NaCl Electrolyte Concentration Research Articles

FLUID FLOW CONTROL IN POROUS MEDIA WITH CONSIDERATION OF ELECTROKINETIC EFFECTS

The paper presents results of the research on the influence of electrokinetic characteristics of fluids on its flow in porous media. Experimental studies have shown the effect of fluid slippage in the channels of porous media due to the electrically charged boundary "liquid-porous medium". It is shown that the change of flow velocity profile and pressure gradient is caused by the display of electrokinetic effects in the filtration of polar liquids.The investigation has shown that the process of the electrolyte solutions filtration in a porous medium is accompanied by the change in the liquid flow rate and the electro-potential of the flow. The periodic nature of changes in flow characteristics is explained by continuous charge formation and charge interaction in the diffuse layer. Periodic charge accumulation and subsequent charge transfer across the channel cross section depending on the charge sign acquired, as well as compression of the diffuse layer with increasing NaCl electrolyte concentration in aqueous solution may be the cause of fluid flow variations. The observed effects may serve as a tool for controlling fluid flow in water-oil-saturated formations and, in particular, injectivity of injection wells by controlling electrical conductivity of water injected into the formation.

A novel combined system for efficient nitrate removal using a continuous flow electrocoagulation and sand filtration (FECF) reactor: Statistical analysis by Taguchi design.

In this study, a new hybrid bench-scale electrocoagulation-sand filtration (FECF) reactor was developed for purifying nitrate-contaminated samples. Before and after electrochemical treatment, two sand filters were included in this continuous system to facilitate the purification procedure, and the contaminated water flows horizontally through the entire system according to a specific hydraulic gradient within the reactor, resulting in water purification. Significant improvement in treatment performance was observed due to the presence of metal hydroxides in the second filter media that were not fully involved in the electrocoagulation treatment. Energy dispersive X-ray (EDX) analysis was performed to detect metal hydroxide species in the sand media, and the need for filter regeneration was evaluated by monitoring changes in the system flow rate. Moreover, an evaluation of the effects of different factors including operating time, current intensity, initial pH, type of anode and cathode, initial nitrate concentration, hydraulic head level inside the reactor, number of electrodes, and NaCl electrolyte concentration on the performance of nitrate removal was conducted through the Taguchi design. Further, ANOVA analysis verified the accuracy of the predicted model, and the variables were classified based on their relative importance in the FECF process. According to the regression model, 97% of nitrates were removed with Al electrodes as anode and Fe as cathode, 70 min purification time, current intensity of 3 A, 100 mg/l initial nitrate concentration, pH 8, electrolyte concentration of 1 g/l, electrode number of 6, and 1.5 cm head level.

Effect of Electrolyte Concentration on Characteristics of Activated Carbon of Cocoa Peel

Cocoa peel activated carbon has been successfully synthesized with 0.3 M KOH activator and NaCl electrolyte as the base material for supercapacitor electrodes. Variations in the concentration of NaCl electrolyte used were 1 M, 2 M, and 3 M to determine their effect on the capacitance, conductivity, and pore area values produced. The activated carbon produced was characterized by Scanning Electronic Microscope (SEM) to see surface morphology, X-Ray Diffraction (XRD) to determine carbon crystals, Cyclic Voltammetry (CV) and LCR-Meter to determine capacitance and conductivity values, and the Brunauer Emmett Teller method. (BET) to measure its surface area. The results of the Indonesian National Standard (SNI) test results obtained water content (8.6%), ash content (8.7%), volatile matter (26.2%), carbon content (65.1%), and iodine absorption (800 mg/g). The pore surface area can be increased by activation up to 24,742 m2/g. XRD analysis shows that the atomic structure is amorphous. Surface morphology proves that the increase in NaCl electrolyte concentration affects the pore structure. The higher the electrolyte concentration, the more even and finer the pore structure will be. The highest specific capacitance value was obtained at 3 M NaCl, which was 1.68375 F/g and the lowest was at 0.10771 F/g NaCl 1 M. The conductivity obtained is 1.83 S/m at 3 M NaCl at frequency of 1000 Hz and the lowest is 0.18 S/m at 1 M NaCl at 100 Hz. This proves that the electrolyte concentration can affect and increase the value of the capacitance and conductivity of the supercapacitor electrode.

A microstructural, mechanical and electrochemical/stress corrosion cracking investigation of a Cr-modified Ti–6Al–4V alloy

The microstructural effects of a Cr-modified Ti–6Al–4V (Ti64) alloy on the mechanical, electrochemical and stress corrosion cracking properties were studied. With the aid of thermodynamic calculations and microstructural characterizations, Ti64–3Cr forged alloy was successfully fabricated with no defects by micro-alloying Ti64 with 3 wt% Cr. The microstructure features of the Ti64–3Cr alloy reveal fine alpha laths with a lamellar structure and strong texturing particularly in the basal and prismatic poles. The mechanical results at room temperature show enhanced yield strength and hardness attributed to the refined alpha laths and solid solution strengthening effect caused by Cr addition. Afterward, the electrochemical properties were investigated under different NaCl electrolyte concentrations. The alloy showed good corrosion resistance in the various NaCl concentrations as a result of the formation of Cr2O3 oxide due to the alloying effect of Ti64–3Cr alloy. X-ray photoelectron spectroscopy was used to confirm the presence of the oxides film on the surface of the alloy after the electrochemical studies. Furthermore, the stress corrosion cracking (SCC) properties of the alloy were investigated using a strain rate of 1 × 10−6 s−1 in 3.5 wt% NaCl aqueous solution under different temperatures. The results showed that as the temperature increased during slow strain rate testing, the SCC susceptibility of the alloy decreased. The outstanding SCC strength and enhanced corrosion properties of the novel alloy could serve as a potential use in marine applications.

A converged approach of electro-biological process for decolorization and degradation of toxic synthetic dyes.

Being one of the leading industries worldwide, the textile industry has been consuming large quantities of groundwater and discharging huge volumes of dye-contaminated effluents into our aquatic environment. Augmentation of water sources via reuse of treated effluents is therefore highly necessary. In the present study, the decolorization and degradation of synthetic toxic dye from an aqueous solution were investigated through an electro-biological route. Initially, decolorization of synthetic dye solutions (100, 500, and 1000mgL-1) was carried out by electrooxidation process using mixed metal oxide and titanium as anode and cathode, respectively. The electrooxidation solutions were further treated using bacteria (Pseudomonas aeruginosa) that were isolated from petroleum-transporting pipelines. UV-Vis, TOC, chemical oxygen demand, and NMR analyses revealed that the biodegradation process with electrooxidation enhanced the mineralization of the synthetic dye solutions. An optimum NaCl electrolyte concentration of 3gL-1 was sufficient to produce reactive species viz., free chlorine and hypochlorite, which are responsible for the Reactive Blue 19 (RB-19) decolorization. Among the three RB-19 concentrations, the highest removal percentage was noticed at 100mgL-1 (100%) with energy consumption and energy costs equal to 5.44kWhm-3 and 0.65 USD m-3, respectively.

Facile synthesis of Cu2O nanorods in the presence of NaCl by successive ionic layer adsorption and reaction method and its characterizations.

Cuprous oxide (Cu2O) nanorods have been deposited on soda-lime glass substrates by the modified successive ionic layer adsorption and reaction technique by varying the concentration of NaCl electrolyte into the precursor complex solution. The structural, electrical and optical properties of synthesized Cu2O nanorod films have been studied by a variety of characterization tools. Structural analyses by X-ray diffraction confirmed the polycrystalline Cu2O phase with (111) preferential growth. Raman scattering spectroscopic measurements conducted at room temperature also showed characteristic peaks of the pure Cu2O phase. The surface resistivity of the Cu2O nanorod films decreased from 15 142 to 685 Ω.cm with the addition of NaCl from 0 to 4 mmol and then exhibited an opposite trend with further addition of NaCl. The optical bandgap of the synthesized Cu2O nanorod films was observed as 1.88–2.36 eV, while the temperature-dependent activation energies of the Cu2O films were measured as about 0.14–0.21 eV. Scanning electron microscope morphologies demonstrated Cu2O nanorods as well as closely packed spherical grains with the alteration of NaCl concentration. The Cu2O phase of nanorods was found stable up to 230°C corroborating the optical bandgap results of the same. The film fabricated in presence of 4 mmol of NaCl showed the lowest resistivity and activation energy as well as comparatively uniform nanorod morphology. Our studies demonstrate that the nominal presence of NaCl electrolytes in the precursor solutions has a significant impact on the physical properties of Cu2O nanorod films which could be beneficial in optoelectronic research.

Corrosion of indium doped E-AlMgSi aluminum conductor alloy (Aldrey)

The effect of impurities on the electrical conductivity of aluminum has been studied in detail. The electrical conductivity of aluminum is 65.45% of that of copper. The tensile strength of aluminum wire is 150–170 MPa which, at equal conductivity, is about 65% of the strength of copper wire. This strength of aluminum wire is sufficient for bearing the wire’s own weight but may be too low in case of snow, ice or wind overloads. One way to improve the strength of aluminum wire is to use aluminum alloys having higher strength combined with sufficiently high electrical conductivity, e.g. the E-AlMgSi alloy (Aldrey). The key strengthening agent of the E-AlMgSi alloy (Aldrey) is the Mg2Si phase which imparts high mechanical strength to aluminum. In this work we present experimental data on the kinetics of high-temperature oxidation and electrochemical corrosion of indium doped E-AlMgSi aluminum conductor alloy (Aldrey). Thermal gravimetric study has shown that indium doping and high temperature exposure increase the oxidation rate of E-AlMgSi alloy (Aldrey), with the apparent alloy oxidation activation energy decreasing from 120.5 to 91.8 kJ/mole. Alloy oxidation rate data determined using a potentiostatic technique in NaCl electrolyte media have shown that the corrosion resistance of the indium doped alloy is 20–30% superior to that of the initial alloy. With an increase in NaCl electrolyte concentration the electrochemical potentials of the alloys decrease whereas the corrosion rate increases regardless of alloy composition.

Simultaneous Electrochemical Degradation of Toxic Food Dyes Wastewater Using Ti/Ru0.3ti0.7o2 composite Electrode

Food dyes constitute a highly diverse group of colouring agents usually used to colour a vast variety of food products. It has been estimated that 15% of total dyes produced worldwide are discharged to water bodies which adversely effects aquatic ecosystem. Dyes in water reduces its transparency thereby declining light penetration in to water hence influencing photosynthesis which consequently reduces dissolved oxygen which is alarming situation for both aquatic flora and fauna. When these dyes are taken in through food by man they induce carcinogenic, cytotoxic, genotoxic and allergic actions, thus poses serious threats to their lives. This study is primarily aimed to assess the efficacy of Ti/Ru0.3Ti0.7O2 electrode to address dyes (Tartrazine and Sunset Yellow) pollution abatement. All experiments were carried out in a 500 mL laboratory scale glass reactor by bulk electrolytic method. The influence of various operational parameters like pH (03 to 10), applied current densities (2.5 to 10 mA cm-2), different NaCl electrolyte concentrations (0.02 to 0.08 mg L-1) and different dye doses on electrochemical degradation of dyes were determined. The progress of decolourization process of twin dyes was monitored regularly by UV-Visible Spectrophotometry while the extent of mineralization was investigated by total organic carbon (TOC) analysis. Moreover energy consumptions of electrochemical treatments were calculated to probe into the process liability for industrial application in future. The electrodes were characterized in situ by Cyclic Voltammetry (CV) in appropriate electrolytes i.e. Na2SO4 and NaCl with each dye separately. The results demonstrated that electrochemical degradation of both dyes were more favored at higher applied current densities and elevated NaCl concentration under weakly acidic medium (pH = 03 to 06). Furthermore the degradation of both dyes was more likely to occur rapidly under low dyes doses rather than higher doses. Out of all electrolytes the NaCl was concluded as best supporting by virtue of its excellent dyes degradation efficiency and low energy consumption.

A hybrid system for groundwater denitrification using electrocoagulation and adsorption

The treatment of nitrate-contaminated groundwater was studied using a hybrid system comprising an electrocoagulation unit and a zeolite adsorption reactor. In the electrocoagulation (EC) process, aluminum alloy electrodes were used in an undivided cell. Experiments in the laboratory-scale reactor were carried out in unregulated temperature conditions to treat synthetic groundwater solutions containing initial nitrate concentrations of 10–100 mg NO3−-N·L−1 in batch mode and without using additional pH buffers. Various operating variables, such as applied current density (about 20 mA cm−2 to 80 mA cm−2), concentration of NaCl electrolyte (0.0–1.0 g L−1) and treatment time (up to 120 min), were tested for their effects on nitrate removal. Results showed that initial NO3−-N concentration, current density and electrolyte concentration, play important roles in EC. For all initial NO3−-N concentrations and current densities tested, the highest NO3−-N removal rates (up to 2.374 g L−1·d−1) were achieved without additional electrolyte and/or with the lowest electrolyte concentration of 0.1 g L−1. In these experiments, EC reduced NO3−-N to below the standard limit of 10 mg L−1 after 10–60 min of electrolysis. A significant quantity of by-products, ammonium and dissolved aluminum, formed during the process, however these were successfully removed by zeolite adsorption in the post-treatment step. The electrochemical reactor using the specific anode/cathode combination and an environmentally-friendly post-treatment step such as zeolite adsorption, can be used to efficiently remove nitrate from groundwaters because of its high efficiency.

Relationships between Electrolyte Concentration and the Supercapacitive Swing Adsorption of CO2.

We quantitatively investigate the influence of the NaCl electrolyte concentration on the adsorptive and energetic characteristics of supercapacitive swing adsorption (SSA) for the separation of CO2 from a simulated flue gas mixture containing 15% CO2 and 85% N2. The investigated concentrations were that of deionized water, 0.010, 0.10, 1.0, 3.0, and 5.0 M NaCl. We find that the energetic metrics strongly improve with the increasing NaCl concentration, whereas the adsorptive metrics improve by a comparatively small degree. The CO2 adsorption capacity increases up to 1.0 M NaCl and then remains constant. The adsorption rate remains near constant for all concentrations, except that it is somewhat smaller for deionized water. The charge efficiency also remains near constant for all experiments with 30 min potentiostatic holding steps but near doubles for pure water when the potential holding step is doubled, because the chemical adsorption equilibrium is reached only after 60 min. The results can be most satisfactorily explained by assuming that both ionic and nonionic adsorption mechanisms contribute to the SSA effect.

Optimization of Sono-Electrocoagulation Process for the Removal of Dye Using Central Composite Design

Sono-electrocaogulation process was successfully applied for the removal of RR120 (Reactive Red 120) in the presence of activated carbon. For this purpose, the process variables were optimized using CCD (Central Composite Design). The operational parameters of the technology were the amount of activated charcoal (0.2-2.0g), amount of NaCl electrolyte (1-10g), sonication time (30-120 min) and RR120 dye concentration (40-120 mg/L), respectively. Consequently, the 100% dye removal was determined at the optimal conditions for the process obtained by CCD. In addition, the sonication time, amount of adsorbent and dye concentrations were found the significant process factors. Furthermore, the effects of other parameters like the electric current, current efficiency, amount of NaCl, temperature and formation of coagulants were also studied in the dye removal process, separately. The FTIR (Fourier Transfer Infrared) spectrums were monitored to identify the classes of functional groups present in the dye molecule before and after the treatment. Therefore, the sono-electrocaogulation process was proved an effective technique for purifying simulated wastewater containing RR120 dye.

Flocculation behaviour of bentonite clay-water systems

ABSTRACTThe effect of polyacrylamide (PAM) as flocculant, NaCl electrolyte concentration and pH on the degree of flocculation of bentonite suspension has been investigated. It has been observed that the increase in PAM dosage reduces the residual turbidity and improves the settling rate of the bentonite particles. At higher pH conditions bentonite dispersions are highly flocculated having high settling rates and low supernatant turbidity. The combined effect of salt concentration and PAM dosage improved the overall flocculation efficiency of the system.

Synergistic effect between ultraviolet irradiation and electrochemical oxidation for removal of humic acids and pharmaceuticals

AbstractThe fate of pharmaceuticals in the aquatic environment is significantly affected by the presence of humic acids (HA). In this work, the synergistic effect of electrochemical oxidation (EO) and ultraviolet irradiation (UVI) was evaluated for HA removal and for the simultaneous degradation of three pharmaceuticals (carbamazepine, propranolol and sulfamethoxazole) in presence of HA. The effectiveness of EO, UVI and their combination for HA removal was assessed using different operating parameters, such as type of anode (Nb/BDD and Ti/IrO2), supporting electrolyte (NaCl, NaBr and Na2SO4), current density (8.1, 16.1, 28.2, 40.3, and 48.4 mA/cm2), pH (3, 7 and 9) and NaCl electrolyte concentration (7, 14 and 21 mM). The use of non‐active anode Nb/BDD, NaCl electrolyte and combination EO‐UVI was the most efficacious option for HA removal, due to the production of hydroxyl radicals as well as active chlorine species (HClO, Cl● and ClO−) generated by anodic oxidation and by UVI. The effectiveness of the EO process was enhanced coupling EO with UVI, however the energetic consumption increased. The composition of the electrolyte was the pivotal parameter since a complete degradation of the pharmaceuticals was achieved by both processes EO and EO‐UVI using NaCl as electrolyte; this is attributed to the indirect oxidation by electrogenerated active chlorine which dominates the pharmaceuticals degradation.

Analysis of an Educational Cathodic Protection System with a Single Drainage Point: Modeling and Experimental Validation in Aqueous Medium.

Cathodic protection, often taught in curricular units, such as corrosion and materials science, is an important subject in the study of chemical engineering. The implementation of lab setups and experimental activities in this field, are core to promoting understanding of the underlying concepts and to developing “hands-on” skills fundamental to the success of future process engineers. This paper reports the influence of different variables on the electrical potential and current behaviors of an educational cathodic protection system operated with a single drainage point. The system comprised a steel bar cathode connected to a zinc sacrificial anode, both placed in aqueous medium. The study variables were the anode area, the cathode diameter, the NaCl electrolyte concentration and the anode placement. Each variable showed a specific influence on the attenuation curves, allowing us to conclude that: (1) increasing the sacrificial anode area, or decreasing the resistivity of the medium, promotes more electronegative potentials on the structure and higher currents; (2) increasing the cathode diameter decreases the protection capacity; (3) positioning the anode in the middle of the cathode lengthwise gives rise to a more balanced potential distribution; and (4), the attenuation curves, both for potential and current, can be successfully predicted using equations based on Morgan and Uhlig’s work. High correlations were obtained between the experimental and modeling data for all the studied variables.

Impact of Experimental Parameters on Degradation Mechanism and Service Life Prediction of CFRP Anode during Simulated ICCP Process

In actual building structure, it usually takes tens of years for the degradation to be significantly observed during impressed current cathodic protection (ICCP) process. Thus, simulated ICCP with aqueous electrolyte (instead of concrete) was used as an accelerated method to study degradation mechanism and make service life prediction. In this work, the impact of parameters including current (density) and NaCl electrolyte concentration on the degradation mechanism and service life prediction was evaluated for a simulated ICCP system with CFRP as anode. Experiments were performed with different levels of applied current (4, 10, and 20 mA) as well as with different NaCl electrolyte concentrations (3, 10, and 20% by mass). Test results showed that under all the designed conditions, both chlorination and oxidation reaction occurred during the simulated ICCP process, ensuring consistency of mechanism. From the aspect of service life prediction of CFRP, it was found that the system was not sensitive to the concentration of NaCl electrolyte but was much more influenced by the current (density) applied. Thus, for the simulated ICCP system, the current (density) should be carefully chosen since a tiny change in level of current may cause a large variation in service life prediction.

Electrokinetic delivery of anodic in situ generated active chlorine to remediate diesel-contaminated sand

Electrokinetic in situ chemical oxidation (EK-ISCO) is an innovative and effective method for removing petroleum contaminants from soil. However, the high cost of exogenous oxidants is one of the main drawbacks of this technology. In this research, a new approach for the electrokinetic (EK) delivery anodic in situ generation of an oxidant was designed with the aim of solving this problem. Six EK experiments lasting 15 d with different electrolytes (NaCl or NaNO3) and different voltage potentials were performed in order to evaluate the feasibility of this approach. It was found that active chlorine was produced by a dimensionally stable anode and a NaCl solution, and can contribute to remediate sand spiked with diesel fuel (10 g/kg) during EK-ISCO. The obtained results showed that an increase in NaCl electrolyte concentration (from 10 to 40 g/L) increases the maximum concentration of active chlorine in the aqueous sand matrix (from 12.5 to 30 mmol/L). The diesel removal efficiencies were increased from 33% to 44% for 1 V/cm and from 43% to 67% for 2 V/cm, respectively, by using 20 g/L NaCl compared to using 20 g/L NaNO3. Vial tests also confirmed that the anodic in situ generated active chlorine in the electrolyte solution had the effect of oxidizing alkanes of diesel. The products had a higher solubility due to the inclusion of polar functional groups. Under optimal conditions, the energy consumption for removing 1% of contaminants was approximately 2 k Wh/ton. Consequently, the EK delivery of anodic in situ generated active chlorine can be considered as a new cost-effective method for removing organic contaminants from porous media.

The liquid-glass-jamming transition in disordered ionic nanoemulsions

In quenched disordered out-of-equilibrium many-body colloidal systems, there are important distinctions between the glass transition, which is related to the onset of nonergodicity and loss of low-frequency relaxations caused by crowding, and the jamming transition, which is related to the dramatic increase in elasticity of the system caused by the deformation of constituent objects. For softer repulsive interaction potentials, these two transitions become increasingly smeared together, so measuring a clear distinction between where the glass ends and where jamming begins becomes very difficult or even impossible. Here, we investigate droplet dynamics in concentrated silicone oil-in-water nanoemulsions using light scattering. For zero or low NaCl electrolyte concentrations, interfacial repulsions are soft and longer in range, this transition sets in at lower concentrations, and the glass and the jamming regimes are smeared. However, at higher electrolyte concentrations the interactions are stiffer, and the characteristics of the glass-jamming transition resemble more closely the situation of disordered elastic spheres having sharp interfaces, so the glass and jamming regimes can be distinguished more clearly.

The synergistic effect of glycerol and sodium chloride on the degree of chitin nano-whisker gels reinforcement

As renewable and biodegradable nanoparticles, chitin nano-whiskers (CNWs) are receiving more attention especially for food or medical industries. Actually, the successful application of nanomaterials requires a better understanding of the viscoelastic properties of chitin CNWs and the interactions among materials in the gels. To provide an increased application of CNWs in the fields related to polysaccharide and protein-based nanocomposite materials, we analyzed the rheological properties of CNW gels in the presence of various glycerol (Gly) and NaCl electrolyte concentrations. The values of the viscosity and G′ increased as well as the gel behavior (tanδ < 1) of CNW gels gradually improved with increasing Gly or CNWs concentrations, respectively. Especially, compared with the above \CNW gels, the NaCl remarkably increased the viscosity and G′ values of CNWs in Gly solution. As the attractive interactions between CNWs and CNWs/Gly/NaCl were enhanced with increasing of NaCl concentration, the G′ values of CNW gels were enhanced remarkably, and thereby the gel-like response of network structure was also strengthened markedly.

Effect of Ionic Atmosphere around DNA/Electrolyte Interface on Potentiometric Signal

Biomolecular recognitions with an ion sensitive field effect transistor (ISFET) are mostly reported to strongly depend on the structure and dynamics of the electric double layer (EDL) at the gate electrode/electrolyte interface, while the effect of an ionic behavior around a biomolecule/electrolyte interface on the potentiometric detection has not been clarified. In this study, we investigated the behavior of water and ions around a DNA/electrolyte interface using molecular dynamics (MD) simulations, where the charge distribution may induce a field effect contributing to electrical signals of a DNA-modified ISFET sensor. As a result, MD simulations showed that the interfacial charge distribution with a gentle slope (ionic atmosphere) was more clearly found around the DNA duplex at a lower concentration of NaCl electrolyte, while the counter ion condensation was observed nearby the DNA duplex with increasing the concentration of NaCl electrolyte. This means the EDL structure was found at the DNA/electrolyte interface. Such an ionic atmosphere around the DNA duplex would cause the shift in the threshold voltage for DNA molecular recognition events such as hybridization on the gate of ISFET. Our knowledge based on the MD simulation for the biomolecule/electrolyte interface contributes to design and develop an optimum device on potentiometric biosensors.

Comparative study of electrochemical oxidation for dye degradation: Parametric optimization and mechanism identification

Present study investigates the direct and indirect electrochemical (EC) oxidation of malachite green (MG) dye in acidic and basic medium using RuO2–TiO2 and Pt coated Ti mesh electrodes (Ti/RuO2–TiO2 and Ti/Pt electrodes). The effects of process parameters such as current density (j), initial pH (pHo) and NaCl (electrolyte) concentration (m) during the EC oxidation were also examined. This study investigates the effect of dissolved chlorine, chlorate, chlorite, and chlorine dioxide formed during EC oxidation at different pH. Active sites of electrodes surface promote the production of OH radicals (OH). Synergistic effect of active chlorine species and OH radicals significantly enhanced the indirect EC oxidation of MG dye solution with Ti/RuO2–TiO2 anode. Gas chromatography-mass spectrometry (GC–MS), high performance liquid chromatography (HPLC), color and chemical oxygen demand (COD) were used to identify the EC oxidative degradation mechanism with both electrodes. Acidic pH was found to promote the dye degradation. Under optimum condition, MG dye was completely decolorized and 98% COD removal was obtained after 140min of EC treatment. Based on the intermediate and by-products identification, it seems that MG dye degradation occurred via N-methylation and conjugated structure destruction.