Electro-oxidation Process Research Articles

Combination of electrocoagulation and electrooxidation processes for treatment of real wood processing effluents

Combination of electrocoagulation and electrooxidation processes for treatment of real wood processing effluents

Operating cost and treatment analysis of cattle slaughterhouse wastewater by coagulation-flocculation and electrooxidation processes

Operating cost and treatment analysis of cattle slaughterhouse wastewater by coagulation-flocculation and electrooxidation processes

TiO2 intercalated MWCNTs nanocomposite sensor for the detection and quantification of 5-Fluorouracil

The present analysis deals with the fabrication of novel electrochemical sensing platforms for the determination of the anti-cancer drug 5-Fluorouracil (5-FLU). Multiwalled carbon nanotubes/titanium dioxide nanoparticles (TiO2·MWCNTs) modified carbon paste electrodes were constructed and used to quantify 5-FLU in pH 7.0. TiO2·MWCNTs nanocomposite reveals a non-uniform distribution of agglomerated TiO2 nanoparticles over the smooth surface of MWCNTs At the TiO2∙MWCNTs/CPE, the 5-FLU molecule underwent an irreversible electro-oxidation process. The proposed electrode platform exhibited a high catalytic effect for the 5-FLU. The TiO2∙MWCNTs/CPE sensor shows the detection limits of 2.7nM for 5-FLU with sensitivity of 82.15µA·µM−1·cm−2. The sensor was employed to detect the desired drug moiety in the urine samples of pharmaceutical drugs along with spiked water and soil samples; the good recovery values demonstrating the applicability and selectivity of the sensor were supported by excipient interference investigation. Thus, the developed sensors and method makes them a promising alternative for future research to determine other bio-active molecules in pharmaceutical and clinical samples.

Electrochemical Detection and Characterization of Caffeine in Selected Tea Samples using Polyglycine Modified Carbon Paste Electrode

Glycine was electro-polymerized against a carbon paste electrode (CPE) to produce a polymer film via the electro-oxidation process comprising amino (-NH2) and carboxylic (-COOH) groups, by a cyclic voltammetric. The electrochemical oxidation of caffeine was examined in 0.2 M phosphate buffer solution (PBS). The Polyglycine modified Carbon Paste Electrode (PGMCPE) demonstrates greater electrocatalytic activity for caffeine as compared to the unmodified CPE (UNMCPE). This made it suitable for analyzing caffeine owing to its increased electrode surface area and/or improved electron transport at the electrode surface. By varying the concentration range from 0.05 to 0.9 mM, the relationship between peak current and caffeine concentration was studied and this produced a correlation coefficient of R2 = 0.9987. This method was extremely capable of evaluating caffeine concentrations. Square wave voltammetry (SWV) was utilized to assess the caffeine in tea samples. The sample was analyzed with square wave voltammetry and was made easier with an ideal pH of 12.0. Additionally, the caffeine levels in a tea sample were successfully measured using the linear range and detection limit, and the results showed a good limit of detection (LOD) in comparison to previous literature.

Highly sensitive voltammetric determination of the fungicide fenhexamid using a cost-effective and disposable pencil graphite electrode

A differential pulse voltammetric (DPV) method is proposed for the highly sensitive determination of fenhexamid (FHX) based on both electrooxidation and electroreduction processes using a disposable and cost-effective pencil graphite electrode (PGE). The electrochemical oxidation and reduction mechanisms of FHX at the PGE were elucidated by recording cyclic voltammograms at various pH values of Britton–Robinson buffer (BRB) solutions at a scan rate of 50 mV s−1 and different scan rate values in the range 10–400 mV s−1 at selected pH of BRB (pH 2.0). Differential pulse voltammograms recorded under optimized conditions revealed an oxidation peak of FHX around + 0.65 V and a reduction peak of FHX around + 0.45 V. The DPV analysis of FHX revealed two linear ranges: 0.001–0.01 µmol L−1 and 0.01–5.0 µmol L−1 for the anodic peak, and 0.001–0.1 µmol L−1 and 0.1–5.0 µmol L−1 for the cathodic peak. The limits of detection were 0.34 nmol L−1 and 0.32 nmol L−1 for the anodic and cathodic peaks, respectively. The proposed methodology demonstrated satisfactory selectivity, as selected pesticides, certain electroactive compounds, and cationic species tested did not interfere with the voltammetric determination of FHX, particularly during its reduction. The recovery results, showing values close to 100% obtained from the analysis of real samples spiked with FHX, indicated that this methodology can accurately determine FHX in water and soil samples.Graphical abstract

Rational design of cobalt oxide nanocubes arrays on Ni foam as durable and robust electrocatalyst for urea electro-oxidation

BackgroundCobalt oxide (Co3O4) is a promising electrocatalyst for efficient urea electro-oxidation, tackling power consumption and environmental challenges. The controllable design of free-standing Co3O4 nanostructures grown on Ni foam (NF) substrates was achieved using a green and facile hydrothermal approach. Different reducing agents were applied to synthesize various morphological structures of Co3O4, including nanoparticles, nanowires, and nanocubes (NCs) morphologies.ResultsThe as-fabricated electrodes were investigated as electrocatalysts for enhanced urea electro-oxidation. Because of its 3D nanostructure with minimal agglomeration and a large interfacial surface area with adequate electroactive sites, the Co3O4 NCs/NF had the best energy conversion efficiency of any electrode toward the urea oxidation process. These distinctive features facilitated the electron and urea routes used in the urea electro-oxidation process. It had a low-onset potential of 194.2 mV (vs. Hg/HgO) and a current density of 90.2 mA cm−2 in a 1 M KOH electrolyte. The electrocatalyst demonstrated excellent anodic activity for urea electro-oxidation with an onset potential of 196.7 mV and a current density of 256.1 mA cm−2 in 1 M KOH + 0.3 M urea concentration. Furthermore, the Co3O4 NCs/NF exhibited long-term stability, as shown by chronoamperometry and stepwise tests after 3600 s in the presence of urea under various operating conditions.ConclusionsCompared to all the fabricated Co3O4 nanostructures, the Co3O4 nanocubes revealed the highest electrocatalytic performance toward urea electro-oxidation in all concentrations. Therefore, Co3O4 NCs/NF is a promising, robust, and efficient electrocatalyst for direct urea fuel cell applications.

MOF-derived NiCo2S4/FeS heterostructures with built-in electric field for enhanced electrooxidation in freshwater/ brine /ethanol/methanol

Oxygen evolution reaction (OER), as a half-reaction of water decomposition, has a high theoretical overpotential. Therefore, the development of electrocatalysts with high OER performance is favorable for electrolytic hydrogen production. In situ growth of nanomaterials on conductive substrates is an effective strategy for the preparation of electrocatalysts. In this work, we grew Ni/Co bimetallic metal-organic framework (MOF) on carbon cloth substrates and successfully constructed a robust NiCo2S4/FeS@CC electrocatalyst through a MOF derivatization strategy. This electrocatalyst can be used for efficient and robust OER performance. MOF-derived NiCo2S4/FeS has the advantage of a porous heterostructure and multicomponent with many active sites and faster charge transfer rate, while sulfur doping greatly improves the OER performance. The current density of this self-supported heterogeneous material in alkaline freshwater reaches up to 10 mA cm−2 with an overpotential of only 238 mV. NiCo2S4/FeS@CC exhibited good OER performance in alkaline brine with an overpotential of only 241 mV at 10 mA cm−2. We speculate that this is due to the generation of a negatively charged SO42− anionic layer on the catalyst surface during the electrooxidation process, which effectively avoids Cl− corrosion. And both conditions demonstrate excellent long time stability. Additionally, we succeeded in further reducing the onset potential and energy consumption by adding ethanol or methanol to the electrolyte. This work provides an effective method to improve the OER performance of MOF-derived transition metal electrocatalysts for hydrogen production from electrolytic water.

Non-target analysis of organic pollutants in oil-production wastewater treatment stations and surrounding soils: Their profiles, electro-transformation, and environmental risks

Although pollution during crude oil production has been paid attention, there is lack of studies on organic pollutants generated/emitted from oil-production wastewater (OPW) treatment processes, especially advanced oxidation process. Based on GC-Q-Orbitrap-HRMS, the present study performed non-target analysis of volatile/semi-volatile organic compounds in physical and electro-oxidation units of OPW treatment stations located in Shengli Oilfield of China. Overall, 64–227 organic compounds were respectively identified in different units, and electro-oxidation was found elevating (by 2.7–66 times) specie numbers (25–71) of CHO, CHNO and halogenated compounds as well as inducing generation of 38 alkanes and 6 alkyl-PAHs in wastewater, indicating the important roles of reactive oxygen and halogen species in pollutant transformation. In soils (n = 22) closed to OPW treatment stations, 580 compounds were identified with hydrocarbons (45%), esters (24.3%), and others (30.7%, including aldehydes, ketones, phenols, amines, nitriles and heteroatomic compounds), while esters had largest concentration contribution (up to 53.0%) to total compounds. The calculated hazard quotients (HQ) showed 55 compounds in OPW effluents and 314 compounds in soils having medium-high risks, considerable portions of which (23.6% for effluent and 12.7% for soil) were generated from electro-oxidation process, especially including esters and halogenated hydrocarbons, highlighting the contribution of OPW electro-oxidation treatment to ecological risk in oil-production areas.

Unique role of Mn(II) in enhancing electro-oxidation of organic pollutants on anodes with low oxygen evolution potential at low current density

This study systematically explored the role of Mn(II) in the removal of 4-chlorophenol (4-CP) by electro-oxidation (EO) employing anodes with low oxygen evolution potential (OEP), i.e., Ti/RuO2-IrO2, Ti/Pt, and Ti/Ti4O7, as well as anodes with high OEP, namely, Ti/PbO2, Ti/SnO2, and boron-doped diamond (Si/BDD). Mn(II) significantly promoted 4-CP removal on the anodes with low OEP at fairly low current density (0.04 to 1 mA/cm2), but had minimal to negative impact on those with high OEP. Cyclic voltammetry and X-ray photoelectron spectra revealed that Mn(II) was oxidized to Mn(III), then to Mn(IV) on the anodes with low OEP, whereas its was oxidized directly to Mn(IV) on those with high OEP. Deposition of manganese oxide on the anodes with low OEP suppressed oxygen evolution reaction (OER) in EO process, but enhanced OER on those with high OEP. Quenching and spectral results consistently indicated that Mn(III) and Mn(IV) were the primary species responsible for enhancing 4-CP removal on the anodes with low OEP. These findings provide mechanistic insights into the redox transformation of Mn(II) in EO and the theoretical basis for a novel strategy to boost pollutant degradation in EO systems using low OEP anodes through coupling with the redox chemistry of manganese.

Origin of Enhanced Oxygen Evolution in Restructured Metal-Organic Frameworks for Anion Exchange Membrane Water Electrolysis.

Metal-Organic Frameworks (MOFs), praised for structural flexibility and tunability, are prominent catalyst prototypes for exploring oxygen evolution reaction (OER). Yet, their intricate transformations under OER, especially in industrial high-current environments, pose significant challenges in accurately elucidating their structure-activity correlation. Here, we harnessed an electrooxidation process for controllable MOF reconstruction, discovering that Fe doping expedites Ni(Fe) MOF structural evolution, accompanied by the elongation of Ni-O bonds, monitored by in situ Raman and UV/Visible spectroscopy. Theoretical modeling further reveals that Fe doping and defect-induced tensile strain in the NiO6 octahedra augments the metal ds-O p hybridization, optimizing their adsorption behavior and augmenting OER activity. The reconstructed Ni(Fe) MOF, serving as the anode in anion exchange membrane water electrolysis, achieves a noteworthy current density of 3300 mA cm-2 at 2.2 V while maintaining equally stable operation 500 mA cm-2 for 300 h and 1000 mA cm-2 for 170 h. This undertaking elevates our comprehension of OER catalyst reconstruction, furnishing promising avenues for designing highly efficacious catalysts across electrochemical platforms.

Origin of Enhanced Oxygen Evolution in Restructured Metal–Organic Frameworks for Anion Exchange Membrane Water Electrolysis

AbstractMetal–Organic Frameworks (MOFs), praised for structural flexibility and tunability, are prominent catalyst prototypes for exploring oxygen evolution reaction (OER). Yet, their intricate transformations under OER, especially in industrial high‐current environments, pose significant challenges in accurately elucidating their structure–activity correlation. Here, we harnessed an electrooxidation process for controllable MOF reconstruction, discovering that Fe doping expedites Ni(Fe) MOF structural evolution, accompanied by the elongation of Ni−O bonds, monitored by in situ Raman and UV/Visible spectroscopy. Theoretical modeling further reveals that Fe doping and defect‐induced tensile strain in the NiO6 octahedra augments the metal ds‐O p hybridization, optimizing their adsorption behavior and augmenting OER activity. The reconstructed Ni(Fe) MOF, serving as the anode in anion exchange membrane water electrolysis, achieves a noteworthy current density of 3300 mA cm−2 at 2.2 V while maintaining equally stable operation 500 mA cm−2 for 300 h and 1000 mA cm−2 for 170 h. This undertaking elevates our comprehension of OER catalyst reconstruction, furnishing promising avenues for designing highly efficacious catalysts across electrochemical platforms.

Metal-organic framework-derived hierarchical flower-like DyCo-layered double hydroxide amalgamated nitrogen-doped graphene for diphenylamine detection in fruit samples: Theoretical density functional theory interpretation

Diphenylamine (DPA) is an environmental pollutant that can be potentially toxic. As a result, it is crucial to use basic and affordable analytical techniques to detect DPA. Electrochemical detection of DPA is a cost-effective and simple method. Modifying the electrodes with nanomaterials can enhance the electrochemical characteristics and sensitivity of the sensor. Herein, metal-organic framework (MOF) derived dysprosium cobalt-layered double hydroxide integrated nitrogen-doped graphene (DyCo-LDH/NG) is reported for the fabrication of the DPA sensing platform. The electrochemical oxidation of DPA is enhanced by the exceptional electrocatalytic activity and electron transfer properties of the DyCo-LDH/NG nanocomposite. Interestingly, the glassy carbon electrode (GCE) modified with DyCo-LDH/NG nanocomposite demonstrates a large linear detection range (0.05–470 μM) and a low limit of detection (0.012 µM). The density functional theory (DFT) study is employed to examine the energy levels and electron transfer sites of DPA during the electro-oxidation process. Furthermore, the practical efficiency test of the developed DPA sensor demonstrates a substantial recovery in fruit samples.

TiO2 aerogel − A sensing electrode matrix for the sensitive detection of diclofenac sodium

This study developed a new composite matrix containing TiO2 aerogel having mesoporous structure (TiO2AG), bioengineered flagellin (bioF) and chitosan (Ch) deposited on a glassy carbon electrode (GCE), for the detection of diclofenac sodium (DS) in aqueous solutions. It is worth mentioning that TiO2AG mesoporous material was used for the first time as a sensitive matrix for DS detection. The morpho-structural properties of the new electrode materials were assessed by X-ray diffraction (XRD), N2 adsorption–desorption measurements, and scanning electron microscopy (SEM) in conjunction with energy-dispersive X-ray spectroscopy. The electrochemical properties of the new bioF + TiO2AG + Ch/GCE modified electrode were determined by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and square wave voltammetry (SWV) techniques. The developed modified electrode exhibits a significant electrocatalytic activity for DS electrooxidation process reflected in the acquired performances (detection limit of 17 nM, sensitivity of 0.41 A/M, linear range from 0.15 to 2.5 µM), and presents excellent reproducibility, repeatability, and stability. The practical use of the new developed electrode was estimated by quantifying DS in pharmaceutical formulations (recovery mean of 100.66 % for DS, with a relative standard deviation of 0.39 %) and wastewater samples (relative error of 3.15 % and a relative standard deviation of 0.393 when compared to the LC-MS standard technique).

Development of the novel advanced electrooxidation process for decolorization of recalcitrant dyes (Methylene Blue, Rhodamine B, Congo Red): Effect of operating factors

The research aims to develop an advanced electrooxidation process for decolorization of recalcitrant dye. To enhance the radical formation, a combination of UV irradiation and electrooxidation (UV/EO) is used. Methylene Blue (MB), Rhodamine B (RB) and Congo Red (CR) dyes were used as model compounds to represent recalcitrant dyes. The performance of UV/EO process was investigated under various operating factors (i.e., current density (CD), voltage, pH, NaCl, anodic material), and compared with chlorination, UV irradiation, and electrooxidation (EO) process. MB was the highest resistant dye to the UV/EO process. The UV/EO process exhibited a synergistic effect on decolorization, and it removed MB 1.35 time faster than the EO process. Based on indirect determination of •OH, the •OH formation in the EO process was 2.4 ×10−13 M, which lower than that in the UV/EO process by 4 times. The second-order rate constant for MB oxidation by HO• (kHO•,MB) was 3.31 × 109 M−1s−1. The pseudo 1st-order decolorization kinetic (k’) was independent with voltages, but directly depended on CD and NaCl concentrations. Lower pH enhanced the k’ value. The specific energy consumption was in a range of 0.408 – 5.303 kWh/m3, depending on the k’ value. The energy consumption decreased with higher the k’ value, except for increasing CD. The Boron Doped Diamond (BDD) was more effective in the decolorization rate than dimensional active anode (DSA) by 1.6 times. Treatment of industrial dye wastewater by the UV/EO process eliminated color intensity (ADMI), COD, and BOD5 by 80 %, 91 %, and 9 %, respectively.

Recent Advances in Urea Electrocatalysis: Applications, Materials and Mechanisms†

Comprehensive SummaryUrea plays a vital role in human society, which has various applications in organic synthesis, medicine, materials chemistry, and other fields. Conventional industrial urea production process is energy−intensive and environmentally damaging. Recently, electrosynthesis offers a greener alternative to efficient urea synthesis involving coupling CO2 and nitrogen sources at ambient conditions, which affords an achievable way for diminishing the energy consumption and CO2 emissions. Additionally, urea electrolysis, namely the electrocatalytic urea oxidation reaction (UOR), is another emerging approach very recently. When coupling with hydrogen evolution reaction, the UOR route potentially utilizes 93% less energy than water electrolysis. Although there have been many individual reviews discussing urea electrosynthesis and urea electrooxidation, there is a critical need for a comprehensive review on urea electrocatalysis. The review will serve as a valuable reference for the design of advanced electrocatalysts to enhance the electrochemical urea electrocatalysis performance. In the review, we present a thorough review on two aspects: the electrocatalytic urea synthesis and urea oxidation reaction. We summarize in turn the recently reported catalyst materials, multiple catalysis mechanisms and catalyst design principles for electrocatalytic urea synthesis and urea electrolysis. Finally, major challenges and opportunities are also proposed to inspire further development of urea electrocatalysis technology. Key ScientistsFor urea electrosynthesis, Furuya et al. firstly investigated the electrochemical coreduction of CO2 and NO3−/NO2− using gas‐diffusion electrodes in 1995. Then, Wang et al. effectively achieved C—N bond formation and urea synthesis on PdCu alloy nanoparticles in 2020. Shortly, Yan and Yu et al. proposed the formation of *CO2NO2 from *NO2 and *CO2 intermediates at early stage on In(OH)3 electrocatalyst in 2021, and employed defect engineering strategy to facilitate the *CO2NH2 protonation in 2022. Amal et al. Investigated the role that Cu‐N‐C coordination plays for both the CO2RR and NO3RR. After that, Zhang's group developed In‐based electrocatalysts with artificial frustrated Lewis pairs for urea, and they offered a systematic screening approach for catalyst design in urea electrosynthesis in 2023. And sargent et al. reported a strategy that increased selectivity to urea using a hybrid catalyst.For urea electrooxidation, Stevenson et al. investigated the effect of Sr substitution toward the urea oxidation reaction. Wang et al. provided insights into the urea electrooxidation process using a β‐Ni(OH)2 electrode and Qiao et al. elucidated a two‐stage reaction pathway for UOR in 2021.

Grafit Katot ve Karışık Metal Oksit Kaplı Ti Anotların Kullanıldığı S2O82-, H2O2 ve O3 ile Desteklenen Elektro-Oksidasyon Prosesinin Optimizasyonu

Anot olarak karışık metal oksitler ile kaplanmış ve kaplanmamış titanyum ve katot olarak ise grafit çubuğunun kullanıldığı, oksidant ile desteklenmiş elektro-oksidasyon (EO) prosesinde gerçek tekstil atık suyunun arıtımı gerçekleştirilmiştir. Oksidant olarak S2O82-, H2O2 ve O3 ile desteklenmiş proseslerin performansı, Pt-Co giderim verimi, renk sayısı giderim verimi ve KOİ giderim verimleri ile değerlendirilmiştir. Proses koşulları Taguchi Deney Tasarımı ile optimize edilmiştir. ANOVA ile performans değişkenleri üzerine önemli etkiye sahip parametreler belirlenmiştir. Oksidant destekli EO prosesinin optimum koşulları; RuO2-IrO2-Ti anot, oksidant tipi S2O82-, pH 3,0, oksidasyon süresi 25 dakika olarak belirlenmiştir. Bu koşullarda, Pt-Co, renk sayısı ve KOİ giderim verimleri (%) sırası ile 83,37, 82,6 ve 51,17 olarak elde edilmiştir. ANOVA sonuçlarından tüm yanıt parametreleri için en önemli işletim parametresinin oksidasyon süresi olduğu ortaya çıkmıştır.

Visualization of Electrooxidation on Palladium Single Crystal Surfaces via In Situ Raman Spectroscopy.

The electrooxidation of catalyst surfaces is across various electrocatalytic reactions, directly impacting their activity, stability and selectivity. Precisely characterizing the electrooxidation on well-defined surfaces is essential to understanding electrocatalytic reactions comprehensively. Herein, we employed in situ Raman spectroscopy to monitor the electrooxidation process of palladium single crystal. Our findings reveal that the Pd surface's initial electrooxidation process involves forming *OH intermediate and ClO4 - ions facilitate the deprotonation process, leading to the formation of PdOx. Subsequently, under deep electrooxidation potential range, the oxygen atoms within PdOx contribute to creating surface-bound peroxide species, ultimately resulting in oxygen generation. The adsorption strength of *OH and the coverage of ClO4 - can be adjusted by the controllable electronic effect, resulting in different oxidation rates. This study offers valuable insights into elucidating the electrooxidation mechanisms underlying a range of electrocatalytic reactions, thereby contributing to the rational design of catalysts.

Visualization of Electrooxidation on Palladium Single Crystal Surfaces via In Situ Raman Spectroscopy

AbstractThe electrooxidation of catalyst surfaces is across various electrocatalytic reactions, directly impacting their activity, stability and selectivity. Precisely characterizing the electrooxidation on well‐defined surfaces is essential to understanding electrocatalytic reactions comprehensively. Herein, we employed in situ Raman spectroscopy to monitor the electrooxidation process of palladium single crystal. Our findings reveal that the Pd surface's initial electrooxidation process involves forming *OH intermediate and ClO4− ions facilitate the deprotonation process, leading to the formation of PdOx. Subsequently, under deep electrooxidation potential range, the oxygen atoms within PdOx contribute to creating surface‐bound peroxide species, ultimately resulting in oxygen generation. The adsorption strength of *OH and the coverage of ClO4− can be adjusted by the controllable electronic effect, resulting in different oxidation rates. This study offers valuable insights into elucidating the electrooxidation mechanisms underlying a range of electrocatalytic reactions, thereby contributing to the rational design of catalysts.

Central composite experimental design for Indigo Carmine dye removal from solutions by applying electro-coagulation and electro-oxidation processes

Textile and food industries produce toxic or harmfull dye-containing wastewaters that should be treated for safely discharge. The electro-coagulation (EC) and the electro-oxidation (EO) methods for removal of dyes from wastewaters are being investigated nowadays by researchers. In this study, the Indigo Carmine, a textile and food coloring agent, removal was investigated by applying the electro-coagulation and the electro-oxidation methods. For this purpose, aluminum electrodes for EC and graphite plates for EO were used. The central composite experimental design was applied as the optimization method for the EC and the EO processes. The optimization parameters were selected as time (10-30 minutes), current density (0.4-2 Ampere/500 mL) and concentration (50-250 mg/L), natural pH (5.78-6.90) and room temperature (20-25 °C). The EO process was determined to be effective than the EC process. Statistically important parameters were concentration and time-current density interaction for the EC, but all the parameters were statistically unimportant for the EO. Dye removal percentages by the EC were calculated between 82.75% and 98.38%, and dye removal percentages by the EO were calculated between 46.88% and 100% for the determined experimental matrix. Electrical consumptions were almost equal for the EO and the EO prosesses. A column ion exchange process (Selion SBA 2000 resin) was applied to the dye residue after the EO treatment. From the oxidation reduction measurements, the treated solutions were determined as dischargeable.

Performance of combined organic precipitation, electrocoagulation, and electrooxidation in treating anaerobically treated palm oil mill effluents

Palm oil mill effluent (POME), wastewater generated from palm oil production, is known for its extremely high chemical oxygen demand and brownish color. Anaerobic digestion is the primary treatment method for POME in the palm oil industry; however, anaerobically treated POME has high concentrations of residual contaminants and color intensity. This study proposes an approach to treat anaerobically-treated POME in recycled water for industrial applications by integrating preliminary organic precipitation, electrocoagulation, and electrooxidation (EO). The EO process was optimized in terms of the current density, electrolysis time, electrode arrangement, and feed flow rate. At a current density of 60 mA/cm2 and an electrolysis time of 9 min, the EO process with a graphite anode and stainless-steel cathode in the monopolar electrode configuration reduced the phenolic concentration and color in the preliminary-treated POME from 8.95 mg/L and 317.19 ADMI to 0.25 mg/L and 26.10 ADMI, respectively. Additionally, the EO process exhibited a 92.26% efficiency in lowering the ammonium-nitrogen content.