Mesh Cathode Research Articles

Novel Water-Splitting Electrolyzer Design Incorporating a Gas Diffusion Electrode and a Gel Membrane for Highly Efficient Hydrogen Production.

Advancements in cost-effective, high-performance alkaline water-splitting systems are crucial for the hydrogen industry. While the significance of electrode material design has been widely acknowledged, the practical implementation of these advancements remains challenging. In this study, we focused on the holistic design of the electrolysis system and successfully developed a novel alkaline water-splitting electrolyzer. The unique configuration of our electrolyzer allows the designed NiFe-LDH/carbon cloth gas diffusion anode to interact solely with the PVA-based gel membrane and air, enabling the direct discharge of oxygen into the gas phase. This innovative feature accelerates anode bubble overflow, reduces gas interference, and decreases the system impedance by minimizing electrode spacing. As a result, by utilizing the NiFeSn-alloy/nickel mesh cathode, our electrolyzer achieves a high current density of 308 mA cm-2 at a cell voltage of 2.0 V and demonstrates exceptional stability over 1000 h.

An innovative electrolytic cation exchange reactor system for cleaner generation of hydrogen gas using ocean water

The study presents a novel integrated three-compartment electrochemical continuous electrodeionization reactor that was constructed in a laboratory environment. In order to extract large amounts of carbon dioxide from naturally occurring oceanwater in the form of bicarbonate and carbonate, it develops a innovative electrolytic cation exchange process. At the same time, it produces hydrogen gas for possible hydrocarbon synthesis. The study employs the Box-Behnken experimental design approach implemented through the Design Expert software to investigate and optimize the performance of electrochemical hydrogen extraction from Ocean water from an integrated reactor. The integrated electrochemical continuous-type electrodeionization reactor comprises two cation-permeable membranes that operate as boundaries between three compartments: a central compartment and electrode compartments that house the cathode and anode, each of which may reverse polarity. These membranes are made of gel polystyrene cross-linked with divinylbenzene, which has acidic properties that allow cation transport while inhibiting anions. The integrated reactor's electrode chambers are enclosed in plexiglass end plates and contain distinct Plexiglass electrode compartments. These compartments have mesh and solid steel anode and cathode electrodes, with an electrode active area of 176.71 cm2. The influence of various factors, such as voltage and electrolyte amount, on the production of hydrogen synthesis is examined. The study results demonstrate a maximum hydrogen production rate of 2.2 mg/min and a hydrogen production efficiency of 7.82%. The lab testing was carried out using experimental equipment to determine viability. The tests included 35-min runs that measured hydrogen generation under various parameters, such as applied voltage, electrolyte concentration, and pH levels. The ocean salt solutions of 0.5M, 1M, and 2M were initially prepared and evaluated for hydrogen generation. Each concentration is assessed at a voltage range of 4–15V, with matching solution pH values ranging from 2 to 7. Optimization studies were conducted to enhance the hydrogen production rate. The results indicate that hydrogen production rises proportionally with applied voltage and electrolyte concentration but falls with pH growth. Within the Design Expert software, the statistical methods for response surface analysis and optimization are utilized accordingly.

Rational Design of Multiple Heterostructures with Synergistic Effect for Efficient and Stable Hydrogen Evolution Toward Industrial Alkaline Water Splitting

AbstractElectrocatalytic hydrogen evolution reaction (HER) via alkaline water splitting holds great promise for industrial clean hydrogen production but is frustrated by limited catalytic activity and inferior stability under high current density. Elaborate manipulating of heterostructure on robust catalytic electrodes is essential but challenging for accelerating HER kinetics with high durability. Herein, a robust nickel mesh electrode, offering high mechanical stability, is directly engineered with catalytic layers of multiple heterostructures (r‐Mn–Ni/CoP) via facile one‐pot electrodeposition followed by surface reconstruction strategy. The abundant heterostructures composed of crystalline CoP, NiP, amorphous region, and additional Mn doping considerably manipulate the electronic structure with optimized charge transfer; while the in situ surface‐reconstructed hydrophilic nanoflakes enable the rapid wetting of active sites to the electrolyte. Consequently, the r‐Mn–Ni/CoP requires only 134 mV overpotential at the current density of 100 mA cm−2, superior to monophasic and undoped samples, and the majority of reported HER catalysts. Remarkably, an electrolyzer with r‐Mn–Ni/CoP on a nickel mesh cathode demonstrates extraordinary activity with a voltage of 1.734 V at 300 mA cm−2 and stable operation of 800 h. The finding provides a feasible strategy for the fabrication of nonprecious‐metal‐based HER electrocatalysts with high activity and stability toward industrial water electrolysis.

Efficacy and power production performance of constructed wetlands coupled with microbial fuel cells for the advanced treatment of saline tailwater from wastewater treatment plants

In this study, the effects of different electrode materials and salt-tolerant plants on the efficacy and power production performance of constructed wetlands coupled microbial fuel cells (CW-MFCs) were analyzed for the advanced treatment of saline tailwater from wastewater treatment plants (WWTPs). The results showed that when carbon felt was used as the cathode material, the voltage was 165.45 ± 14.90 mV after system stabilization, the maximum power density was 3.20 mW/m2 when the current density was 25.58 mA/m2, and the power production performance of carbon felt was better than that of common titanium mesh and granular activated carbon-stainless steel mesh cathode materials (p < 0.05). When the two groups of systems were operated and stabilized, the average removal rates of TN, TP, NH4+-N and COD in RS-CW-MFC were 86.48 %, 88.1 %, 82.67 % and 88.96 %, respectively, and those of TN, TP, NH4+-N and COD in RN-CW-MFC were 84.33 %, 87.34 %, 81.63 % and 87.64 %, respectively. Salinity enhanced the power production efficiency by increasing ionic strength and decreasing the internal resistance of the system. The microbial community in the saline tailwater systems gradually evolved toward salt-tolerant species, which enhanced the power production efficiency of the system without affecting the treatment of traditional pollutants in the CW-MFC systems.

Polymer-based LFP cathode/current collector microfiber-meshes with bi- and interlayered architectures for Li-ion battery

In this study, we report the development of a free-standing fiber-based mesh cathode made of electrospun composite microfibers containing 80 wt% lithium iron phosphate (LFP), as well as conductive microfibers containing carbon nano-fillers acting as the current collector (CC). Neither the electrode nor the current collector undergoes post-fabrication treatment or calcination. Scanning electron microscopy confirmed that the meshes are constructed of well-shaped microfibers and exhibit a high porosity, enabling efficient electrolyte penetration and improved electron and ion-transport channels.Two cathode architectures of the LFP/polymer-based CC meshes were explored: bilayered and interlayered. Both architectures are characterized by a high surface-to-volume ratio. The interlayered structure showed superior electrochemical performance due to enhanced LFP-CC fiber-to-fiber contacts and reduced resistance. Comparative analysis with electrospun LFP on aluminum foil revealed comparable specific capacity but higher polarization in the electrospun LFP/CC meshes, attributed to increased internal resistance and limited fiber-to-fiber contacts. However, the electrospun interlayered LFP/CC mesh exhibited significantly higher gravimetric energy density (197 Wh/kg (LFP + CC) and 94 Wh/kg (LFP + Al), respectively), offering lightweight and higher-energy-density electrode materials, thus guiding the design of high-performance flexible lithium-ion batteries.

Sustainable bioelectric activation of periodate for highly efficient micropollutant abatement

The periodate (PI)-based advanced oxidation process is valued for environmental remediation, but current activation methods involve high costs, secondary contamination risks, and limited applicability due to external energy inputs (e.g., UV), catalyst incorporation (e.g., Fe2+), or environmental modifications (e.g., freezing). In this work, novel bioelectric activation of PI using the electrons generated by electroactive bacteria was developed and investigated for rapid removal of carbamazepine (CBZ), achieving 100 %, 100 %, and 76 % removal efficiency for 4.22 µM of CBZ in 20 min at pH 2, 120 min at pH 6.4, and HRT of 30 min at pH 8.5, respectively, with a 1 mM PI dose and without an input voltage. It was deduced that electrons derived from bacteria could directly activate PI using Ti mesh electrodes and generate •IO3 via single electron transfer under strongly acidic conditions (e.g., pH 2). Nevertheless, under weak alkaline conditions (e.g., pH 8.5), biogenic electrons indirectly activated PI by generating OH−via 4e−reduction at the Ti mesh cathode, resulting in the formation of •O2− and 1O2. In addition to the metal cathode, a carbon-based cathode finely modulates the 2e−reduction, yielding H2O2 and activating PI to mainly form •OH. Moreover, primarily non-toxic IO3− was produced during treatment, while no detectable reactive iodine species (HOI, I2, and I3−) were observed. Furthermore, the bioelectric activation of PI demonstrated its capability to remove various micropollutants present in secondary-treated municipal wastewater, showcasing its broad-spectrum degradation ability. This study introduces a novel, cost-effective, and environmentally friendly PI activation technique with promising applicability for micropollutant elimination in water treatment.

Electrocoagulation Coupled to Electro-Oxidation for the Electrochemical Treatment of Hemodialysis Wastewater

Hemodialysis is an extracorporeal kidney replacement procedure to remove impurities or waste products from the blood used to treat kidney failure. During this process, large amounts of water are used, which, lacking control, end up in sewage systems, potentially flushing high levels of organic and inorganic contaminants into the receiver’s aqua biota. In recent years, a hybrid electrocoagulation (EC) and electro-oxidation (EO) process in sequential or simultaneous coupling has been used for the treatment of wastewater.This research considered synthetic water from hemodialysis under acid and basic conditions. To better simulate the presence of organic compounds, 10 mg L-1 of amoxicillin (AMX), an antibiotic commonly present in wastewater from clinics and hospitals, was added. Laboratory and pilot tests were performed using coupled EC and EO. They used stainless-steel (SS-304) and aluminum (Al-6061) as sacrificial anodes that were compared in acidic and basic pH during EC. The SS-304 rod anode and a titanium (Ti) mesh cathode were used during EC in acidic conditions at a field strength of 3.0 V, which was applied for 60 min. After EC, the solution obtained was filtered to separate precipitates. The supernatant was then treated with EO using an IrO2-Ta2O5|Ti (70:30) anode and the Ti mesh cathode while applying 10 mA for 120 min. The wear of the SS-304 anode was identified by scanning electron microscopy (SEM) and microanalysis (EDS). Removal of organic compounds, including AMX, was significant. This result was confirmed by decreased concentration found by diode coupled chromatography (UPLC-UV-Vis) detection.In conclusion, combining EC and EO in a sequential arrangement for the treatment of hemodialysis wastewater was carried out. EC was performed using a cylindrical SS-304 bar electrode (f = 0.8 cm) as an anode and a concentric Ti mesh as the counter electrode. A 3.0 V cell potential was maintained over one hour of electrolysis in acidic pH (pH = 5.06, s = 227 mS cm-1). This treatment yielded a removal efficiency of 86 ± 1.25 % of AMX contaminate (pH = 8.21, s = 217.26 mS cm-1, i = 11.36 mA, E = 0.568 kWh m-3). After EC, it was necessary to include a filtration or separation process to remove the Fe(OH)3 and [AMX-cation-AMX] sludge generated (2.3 g). This separation employed a settler. Subsequently, the supernatant was placed in an EO cell to remove residual organic compounds as AMX. It used a similar cell arrangement as in EC but changed the anode to IrO2-Ta2O5|Ti (70:30) (f = 0.5 cm) to perform the EO of the pharmaceutical product. During this step, the team achieved an overall removal efficiency of AMX of 100 % (pH = 8.14, s = 179.83 mS cm-1, E = 500 kWh m-3). EO was performed using a continuous 10 mA cell current for 2 h. EO generated reaction products ADP 1, ADP 2, and ADP 3. Additionally, this process decreased the content of ‘salty’ cations: Na+, K+, Ca2+, and Mg2+, while generating Cl2 gas at the electrode.

Serrated Mesh Cathode for Low-Energy-Consumption Electrochemical Descaling: Mechanism and Process Optimization

Serrated Mesh Cathode for Low-Energy-Consumption Electrochemical Descaling: Mechanism and Process Optimization

Electrochemical oxidation of azo dyes degradation by RuO2–IrO2–TiO2 electrode with biodegradation Aeromonas hydrophila AR1 and its degradation pathway: An integrated approach

Azo dyes are the most varied class of synthetic chemicals with non-degradable characteristics. They are complex compounds made up of many different parts. It was primarily utilized for various application procedures in the dyeing industry. Therefore, it's crucial to develop an economical and environmentally friendly approach to treating azo dyes. Our present investigation is an integrated approach to the electrooxidation (EO) process of azo dyes using RuO2–IrO2–TiO2 (anode) and titanium mesh (cathode) electrodes, followed by the biodegradation process (BD) of the treated EO dyes. Chemical oxygen demand (COD) removal efficiency as follows MB (55%) ≥ MR (45%) ≥ TB (38%) ≥ CR (37%) correspondingly. The fragment generated during the degradation process which was identified with high-resolution mass spectrometry (HRMS) and its degradation mechanism pathway was proposed as demethylation reaction and N–N and C–N/C–S cleavage reaction occurs during EO. In biodegradation studies by Aeromonas hydrophila AR1, the EO treated dyes were completely mineralized aerobically which was evident by the COD removal efficiency as MB (98%) ≥ MR (92.9%) ≥ TB (88%) ≥ CR (87%) respectively. The EO process of dyes produced intermediate components with lower molecular weights, which was effectively utilized by the Aeromonas hydrophila AR1 and resulted in higher degradation efficiency 98%. We reported the significance of the enhanced approach of electrochemical oxidation with biodegradation studies in the effective removal of the pollutants in dye industrial effluent contaminated water environment.

Simultaneous degradation and rejection of PPCPs from wastewater in a 3DEO-FO-RO process

This study established a novel three-dimensional electrochemical oxidation coupled with forward osmosis and reverse osmosis (3DEO-FO-RO) system with the purpose to achieve simultaneous degradation and rejection of pharmaceuticals and personal care products (PPCPs) in wastewater. 18 frequently detected PPCPs were selected as the target pollutants to prepare the synthetic wastewater with a concentration of 200 μg/L for each pollutant. Ti/IrO2–Ta2O5–SnO2 mesh anode, titanium mesh cathode and Sn–Sb–Bi/γ-Al2O3 particles electrodes were integrated in the 3DEO-FO reactor. Experimental results demonstrated that degradation efficiency exceeding 98.5 % and rejection exceeding 99.4 % for each PPCP were achieved simultaneously in the 3DEO-FO-RO processes at a current density of 1 mA/cm2 after 8 h treatment. Despite variations in applied current density, the 3DEO-FO-RO processes exhibited superior PPCPs removal efficiencies, particularly for refractory compounds, compared to the 2DEO-FO-RO processes. Increased hydroxyl radical (·OH) generation in the 3D reactor was considered to be responsible for the excellent performance. Furthermore, results derived from ultraviolet (UV) absorption spectra and fluorescence excitation-emission matrix (EEM) spectra provided additional validation for the effective removal of PPCPs in the 3DEO-FO-RO processes, along with evidence indicating the decomposition of PPCPs into smaller constituents. Ultimately, the 3DEO-FO-RO process demonstrated its capacity in removing PPCPs from actual secondary effluent from a wastewater treatment plant. This integrated system coupling 3D EO with FO-RO membranes can provide an efficient approach for simultaneous degradation and rejection of trace contaminants for wastewater reuse.

Relationship Between Current and Mesh Cathode Structure for a Coaxial Cylindrical Diode

Relationship Between Current and Mesh Cathode Structure for a Coaxial Cylindrical Diode

Ce Site in Amorphous Iron Oxyhydroxide Nanosheet toward Enhanced Electrochemical Water Oxidation.

Iron oxyhydroxide has been considered an auspicious electrocatalyst for the oxygen evolution reaction (OER) in alkaline water electrolysis due to its suitable electronic structure and abundant reserves. However, Fe-based materials seriously suffer from the tradeoff between activity and stability at a high current density above 100mA cm-2 . In this work, the Ce atom is introduced into the amorphous iron oxyhydroxide (i.e., CeFeOx Hy ) nanosheet to simultaneously improve the intrinsic electrocatalytic activity and stability for OER through regulating the redox property of iron oxyhydroxide. In particular, the Ce substitution leads to the distorted octahedral crystal structure of CeFeOx Hy , along with a regulated coordination site. The CeFeOx Hy electrode exhibits a low overpotential of 250mV at 100mA cm-2 with a small Tafel slope of 35.1 mVdec-1 . Moreover, the CeFeOx Hy electrode can continuously work for 300h at 100mA cm-2 . When applying the CeFeOx Hy nanosheet electrode as the anode and coupling it with the platinum mesh cathode, the cell voltage for overall water splitting can be lowered to 1.47V at 10mA cm-2 . This work offers a design strategy for highly active, low-cost, and durable material through interfacing high valent metals with earth-abundant oxides/hydroxides.

Spatial and temporal regulation of homogeneous nucleation and crystal growth for high-flux electrochemical water softening

Electrochemical softening is an effective technology for the treatment of circulating cooling water, but its hardness removal efficiency is limited because that nucleation and growth of scale crystals depended on cathode surface. In this study, a novel method was proposed to break through this limit via spatiotemporal management of nucleation and growth processes. A cube reactor was divided into cathodic chamber and anodic chamber via installing a sandwich structure module composed of mesh cathode, nylon nets, and mesh anode. Using this continuous-flowing electrochemical reactor, OH ̄ generated by water electrolysis was rapidly pushed away from cathode surface by water flow and hydrogen bubbles movement. As a result, a wide range of strongly alkaline regions was rapidly constructed in cathodic chamber to play a nucleation region, and homogeneous nucleation in liquid phase replaced heterogeneous nucleation on cathodic surface. Furthermore, the growth process of scale crystals in alkaline regions was monitored in situ. It took only 150 s of residence time to grow to 500 nm, which may be easily separated from water by a microfiltration membrane. With this new method, the precipitation rate was 290.8 g/(hˑm2) and corresponding energy consumption was 2.1 kW·h/kg CaCO3, both were superior to those reported values. Therefore, this study developed an efficient electrochemical softening method by spatial and temporal regulation of homogeneous nucleation and crystal growth processes.

Self-powered wastewater purification and phosphorus recovery systems with novel self-filtering Al-air batteries

Sustainable water treatment systems are crucial for water recycling and resource recovery. However, the existing self-powered water treatment technology for metal-air batteries has several challenges. This study proposed a new self-powered water treatment system concept by developing self-filtering aluminum-air (SF Al-air) batteries. The sandwich-shaped flexible air cell comprised an aluminum (Al) scrap anode, an inexpensive hydrophilic separator, and a graphite-coated titanium mesh cathode. By utilizing the capillary action and porous structure of the separator, the autonomous flow and filtration of electrolytes or wastewater were achieved inside the battery. Owing to the high Al purity of 95 % and the ultra-thin structure, the low-cost kitchen Al foil is a promising anode, with the highest power density of 23.02 mW g−1 (anode weight), 4.60 × 10−2 W $−1 (anode cost). Kitchen paper is the preferred separator facilitating electrolyte transfer and automatic renewal inside the battery owing to the strong water storage property. The SF Al-air cell can also efficiently removed 90% of phosphorus at an initial concentration of 100 mg P/L and initial pH = 7. Specifically, the cell converted phosphate pollutants and Al foil waste into a valuable AlPO4·2H2O flame retardant coating on kitchen paper, resulting in a first-class flame retardancy of the separators. Lake water treatment results showed that the self-powered SF-Al-air cell purified real surface water and obtained a stable power production of 146.7 mW g−1. Our study demonstrates a promising sustainable water treatment technology for simultaneous power generation, wastewater purification, phosphorus recovery, and waste Al disposal.

Effect of electrode parameters in the electro-production of reactive oxidizing species via boron-doped diamond under batch mode.

Ozone and hydroxyl radicals (• OH) are powerful reactive oxidizing species (ROS) that are commonly utilized in water disinfection. The electrochemical advanced oxidation process (EAOP) is often used to generate such oxidants, whereas optimizing its experimental setup and electrode parameters plays a crucial role in its performance. This research aims to find the optimal setup for ROS generation process from tap water via the boron-doped diamond. The effect of electrode's active area, type of electrode substrates (mesh or sheet), type of mesh substrate (rolled and unrolled), and number of anodes and cathodes are examined. The results showed that the use of two long-rolled BDD/Nb meshes as anode and one long-rolled mesh as a cathode gives the optimal performance of electrolysis process at 15 V potential and 3min. These results will provide a start for developing a cost accepted, health-safe, household disinfection device that reduces susceptibility to human life-threatening waterborne diseases. PRACTITIONER POINTS: This research aims to find the optimal setup for ROS generation process from tap water via the boron-doped diamond. The effect of electrode's parameters on the electro-production of ROS is examined. The best performance is achieved using rolled mesh electrodes. Two long-rolled BDD/Nb meshes as anode electrodes and one long-rolled mesh cathode electrode give the optimal electrolysis process performance.

Electrochemical treatment of hemodialysis wastewater including pharmaceutical products

Hemodialysis is an extracorporeal kidney replacement procedure to remove impurities or waste products from the blood that is used in the treatment of kidney failure. During this process, large amounts of water are used, which, lacking control, end up in sewage systems, potentially flushing high levels of organic and inorganic contaminants into the receiver's aqua biota. This research considered the treatment of synthetic hemodialysis water under acid and basic conditions. To better simulate the presence of organic compounds, 10 mg L−1 of amoxicillin, an antibiotic commonly present in wastewater from clinics and hospitals, was added. Laboratory and pilot tests were performed using coupled electrocoagulation and electro-oxidation. During electrocoagulation, the use of stainless steel and aluminum, as sacrificial anodes, were compared in acidic and basic pH. The stainless steel rod anode and a titanium mesh cathode were used during electrocoagulation in acidic conditions at a field strength of 3.0 V which was applied for 60 min. After electrocoagulation, the solution obtained was filtered to separate precipitates. The supernatant was then treated with electro-oxidation using an IrO2-Ta2O5|Ti anode and the titanium mesh cathode while applying 10 mA for 120 min. Wear of the stainless steel anode was identified by scanning electron microscopy and microanalysis. Removal of organic compounds including amoxicillin was significant. These results were confirmed by decreased contaminant concentration found by diode coupled chromatography detection. In the final analysis this coupled treatment system completely eliminated amoxicillin and significantly reduced entrained salts.

The microbial synergy and response mechanisms of hydrolysis-acidification combined microbial electrolysis cell system with stainless-steel cathode for textile-dyeing wastewater treatment

Microbial electrolysis cell (MEC) has been existing problems such as poor applicability to real wastewater and lack of cost-effective electrode materials in the practical application of refractory wastewater. A hydrolysis-acidification combined MEC system (HAR-MECs) with four inexpensive stainless-steel and conventional carbon cloth cathodes for the treatment of real textile-dyeing wastewater, which was fully evaluated the technical feasibility in terms of parameter optimization, spectral analysis, succession and cooperative/competition effect of microbial. Results showed that the optimum performance was achieved with a 12 h hydraulic retention time (HRT) and an applied voltage of 0.7 V in the HAR-MEC system with a 100 μm aperture stainless-steel mesh cathode (SSM-100 μm), and the associated optimum BOD5/COD improvement efficiency (74.75 ± 4.32 %) and current density (5.94 ± 0.03 A·m−2) were increased by 30.36 % and 22.36 % compared to a conventional carbon cloth cathode. The optimal system had effective removal of refractory organics and produced small molecules by electrical stimulation. The HAR segment could greatly alleviate the imbalance between electron donors and electron acceptors in the real refractory wastewater and reduce the treatment difficulty of the MEC segment, while the MEC system improved wastewater biodegradability, amplified the positive and specific interactions between degraders, fermenters and electroactive bacteria due to the substrate complexity. The SSM-100 μm-based system constructed by phylogenetic molecular ecological network (pMEN) exhibited moderate complexity and significantly strong positive correlation between electroactive bacteria and fermenters. It is highly feasible to use HAR-MEC with inexpensive stainless-steel cathode for textile-dyeing wastewater treatment.

Boosting hydrogen production from fermentation effluent of biomass wastes in cylindrical single-chamber microbial electrolysis cell.

Microbial electrolysis cells (MECs) are considered as green technologies for H2 production with simultaneously wastewater treatment. Low H2 recovery and production rate are two key bottlenecks of MECs fed with real H2 fermentation effluent of biomass wastes. This work established a 1 L cylindrical single chamber MEC and enriched electroactive anodic biofilms from cow dung compost to overcome the bottlenecks. These MEC components (platinum-coated cylindrical titanium mesh cathode and cylindrical graphite felt anode) were arranged in a concentric configuration. A high H2 production rate of 6.26 ± 0.23 L L-1day-1 with H2 yield of 5.75 ± 0.16 L H2 L-1 fermentation effluent was achieved at 0.8V. The degradation of acetate and butyrate (main components of H2 fermentation effluent) could reach to 95.3 ± 2.1% and 78.4 ± 3.6%, respectively. The microbial community analysis for anode showed the abundance of Geobacter (22.6%), Syntrophomonas (8.7%), and Dysgonomonas (6.3%) which are responsible to complex substrate oxidation, electrical current generation, and H2 production. These results prove the feasibility of cylindrical single-chamber MEC for high H2 production rate and high acetate and butyrate removal from H2 fermentation effluent.

Degradation of dissolved RDX, NQ, and DNAN by cathodic processes in an electrochemical flow-through reactor

Both legacy munitions compounds (e.g., RDX) and new insensitive high explosives (e.g. DNAN, NQ) are being manufactured and utilized concurrently, and there exists a need for wastewater treatment systems that are able to degrade both classes of explosives. Electrochemical systems offer treatment possibilities using inexpensive materials and no chemical additions. Electrochemically induced removal of RDX, NQ, and DNAN were separately studied within an electrochemical plug flow reactor hosting a stainless steel (SS) cathode and downstream Ti/MMO anode. Varying wire mesh cathodes and operating conditions were evaluated in an effort to identify the optimal cathode material, to determine the relative contributions of cathodically-induced removal processes, to shorten time to steady-state removal conditions, and to find practical ranges of operating conditions. Applied current allowed the cathode to support munitions removal mainly by direct reduction at the cathode surface, and the secondary reactions of cathodically-induced alkaline hydrolysis and catalytic hydrogenation by adsorbed H on Ni-containing cathode surfaces might contribute to some munitions degradation. The optimal cathode material was identified as SS grade 316, possibly due to its superior Ni content and lack of corrosion protection coating. Higher current, longer cathode length, and smaller mesh pore sizes resulted in slightly greater removal extents and shorter acclimation times to steady state removal conditions, but there are practical upper limits to these properties. Higher Ni content within SS improved RDX and NQ removal but does not affect DNAN removal. Prolonged use of SS grade 316 showed no debilitating changes in electrical performance or chemical content.

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.