagulation (EC) with Al electrodes and the effects of current density (CD), operating time ( t ), and initial pH (pH i ) were investigated. The results showed that EC at optimum treatment conditions (CD: 7.5 mA/cm 2 , pH i : 7.0 and t : 60 min) have limited removal efficiencies for total organic carbon (TOC; 17.1%) and chemical oxygen demand (COD, 14.2%), on the contrary of turbidity (98.7%). Due to the low TOC and COD removal efficiencies, a secondary treatment was needed and the electrocoagulated effluent was subjected to electrooxidation (EO) by using a boron doped diamond (BDD) electrode for investigating the effect of CD, t , pH i and electrolyte concentration ( C e ). Higher TOC (83.7%) and COD (82.9%) removal efficiencies were obtained by EO under the optimum treatment conditions (CD: 100 mA/cm 2 , pH i : 7.2, C e : 5.0 g/L Na 2 SO 4 and t : 180 min). In addition, a toxicity test was carried out to the raw and treated wastewater under the optimum operating conditions. This study demonstrated that the combination of EC and EO have a satisfactory potential for real industrial wastewater with a high organic content, suspended solids and toxicity. [ABSTRACT FROM AUTHOR]

Water stress must be addressed by developing cost-effective wastewater treatment technologies. Reactive electrochemical membranes (REM) have gained popularity in this scenario due to the benefits of both electrochemical advanced oxidation processes (EAOP) and membrane filtration processes (MFP) in reducing mass transport limitations and fouling issues. In this context, this review aims to consolidate recent advances in REM, focusing on sub-stoichiometric titanium oxide-based REM (TiSO-REM), mainly Ti 4 O 7 , the most promising ceramic material due to its high conductivity and ability to generate •OH. The primary fabrication methods for TiSO porous anodes are discussed, resulting in a significant reminder of their electrocatalytic, porosimetric and physicochemical intrinsic properties. In addition to the real advantages of using this material in flow-through configurations, which allow convection-enhanced mass transport and provide a high electrochemical surface area. The latest progresses in TiSO-REM are presented, with specific emphasis on understanding the main operating parameters in performance efficiency: the determinative key role among pollutant nature, matrix effect and anode in removal mechanisms, and where the anode is in relation to the cathode in the reactor design. These points are intended to identify process limitations and challenges to be overcome when implementing various reactor configurations until the scaling-up. All these aspects are reviewed critically in order to provide future research directions for the industrial advancement of this technique, which has proven to be more energy-efficient and therefore economically feasible than alternative EAOP. [Display omitted] • A comprehensive review of the TiSO-REM use for wastewater treatment is provided. • Pollutant nature and matrix effect play a determinative role in removal mechanism. • Cross-flow with cathode-to-anode mode is the most efficient configuration. • REM is more energy-efficient and economically feasible than other EAOP. [ABSTRACT FROM AUTHOR]

• Successful preparation of Co-S/Ni x Se y /C@TiO 2 electrode with 3D structure. • Se doping gives the Co-S/Ni x Se y /C@TiO 2 electrode excellent catalytic performance. • A novel rotating cylinder electrode system was fabricated. • Concentration polarization and bubble adsorption of electrode are alleviated. • Rotating cylinder electrode system improves electrode performance by 85%. The cleanliness and ease of storage and transportation of H 2 O 2 make it a promising fuel of fuel cell, but improving the catalytic activity of H 2 O 2 electrooxidation is a prerequisite. The Co-S/Ni x Se y /C@TiO 2 electrode was prepared by "vapor deposition" and "two-step electrodeposition", and the electrode was scaled up and fabricated into a rotating cylinder electrode to improve the catalytic performance of H 2 O 2 electrooxidation. The presence of Se-Se bonds and the synergistic effect of Co-S compound and Ni x Se y gave the electrode a reduced oxidation potential for the electrooxidation of H 2 O 2. The three-dimensional (3D) structure of the electrode facilitated the exposure of the catalyst active site, and the loading of Co-S compound improved the hydrophilicity of electrode. It's important to note that an original rotating cylinder electrode system was fabricated using an enlarged Co-S/Ni x Se y /C@TiO 2 electrode to weaken concentration polarization and reduce bubble adsorption on the electrode surface. Through the study, rotation of electrode and circulation of reaction solution exhibit positive effect for the electrooxidation reaction. Especially with a rotation speed of 37 r min−1 of electrode, the performance was improved by 85%. This study provides new strategies for improving the performance of H 2 O 2 electrooxidation, which is of high research significance. [Display omitted] The introduction of Se-Se bonds and the synergistic effect of Co-S compound and Ni x Se y in the Co-S/Ni x Se y /C@TiO 2 electrode improved the performance of Ni, Co-based catalysts for the electrooxidation of H 2 O 2. Meanwhile, the Co-S/Ni x Se y /C@TiO 2 electrode was applied to a novel rotating cylinder electrode to solve the problem of degradation of electrode performance caused by the concentration polarization and bubble adsorption. [ABSTRACT FROM AUTHOR]

As substitutes for perfluoroalkyl substances (PFASs), hexafluoropropylene oxide (HFPO) homologues are still environmentally problematic for their issues in toxicity, bioaccumulation, and long-distance mobility, which urges efficient removal technologies and in-depth mechanistic studies. Herein, we present the systematic optimizations on the electrochemical oxidation of 100 mg L−1 HFPO dimer acid (HFPO-DA) at a boron-doped diamond anode (3.6 V, 100 mM Na 2 SO 4 , pH 7.0), which exhibits a powerful mineralization capacity over 97% within 210 min of operation and is highly tolerant to various environmental factors. Under the optimized conditions, the structure-reactivity relationship has been analyzed by comparing six kinds of PFASs, proving that the increasing numbers of ether bonds in the HFPO homologues favor their removal and defluorination processes. Density functional theory (DFT) calculations further indicate that the facile, water-assisted cleavage of the ether bonds in the HFPO homologues can significantly reduce the energy barriers and shorten the "-CF 2 " unzipping degradation cycles, which is different from the conventionally proposed mechanism for degrading PFASs. Our findings demonstrate the promising application of electrochemical oxidation in the efficient removal of PFAS substitutes and offer new mechanistic insights for designing environment-friendly F-based chemicals. [Display omitted] Optimized electrochemical oxidation of HFPO-DA with a >97 % defluorination rate. The removal rates of all HFPO homologues all approach 100 %. DFT calculation shows the facile ether-bond cleavage promotes mineralization. [ABSTRACT FROM AUTHOR]

This study investigated the performance of combined zero-valent aluminum (ZVAl) and electrochemically activated persulfate (PS) oxidation for the leachate nanofiltration concentrate (NFC) treatment. Firstly, operating parameters in the ZVAl procedure were optimized and under the optimum conditions (ZVAl dose 1 g/L, initial pH 1.5) the removal efficiency of the chemical oxygen demand (COD), UV 254 , and color were 22.39%, 29.03%, and 48.26%, respectively. Secondly, the effect of various anode types (Ti/RuO 2 , Ti/IrO 2 , and Ti/SnO 2) within the electrooxidation (EO) process was evaluated. The Ti/RuO 2 anode was found to be the most effective one in terms of pollutant removal efficiencies and operation cost. The efficiency of single, binary, and hybrid processes was evaluated by control experiments and the results were ranked as PS < ZVAl < ZVAl + PS < EO < EO + PS < EO + ZVAl < EO + ZVAl + PS. In the following part of the study, the Box-Behnken design was preferred to optimize the operating parameters of the hybrid EO + ZVAl + PS process. The COD, UV 254 , and color removal efficiencies under optimum conditions (4.88 mM PS dose, 1.6 A current applied, and 120 min reaction time) were 62.1%, 75.2%, and 99.9%, respectively. The estimated and experimentally obtained data were close to each other. The pollutant removal efficiencies increased in parallel with the current density and reaction time; however, the effect of the PS dose remained at a negligible level. The obtained results indicate the effectiveness of the hybrid EO + ZVAl + PS process for the treatment of leachate nanofiltration concentrate under optimized conditions. [Display omitted] • The hybrid EO + ZVAl + PS process was optimized. • The highest reaction rate constant for COD is 0.0061 1/min with the EO + ZVAl + PS process. • The optimum conditions were 4.88 mM PS dose, 1.6 A applied current, and 120 min. • COD, UV 254 , and color removals were 62.1%, 75.2%, and 99.9%, respectively. [ABSTRACT FROM AUTHOR]

Herein, the role of modified electrode comprised of polypyrrole (PPy), graphene oxide (GO), multi walled carbon nanotubes (MWCNTs) and copper (I) oxide nanoparticles in the electrochemical methanol oxidation is considered. The modified electrodes prepared through the successive Layer by Layer (LBL) electrochemical and sonoelectrochemical deposition processes. As-fabricated electrodes were characterized by FT-IR spectroscopy and scanning electron microscopy (SEM), which confirmed the incorporation of GO into the PPy matrix. Afterward, the electrocatalytic performance of as-prepared electrodes was evaluated for methanol oxidation reaction by cyclic voltammetry (CV), chronoamperometry, and electrochemical impedance spectroscopy (EIS). It was found that the Pd sub-layer has a vital role in synthesis of Cu 2 O nanostrucures, because this noble nano-layer can protect the copper substrate and consequently lead to synthesis of Cu 2 O nanostrucures. CV measurements indicated that the simultaneous presence of GO with PPy and MWCNTs in the structure of electrode enhances the overall electrocatalytic performance of the LBL electrodes for methanol oxidation. So, a strong synergistic interaction is expected to be between these components. Moreover, the results from chronoamperometry confirmed that the modified electrode had a good stability and repeatability as electrocatalyst. [ABSTRACT FROM AUTHOR]

This study aims to demonstrate that a combined system of membrane bioreactor (MBR) with electro-oxidation (EO) can be a promising technology to treat compounds such as carbamazepine (CBZ). The MBR showed high capacity to remove the chemical oxygen demand (COD) and low capacity for the degradation (20% of removal), after 120 d of operation; which presumably indicates that CBZ was not toxic for microorganisms, despite its poor degradation. On the other hand, the EO system was capable to completely degrade CBZ (99.99% of removal). In addition, the MBR achieved 83% of conversion efficiency of NH 4 + to NO 3 − or NO 2 − ; and only 20.5% of PO 4 − removal. A toxicity test using Dapnia magna and Vibrio fischeri was carried out. Results indicated that MBR is an efficient method to decrease wastewater toxicity but during electrooxidation treatment higher toxicity was obtained, probably due to the generation of more toxic compounds than the initial pollutants. [ABSTRACT FROM AUTHOR]

An antibiotic drug, d -cycloserine (CYS), in phosphate buffer at different pH values was electrochemically studied using a gold electrode. A well-resolved, irreversible, diffusion-controlled voltammetric peak was obtained at 0.873 V in a pH 9.2 phosphate buffer solution with an ionic strength of 0.2 M. The experimental conditions, such as the solution pH and scan rate, were optimized. The pH dependence suggested that equal numbers of protons and electrons were involved in the electrochemical oxidation of CYS. A plausible oxidation mechanism was proposed. Under the selected conditions, the dependence on the concentration of CYS revealed that the detection limit for CYS was 3.3 × 10 −8 M for differential pulse voltammetry and 4.91 × 10 −8 M for square wave voltammetry. The proposed method was successfully applied to the determination of CYS in drug capsules and urine samples. The electrode exhibits good reproducibility and stability. In addition, the influence of various foreign species was studied. [ABSTRACT FROM AUTHOR]

Palladium nanoparticles/nanostructured carbon black composite (PdNPs/NCB), supported on the carbon–ceramic electrode (CCE), has been prepared by a chemical reduction method using sodium borohydride as a reducing agent. The synthesized composite was characterized by scanning electron microscopy, high resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction and electrochemical methods to delineate its surface morphology, nanostructure properties, composition, crystal phases and electrochemical properties. The obtained modified electrode, PdNPs/NCB/CCE, was used as an efficient electrocatalyst for the oxidation of formic acid. Electrochemical techniques including cyclic voltammetry and chronoamperometry were applied for electrocatalytic investigations and it was found that the PdNPs/NCB/CCE was catalytically more active than the Pd nanoparticles supported on the CCE without NCB (PdNPs/CCE). The effect of some experimental factors was studied and optimum conditions were suggested. The obtained results show that the PdNPs/NCB/CCE has satisfactory stability and reproducibility for electrooxidation of formic acid when stored in ambient conditions and improved electrocatalytic activity in continued cycling which make it more attractive for formic acid fuel cell applications. [ABSTRACT FROM AUTHOR]

Diclofenac (DCF), which belongs to nonsteroidal anti-inflammatory drugs (NSAIDs), is a biorefractory micropollutant and its removal from wastewaters has become strongly necessary. This paper dealt with the DCF removal from aqueous solutions by electrooxidation at boron-doped diamond (BDD) electrode. In addition, the dual character of BDD electrode in electrochemical degradation processes and their control was investigated. The electrooxidation process was assessed based on ultraviolet (UV) spectra and total organic carbon (TOC) determinations in the electrolysed solutions. Also, the specific power consumption was determined for various applied current densities (1 - 7.5 mA/cm²) and DCF concentrations (10 - 200 mg/L). Cyclic voltammograms (CVs) recorded on BDD in the presence of DCF were used as analytical tool for the degradation process characterisation. The peak currents recorded at +0.7 and +1 V/SCE allowed characterizing accurately DCF degradation process. UV spectra, TOC removal and CV results proved that the BDD was highly effective in the DCF degradation and mineralization. Thus, TOC removal of about 90% was obtained for all studied DCF concentrations. [ABSTRACT FROM AUTHOR]

Synthetic azo dyes are extensively used in the textile industries, which are being released as textile effluent into the environment presence of azo dyes in the environment is great environmental concern therefore treatment of textile effluent is crucial for proper release of the effluent into the environment. Electrochemical oxidation (EO) is extensively used in the degradation of pollutants because of its high efficiency. In this study, photo-assisted electrooxidation (PEO) followed by biodegradation of the textile effluent was evaluated. The pretreatment of textile effluent was conducted by EO and PEO in a tubular flow cell with TiO 2 –Ti/IrO 2 –RuO 2 anode and titanium cathode under different current densities (10, 15, and 20 mA cm−2). The chemical oxygen demand level reduced from 3150 mg L−1 to 1300 and 600 mg L−1under EO and PEO, respectively. Furthermore, biodegradation of EO and PEO pretreated textile effluent shows reduction in chemical oxygen demand (COD) from 1300 mg L−1 to 900 mg L−1and 600 mg L−1to 110 mg L−1, respectively. The most abundant genera were identified as Acetobacter, Achromobacter, Acidaminococcus , Actinomyces, and Acetomicrobium from the textile effluent. This study suggests that an integrated approach of PEO and subsequent biodegradation might be an effective and eco-friendly method for the degradation of textile effluent. [Display omitted] [ABSTRACT FROM AUTHOR]

The electrochemical removal of tramadol hydrochloride from aqueous solutions has been investigated under several operating conditions using a Pb/PbO 2 electrode. The optimum conditions of the treatment process are: current density of 1000 mA/cm −2 , pH ≈6, temperature of 10 °C and initial tramadol hydrochloride concentration of 100 mg/L. The time of electrolysis is 25 min for degradation rate of tramadol hydrochloride and chemical oxygen demeaned (COD) removal is 22 h. The results were obtained by UV–Vis spectrophotometer and the presently designed electrode was coincident. [ABSTRACT FROM AUTHOR]

PdCu/C (XC-72) electrocatalyst was synthesized by a chemical reduction method using ethylene glycol as reaction media, polyvinylpyrrolidone as surfactant and sodium borohydride as reducing agent. Vulcan carbon XC-72 was employed as support and added through the PdCu synthesis procedure; further, Pd commercial (Pd/C, 20% ETEK) was used for comparison purposes. Physicochemical characterization consisted in XRD, XRF, EDS and TEM analyses. TEM micrographs showed the presence of semi-spherical nanoparticles with a particle distribution around 6 nm. X-ray diffraction patterns showed the typical face-centered cubic structure of Pd materials for commercial Pd and revealed a low crystallinity for PdCu/C. The XRF analysis showed a mass metal composition of 81% Pd and 19% Cu. EDS analysis was made to single particles exhibiting an average elemental composition of 92% Pd and 8% Cu. The electrocatalytic activity of PdCu/C and Pd/C was evaluated by cyclic voltammetry experiments toward ethylene glycol and glycerol oxidations using three concentrations (0.1, 1 and 3 M) and 0.3 M KOH as electrolyte. These experiments exhibited the superior performance of PdCu compared with commercial Pd by means of current densities associated to the electro-oxidation reactions where values at least 3-fold higher than Pd/C were found. [ABSTRACT FROM AUTHOR]

This work reports the electrochemical treatment of municipal solid waste landfill leachates in a parallel plate cell provided with boron doped diamond (BDD) anodes. Two types of samples were electrooxidized at three current densities between 200 and 800 A/m2: (i) raw leachates; and (ii) the leachate after treatment in a membrane bioreactor (MBR), characterized by its near-zero ammonia content. In absence of ammonia, the electrogenerated chlorine oxidants accelerated the removal of chemical oxygen demand but barely influenced the mineralization of persistent organic pollutants still retained in the MBR-treated leachate. Furthermore, we investigated the removal of 17 poly- and perfluoroalkyl substances (PFAS) contained in the real MBR-treated leachate (∑ 17 PFAS = 3456 ng/L). The operation at 200 A/m2 increased perfluorocarboxylic acids (PFCAs) concentration, indicating the presence of unknown precursors in the MBR-treated leachate. Working at 800 A/m2 successfully reduced the Σ 17 PFAS content by 95% in 6 h. Σ 17 PFAS showed decreasing trends, and only perfluoropentanoic and perfluorobutanoic acids showed temporal increases that later on went down as the long chain PFCAs were degraded into shorter chain homologs. 1-log (90%) Σ 17 PFAS reduction was achieved in 4.5 h, when the formation of undesirable perchlorate was still near undetectable. We estimate that the PFAS electrooxidation rate in the leachate matrix was one-sixth of the removal rate observed in a previous study treating a cocktail of PFAS in synthetic contaminated groundwater. Overall, this work provides useful data to guide the design of advanced onsite treatment of landfill leachates, one of the main secondary PFAS entry to the environment. [Display omitted] • MBR treatment significantly enhanced the energy efficiency of ELOX leachate treatment. • Detected PFAS in MSW landfill leachate (LL) increased after MBR treatment. • Electrooxidation with BDD anodes removed > 95% of 17 PFAS analyzed in real MBR-treated LL. • The LL matrix reduced PFAS removal kinetics to one-sixth, compared to groundwater matrix. [ABSTRACT FROM AUTHOR]

Highlights: [•] We studied the electrochemical degradation of a real industrial effluent. [•] Chemical oxygen demand can be efficiently removed from the effluent. [•] Cathodic reaction does not interfere on the overall degradation kinetics. [•] High energy consumption is still a challenge for electrochemical oxidation. [•] Nb/BDD anode was not stable for the degradation of real and simulated wastewaters. [Copyright &y& Elsevier]

Abstract: The effluents of gelatin production plant are highly complex and difficult to treat by conventional methods. The electrochemical techniques involving electrocoagulation and electrooxidation were attempted for the treatment of wastewater from gelatin production plant. Around 60% of TOC removal was achieved by electrocoagulation using aluminum as anode. However, the performance was severely affected due to scaling of the electrodes. The high concentration of dissolved calcium was found to be responsible for scaling of electrodes. To minimize the scaling, calcium was precipitated as CaCO3 using bicarbonate. After the calcium was precipitated, scaling was reduced and the performance of the electrodes was drastically improved. The effect of applied current density and flow rate on TOC removal was studied and the energy consumption for electrocoagulation was estimated. Since the removal of pollutants by electrocoagulation is only partial, the wastewater was processed further by electrooxidation using IrO2–Ta2O5 coated Ti electrode and TiO2 nanotubes grown on titanium sheet (TiO2 NT) as electrodes. The TOC removal was drastically improved in the presence of TiO2 NT electrode. [Copyright &y& Elsevier]

Electrochemical decomposition of leachate, which has previously undergone A/O (anaerobic-aerobic biological) treatment and chemical coagulation, was investigated over Ti/ Ru02lr02 anode, stainless steel cathode and coke pow-der particle electrodes packed into the electrodes in a bi-polar three-dimensional electrode reactor (BTDR). The removal efficiency of COD and ammonia nitrogen in-creased with applied current density. The main influenc-ing factors of BTDR were evaluated by an orthogonal test including reaction time, current density, plate distance, plate amounts and aeration flow-rate. With reaction time of 80 min, current density of 25 mA/cm². plate distance of 1.0 cm, plate amounts of 4 pairs, and aeration flow-rate of 2 L/min, most of contaminants in leachate were decreased by BTDR, which can supply the discharge limit for land-fill leachate in China. The BTDR could be employed as a step of advanced treatment for landfill leachate. [ABSTRACT FROM AUTHOR]

A study on the electrochemical decolourisation, aromatic ring degradation and mineralization of Reactive Red 147 (RR) synthetic solutions using boron-doped diamond (BDD) electrodes is presented. Electrolyses were carried out under galvanostatic conditions in 0.1 M Na2SO4 supporting electrolyte using undivided electrolytic cell. Prior to electrolysis application, the electrochemical behaviour of BDD electrode was characterized in the presence of RR dye by cyclic voltammetry in order to establish the working potential-current conditions. The influence of operating variables, such as current density, initial pH, initial concentration of the RR was studied. Under all the experimental conditions applied, the total decolourisation of dye solution was achieved within several min of electrolysis period (maximum 8 min). The aromatic ring cleavage occurred depending on current density, the pH and the dye concentration. The complete mineralization of dye synthetic solution was not achieved, and the maximum mineralization efficiency of 77.2 % occurred for initial RR concentration of 50 mg L-1, initial pH 5 and the current density of 10 mAcm-2. [ABSTRACT FROM AUTHOR]

In this study, decolorization and degradation of aqueous nickel phthalocyanine reactive dye solutions was comparatively studied by electrochemical methods, such as electrocoagulation, electrooxidation and electro-Fenton processes. In the electrocoagulation process with aluminum electrodes the colored aqueous solutions containing 100 mg/L nickel phthalocyanine and 6 g/L NaCl were treated at initial pH 7.5 and applied current densities of 5, 10 and 20 mA/cm², where fast and 100% decolorization was achieved in 10, 5 and less than 2.5 minutes of electroprocessing respectively. The electrooxidation process was conducted in acidic electrolyte solutions containing 100 mg/L nickel phthalocyanine and 6 g/L Na2SO4 with Ti/Pt and graphite plate electrodes at the applied current density of 5 mA/cm². Even after 60 minutes of electrolysis time the dye remained undegradable by 17 and 40%, respectively. Substituting Na2SO4 with the same concentration of NaCl, complete degradation of the dye was achieved in 30 and 20 minutes with Ti/Pt and graphite electrodes respectively. In the electro- Fenton process with Fe electrodes and added amounts of H2O2 at pH 3 and an applied current density of 5 mA/cm² complete degradation of nickel phthalocyanine occurred in 20 minutes. [ABSTRACT FROM AUTHOR]

In this study, the potential use of electrooxidation-electrocoagulation and ultrasound-assisted electrooxidation-electrocoagulation processes with hybrid electrodes to improve the dewaterability and degradability of active sludge was investigated. Effects of electrode type, current density, electrode connection mode, air injection flow rate, and electrode distance on sludge dewaterability and degradability were determined through measuring specific resistance to filtration (SRF), filtration time (s), degree of degradation (DD, %) and sludge moisture content (Mc, %). To determine the effects of the ultrasound-assisted electrochemical process, experiments were conducted in a different reactor under optimum conditions of the electrochemical process, constant frequency (40 kHz), and varying ultrasound powers (60–240 W). The experiments results showed that for all electrode materials, at high values of current density, the dewaterability of the sludge decreased while the degradability of the sludge increased. Besides, both filtration times and degree of degradation decreased with increasing air injection flow rates. Under the optimum operational conditions (TiPbO 2 -Fe-SS-SS hybrid electrode type, 100 A/m2 current density, MP-P connection mode, 1 L/min air injection flow rate, 1 cm electrode distance, and 20 min operation time), SRF value decreased from 50 × 1012 m/kg to 2.02 × 1012 m/kg, filtration times decreased from 132 s to 9 s, DD value was observed as 20.2% and Mc value was observed as 42.3%. Under the optimum operational conditions of electrooxidation-electrocoagulation process, sludge DD values in the ultrasound-assisted electrooxidation-electrocoagulation process increased, but SFR values decreased. The structural change in the sludge after each process was determined by SEM analysis. [Display omitted] • Effects of combined EOx-EC, US-EOx-EC and only US processes on sludge were studied. • EOx-EC process was an effective method to dewaterability of sludge and reduced 99% specific resistance to filtration. • US-EOx-EC process improved both dewaterability and degradability of sludge. • Only US process was more effective to degradability of sludge and enhanced 32.3% degree of degradation. • The optimum operation parameters for treatment processes were determined. [ABSTRACT FROM AUTHOR]

Water pollution by microplastics (MPs) is a contemporary issue which has recently gained lots of attentions. Despite this, very limited studies were conducted on the degradation of MPs. In this paper, we reported the treatment of synthetic mono-dispersed suspension of MPs by using electrooxidation (EO) process. MPs synthetic solution was prepared with distilled water and a commercial polystyrene solution containing a surfactant. In addition to anode material, different operating parameters were investigated such as current intensity, anode surface, electrolyte type, electrolyte concentration, and reaction time. The obtained results revealed that the EO process can degrade 58 ± 21% of MPs in 1 h. Analysis of the operating parameters showed that the current intensity, anode material, electrolyte type, and electrolyte concentration substantially affected the MPs removal efficiency, whereas anode surface area had a negligible effect. In addition, dynamic light scattering analysis was performed to evaluate the size distribution of MPs during the degradation. The combination of dynamic light scattering, scanning electron microscopy, total organic carbon, and Fourier-transform infrared spectroscopy results suggested that the MPs did not break into smaller particles and they degrade directly into gaseous products. This work demonstrated that EO is a promising process for degradation of MPs in water without production of any wastes or by-products. Image 1 • Degradation of MPs by EO process using catalytic anode materials was investigated. • Synthetic suspension was prepared using polystyrene microbeads with 26 μm size. • Current intensity, type of anode and electrolyte greatly affected MPs degradation. • Performance of EO process was evaluated using DLS, SEM, TOC and FTIR analyses. • EO process can degrade more than 58 ± 21% of MPs in 1 h of electrolysis. [ABSTRACT FROM AUTHOR]

Total ammonia nitrogen (TAN) is present in several types of effluents including drainage waters from fertilizers storage and handling facilities. Several countries have established a maximum accepted value for TAN and nitrate ion concentration to protect the human health and living environment. This way, the objective of this paper was to investigate the influence of some parameters on TAN electrooxidation, without nitrate generation, from a real effluent using an undivided batch electrolytic reactor with recirculation and Ti/RuO 2 electrodes. Results indicated that TAN concentration decreased with the increase of electrolysis length of time, for all current densities and chloride concentrations investigated. The increase of current density and chloride ions concentration lead to a shorter electrolysis period. Nitrate formation during TAN degradation in the presence of chloride ions by electrolysis is influenced by pH and residual TAN concentration. Concentration of nitrate ions increased from 29.7–711 mg.L−1 after complete TAN degradation, whereas pH increased from 4.6–7.8. Under the investigated conditions, electrolysis should be interrupted after 90% of TAN degradation to avoid nitrate formation. 96% of TAN was removed from an effluent sample containing 6.2 mg.L−1 of NaCl after 120 min of electrolysis with a current density of 25 mA.cm-2. Specific energy consumption was 40.7 kW h.m-3 with a cost of US$ 2.30/m-3. [ABSTRACT FROM AUTHOR]

Advanced oxidation of atrazine (ATZ) via electrolysis and ozonation separately and in combination was studied in the presence of concentrated chloride and bromide electrolytes at pH 7. Ozone (O 3) was bubbled at a rate of 0.3 L/min into a batch electrolysis reactor utilizing a boron-doped diamond (BDD) anode and stainless steel (SS) cathode operating at a current density of 10 mA/cm2. Results from separate experiments in a 54 mM sodium chloride (NaCl) or 54 mM sodium bromide (NaBr) electrolyte were compared with data previously reported by the authors produced in the same system utilizing a sulfate (SO 4 2−) electrolyte. Bromide and chloride slightly increased the rate of ATZ degradation compared to sulfate when electrolysis only was applied. When ozone was applied individually, the estimated first-order degradation rate of atrazine decreased 20% with chloride and 87% with bromide compared to sulfate. The degradation rate of ATZ decreased 86% with chloride in the combined electrolysis and ozonation mode and 93% with bromide, both as compared to sulfate. This is significant since combined electrolysis and ozonation has been shown in previously published works to produce strong synergism for contaminant removal in sulfate. The proposed mechanism for antagonism with a reactive electrolyte such as chloride or bromide is increased competition in the system for hydroxyl radicals (HO). Free halogen species and bromide are reactive with HO, decreasing the likelihood of direct reaction between HO and ATZ. In addition to the antagonism, all cases except ozonation in chloride generated either bromate (BrO 3 -) or chlorate (ClO 3 −). [ABSTRACT FROM AUTHOR]