Performance Of Electrocoagulation Research Articles

Effect of Punched-Hole Electrodes on the Performance of Electrocoagulation

Effect of Punched-Hole Electrodes on the Performance of Electrocoagulation

Electrocoagulation-based AZO DYE (P4R) Removal Rate Prediction Model using Deep Learning

This article presents a study on the effectiveness of electrocoagulation (EC) for the removal of azo dyes from wastewater. The analysis was performed using a combination of statistical methods, including density estimation, correlation analysis, and deep learning for electrocoagulation performance prediction. The results showed that electrocoagulation was able to effectively remove azo dyes from the wastewater, considering the energy consumption and the mass of flocs being important factors in the process. Deep Learning (DL) is used to build our predictive model using the datasets collected during the experimentation stage. Overall, the findings suggest that electrocoagulation is a promising technique for the treatment of wastewater containing azo dyes, and that the use of statistical and machine learning methods can aid in the optimization of the process.

Cathodic microenvironment reconstruction boost electrocoagulation treatment of photovoltaic wastewater

Electrocoagulation has emerged as a rapidly advancing area in the field of wastewater treatment due to its capability to eliminate pollutants that are typically resistant to filtration or chemical treatment methods, as well as its overall effectiveness, which is often impeded by the formation and growth of flocs. In this study, simulated photovoltaic wastewater was treated using the electrocoagulation method, with cathodic water reduction employed to induce a highly efficient electrocoagulation rate towards the removal of SiO2 and F−. Our results demonstrate that the optimal conditions for this process involved the use of an Al anode, Nickel foam as cathode, an inter-electrode distance of 1.0 cm, a current density of 30 mA cm−2, a stirring speed of 300 rpm, sodium chloride as supporting electrolyte, and an initial pH of 7. Our experimental findings indicated satisfactory performance with respect to EC, as evidenced by the reduction of F− content from 25 mg L−1 to 3.68 mg L−1, and the complete removal of SiO2 from 16 mg L−1. Furthermore, electrochemical analysis and texture characterization revealed that the overall rate of flocculation was dependent on the cathodic material, with in-situ generated OH− in the electrolysis cell influencing the microenvironment of iron hydroxide floc formation and sedimentation. Our study offers conclusive evidence that the optimal cathodic material capable of intensifying OH− concentration from water dissociation is key to achieving superior electrocoagulation performance.

Electrocoagulation Process Efficiency for Removing Effluent Pollution Caused by Drilling of Oil Rigs

Background: Electrocoagulation (EC) is a safe method for removing environmental pollutants without the need for additional chemical materials. This study investigates the performance of EC in removing chemical oxygen demand (COD), total organic carbon (TOC), total suspended solids (TSS), and turbidity from drilling waste generated by oil rigs. Methods: An experimental study was performed on a pilot scale in an EC reactor provided from a cylindrical glass cell (height: 30 cm and inner diameter: 5 cm), a pair of aluminum and iron electrodes, a power supply, an aeration system. wastewater Samples were collected from one of the drilling rigs in Khuzestan. The effect of current density, operation time and pH parameters on removal of COD, TOC, TSS and turbidity were determined and the optimal values of the parameters were determined. Results: It was found that system voltage, operation time and pH values on the removal efficiency of pollutants were statistically significant at the 0.01 level. The optimum values of pH, current density and operation time were obtained 7, 20 mA/cm2 and 60 minutes, respectively and the removal efficiencies of COD, TOC, TSS and turbidity under the optimum conditions were 72%, 79%, 67% and 63%, respectively. Also, the consumption of energy was estimated to be 8.4 kWh/m3 . Conclusion: The results indicated that the EC process is a cost-effective method in removing pollutants caused by drilling of oil rigs and its efficiency can be improved by applying optimal conditions such as current density and pH.

Systematic literature electrocoagulation for wastewater treatment: Mini-review

Electrocoagulation is a method that can be used to remove pollutants and nutrients from liquid waste. This method has been found for a long time but has exclusively recently been developed for wastewater treatment after a lengthy process. Electrocoagulation can remove colloidal materials, i.e., suspended solids, metals, and other dissolved solids in wastewater. Several studies have shown that electrocoagulation has been successfully operated in various industrial wastewaters, i.e., bakery, chocolate, cork boiling, olive, biodiesel, Etc. This review uses the systematic review scale mini-review method. Literature was collected from various databases using Harzing's Publish or Perris Software and analyzed by Mendeley Software. The results indicate that the electrocoagulation method has received excellent attention for development, i.e., the effectiveness and energy that must be consumed, and that research is evolving to show the best performance of electrocoagulation.

Titanium dioxide effect on the decolourisation of organic dyes Remazol Black B using electrocoagulation in situ-Fe2O3

ABSTRACT In this research, combination of TiO2 pillared clay with electrocoagulation in situ-Fe2O3 provides excellent performance to remove dyes water waste Remazol Black B(RBB). The best TiO2:clay ratio is 1:6, with highest degradation performance 89.8% in 30 minutes photodegradation process under UV light 254 nm. The excellent performance of pillared clay causes mesoporous pore that can be achieved by pillarisation of the clay layer using titanium dioxide sol which was made by diluting TiCl4 in ethanol solution. Besides, the excellent electrocoagulation performance was conducted by dual compartment system using 10ppm of RBB in the alkaline system containing 1 g NaCl as an electrolyte at potential apply+6 V with 98% degradation efficiency in 3 hours running compared to the 78% in single compartment system towards the formation of in situ-Fe2O3 that is directly driven by formation of intermediate species Fe(OH)3. This optimum decolourisation efficiency was gained at 0.1 A, pH 7.2 and 2 cm of inter-electrode distance. The power consumption was very low with the excellent and fast degradation performance towards organic dyes Remazol Black B, where this tandem cell can produce 100 mL clean water using 0.0052 kWh energy with cheaper cost operation.

Nickel removal from an industrial effluent by electrocoagulation in semi-continuous operation: Hydrodynamic, kinetic and cost analysis

In the nickel and cobalt production plant located in Punta-Gorda Cuba, an effluent liquor is obtained with several pollutants species of Ni(II)–NH3–CO2–SO2–H2O system. In previous studies the performance of electrocoagulation (EC) for the nickel removal from this effluent was demonstrated on a lab-scale and bench-scale. In this research, geometric, electrical and equilibrium parameters used as criteria for scaling-up the EC process were evaluated through hydrodynamic, kinetic and operating cost analysis. For this purpose, four semi-continuous stirred-tank electrochemical reactors of equal sized with 200 L useful volume were design. Based on the residence time distribution (RTD) curve, the hydrodynamic behavior of EC systems followed multi-branch tanks-in-series model. Experimental mean residence time was of 92 min and hydraulic efficiency 92% for a liquor flow rate 2 L∙min−1, due to the presence of short-circuit, internal recirculation and 3% dead zone. Then, at the operating parameters: nickel concentration 277 ± 52 mg L−1, current density 6.26 mA cm−2, pH 8.40 ± 0.28 and temperature 50 ± 2 °C, the maximum nickel removal was 97.8% with an operating cost $1.008 kg−1 Ni. Combination of RTD model and the conversion time kinetic model (CTV) was presented to predict the removal efficiency with successful outcomes, and the time for complete conversion was 23.3 min under control of chemical reaction. The precipitate presented a nickel concentration of 35.71 ± 2.13%, aluminum 6.05 ± 0.83%, true density 2836 ± 449 kg m−3 and typical layered structure. These results suggest the opportunity for the projection of an industrial production unit of double lamellar hydroxide and reduce the adverse environmental impact.

Emerging investigator series: impacts of aeration flow rates and bubble sizes on PFOA/PFOS removal in electrocoagulation

The impacts of aeration (in terms of bubble sizes and airflow rates) on PFOA/PFOS removal as well as electrocoagulation performance were examined in this study.

Statistical indicators to evaluate the performance of electrocoagulation with membrane bioreactor (EC-MBR) for treatment of organic matters in domestic wastewater

An electrocoagulation with membrane bioreactor technique (EC-MBR) was developed to treat domestic wastewater and prevent membrane fouling. To support the new design, experiments were conducted on a few levels. The structure and distribution of organic matter removal utilizing the membrane are investigated using a laboratory-scale (EC-MBR) treatment of domestic wastewater. The study's goals were to assess the removal efficiency of organic matter (biological oxygen demand (BOD) and chemical oxygen demand (COD) in Al-Hawraa's wastewater, as well as its links to statistical indicators. It was chosen to sample and evaluate effluent from domestic wastewater using EC-MBR with operating temperature (25 0C), pH (7-8), DO (4-6) mg/L, beginning and final concentrations of BOD (184-6 mg/L), and COD (489-20 mg/L) using biological and electrochemical treatment procedures. According to the results, the organic matter removal efficiency may be calculated using the multilinear regression (MLR) and neural network (NN) models in the SPSS modeler. In addition, the results showed that the entire reactor had good BOD and COD maximum removal efficiencies of 96.7% and 95.9%, respectively. Finally, the highest accuracy of the MLR algorithm for COD and BOD is 99.6 for both, whereas the maximum accuracy of the NN algorithm for COD and BOD is 99.2 % and 99.1%, respectively. To choose the best algorithm for analysis and modeling the outcomes, a comparative study has been achieved to compare the results of two algorithms that used in this study. Therefore, for this study MLR algorithm was chosen.

Nickel removal from wastewater using electrocoagulation process with zinc electrodes under various operating conditions: performance investigation, mechanism exploration, and cost analysis

Economically feasible approaches are needed for wastewater treatment. Electrocoagulation (EC) is an electrochemical treatment method that removes various pollutants from wastewater. It has grown in popularity over conventional treatment methods, especially in industrial wastewater, due to its high performance and the ability to remove toxic compounds. However, it is crucial to reduce the costs associated with EC for widespread implementation. It is also important to decrease nickel (Ni) concentrations in wastewater to prevent potential health and environmental problems. Therefore, this study investigates Ni removal from synthetic and real wastewater using electrocoagulation. Zinc, as a novel electrode, was used as the sacrificial anode. Several operating conditions were assessed, including current density, initial pH, electrolysis time, and spacing between electrodes. The maximum Ni removal efficiency, after 90 min, reached 99.9% at a current density of 10 mA/cm2 when the pH was 9.2 and the gap distance was 4 cm. The Ni removal rate reached 94.4% and 94.9% at a 2- and 6-cm spacing, respectively, after 90 min. Anode morphology, kinetic modeling, electrical energy consumption, and cost analysis were also investigated. The type of corrosion was uniform, which is easily predicted compared to pitting corrosion. The comparison between chemical coagulation and electrocoagulation was also reported. Experimental results indicated that the maximum Ni removal rates reached 99.89% after 90 min. The optimum spacing between electrodes was 4 cm, and the optimum current density was 10 mA/cm2. Additionally, the kinetic data were best represented through the second-order Lagergren model. The results demonstrated that the electrocoagulation performance was better than that of chemical coagulation for Ni removal. The maximum electrical energy consumption was 23.79 KWh/m3 for Ni removal.

Separation of oil-water emulsions by a novel packed bed electrocoagulation (EC) process using anode from recycled aluminum beverage cans

Electrocoagulation (EC) is an emerging technology for the elimination of oil and COD content from oily wastewaters. However, higher operating costs and electrode passivation are pressing challenges for its wide speared application. To overcome this setback, the present work has attempted to develop a new and inexpensive electrode using recycled aluminum (Al) beverage cans for the treatment of oily wastewater by electrocoagulation (EC) technology. It could be an alternative to conventional plate or tube electrodes in the EC process, it is the first contribution into the literature. In current work, recycled Al beverage cans filled with steel wool was used as anode, and commercial stainless-steel mesh (304) with cylindrical shape was used as cathode. The main EC performance measure was COD removal efficiency, impacts of significant process parameters in the EC process (such as operating voltage, electrocoagulation time, stirring rate, and NaCl concentration) on the effectiveness of EC process were investigated by using response surface methodology (RSM) based Box-Behnken Design (BBD) model. The RSM analysis results demonstrated that the highest COD removal rate of 93.53% was achieved under optimal conditions of operating voltage (15 V), electrocoagulation time (10 min), stirring rate (250 rpm), and NaCl concentration (1 g/L). In addition, energy consumption analysis was performed, an electrical energy efficiency of 0.160 kWh/kg COD was achieved. Afterward, ATR-FTIR spectroscopy, scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), and XRD analysis were performed under optimal conditions to characterize anode, and generated sludge during the EC process. Collectively, the findings in this study paves the way toward the development of sustainable EC technology for separation of emulsified oil-water mixtures, which gives the importance of the circular economy and sustainable management of industrial wastewaters.

(Digital Presentation) Application of Polarity Reversal and Performance Analysis of Continuous Electrocoagulation

An important challenge for continuous treatment by electrocoagulation (EC) is the passivation and fouling of electrodes which increases during the longer operation (Ingelsson et al., 2020). The application of polarity reversal (PR) and treatment performance of EC was investigated using continuous flow reactor for simultaneous removal of silica and hardness (calcium and magnesium) from produced water. Polarity reversal times (PRT) from 30 s to 10 min were studied at a fixed charge loading of 2000 C L- 1 (i.e., the amount of charge passed per unit volume of produced water treated) using Fe and Al electrodes. Periodic PR was found to reduce the fouling and de-passivate the electrodes by changing the surface chemistry at the electrode-electrolyte interface (Ingelsson et al., 2020; Yasri et al., 2022). During 90 minutes of continuous treatment the chronopotentiometric data indicated that a PRT of 10 min was more effective in reducing the cell voltage for both Fe and Al electrodes [Fig. 1 (a & b)]. With a longer PRT of 10 min, there is more time for the acid boundary layer to form on the anode, which mitigates metal precipitation at the anode. In contrast the higher cell voltage that persists in direct current EC (DC-EC) could be due to the precipitation of Ca and Mg minerals in the alkaline solution on the cathode surface, leading to cathode passivation (Chow et al., 2021). After the first polarity reversal, both electrodes have been anodic, removing passivation layers from the surface and reducing the cell voltage. On reversing the polarity, the cathode becomes the anode, and the acidic pH on the formed at the electrode interface will facilitate the dissolution of Ca and Mg precipitates on the electrode surface, reducing the cell voltage significantly. For Fe-EC, the contaminant removal performance increased with PRT, and the highest removal was observed with DC-EC (Fig. 1c). The increasing removal performance with PRT for Fe-EC is consistent with the increase in faradaic efficiency observed of 55%, 68%, 85%, and 99.8% with 30 sec, 2 min and 10 min PRT, and DC respectively. The lower faradaic efficiencies for Fe-EC with short PRTs are likely due to redox reactions of iron species at the electrode surface (Chow et al. 2021).The contaminant removal at a charge loading of 2000 C L–1 using DC-EC with Al electrodes was similar to that for PR-EC with PRTs of 2 to 10 min (Fig. 1d). Slightly lower Si and hardness removal was observed for Al-EC at the shortest PRT of 30 s. For Al-EC, the faradaic efficiency was also observed to increase with PRT, with values of 150%, 220% and 287% obtained at 30 sec, 2 min and 10 min PRT respectively. The super-faradaic (>100%) efficiencies can be explained by dissolution of the Al from the cathode under the local alkaline conditions that develop on the electrode surface. With a short PRT, there is less time for the alkaline pH to develop at the surface and hence the faradaic efficiency was reduced.

A comprehensive review on green perspectives of electrocoagulation integrated with advanced processes for effective pollutants removal from water environment

The rapidly expanding global energy demand is forcing a release of regulated pollutants into water that is threatening human health. Among various wastewater remediating processes, electrocoagulation (EC) has scored a monumental success over conventional processes because it combines coagulation, sedimentation, floatation and electrochemical oxidation processes that can effectively decimate numerous stubborn pollutants. The EC processes have gained some attention through various academic and industrial publications, however critical evaluation of EC processes, choices of EC processes for various pollutants, process parameters, mechanisms, commercial EC technologies and performance enhancement via other degradation processes (DPs) integration have not been comprehensively covered to date. Therefore, the major objective of this paper is to provide a comprehensive review of 20 years of literature covering EC fundamentals, key process factors for a reactor design, process implementation, current challenges and performance enhancement by coupling EC with pivotal pollutant DPs including, electro/photo-Fenton (E/P–F), photocatalysis, sono-chemical treatment, ozonation, indirect electrochemical/advanced oxidation (AO), and biosorption that have substantially reduced metals, pathogens, toxic compound BOD, COD, colors in wastewater. The results suggest that the optimum treatment time, current density, pulse frequency, shaking speed and spaced electrode improve the pollutants removal efficiency. An elegant process design can prevent electrode passivation which is a critical limitation of EC technology. EC coupling (up or downstream) with other DPs has resulted in the removal of organic pollutants and heavy metals with a 20% improved efficiency by EC-EF, removal of 85.5% suspended solid, 76.2% turbidity, 88.9% BOD, 79.7% COD and 93% color by EC-electroflotation, 100% decolorization by EC-electrochemical-AO, reduction of 78% COD, 81% BOD, 97% color by EC-ozonation and removal of 94% ammonia, 94% BOD, 95% turbidity, >98% phosphorus by aerated EC and peroxicoagulation. The major wastewater purification achievements, future potential and challenges are described to model the future EC integrated systems.

Poultry Slaughterhouse Wastewater Treatment Using an Integrated Biological and Electrocoagulation Treatment System: Process Optimisation Using Response Surface Methodology

The feasibility of a biological (EcoflushTM) and/or electrocoagulation (EC) treatment system in removing chemical oxygen demand (COD) and fats, oils, and grease (FOG) from poultry slaughterhouse wastewater (PSW) were studied. The response surface methodology (RSM) was used to identify the optimum operating condition for EC and its integration with EcoflushTM as a pre-treatment for the removal of lipids. The optimum operating conditions were obtained at a pH of 3.05, a current density of 66.9 A/m2, 74-min of treatment time, and without Ecoflush™. These conditions produced a high-quality clarified effluent after 92.4% COD reduction and 99% FOG reduction. The treatment with EcoflushTM only resulted in 85–99% FOG reduction, 20–50% COD reduction, and odourless effluent. However, the combination of both processes (EcoflushTM and EC) did not yield a significant difference (F test, p > 0.05) when compared to the performance of EC alone. Despite the low removal percentages of nitrogen and phosphorus, the present study proved that EC is an effective method for the removal of COD and FOG, rendering an effluent that meets the permissible discharge standards for the City of Cape Town. The novel Ecoflush™ also proved to be very efficient in the removal of FOG from PSW.

Electrocoagulation: operational parameters, sludge & economic analysis

ABSTRACT The performance of electrocoagulation (EC) was studied by conducting experiments for the removal of Reactive Orange 4 dye from its synthetic aqueous solution. The effect of operational parameters (initial solution pH, current density, inter-electrode distance, electrolysis time and retention time, solution temperature, conductivity and different electrode combinations) on the efficiency of EC was studied and the results were analysed in terms of colour removal efficiency (CRE), electrical energy consumption (EEC) and operating cost (OC). The effect of different anions on the efficiency of EC was studied by conducting experiments with electrolytes containing chloride, sulphate, carbonate and nitrate ions. The characterisation of EC generated sludge was performed using XRD. A maximum CRE of 95% was obtained for EEC of 1.7 kWh/m3 and OC of 0.45 US $/m3. It was found that the addition of electrolyte containing chloride ions resulted in higher CRE (93–95%) compared to electrolytes containing sulphate and carbonate ions as their presence can lead to passivation of the electrode surface & thereby resulting in a reduction in CRE (60% and 41%, respectively). The addition of sodium chloride as an electrolyte resulted in minimum EEC and OC. The Al/Al electrode combination provided the maximum CRE and least EEC & OC. The increase in solution temperature leads to reduction in CRE and CE due to formation of passive layer on the surface of electrodes. However, a reduction in cell potential and EEC was noticed with an increase in solution temperature.

Development and Evaluation of Lamella Settlers Combined with Electrocoagulation for Treating Suspended Sediment

Stormwater quality has become an increasingly important issue in agricultural, urban, and construction sectors. Soil, nutrient, and pollutant discharge caused during rainfall events is one of the greatest sources of stormwater quality degradation. Enhanced stormwater treatment mechanisms are needed to economically and efficiently remove suspended pollutants in runoff. In this research, the performance of electrocoagulation (EC) combined with lamella settlers (LS) was investigated. EC is a highly effective and proven water-treatment technology that uses an electrochemical anode corrosion process to destabilize and remove contaminants and that has been shown to have widespread applications for treating a variety of wastes. LSs have been shown to enhance soil-particle capture by increasing the surface area and reducing the settling distance. This research demonstrated that the combination of EC and LS can enhance the sedimentation process while simultaneously decreasing the required detention time and size of traditional sediment control practices (i.e., detention basins, sediment basins). Combining EC with a LS is a novel approach for treating suspended particles in stormwater. In this project, bench-scale experiments were conducted using EC as pretreatment upstream of a LS reactor. Synthetic silica filler at concentrations of 500 mg/L, 1,000 mg/L, and 5,000 mg/L were used to evaluate treatment efficiency at 0.5-h, 1.0-h, and 1.5-h residence times. Collected data, including turbidity, total suspended solids, and particle size distribution, were used to statistically characterize the system’s sediment removal performance. Through a series of experiments and statistical analyses of the results, an optimized EC+LS reactor with 1.27-cm (0.5-in.) LS plate spacing and 1.5-h residence time reduced turbidity by up to 98% and total suspended solids by 99% in effluent when compared with a base case reactor with a 31.8 cm (12.5 in.) settling distance (no LS plates installed) and 0.5-h residence time without EC pretreatment. In addition, particle size distribution analyses resulted in a decrease in the D90 value by 84%, indicating that the optimized reactor was effective in capturing larger-diameter soil particles. To validate the laboratory results with synthetic sediment-laden influent, stormwater samples were collected from a construction site and treated through the optimized system, resulting in a turbidity reduction of 50% and TSS reduction of 69%.

Moringa oleifera seed extract assisted electrocoagulation process for efficient direct dye removal from textile wastewater: Modelling, optimisation and techno-economic study

ABSTRACT This work reports the results of coupling Moringa oleifera seed extract (MOSE) with electrocoagulation (EC) for the remediation of Direct Red 80 azo dye (DR80) from contaminated synthetic aqueous solution and real textile wastewater. The electrochemical treatment was carried out using a pair of aluminium electrodes in monopolar-parallel mode. EC runs determined using Box-Behnken design under the response surface methodology (RSM) for three parameters including current density, pH, and operation time. The EC optimal conditions were current density 0.9 mA/cm2, pH 3, and time 10 min. The maximum experimental DR80 dye removal of 89.37% was close to the model prediction (76.4%). The kinetic study of the EC system represented that the removal of dye obeyed the first-order kinetic model. To improve dye removal efficiency from treated wastewater under optimal conditions, 2.5 mL/L of MOSE was added and the efficiency enhanced to above 98%. SEM and microscopic images of the sludge produced showed that the flocs formed in the hybrid system were denser and thicker than the conventional EC. The economic study revealed that switching from the EC to hybrid process reduced energy and electrode consumption from 0.015 to 0.008 kWh/m3 and 0.016 to 0.014 kg/m3, respectively, for 98% DR80 dye removal. MOSE has a substantial effect on the EC performance. Therefore, the EC/MOSE coupling process is recommended for the treatment of coloured wastewater due to its high efficiency, short operation time, and electrode and energy consumption costs.

Removing refractory organic matter from nanofiltration concentrated landfill leachate by electrooxidation combined with electrocoagulation: Characteristics and implication for leachate management

To guide optimization of electrochemical process for landfill leachate concentrate (LLC), systematical experiments were performed on treating LLC with electrooxidation (EO), electrocoagulation (EC) and various combined processes. The results show that EC for 60 min followed by EO for 180 min gave the most satisfactory treatment performance, in which the removal rates of TOC, UV254, COD and CN were 79.00%, 97.30%, 80.32% and 95.0%, respectively. Three fluorescent components were identified in LLC, fulvic acid-like substances (C1), humic-like (C2) substances and long-wave humus (C3) by fluorescence excitation-emission matrix coupled with parallel factor analysis (EEM-PALAFAC). EC effectively remove most of humic-like humus from LLC, and EO could remove fulvic acid (FA) and humic acid (HA) simultaneously and promote the transformation of FA to hydrophilic (HyI). Compared with EC after EO (EO + EC), EO after EC (EC + EO) was more effective in reducing aromaticity and molecular weight, and could remove humus more efficiently. The characteristics of degrading organic matter from LLC were further verified with XAD-8 resin separation technology, which is beneficial to reduce the treatment load of sequent EO. Improving the performance of EC to remove large molecule humic organic matters is vital to comprehensively manage landfill leachate with lower cost.

Performance optimization of a batch scale electrocoagulation process using stainless steel mesh (304) cathode for the separation of oil-in-water emulsion

Electrocoagulation (EC) as a favorable treatment technique has been used for the elimination of oil from oil-in-water emulsions. However, how to reduce the energy consumption of EC technology is still a major challenge, which hinders the industrial scale development of this technique. In the present work, a low-cost and commercially available stainless-steel mesh was proposed as cathode due to its chemical corrosion resistance, high conductivity, good mass transfer as well as heat dissipation performance which can prolong lifespan of electrode material and decrease operational cost. In addition, RSM was employed to evaluate the removal performance of EC with new electrode combination of Al plate-SS mesh (304), and synergistic effects of significant process parameters on COD removal, as well as the interaction between experimental factors. It was found that the peak oil removal efficiency of 90.86% was obtained under the optimum experimental conditions of pH=7.0, applied voltage: 25 V, and working time: 60 min. What's more, main properties of sludge generated in the EC were examined by SEM/EDS and ATR-FTIR spectroscopy methods. Overall, this study provides the necessary leeway for achieving and accelerating the industrial scale application of EC process and its greater performance in the separation of emulsified oil-water mixtures.

Demulsification performance and mechanism of oil droplets by electrocoagulation: Role of surfactant

Surfactants are widely used to improve the solubility of oil in water in petrochemical, making it more difficult to remove oil–water emulsions during the water treatment process. Electrocoagulation (EC) is an appropriate method for treating oily wastewater and destabilizing emulsions. However, the demulsification mechanism of oil–water droplets emulsified by surfactants with different charges have not been investigated systematically. The demulsification performance of electrocoagulation on emulsions wastewater containing cationic, non-ionic, and anionic surfactants was studied. The results showed that the removal rate of total organic carbon (TOC) in oily wastewater with anionic surfactant by EC reached 92.98% ± 0.40% at a current density of 1 mA/cm2, while that of the non-ionic surfactant was 84.88% ± 0.63%. The characterization of flocs showed that EC has the highest coagulation and demulsification of oil droplets with a negative charge on the surface (−70.50 ± 10.25 mV), which indicated that the charge neutralization of oil droplets was beneficial for the destabilization of the formed oily flocs. However, when the zeta potential of the oil droplets reached 75.50 ± 1.25 mV, the TOC removal efficiency was only 11.80% ± 1.43%. The TOC removal could achieve 33.23% ± 3.21% when the current density improved from 1 mA/cm2 to 10 mA/cm2. The enhanced removal was due to the sweep coagulation rather than charge neutralization. This study provides a fundamental basis for the electrochemical treatment of oily wastewater.