Supporting Electrolyte Concentration Research Articles

Treatment of cattle slaughterhouse wastewater by sequential coagulation-flocculation/electrooxidation process

The objective of this study was to assess the efficiency of electrochemical treatment after pre-treatment coagulation-flocculation (CF) in removing chemical oxygen demand (COD) and turbidity from slaughterhouse wastewater (SWW). During the pre-treatment, FeCl3 showed superior efficacy compared to the other coagulant, effectively eliminating 50% of the COD and 68% of the turbidity. Due to the insufficient removal efficiencies of COD and turbidity, a secondary treatment was required. The coagulated effluent was then treated in a continuous electrooxidation reactor (CEO) using a boron-doped diamond (BDD) electrode. The objective was to examine the impact of current density (5 to 30 mA/cm2), wastewater flow rate (0.9 to 3.6 L/hour), and supporting electrolyte concentration (1 to 3 g/L NaCl). The CEO reactor had higher removal efficiency for COD (97%) and turbidity (~100%) when operated under the optimum treatment conditions (j = 30 mA/cm2, Q = 0.9 L/h, pH = 8.5, SE = 3.0 g/L NaCl, and hydraulic retention time (HRT) = 1 hour). At these optimum conditions, the total operating cost (OC) was 3.5 US $/m3 (1.5 US $/kgCOD). The findings demonstrated that the CF + CEO reactor proved to be a very efficient alternate method for the treatment the SWW.

Electrocatalytic and photoelectrocatalytic investigation of Orange G degradation utilizing a novel BHP@Bi2O3 photoanode employing the CCD-RSM experimental design

In this study, we synthesized a bilayer film consisting of BaHPO4 (BHP) and Bi2O3 through the electrodeposition technique. The produced anode was subjected to characterization using cyclic voltammetry to clarify the deposition reactions. Subsequent to this, structural and morphological analyses were conducted utilizing X-ray diffraction alongside scanning electron microscopy, coupled with energy-dispersive X-ray spectroscopy. Additionally, UV–vis diffuse reflectance spectroscopy was employed to determine the bandgap energies of both semiconductors. Following an electrochemical characterization using linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), and Mott-Schottky (MS) measurements, the photoanode was employed for the electro-degradation of the anionic dye Orange G (OG), varying key degradation parameters such as current density, pollutant concentration, supporting electrolyte concentration, and pH using the CCD-RSM experimental design method. A degradation efficiency of 98% was achieved within a 20-minute timeframe. Photoelectrocatalytic tests under UV irradiation reduced the degradation time from 20 to 6 min, with a degradation rate of 99%. Additionally, under the same conditions, the BHP@Bi2O3 photoanode exhibited good stability, enduring up to 11 cycles of use.

The Investigation of Treatment of Pistachio Processing Industrial Wastewater by Electrochemical Methods in Terms of Chemical Oxygen Demand and Total Phenol Removal

<p>This work aims to investigate the efficiency of electrocoagulation (EC) of pistachio processing industrial wastewater (PPIW) using the continuous EC process. The tubular reactor made of stainless steel with an internal diameter of 60 mm was used as a cathode electrode. The effect of some parameters was examined on the removal of chemical oxygen demand (COD) and total phenols (TP) removal efficiency. The influences of the initial pH of wastewater (from 4 to 8), flow rate (from 25 to 125 mL/min), current density (from 7 to 21 mA/cm<sup>2</sup>), and supporting electrolyte type (NaCl, NaNO<sub>3</sub>, and Na<sub>2</sub>SO<sub>4</sub>), supporting electrolyte concentration (from 10 to 100 mg/L NaCl) on removal efficiency were investigated to determine the best experimental conditions. The examination of the physico-chemical parameters during the EC treatment showed that the best removal efficiency was obtained under conditions where the flow rate was 25 mL/min (20 min reaction time), the pH value was 5.2, and the current density was 21 mA/cm<sup>2</sup> has set. Under these experimental conditions, COD and TP removal efficiency were found to be 75% and 97%, respectively, while energy consumption was 18.5 kW h/m<sup>3</sup>. The study results show that the EC can be applied to PPIW pre-treatment.</p>

Didactic experiment for voltametric determination the complexing capacity of natural waters

The titration method can be applied to determine the complexation capacity between metal ions and ligands in natural water samples. The process involves the incremental addition of the metal to the sample containing a specific ligand, resulting in a titration curve that reflects the formation of complexes. The change in the curves slope indicates the saturation of the complexation capacity. In this study, the copper (II) ion was used due to its stability with organic ligands. The titration curve was analyzed to determine the complexation capacity (CC) and conditional formation constant (K) of the complex. Different mathematical treatments are proposed for this analysis. In the described experiment, differential pulse anodic stripping voltammetry was used to determine the complexation capacity of humic substances in natural waters. Experimental parameters such as pH, supporting electrolyte concentration, and volume of additions were previously optimized for the voltammetry technique. The obtained data were processed and analyzed, resulting in titration curves and voltammograms. The analysis of the curves allowed for the calculation of the complexation capacity and conditional stability constant of the formed complex. The results demonstrate the feasibility of the method as a didactic experiment for the voltammetric determination of natural water complexation capacity.

One step production of phosphorene from red phosphorus and investigation of their supercapacitor applications with conducting polymers

In this work, phosphorene, which was used as an additive to the conductive polymer (polyaniline), was produced in a single step using the chemical method at 80 °C in 6 h for the first time in the literature. In addition, composites of polyaniline with phosphorene have also been produced for the first time in the literature, and these materials have been used as electrode materials in supercapacitors. The parameters of supporting electrolyte concentration, monomer concentration and cycle number, which are the factors affecting the success of electrochemical synthesis, were optimized and the optimum values for these parameters were determined for polymers. The structural and morphological properties of the produced 2D phosphorene were investigated using spectroscopic and microscopic methods. After that, phosphorene was simultaneously and electrochemically incorporated into the structure of polyaniline (Pani), which was produced by the electrochemical method, likewise. Finally, the phosphorene-based materials produced have been used as electrode components in supercapacitors. Hybrid supercapacitor electrodes (Phosphorene@Pani/PGEs) were characterized by cyclic voltammetry and electrochemical impedance spectroscopy methods and the changes in the capacitive behavior of these systems according to the number of cycles were examined using the galvanostatic charge-discharge technique. Specific capacitance value of phosphorene-doped composite material was 335.54 F·g−1 at a charge-discharge current density of 1.6 A·g−1.Capacitance retention of the composite material was 85 % at end of 1000 cycles with 1.6 A·g−1. It was also around of 80 % after 4000 cycles with 2.5 A·g−1 charge/discharge current densities. A significant increase in specific capacitance of 259.21 % was seen when compared with the electrode without phosphorene added. By adding of phosphorene in the conducting polymer structure, specific capacitance of the system is improved.

The Effect of Electrolyte Composition on the Performance of a Single‐Cell Iron–Chromium Flow Battery

Flow batteries are promising for large‐scale energy storage in intermittent renewable energy technologies. While the iron–chromium redox flow battery (ICRFB) is a low‐cost flow battery, it has a lower storage capacity and a higher capacity decay rate than the all‐vanadium RFB. Herein, the effect of electrolyte composition (active species and supporting electrolyte concentrations), Fe/Cr molar ratio, and supporting electrolyte type (HCl and H2SO4) on the performance (current efficiency (CE), voltage efficiency (VE), energy efficiency, discharge capacity, and capacity decay) of an ICRFB is investigated. The storage capacity of the optimum electrolyte (1.3 m FeCl2, 1.4 m CrCl3, 5.0 mm Bi2O3 in 1.0 m HCl) is 40% higher (from 17.5 to 24.4 Ah L−1), while the capacity decay rate is tenfold lower (from 3.0 to 0.3% h−1) than the performance of the previously used 1.0 m FeCl2, 1.0 m CrCl3 in 3.0 m HCl. At the optimum Fe and Cr concentrations and ratio in 0.5 m HCl, a near constant CE (92.3%), VE (78.7%), and EE (72.6%) are obtained over 50 cycles. The significantly higher capacity decay when using 1.0 m H2SO4 (1.6% h−1) compared to 1.0 m HCl (0.3% h−1) confirms that HCl is the more suitable supporting electrolyte.

Describing the permeability of permanganate co-ions in a CEM with varying supporting electrolyte concentrations

Redox flow batteries (RFBs), a promising technology for large-scale power grid energy storage, utilize a membrane separator to facilitate an ionic current while preventing mixing of the anolyte and catholyte solutions. The anolyte and catholyte of an RFB each contain an electroactive species, and usually an additional supporting electrolyte to charge balance the anode and cathode redox reactions and reduce overall ohmic losses. This study investigates the impact of the supporting electrolyte concentration and composition on Nafion’s transport properties using permanganate as the permeant. The permanganate concentration was kept constant at 0.1m, while sodium chloride and sodium hydroxide were both studied as supporting electrolytes. The sodium chloride concentration was varied from 0.1m to 4.0m, while the sodium hydroxide concentration was varied from 0.1m to 10m. The permanganate permeability, water sorption coefficient, and salt sorption coefficients were measured for Nafion, with a peak permeability being observed at a supporting electrolyte concentration of 1m for both electrolytes. A framework to describe the observed behavior was derived using first principles to determine the transport coefficients under these conditions. It was found that at low concentrations, the permanganate permeability is controlled by Donnan exclusion and salt sorption, while at high concentrations it is controlled by salt diffusion and osmotic deswelling.

Organic and inorganic pollutants removal from tannery effluent using electrocoagulation technique

Abstract Electrocoagulation is an efficient treatment for the concurrent elimination organic and inorganic contaminants from tannery wastewater. The batch electrocoagulation investigations were carried out using mild steel and aluminium as sacrificial anodes and stainless steel as the cathode. Various operating constraints, such as the electrolyte pH, realistic current density, electrolysis time, effluent concentration and supporting electrolyte concentration were appraised to study their effects on electro-coagulation efficiency. The maximum Total Organic Carbon (TOC) removal has been observed was 90 % and 77 % under optimum operating conditions, and the maximum chromium removal has been recorded was 99 % and 90 % using mild steel and aluminium anodes respectively. The experimental data was also fitted with the first order kinetic model. The experimental data were investigated with the Langmuir and Freundlich adsorption isotherm models. The result shows that the experimental data fitted with the Langmuir isotherm model, with a rate of confidence of 0.98, using mild steel as an anode. The solid sludge and the liquid samples were characterized using the SEM (scanning electron microscopy) EDX (energy dispersive X-ray spectrometry), FT-IR (Fourier transform infrared spectrometer) and UV–Visible (Ultraviolet–visible spectroscopy) analyses. All experimental results show that mild steel was an efficient anode, for the instantaneous elimination of organic and inorganic contaminants from tannery wastewater.

Dehydrogenative Electrochemical Synthesis of N-Aryl-3,4-Dihydroquinolin-2-ones by Iodine(III)-Mediated Coupling Reaction.

Electrochemically generated hypervalent iodine(III) species are powerful reagents for oxidative C-N coupling reactions, providing access to valuable N-heterocycles. A new electrocatalytic hypervalent iodine(III)-mediated in-cell synthesis of 1H-N-aryl-3,4-dihydroquinolin-2-ones by dehydrogenative C-N bond formation is presented. Catalytic amounts of the redox mediator, a low supporting electrolyte concentration and recycling of the solvent used make this method a sustainable alternative to electrochemical ex-cell or conventional approaches. Furthermore, inexpensive, readily available electrode materials and a simple galvanostatic set-up are applied. The broad functional group tolerance could be demonstrated by synthesizing 23 examples in yields up to 96 %, with one reaction being performed on a 10-fold higher scale. Based on the obtained results a sound reaction mechanism could be proposed.

Precise redox strategy to fabricate CuO/Cu2O hetero-electrodes for ultrafast electrochemical nitrate reduction into valuable ammonia resources

Electrochemical reduction of nitrate is a highly promising method for removing nitrate from water bodies. However, slow reaction rates have been a major challenge in its practical application. In this study, a novel CuO/Cu2O@CC hetero-electrode was developed by using a precise redox strategy, where CuO and Cu2O were simultaneously introduced to provide catalytic active sites for the reduction of nitrate into ammonia. This compositing design could significantly enlarge the electrochemically active surface area, reduce the electron transfer resistance and increase hydroxyl oxygen content on the electrode surface. The effect of operating parameters (cathodic potential, initial pH, supporting electrolyte concentration, initial NO3–−N concentration and coexisting Cl– concentration) on nitrate reduction was studied to optimize the reduction efficiency. Under −1.4 V (vs. Ag/AgCl) cathodic potentials and initial pH = 7 parameters, CuO/Cu2O@CC 3 achieved a remarkable 92.9% removal of 100 mg L–1 initial nitrate and a high ammonia selectivity of 78.33% in 1 h using 0.5 mol L–1 K2SO4 as supporting electrolyte, with a pseudo-first-order kinetic constant of 2.5856 h–1. Additionally, based on the experimental results, a reaction mechanism for the heterostructures electrode was proposed. The successful construction of CuO/Cu2O hetero-electrode provides a unique insight into the electrochemical reduction of nitrate.

Effect of ion-paring on the kinetics of redox systems with concentrated supporting electrolyte

The electron-transfer reaction is of pivotal importance not only in electrochemistry, but also in other scientific disciplines, such as catalysis, biochemistry and biology. The kinetics of such reactions has been thoroughly investigated under ideal conditions (Butler and Volmer or Marcus theories) considering the Frumkin effects; however, the electron-transfer in concentrated electrolytes still lacks a general theory. Here we discuss the effect of the concentration of the supporting electrolyte (an inert salt) on the kinetics of three redox couples with different nominal charge: hexaammineruthenium, ferricyanide and ferrocene methanol. The redox couples are diluted but the supporting electrolyte concentration is high enough that significant deviations of the formal electrode potential from the ideality are observed; the kinetics is also altered. We propose a model in which the electrostatic interactions are described as a complexation between the redox active species and the counter-ions of the supporting electrolyte, in analogy with the treatment of the ion pairs. The model correctly fits the dependence of the formal potential and of the charge transfer resistance on the concentration, thus suggesting that the ion-transfer accompanying an electron-transfer plays a significant role in the overall reaction kinetics. This finding enables a more realistic description of the complex electron-transfer reactions occurring e.g., in electrocatalysis and catalysis, bioelectrochemistry and biochemistry, and electrochemical energy storage.

RESPONSE SURFACE METHODOLOGY APPLIED TO ELECTRO-FENTON PROCESS FOR DEGRADATION OF RED BEMACID AS TEXTILE DYE MODEL

The textile industry produces persistent organic pollutants (POPs) that pose significant risks to ecosystems because of their toxic and hazardous nature. Consequently, there is an urgent requirement for the development of effective techniques to treat the effluents and remove these compounds. This work studied the viability of the Electro-Fenton (EF) process as a potential alternative for treating textile wastewater contaminated with POPs. A batch electrochemical reactor, equipped with a platinum grid cathode and stainless-steel sacrificial anode, was utilized to eliminate Red Bemacid (RB) dye. The study investigated the impact of four key operational parameters: (i) stirring speed (rpm), (ii) oxygen flow rate (L/min), (iii) supporting electrolyte concentration [Na2SO4] (mg/L), and (iv) current intensity (A), as well as their interactions on RB removal. To perform this, Central Composite Experimental Design (CCD) and Response Surface Methodology (RSM) were employed. Under optimized EF conditions for RB removal (stirring speed = 205.09 rpm, oxygen flow rate = 0.20 L/min, current intensity = 0.306 A, and supporting electrolyte concentration = 0.09 M), the EF process demonstrated exceptional removal efficiency, achieving approximately 94.51% removal of RB. The obtained results showed that the kinetic data of RB removal were in good agreement with the Behnajady-Modirshahla-Ghanbery (BMG) model. The CCD analysis revealed that the main effect of the current intensity had a significant impact on RB removal, as well as the interaction of all paired variables.

Electrochemical and photoelectrochemical degradation of Rhodamine B using a novel BHP@ZnO photoelectrode: Synthesis, characterization, and statistical study

This study focuses on the preparation of a novel photoanode by combining BAHPO4 (BHP) and ZnO, aiming to harness their synergistic impact on degrading Rhodamine B dye (RhB). Characterization involved X-ray diffraction (XRD), SEM-EDX morphological analysis, FT-IR vibrational analysis, and UV-Vis DRS optical analysis. Both semiconductors exhibited band gaps in the UV region, with ZnO at 3.1 eV and BHP at 3.9 eV. Electrochemical analyses, including Mott-Schottky (MS), open circuit potential (OCP), photocurrent (PT), and linear sweep voltammetry (LSV), were conducted. The electrocatalytic investigation of BHP@ZnO was optimized using statistical CCD-RSM analysis, identifying key parameters for improved degradation efficiency: applied current density, pollutant concentration, supporting electrolyte concentration, and pH. Remarkably, degradation efficiency achieved 100% within 30 min. Furthermore, photoelectrocatalytic experiments under UV light reduced degradation time to 8 min. Examination of trap states at the n-n junction of BHP@ZnO unveiled insights into the degradation mechanism, pinpointing •O2- as the primary radicals accountable. The photoanode demonstrated sustained stability and repeatability, showcasing its potential as a dependable and effective tool for RhB degradation. this study presents a promising approach utilizing BHP and ZnO within a novel photoanode, highlighting their synergistic effect in degrading RhB and contributing to the field of advanced photocatalytic materials.

Intensified treatment of kitchen wastewater in a filter- press type electrochemical reactor

Commercial kitchen wastewater (KW), characterized by a high load of bio-refractory organics, can be effectively treated by electrochemical methods for non-potable applications. This work explores the electrochemical degradation of KW in a batch recirculation type flow reactor consisting of mixed metal oxides coated titanium mesh anode and stainless steel cathode. The effect of operating factors such as current density, supporting electrolyte concentration, initial pH, and recirculation flow rate on chemical oxygen demand (COD) reduction was examined by following one-factor-at-a-time method. The %COD reduction increased with an increase in electrolyte concentration and current density. The optimum current density and electrolyte concentration were found to be 2 A/dm2 and 2 g/L, respectively. The treatment was intensified by incorporating mechanical stirring and ultrasound irradiation in the reservoir. The results showed about 99 % COD reduction, and the kinetic model proposed predicted the experimental data satisfactorily.

A comparison of FEM results from the use of different governing equations in a galvanic cell part II: Impact of low supporting electrolyte concentration

Finite Element Method modeling has been widely used to simulate the distributions of potential, current density, and dissolved species for a wide range of electrochemical systems. The use of the Nernst–Planck–Poisson equations as governing equations is the most rigorous approach, but it brings with it a substantial computational time cost. Reduced-order models offer options in which different assumptions allow more rapid computational solutions. In Part I of this work, it was shown that the loss in accuracy of the reduced-order models is small in high supporting electrolyte concentrations, and there were substantial savings in computational time. The analysis is extended to lower supporting electrolyte concentrations. The most reduced-order modeling approach performs poorly in low supporting electrolyte to electrochemically reactive species (SER) ratios. A modified Laplace approach, in which the conductivity is recalculated at each position at each time step, improves the solution by updating the electrolyte conductivity at each time step, but the errors can still be significant in low SER ratios due to the absence of the diffusion potential term in the calculations.

Electrodialysis as a potential technology for 4-nitrophenol abatement from wastewater.

4-Nitrophenol is a widely used emerging pollutant in various industries, including the production of agrochemicals, drugs, and synthetic dyes. Due to its potential environmental harmful effects, there is a need to study its reuse and removal from wastewater. This study used electrodialysis technology to separate 4-nitrophenol ions using a four-compartment stack. The effects of supporting electrolyte concentration, pH, voltages, and current density on the performance of electrodialysis for separating 4-nitrophenol were investigated. A high extraction percentage of 77% was achieved with low energy consumption (107 kWh kg-1) when high 4-nitrophenol flows and transport numbers were reached.

Removal of triazole fungicides of 1H-1,2,4-triazole from pesticide tailwater by electrochemical oxidation using meso-flower PbO2 layer electrode

In this work, a novel Ti/TiO2-NTA/meso-flower PbO2 electrode (TMF-PbO2) was developed by anodic oxidation and modified oxygen bubble-template electrodeposition. Characterization of the electrode confirmed that the meso-flower layer exhibited a unique 3D and hierarchical structure with a rough morphology. N2 adsorption-desorption isotherms and cyclic voltammetry suggested that TMF-PbO2 possessed a 2.18 times larger specific surface area and at least a 1.46 times larger electroactive area than the electrode with a porous PbO2 layer. The investigation of the effect of the operation parameters indicated that the optimal conditions were a pH value of 3, supporting electrolyte concentration of 10.0 g L−1 and current density of 25 mA cm−2. The electrochemical degradation of 1H-1,2,4-triazole (Tz) by TMF-PbO2 was studied by HPLC and LC‒MS with the assistance of quantum chemical calculations. The TMF-PbO2 achieved 100% removal of Tz and 70.4% removal of COD on the advanced treatment of actual pesticide tailwater with an energy consumption of 29.40 kWh kg−1 COD. The EC50,48 h value and BOD5/COD ratio of the treated wastewater were 70.6±5.9% and 0.64, respectively, indicating significantly low toxicity and high biodegradability. Cyclic testing also suggested that TMF-PbO2 was stable during application. The excellent performance of TMF-PbO2 in this study indicated that this kind of electrode is highly applicable for the treatment of pesticide tailwater.

Tunability of zinc electrochemistry in potassium acetate: effects of supporting electrolyte concentration

Tunability of zinc electrochemistry in potassium acetate: effects of supporting electrolyte concentration

Sulfonate-Based Triazine Multiple-Electron Anolyte for Aqueous Organic Flow Batteries.

A new highly soluble triazine derivative (SPr)34TpyTz showing three reversible redox processes with fast kinetics and high diffusion coefficients has been synthesized using an efficient, low-cost, and straightforward synthetic route. Concentrated single cell tests and DFT studies reveal a tendency of the reduced triazine species to form aggregates which could be avoided by tuning the supporting electrolyte concentration. Under the right conditions, (SPr)34TpyTz shows no capacity decay and good Coulombic, voltage, and energy efficiencies for the storage of two electrons. The storage of further electrons leads to a higher capacity decay and an increase of the electrolyte pH, suggesting the irreversible protonation of the generated species. So, a plausible mechanism has been proposed. A higher concentration of (SPr)34TpyTz shows slightly higher capacity decay and lower efficiencies due to the aggregate formation.

Aqueous Polyelectrolyte Electrodeposition: The Effects of Alkyl Substitution and Varying Supporting Electrolyte Concentrations on the Deposition Efficiency

AbstractThe controlled growth of surface‐modifying polymer films by electrodeposition often fails because of the lack of redox activity of these compounds. Here, electroactive complexants help to electrodeposit non‐electroactive polymers. Hence, we investigate the counterion‐induced electrodeposition of polyelectrolytes: three quaternized poly(N,N‐dialkylaminoethyl methacrylate)s (qPDAAEMA), in particular their methyl, ethyl, and isopropyl derivatives (i. e. qPDMAEMA, qPDEAEMA, and qPDPAEMA), provide transparent solutions in the presence of hexacyanoferrate(II) (ferrocyanide) at specific concentration windows of the KCl supporting electrolyte. Below a certain KCl concentration, insolubility dominates irrespective of the hexacyanoferrate valency, whilst above an upper threshold, full solubility is observed. Between these limits, oxidation reversibly electrodeposits polymer/hexacyanoferrate(III) (ferricyanide) complexes. Hydrodynamic voltammetry (and data analysis using in‐house software) provides access to the deposition efficiency (DE). qPDEAEMA with ethyl substituents shows highest DEs; larger or smaller substituents fall short because of a balance between “hydrophobicity” and charge separation, shifting the window toward smaller salt concentrations with increasing alkyl size. We always observe a DE maximum close to the minimum salt concentration, whilst electrochemical quartz crystal microbalance (EQCM) measurements indicate a change in film water content close to the maximum. These effects, being also discussed in terms of polymer conformation, can direct the future engineering of electroassisted coatings.