Three-dimensional Electrode Reactor Research Articles

Enhanced degradation of nitrogen-containing disinfection by-products via radical attack in ZnAl particle electrode system: Mechanism and density functional theory calculations

Disinfection by-products (DBPs), in water receive attention because of their toxicity, mutagenicity and carcinogenicity. In this study, Nitrosopyrrolidine (NPYR) in water is electrocatalytically degraded by using ZnAl layered double hydroxide/activated carbon (ZnAl-LDH/AC) as a particle electrode in a three-dimensional electrode reactor (3DER). The results of SEM, TEM and XRD showed the successful synthesis of ZnAl-LDH, in which Zn2Al1-LDH had regular morphology and better crystallinity. The results of electrochemical characterization tests indirectly showed that Zn2Al1-LDH/AC had the largest OPE, the smallest mass transfer resistance, and higher mass transfer rate, and better electrocatalytic performance. The pollutant concentration had the greatest effect on the removal rate of NPYR in the one-way experiment, and the interaction effect between different influencing factors is determined by response surface optimization experiments. The optimal operating conditions showed a pollutant removal rate of 83.78%. A response surface prediction model is constructed. Hydroxyl radicals and superoxide radicals are demonstrated to be the main contributors to indirect oxidation by free radical quenching experiments and EPR. DFT calculations combined with GC-MS and LC-MS results deduced two possible degradation pathways. Toxicity prediction of NPYR and its intermediates is performed using software. Based on the above study, a mechanism for the degradation of NPYR by 3DER is proposed.

Removal of N-nitrosopyrrolidine from GAC by a three-dimensional electrochemical reactor: degradation mechanism and degradation path.

Nitrogen-containing disinfection by-products (N-DBPs) produced in the process of drinking water disinfection are widely concerning due to the high cytotoxicity and genotoxicity. It is due to the difficulty of natural degradation of N-DBPs in water and the fact that conventional treatment systems do not effectively treat N-DBPs in drinking water. In this study, N-nitrosopyrrolidine (NPYR) in water was electrocatalytically degraded by a three-dimensional electrode reactor (3DER). This system applied graphite plates as anode and cathode. The granular activated carbon (GAC) was used as third electrode. The degradation of NPYR using a continuous flow three-dimensional electrode reactor was investigated by examining the effects of flow rate, current density, electrolyte concentration, and pollutant concentration on the degradation efficiency, energy consumption, and reaction kinetics of GAC particle electrodes. The results showed that the optimal operating conditions were flow rate = 0.45mL/min, current density = 6mA/cm2, Na2SO4 concentration = 0.28mol/L, and NPYR concentration = 20mg/L. Under optimal conditions, the degradation of NPYR exceeded 58.84%. The main contributor of indirect oxidation was deduced from free radical quenching experiments. NPYR concentration was measured by GC-MS with DB-5 capillary column, operating in full scan monitoring mode for appropriate quantification of NPYR and intermediates. Based on the identification of reaction intermediates, a possible pathway for the electrochemical oxidation of NPYR on GAC particle electrodes was proposed.

Intensive Treatment of Organic Wastewater by Three-Dimensional Electrode System within Mn-Loaded Steel Slag as Catalytic Particle Electrodes.

Developing a green, low-carbon, and circular economic system is the key to achieving carbon neutrality. This study investigated the organics removal efficiency in a three-dimensional electrode reactor (3DER) constructed from repurposed industrial solid waste, i.e., Mn-loaded steel slag, as the catalytic particle electrodes (CPE). The CPE, a micron-grade material consisting primarily of transition metals, including Fe and Mn, exhibited excellent electric conductivity, catalytic ability, and recyclability. High rhodamine B (RhB) removal efficiency in the 3DER was observed through a physical modelling experiment. The optimal operating condition was determined through a single-factor experiment in which 5.0 g·L-1 CPE and 3 mM peroxymonosulfate (PMS) were added to a 200 mL solution of 10 mM RhB under a current intensity of 0.5 A and a 1.5 to 2.0 cm distance between the 2D electrodes. When the initial pH value of the simulated solution was 3 to 9, the RhB removal rate exceeded 96% after 20 min reaction. In addition, the main reactive oxidation species in the 3DER were determined. The results illustrated that HO• and SO4•- both existed, but that the contribution of SO4•- to RhB removal was much lower than that of HO• in the 3DER. In summary, this research provides information on the potential of the 3DER for removing refractory organics from water.

Removal of arsenic from arsenic-containing solution in a three-dimensional electrode reactor

Removal of arsenic from arsenic-containing solution in a three-dimensional electrode reactor

Recent progress of particle electrode materials in three-dimensional electrode reactor: synthesis strategy and electrocatalytic applications.

With the complete promotion of a green, low-carbon, safe, and efficient economic system as well as energy system, the promotion of clean governance technology in the field of environmental governance becomes increasingly vital. Because of its low energy consumption, great efficiency, and lack of secondary pollutants, three-dimensional (3D) electrode technology is acknowledged as an environmentally beneficial and sustainable way to managing clean surroundings. The particle electrode is an essential feature of the 3D electrode reactor. This study provides an in-depth examination of the most current advancements in 3D electrode technology. The significance of 3D electrode technology is emphasized, with an emphasis on its use in a variety of sectors. Furthermore, the particle electrode synthesis approach and mechanism are summarized, providing vital insights into the actual implementation of this technology. Furthermore, by a metrological examination of the research literature in this sector, the paper expounds on the potential and obstacles in the development and popularization of future technology.

Enhanced nitrogen removal in low-carbon saline wastewater by adding functional bacteria into Sesuvium portulacastrum constructed wetlands

Functional bacterial communities (FBC) have members of different taxonomic biochemical groups, such as N2-fixation, nitrification and denitrification. This study explored the mechanism of the FBC from an upflow three-dimensional biofilm electrode reactor on enhancing the nitrogen removal efficiencies in a Sesuvium potulacastum (S. potulacastum) constructed wetland. There were high abundances of denitrifying bacteria detected in the FBC, and they had potential metabolic processes for nitrogen reduction. In the constructed wetland, cellular nitrogen compounds of S. potulacastum were enriched by overexpressed differentially expressed genes (DEGs), and the napA, narG, nirK, nirS, qnorB, and NosZ genes related to the denitrification process had more copies under FBC treatment. Nitrogen metabolism in root bacterial communities (RBCs) was activated in the FBC group compared with the control group without FBC. Finally, these FBCs improved the removal efficiencies of DTN (dissolved total nitrogen), NO3¯­N, NO2¯­N, and NH4+-N by 84.37 %, 87.42 %, 67.51 %, and 92.57 %, respectively, and their final concentrations met the emission standards of China. These findings indicate that adding FBC into S. potulacastum-constructed wetlands would result in high nitrogen removal efficiencies from wastewater and have large potential applications in further water treatment technology.

Three-Dimensional Biofilm Electrode Reactors with a Triple-Layer Particle Electrode for Highly Efficient Treatment of Micro-Polluted Water Sources

Micro-polluted water, which is widespread in rural areas, poses a serious health risk. To address this issue, we propose a three-dimensional biofilm electrode reactor with triple-layer particle electrodes (TL-BERs) for the decentralized and small-scale treatment of micro-polluted water. The first and second layers of the electrode, granular activated carbon (GAC) and biological ceramsite (BC), respectively, are responsible for electric field oxidation and microbial degradation, respectively, while the third, quartz sand (QS), is responsible for further improving turbidity and pollutant removal. Our tests indicated that the TL-BER-treated effluent met the drinking water quality standards of China. At 10 V, the average turbidity, CODMn, NH4+-N, and UV254 removal rates of the TL-BERs system were 97.66%, 61.11%, 91.67%, and 72.94%, respectively. Furthermore, the intensities of the main fluorescence peaks, A, B, C, and D, of the raw water sample, decreased by 36.67%, 66.22%, 67.08%, and 69.76%, respectively, after treatment, indicating that tryptophan-like proteins, fulvic acid, and humic acid were also effectively removed. High-throughput sequencing analysis showed the enrichment of microorganisms, such as Proteobacteria, Bacteroidota, and Actinobacteriota, which play important roles in the removal of various pollutants. Therefore, the application of this strategy will enable the practical treatment of micro-polluted water.

Evaluating the degradation of Rhodamine B using a sequential batch three-dimensional electrode reactor

This study investigated the efficiency of a sequential batch three-dimensional electrode reactor (3DER) using stainless steel electrodes and Mn-loaded steel slag as the particle electrodes (PE) to degrade refractory organics. The PE, a micron-grade material consisting primarily of SiO2, Fe2O3, and MnO2, exhibits excellent electric conductivity and catalysis ability. Then, a single-factor experiment determined the optimal conditions for removing 20 mg·L−1 of RhB in the 3DER. It involved introducing 5 mM H2O2 and 1.0 g·L−1 PE to 200 mL of simulated wastewater under acidic-to-neutral conditions, under a current density of 57.14 mA·cm−2 and 15 mm distance between 2D electrodes. Approximately 99.52% RhB removal after 15 min of reaction was achieved. Although the inorganic ions in actual water negatively affect the 3DER performance, the system still showed excellent applicability in treating wastewater. In addition, the RhB degradation pathway was explored by determining the reactive oxidizing species (ROS) and intermediate products. The results illustrated that HO• (the main ROS that degraded organics) and SO4•− existed in the 3DER. Through de-ethylation, ring-opening, and C-C or CC bone rupturing, RhB degraded to chain organics with simple molecular structures before finally mineralizing to CO2, H2O, NO3-, and NH4+. In summary, this research informs on the potential of 3DER for removing refractory organics from water.

Sulfamethazine degradation by sulfite through GAC@Ni/Fe Three-Dimensional (3D) particle electrode activation: Contribution of active substance and synergy

The widespread production and use of antibiotics, which accumulate in the environment and lead to chronic poisoning of non-target organisms, causing potential safety risks to the environment and human health. In this study, GAC@Ni/Fe was used as particle electrode and sulfite hetero activator for synergistic degradation of Sulfamethazine(SMR) in a three-dimensional electrode reactor. Under the optimal experimental parameters (trough voltage = 5 V, sulfite addition =1 mM, particle electrode addition = 40 g, PH = 7), the removal rate of SMR can reach 96.91% within 30 min. The surface changes before and after the reaction at the GAC@Ni/Fe particle electrode was characterized using XRD, XPS, and FTIR. LSV, Tafel, and EIS were used to investigate the electrochemical performance of the GAC@Ni/Fe particle electrodes. The superiority of Three-Dimensional(3D) (GAC@Ni/Fe)/Sulfite system in SMR removal was confirmed by comparative experiments and reaction synergistic factor analysis. Electron paramagnetic resonance (EPR) and quenching experimental studies demonstrate that the degradation of SMR within the 3D (GAC@Ni/Fe)/Sulfite system is the result of both free radical and non-free radicals, with·OH, SO4−·and 1O2 contributing 51%, 12% and 37% to SMR removal, respectively. The 54.57% TOC removal rate (30 min) also demonstrates the efficient mineralization of SMR by the system. The results show that the 3D (GAC@Ni / Fe) / Sulfite system can be used to treat the wastewater containing SMR and other antibiotics, which is a green and ecologically friendly method with potential application value.

Efficient degradation of COD from coking wastewater by corncob biochar-modified particles using a three-dimensional electrode reactor

In this work, Fe–Mn/BC particle electrodes with different loading ratios were prepared by sol–gel method using corncob biochar (BC) as carrier, and could be used for highly-efficient treatment of coking wastewater by three-dimensional electrode reactor (3DER) system.

Deciphering the effects of antibiotics on nitrogen removal and bacterial communities of autotrophic denitrification systems in a three-dimensional biofilm electrode reactor

In this study, three-dimensional biofilm electrode reactors (3D-BERs) were constructed, and the effects of metronidazole (MNZ) on the nitrogen removal performance and bacterial communities of autotrophic denitrification systems were evaluated. The results showed that nitrogen removal decreased slightly as the MNZ concentration increased. Specifically, nitrate-nitrogen removal efficiency decreased from 97.98% to 89.39%, 86.93%, 82.64%, and 82.77% within 12 h after the addition of 1, 3, 5, and 10 mg/L MNZ, respectively. The 3D-BERs showed excellent MNZ degradation ability, especially at a concentration of 10 mg/L. The MNZ removal efficiency could be as high as 94.38% within 6 h, and the average removal rate increased as the MNZ concentration increased. High-throughput sequencing results showed significant changes in the bacterial community under different MNZ concentrations. As the antibiotic concentration increased, the relative abundances of Hydrogenophaga and Silanimonas increased, from only 0.09% and 0.01% without antibiotics to 3.55% and 2.35%, respectively, at an antibiotic concentration of 10 mg/L. Changes in antibiotic concentration altered the abundances of genes involved in nitrogen metabolism. Redundancy analysis showed that MNZ removal efficiency was positively correlated with SBR1031, SC-I-84, Hydrogenophaga, Silanimonas and Denitratesoma, whereas the removal efficiencies of nitrate-nitrogen and total nitrogen were negatively correlated with these genera. The results of this study provide a theoretical basis for studying the toxic effects of antibiotics on the denitrification process and also provide guidance for the control of antibiotics and nitrogen pollution in ecosystems.

Integration of the adsorption and electro-oxidation process using 3D printed activated carbon monoliths for the degradation of pharmaceutical compounds

A three-dimensional electrode reactor (3DER) was developed and evaluated for the degradation of recalcitrant pharmaceutical compounds such as diclofenac (DCF) and acetylsalicylic acid (ASA) from water, using for the first-time activated carbon monoliths (ACm) fabricated by 3D printing as a third electrode in the oxidation process. The degradation and mineralization percentages for the 3DER system were 81% and 74% respectively, which was up to 2.5 times higher than the system without using a third electrode. On the other hand, synergy calculations were performed, obtaining values of up to 35% when the integrated adsorption-oxidation technology was used compared to the degradations obtained by both processes sequentially. Operating parameters such as initial ACm saturation time (60 and 240 min) and applied voltage (0.6 and 0.9 V) were evaluated. Kinetic constants (kapp) were 3.2 times larger when the saturation time was shorter and the voltage higher. In addition, ACm regeneration tests were carried out to evaluate the regeneration of the material during the process, obtaining regenerations of up to 99%. Finally, the energy consumption by order of magnitude (EEO) was calculated for the best operating conditions in the 3DER, obtaining a value of 2.06 kWh/m3, which implies 50% less energy than the system without ACm. Despite the challenges in understanding the integrated processes in adsorption-electrooxidation, this study proposes compact and well-structured structures as an alternative for process optimization in 3DER.

Electro-enhanced adsorption of As(V) by activated carbon in three-dimensional electrode reactor

This study focused on As(V) removal by electrosorption in a self-made three-dimensional electrode reactor, in which granular activated carbon (GAC) was used as the particle electrode. Under the optimal conditions, the removal efficiency of As(V) was 84%, and its residual concentration in solution was 0.08 mg/L. From kinetic investigation, the rate determining steps of the entire process may involve more than two processes: membrane diffusion, material diffusion and physical/chemical adsorption processes. During the desorption process, As(V) can be desorbed from GAC, and the GAC was able to electro-adsorb As(V) again after desorption, which means that the electrode has good cycling performance.

Electrocatalytic degradation of sulfamethylthiadiazole by GAC@Ni/Fe three-dimensional particle electrode

In this work, GAC@Ni/Fe particle electrodes were prepared and employed for the degradation of sulfamethylthiadiazole (SMT) by three-dimensional electrocatalytic technology. The effects of particle electrode bi-metal loading ratio, cell voltage, particle electrode dosage, electrode plate spacing, and SMT initial concentration on SMT removal were studied. In addition, GAC@Ni/Fe particle electrode was analyzed by the scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffractometer (XRD), X-ray photoelectron spectrometer (XPS), and Fourier transform infrared spectrometer (FTIR) to characterize which indicated that a significant amount of iron-nickel oxide was formed on the surface of GAC@Ni/Fe particle electrode. The results indicated that when the nickel-iron loading ratio is 1:1, the SMT removal effect is the best, and the removal rate can reach 90.89% within 30min. Compared with the granular activated carbon without bimetal, the removal efficiency is increased by 37.58%. The degradation of SMT in the GAC@Ni/Fe particle three-dimensional electrode reactor is the joint result of both direct oxidation and indirect oxidation. The contribution rates of direct oxidation of anode and particle electrode and indirect oxidation of ·OH in the degradation are 32%, 27%, and 41%, respectively. Based on the intermediate detected by ultra-high liquid chromatography and the calculation of bond energy of SMT molecule by Gauss software, the degradation pathway of SMT in the GAC@Ni/Fe three-dimensional electrode reactor is proposed. This research provides a green, healthy, and effective method for removing sulfonamide micro-polluted wastewater.

Performance analysis of a half-batch multi-cell three-dimensional electrode reactor for drilling wastewater: COD removal, energy consumption and hydrodynamic characteristic

Although a three-dimensional electrode system (3DES) has made remarkable achievements in improving the property of electrodes and investigating pollutant degradation mechanism, the design of an electrochemical reactor for application in drilling wastewater has not been reported yet. In this study, a novel half-batch multi-cell 3DES reactor was constructed by us to degrade organic compounds from drilling wastewater. The separate effect of electrolysis time, current density, the configuration of granular activated carbon (GAC) electrodes, aeration rate and volumetric recirculation flow on chemical oxygen demand (COD) removal and energy consumption of the half-batch reactor were analyzed, and further optimization via response surface methodology (RSM). Results showed that the optimal operation conditions for the reactor included electrolysis time of 100 min, a current density of 9.2 mA/cm2, GAC electrode vertical configuration, an aeration rate of 2.67 L/min and a volumetric recirculation flow of 100 mL/min. Under these conditions, the maximum percentage COD removal was found to be 97.39% with an energy consumption of 77.89 kWh(kg COD)-1. The residence time distribution (RTD) method was carried out in continuous flow pattern to investigate the hydrodynamic characteristics of the reactor. Results showed that flow rate was the most dominant factor for the flow pattern of the reactor, followed by the aeration rate and current density. The low dispersion number and the percentage of dead volume are 0.214 and 3.87% when the flow rate of 100 mL/min, respectively, which indicates that there is an intermediate flow pattern existing in between plug-flow ideal and complete mixing flow, furthermore, it is close to the plug-flow ideal.

Advanced electro-Fenton degradation of a mixture of pharmaceutical and steel industrial wastewater by pallet-activated-carbon using three-dimensional electrode reactor

In the present work, a three-dimensional electrode reactor (3Der) using pallet activated carbon (PAC), as particle electrodes, was investigated to degrade non-biodegradable organic pollutants in pharmaceutical wastewater and steel industry wastewater. The effect of operating parameters, such as pH, electrode distance, O2 flow rate, and current density was investigated. The TOC removal efficiency in 3Der was achieved at the highest mineralization yield of 94.1% after 180 min electrolysis, which was 10–19% higher than the two-dimensional electrode reactor (2Der). The higher performance of the 3Der can be attributed to the indirect and direct oxidation mechanisms. The impact of supporting electrolytes was decreased in order as chloride > nitrate > sulfate. The morphology of sludge and the presence of Fe(OH)3 after Fenton-oxidation were investigated. 3Der system improved biodegradability of pharmaceutical wastewater after electro-Fenton treatment at a PW/SIW ratio of 3:1 (BOD5/COD = 0.6). Hence, the mechanism of 3Der/PAC, as particle electrodes was also proposed. 3Der with PAC particle electrodes using steel industry wastewater as a catalyst is an exciting technique for remediation of organic contaminated pharmaceutical wastewater.

Decomplexation of Cu-1-hydroxyethylidene-1,1-diphosphonic acid by a three-dimensional electrolysis system with activated biochar as particle electrodes

The feasibility of decomplexation removal of typical contaminants in electroplating wastewater, complexed Cu(II) with 1-hydroxyethylidene-1,1-diphosphonic acid (Cu-HEDP), was first performed by a three-dimensional electrode reactor with activated biochar as particle electrodes. For the case of 50 mg/L Cu-HEDP, Cu(II) removal (90.7%) and PO43− conversion (34.9%) were achieved under the conditions of electric current 40 mA, initial pH 7, acid-treated almond shell biochar (AASB) addition 20 g/L, and reaction time 180 min, with second-order rate constants of 1.10 × 10−3 and 1.94 × 10−5 min−1 respectively. The growing chelating effect between Cu(II) and HEDP and the comprehensive actions of adsorptive accumulation, direct and indirect oxidation given by particle electrodes accounted for the enhanced removal of Cu-HEDP, even though the mineralization of HEDP was mainly dependent on anode oxidation. The performance attenuation of AASB particle electrodes was ascribed to the excessive consumption of oxygen-containing functionalities during the reaction, especially acidic carboxylic groups and quinones on particle electrodes, which decreased from 446.74 to 291.48 µmol/g, and 377.55 to 247.71 µmol/g, respectively. Based on the determination of adsorption behavior and indirect electrochemical oxidation mediated by in situ electrogenerated H2O2 and reactive oxygen species (e.g., •OH), a possible removal mechanism of Cu-HEDP by three-dimensional electrolysis was further proposed.

Long-term performance of granular activated carbon electrode system for the removal of amoxicillin

Three-dimensional electrode reactor, packed with conductive particles, is more cost-effective than traditional two-dimensional electrode reactor. In this study, granular activated carbon (GAC) was applied as particle electrode, then the long-term performance on amoxicillin (AMX) removal and activated carbon regeneration of the GAC particle electrode oxidation process (GAC EOP) was investigated, and the GAC adsorption process (GAC ADS) was carried out for comparison. Both of them ran continuously to remove AMX. Because of the regeneration effect of electrochemical action, the GAC EOP showed a more stable physisorption capacity than GAC ADS, with less change in micropore volume, pore size distribution and surface morphology of GAC. The result of XPS revealed the AMX chemisorption mechanism: the carbonyl (CO) and phenolic hydroxyl (OH) on activated carbon combined with carboxyl (COOH) and ammonium group (NH3+) on AMX, respectively. Correspondingly, the content of CO and OH on GAC fell significantly during the GAC ADS. However, due to the chemical bond regeneration effect of electrolysis, noticeable declines were not observed in GAC EOP, which ensured the stable chemisorption capacity of this system. It was shown that during the 50 consecutive runs, the AMX removal in GAC EOP was always higher than 60%. Even the removal efficiency showed an upward tendency, with the average value reached 86.1% and 99.1% in the 31–40 and 41–50 run times respectively. It was because of the rising specific surface area of GAC and the effect of electro-polarization, which made it more meaningful to explore the long-term performance of three-dimensional electrode reactor.

Azo dye wastewater treatment in a novel three-dimensional electrode reactor

Azo dye wastewater treatment in a novel three-dimensional electrode reactor

Azo dye wastewater treatment in a novel three-dimensional electrode reactor

Azo dye wastewater treatment in a novel three-dimensional electrode reactor