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Ingelsson M, Yasri N, Roberts EPL. Electrode passivation, faradaic efficiency, and performance enhancement strategies in electrocoagulation-a review. WATER RESEARCH 2020; 187:116433. [PMID: 33002774 DOI: 10.1016/j.watres.2020.116433] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 08/30/2020] [Accepted: 09/15/2020] [Indexed: 06/11/2023]
Abstract
Treating water and wastewater is energy-intensive, and traditional methods that require large amounts of chemicals are often still used. Electrocoagulation (EC), an electrochemical treatment technology, has been proposed as a more economically and environmentally sustainable alternative. In EC, sacrificial metal electrodes are used to produce coagulant in-situ, which offers many benefits over conventional chemical coagulation. However, material precipitation on the electrodes during long term operation induces a passivating effect that decreases treatment performance and increases power requirements. Overcoming this problem is considered to be the greatest challenge facing the development of EC. In this critical review, the studies that have examined the nature of electrode passivation, and its effect on treatment performance are considered. A fundamental approach is used to examine the association between passivation and faradaic efficiency, a surrogate for EC performance. In addition, the strategies that have been proposed to remove or avoid passivation are reviewed, including aggressive ion addition, AC current operation, polarity reversal, ultrasonication, and mechanical cleaning of the electrodes. It is concluded that the success of implementing each method is dependent on critical operating parameters, and careful consideration should be taken when designing an EC system based on the phenomena discussed in this article. In conclusion, this review provides insight into passivation mechanisms, delivers guidelines for sustaining high treatment performance, and offers an outlook for the future development of EC.
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Review |
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66 |
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Jiang Y, Zeng RJ. Bidirectional extracellular electron transfers of electrode-biofilm: Mechanism and application. BIORESOURCE TECHNOLOGY 2019; 271:439-448. [PMID: 30292689 DOI: 10.1016/j.biortech.2018.09.133] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Revised: 09/25/2018] [Accepted: 09/27/2018] [Indexed: 06/08/2023]
Abstract
The extracellular electron transfer (EET) between microorganisms and electrodes forms the basis for microbial electrochemical technology (MET), which recently have advanced as a flexible platform for applications in energy and environmental science. This review, for the first time, focuses on the electrode-biofilm capable of bidirectional EET, where the electrochemically active bacteria (EAB) can conduct both the outward EET (from EAB to electrodes) and the inward EET (from electrodes to EAB). Only few microorganisms are tested in pure culture with the capability of bidirectional EET, however, the mixed culture based bidirectional EET offers great prospects for biocathode enrichment, pollutant complete mineralization, biotemplated material development, pH stabilization, and bioelectronic device design. Future efforts are necessary to identify more EAB capable of the bidirectional EET, to balance the current density, to evaluate the effectiveness of polarity reversal for biocathode enrichment, and to boost the future research endeavors of such a novel function.
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Review |
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Mena E, Villaseñor J, Cañizares P, Rodrigo MA. Effect of electric field on the performance of soil electro-bioremediation with a periodic polarity reversal strategy. CHEMOSPHERE 2016; 146:300-307. [PMID: 26735730 DOI: 10.1016/j.chemosphere.2015.12.053] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2015] [Revised: 12/15/2015] [Accepted: 12/16/2015] [Indexed: 06/05/2023]
Abstract
In this work, it is studied the effect of the electric fields (within the range 0.0-1.5 V cm(-1)) on the performance of electrobioremediation with polarity reversal, using a bench scale plant with diesel-spiked kaolinite with 14-d long tests. Results obtained show that the periodic changes in the polarity of the electric field results in a more efficient treatment as compared with the single electro-bioremediation process, and it does not require the addition of a buffer to keep the pH within a suitable range. The soil heating was not very important and it did not cause a change in the temperature of the soil up to values incompatible with the life of microorganisms. Low values of water transported by the electro-osmosis process were attained with this strategy. After only 14 d of treatment, by using the highest electric field studied in this work (1.5 V cm(-1)), up to 35.40% of the diesel added at the beginning of the test was removed, value much higher than the 10.5% obtained by the single bioremediation technology in the same period.
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Lu H, Zhan Y, Ai L, Chen H, Chen J. AQP4-siRNA alleviates traumatic brain edema by altering post-traumatic AQP4 polarity reversal in TBI rats. J Clin Neurosci 2020; 81:113-119. [PMID: 33222898 DOI: 10.1016/j.jocn.2020.09.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 07/13/2020] [Accepted: 09/06/2020] [Indexed: 11/18/2022]
Abstract
The spatial and temporal distribution of aquaporin-4 (AQP4) expression in rat brain following brain trauma and AQP4-siRNA treatment, as well as corresponding pathological changes, were studied to explore the mechanism underlying the effect of AQP4-siRNA treatment on traumatic brain injury (TBI). The rats in the sham operation group had normal structure, with AQP4 located in the perivascular end-foot membranes and astrocytic membranes in a polarized pattern. The accelerated polarity reversal was observed in the TBI group in 1-12 h after TBI. During this period, AQP4 abundance on the astrocytic membrane is gradually increased, while AQP4 abundance on the perivascular end-foot membrane declined rapidly. Twelve hours after TBI, AQP4 expression was depolarized, showing a shift from the perivascular end-foot membrane to the astrocytic membrane. Pathological observation showed that vasogenic edema occurred immediately after TBI, at which time the extracellular space was expanded, leading to severe intracellular edema. AQP4-siRNA reduced the polarity reversal index at the early stage of TBI recovery and reduced edema, demonstrating the potential benefit of reduced AQP4 expression during recovery from TBI.
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Journal Article |
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Mena Ramírez E, Villaseñor Camacho J, Rodrigo MA, Cañizares P. Combination of bioremediation and electrokinetics for the in-situ treatment of diesel polluted soil: A comparison of strategies. THE SCIENCE OF THE TOTAL ENVIRONMENT 2015; 533:307-316. [PMID: 26172598 DOI: 10.1016/j.scitotenv.2015.06.127] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 06/18/2015] [Accepted: 06/28/2015] [Indexed: 06/04/2023]
Abstract
The aim of this work is to compare different strategies based on electrokinetic soil flushing and bioremediation for the remediation of diesel-polluted soil. Four options were tested at the laboratory scale: single bioremediation (Bio), performed as a control test; a direct combination of electrokinetic soil flushing and biological technologies (EKSF-Bio); EKSF-Bio with daily polarity reversal of the electric field (PR-EKSF-Bio); and a combination of electrokinetic soil flushing and a permeable reactive biological barrier (EKSF-BioPRB). Four batch experiments of 14 days duration were carried out for comparing technologies at room temperature with an electric field of 1.0 V cm(-1) (in EKSF). A diesel degrading microbial consortium was used. The experimental procedure and some specific details, such as the flushing fluids used, varied depending on the strategy. When using the EKSF-Bio option, a high buffer concentration was required to control the pH, causing soil heating, which negatively affected the biological growth and thus the diesel removal. The PR-EKSF-Bio and the EKSF-BioPRB options attained suitable operating conditions and improved the transport processes for biological growth. Polarity reversal was an efficient option for pH, moisture and temperature control. Homogeneous microbial growth was observed, and approximately 20% of the diesel was removed. The BioPRB option was not as efficient as PR-EKSF-Bio in controlling the operating conditions, but the central biobarrier protected the biological activity. Microbial growth was observed not only in the biobarrier but also in a large portion of the soil, and 29% of the diesel was removed in the short remediation test.
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Comparative Study |
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Barba S, Villaseñor J, Rodrigo MA, Cañizares P. Effect of the polarity reversal frequency in the electrokinetic-biological remediation of oxyfluorfen polluted soil. CHEMOSPHERE 2017; 177:120-127. [PMID: 28288422 DOI: 10.1016/j.chemosphere.2017.03.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2016] [Revised: 03/01/2017] [Accepted: 03/02/2017] [Indexed: 06/06/2023]
Abstract
This work studies the feasibility of the periodic polarity reversal strategy (PRS) in a combined electrokinetic-biological process for the remediation of clayey soil polluted with a herbicide. Five two-weeks duration electrobioremediation batch experiments were performed in a bench scale set-up using spiked clay soil polluted with oxyfluorfen (20 mg kg-1) under potentiostatic conditions applying an electric field between the electrodes of 1.0 V cm-1 (20.0 V) and using PRS with five frequencies (f) ranging from 0 to 6 d-1. Additionally, two complementary reference tests were done: single bioremediation and single electrokinetic. The microbial consortium used was obtained from an oil refinery wastewater treatment plant and acclimated to oxyfluorfen degradation. Main soil conditions (temperature, pH, moisture and conductivity) were correctly controlled using PRS. On the contrary, the electroosmotic flow clearly decreased as f increased. The uniform soil microbial distribution at the end of the experiments indicated that the microbial activity remained in every parts of the soil after two weeks when applying PRS. Despite the adapted microbial culture was capable of degrade 100% of oxyfluorfen in water, the remediation efficiency in soil in a reference test, without the application of electric current, was negligible. However, under the low voltage gradients and polarity reversal, removal efficiencies between 5% and 15% were obtained, and it suggested that oxyfluorfen had difficulties to interact with the microbial culture or nutrients and that PRS promoted transport of species, which caused a positive influence on remediation. An optimal f value was observed between 2 and 3 d-1.
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Seirin Lee S. Positioning of polarity formation by extracellular signaling during asymmetric cell division. J Theor Biol 2016; 400:52-64. [PMID: 27086039 DOI: 10.1016/j.jtbi.2016.04.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 03/03/2016] [Accepted: 04/02/2016] [Indexed: 11/20/2022]
Abstract
Anterior-posterior (AP) polarity formation of cell membrane proteins plays a crucial role in determining cell asymmetry, which ultimately generates cell diversity. In Caenorhabditis elegans, a single fertilized egg cell (P0), its daughter cell (P1), and the germline precursors (P2 and P3 cells) form two exclusive domains of different PAR proteins on the membrane along the anterior-posterior axis. However, the phenomenon of polarity reversal has been observed in which the axis of asymmetric cell division of the P2 and P3 cells is formed in an opposite manner to that of the P0 and P1 cells. The extracellular signal MES-1/SRC-1 has been shown to induce polarity reversal, but the detailed mechanism remains elusive. Here, using a mathematical model, I explore the mechanism by which MES-1/SRC-1 signaling can induce polarity reversal and ultimately affect the process of polarity formation. I show that a positive correlation between SRC-1 and the on-rate of PAR-2 is the essential mechanism underlying polarity reversal, providing a mathematical basis for the orientation of cell polarity patterns.
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Research Support, Non-U.S. Gov't |
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Rajic L, Fallahpour N, Yuan S, Alshawabkeh AN. Electrochemical transformation of trichloroethylene in aqueous solution by electrode polarity reversal. WATER RESEARCH 2014; 67:267-75. [PMID: 25282093 PMCID: PMC4262522 DOI: 10.1016/j.watres.2014.09.017] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Revised: 09/09/2014] [Accepted: 09/11/2014] [Indexed: 05/12/2023]
Abstract
Electrode polarity reversal is evaluated for electrochemical transformation of trichloroethylene (TCE) in aqueous solution using flow-through reactors with mixed metal oxide electrodes and Pd catalyst. The study tests the hypothesis that optimizing electrode polarity reversal will generate H2O2 in Pd presence in the system. The effect of polarity reversal frequency, duration of the polarity reversal intervals, current intensity and TCE concentration on TCE removal rate and removal mechanism were evaluated. TCE removal efficiencies under 6 cycles h(-1) were similar in the presence of Pd catalyst (50.3%) and without Pd catalyst (49.8%), indicating that Pd has limited impact on TCE degradation under these conditions. The overall removal efficacies after 60 min treatment under polarity reversal frequencies of 6, 10, 15, 30 and 90 cycles h(-1) were 50.3%, 56.3%, 69.3%, 34.7% and 23.4%, respectively. Increasing the frequency of polarity reversal increases TCE removal as long as sufficient charge is produced during each cycle for the reaction at the electrode. Electrode polarity reversal shifts oxidation/reduction and reduction/oxidation sequences in the system. The optimized polarity reversal frequency (15 cycles h(-1) at 60 mA) enables two reaction zones formation where reduction/oxidation occurs at each electrode surface.
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Research Support, N.I.H., Extramural |
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Gobbi LCA, Nascimento IL, Muniz EP, Rocha SMS, Porto PSS. Electrocoagulation with polarity switch for fast oil removal from oil in water emulsions. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2018; 213:119-125. [PMID: 29482092 DOI: 10.1016/j.jenvman.2018.01.069] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 01/09/2018] [Accepted: 01/24/2018] [Indexed: 06/08/2023]
Abstract
An electrocoagulation technique using a 3.5 L reactor, with aluminum electrodes in a monopolar arrangement with polarity switch at each 10 s was used to separate oil from synthetic oily water similar in oil concentration to produced water from offshore platforms. Up to 98% of oil removal was achieved after 20 min of processing. Processing time dependence of the oil removal and pH was measured and successfully adjusted to exponential models, indicating a pseudo first order behavior. Statistical analysis was used to prove that electrical conductivity and total solids depend significantly on the concentration of electrolyte (NaCl) in the medium. Oil removal depends mostly on the distance between the electrodes but is proportional to electrolyte concentration when initial pH is 8. Electrocoagulation with polarity switch maximizes the lifetime of the electrodes. The process reduced oil concentration to a value below that stipulated by law, proving it can be an efficient technology to minimize the offshore drilling impact in the environment.
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Fuladpanjeh-Hojaghan B, Shah RS, Roberts EPL, Trifkovic M. Effect of polarity reversal on floc formation and rheological properties of a sludge formed by the electrocoagulation process. WATER RESEARCH 2023; 242:120201. [PMID: 37336184 DOI: 10.1016/j.watres.2023.120201] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Revised: 05/21/2023] [Accepted: 06/07/2023] [Indexed: 06/21/2023]
Abstract
Anode fouling is one of the key limiting factors to the widespread application of electrocoagulation (EC) for treatment of different types of contaminated water. Promising mitigation strategy to fouling is to operate the process under polarity reversal (PR) instead of direct current (DC). However, the PR operation comes at the cost of process complexity due to the alternation of electrochemical and chemical reactions. In this study, we systematically investigated the link between evolving fouling layer during DC and PR close to iron and aluminum electrodes and morphological and rheological properties of the formed sludge. By operando visualization of EC process, we demonstrate that during PR operation, precipitation of the iron and aluminum species occurs close to the anode interface, resulting in flocs with higher porosity and lower density than those formed under DC conditions. However, rheological investigation revealed that the PR conditions resulted in a sludge with more pronounced solid-like signature, but this enhancement in its viscoelastic properties is closely related to a period of the current's polarity reversal. We attribute this unexpected result to higher shear rate and collision of particles during PR conditions.
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Abdollahi J, Alavi Moghaddam MR, Habibzadeh S. The role of the current waveform in mitigating passivation and enhancing electrocoagulation performance: A critical review. CHEMOSPHERE 2023; 312:137212. [PMID: 36395897 DOI: 10.1016/j.chemosphere.2022.137212] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 11/07/2022] [Accepted: 11/08/2022] [Indexed: 06/16/2023]
Abstract
Electrocoagulation (EC) can be an efficient alternative to existing water and wastewater treatment methods due to its eco-friendly nature, low footprint, and facile operation. However, the electrodes applied in the EC process suffer from passivation or fouling, an issue resulting from the buildup of poorly conducting materials on the electrode surface. Indeed, such passivation gives rise to various operational problems and restricts the practical implementation of EC on a large scale. Therefore, it has been suggested that using pulsed direct current (PDC), alternating pulse current (APC), and sinusoidal alternating current (AC) waveforms in EC as alternatives to conventional direct current (DC) can help mitigate passivation and alleviate its associated detrimental effects. This paper presents a critical review of the impact of the current waveform on the EC process towards the capabilities of the PDC, APC, and AC waveforms in de-passivation and performance enhancement while comparing them to the conventional DC. Additionally, current waveform parameters influencing the surface passivation of electrodes and process efficiency are elaborately discussed. Meanwhile, the performance of the EC process is evaluated under different current waveforms based on pollutant removal efficiency, energy consumption, electrode usage, sludge production, and operating cost. The proper current waveforms for treating various water and wastewater matrices are also explained. Finally, concluding remarks and outlooks for future research are provided.
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Review |
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Chow H, Ingelsson M, Roberts EPL, Pham ALT. How does periodic polarity reversal affect the faradaic efficiency and electrode fouling during iron electrocoagulation? WATER RESEARCH 2021; 203:117497. [PMID: 34371234 DOI: 10.1016/j.watres.2021.117497] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 07/26/2021] [Accepted: 07/27/2021] [Indexed: 06/13/2023]
Abstract
Electrocoagulation (EC) is a promising electrochemical water treatment technology. However, a major challenge to sustaining effective long-term EC operation is controlling the precipitation of materials on the electrodes, commonly referred to as fouling. Periodically reversing electrode polarity has been suggested as an in-situ fouling mitigation strategy and is often implemented in EC field applications. However, the utility of this approach has not been investigated in detail. In this study, the effect of polarity reversal (PR) on the performance of EC using iron electrodes was examined under different water chemistry conditions and at a range of reversal frequencies. It was observed that the faradaic efficiency in PR-EC was always lower than that in the EC systems operated with a direct current (i.e., DC-EC). It was also observed that the faradaic efficiency progressively decreased as the current reversal frequency increased, with the faradaic efficiency dropping as low as 10% when the PR interval was 0.5 min. Results from fouling layer, chronopotentiometric, and cyclic voltammetric investigations indicated that the decrease in the faradaic efficiency was caused by (i) increased electrode fouling by iron precipitates and (ii) electrochemical side reactions at the electrode-electrolyte interface. The extent of these effects was dependent on the solution chemistry; oxyanions and sulfide were found to be particularly detrimental to the performance of PR-EC, causing severe electrode fouling while decreasing the faradaic efficiency. Fouling could be mitigated by increasing the solution convection rate, resulting in a shear on the electrode surface that removed iron and other electrochemically reactive species from the electrodes.
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Temporal frequency dependence of the polarity inversion between upper and lower visual field in the pattern-onset steady-state visual evoked potential. Doc Ophthalmol 2023; 146:53-63. [PMID: 36272048 PMCID: PMC9911476 DOI: 10.1007/s10633-022-09904-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 10/06/2022] [Indexed: 01/29/2023]
Abstract
PURPOSE According to the cruciform model, the upper and lower halves of the visual field representation in the primary visual cortex are located mainly on the opposite sides of the calcarine sulcus. Such a shape would have consequences for the surface-recorded visual evoked potential (VEP), as V1 responses to stimulation of the upper and lower hemifield manifest with opposite polarity (i.e., polarity inversion). However, the steady-state VEP results from a complex superposition of response components from different cortical sources, which can obscure the inversion of polarity. The present study assesses the issue for different stimulation frequencies which result in different patterns of superposition in the steady-state response. METHODS Sequences of brief pattern-onset stimuli were presented at different stimulation rates ranging from 2 Hz (transient VEP) to 13 Hz (steady-state VEP). The upper and lower hemifields were tested separately and simultaneously. The data were assessed both in the time domain and in the frequency domain. RESULTS Comparing the responses to the stimulation of upper and lower hemifield, polarity inversion was present within a limited time interval following individual stimulus onsets. With increasing frequency, this resulted in an approximate inversion of the full steady-state response and consequently in a phase shift of approximately 180° in the time-domain response. Polarity inversion was more prominent at electrode Pz, also for transient responses. Our data also demonstrated that the sum of the hemifield responses is a good approximation of the full-field response. CONCLUSION While the basic phenomenon of polarity inversion occurs irrespective of the stimulus frequency, its relative impact on the steady-state response as a whole is the largest for high stimulation rates. We propose that this is because longer-lasting response components from other visual areas are not well represented in the steady-state VEP at higher frequencies.
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research-article |
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Li Y, Zhang Y, Wang X, Zhu Y, Yuan J, Ren L, Chen J, Wang Z. A novel electrochemical membrane filtration system operated with periodical polarity reversal for efficient resource recovery from nickel nitrate laden industrial wastewater. WATER RESEARCH 2024; 266:122424. [PMID: 39293309 DOI: 10.1016/j.watres.2024.122424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2024] [Revised: 09/05/2024] [Accepted: 09/08/2024] [Indexed: 09/20/2024]
Abstract
The economical and efficient removal of nickel nitrate from industrial wastewater remains a challenge. Herein, we developed an innovative electrochemical membrane filtration system that used a periodic polarity reversal process to adjust the acid-base environment near membrane interface for the recovery of nickel (II) and ammonia. The Ru based electrocatalytic layer could boost the selective reduction of nitrate to ammonia by generating atomic hydrogen, resulting in the precipitation of Ni2+ by the increasing pH at the membrane interface. Then, the precipitation of Ni(OH)2 could be effectively stripped and collected under the periodic polarity reversal process. In-situ interfacial measurements demonstrated that the polarity reversal process enabled a reversible transformation between strongly acidic (pH < 2) and alkaline (pH > 13) environments within a 200 µm range at the membrane interface. In continuous flow operation treating real industrial wastewater containing 96.7 mg-N L-1 nitrate and 135.0 mg L-1 Ni2+, the system demonstrated the capability to achieve 92.5 ± 2.6 % nitrate removal (with a recovery efficiency of 15.1 ± 1.9 g-NH3 kWh-1) and 99.7 ± 0.1 % Ni²⁺ removal (with a recovery efficiency of 24.9 ± 2.4 g-Ni kWh-1). Additionally, the specific treatment cost was approximately $0.17 m-3, attributed to the recovery of Ni(OH)₂ and ammonia. Furthermore, this system could deliver a significant economic benefit ($1.64 per m3) for treating a high concentration real wastewater (331.5 mg-N L-1 nitrate and 1496.3 mg L-1 Ni2+), outperforming traditional alkali precipitation and biological nitrification/denitrification processes. Overall, our study presents an economical and sustainable method for recovering valuable chemicals from wastewater containing heavy metals and inorganic nitrogen, potentially advancing cost-effective water treatment technologies.
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Yu Y, Liu H, Wang P, Kong X, Jin H, Chen X, Chen J, Chen D. Tactfully introducing amphoteric group into electroactive membrane motivates highly efficient H 2O splitting for reversible removal and recovery of nickel(II). JOURNAL OF HAZARDOUS MATERIALS 2025; 481:136527. [PMID: 39566454 DOI: 10.1016/j.jhazmat.2024.136527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2024] [Revised: 10/16/2024] [Accepted: 11/13/2024] [Indexed: 11/22/2024]
Abstract
Membrane-based electro-deposition (MED) is an original process promising for reversible removal and recovery of toxic heavy metal ions from wastewater. The removal efficiency of heavy metal ions, however, was limited by the poor membrane surface H2O splitting in the conventional ion exchange membrane (IEM). Inspired by the amphoteric interface-triggered ion exchange resin regeneration phenomenon in electro-deionization, herein we subtly introduced the amphoteric group into IEM as a proof of concept to solve the above bottleneck. By virtue of the "electronic porter" role of the amphoteric -3OS-R-N(CH3)3+, the electron extraction from adsorbed H2O could be accelerated, extending the H2O splitting from the conventional membrane surface to the bulk membrane interior. Such an H2O splitting extension favorably produced an intensified and well-modeled OH- production region at the anodic side of IEM, enhancing the Ni2+ basic deposition accordingly. This special characteristic allowed our MED to realize a super-eminent metal ion removal rate (10.5 mol·h-1·m-2) along with an ultra-low specific energy consumption (0.1 kWh·mol-1) for Ni2+ removal, which considerably surpassed those of state-of-the-art heavy metal ion removal processes reported yet. Further, the deposited Ni2+ could be in situ recovered in conjunction with the facile polarity reversal method. The amphoteric electroactive membrane with high H2O splitting activity is expected to pave the path to engineering MED for efficient heavy metal ion removal and recovery.
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Wang Z, Tang T, Chen L, Wu S, Li X, Liu Y. Electrokinetic remediation of cadmium-contaminated soil using polarity reversal method: Optimization analysis and mechanism exploration. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 370:122732. [PMID: 39369536 DOI: 10.1016/j.jenvman.2024.122732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2024] [Revised: 09/24/2024] [Accepted: 09/29/2024] [Indexed: 10/08/2024]
Abstract
Electrokinetic remediation (EKR) has been applied for in-situ removal of Cd from contaminated soil, and the EKR enhanced with polarity reversal has achieved a higher Cd removal efficiency. However, the migration and accumulation mechanisms of Cd in the EKR process have not been investigated. In this paper, the cross-impacts of the voltage gradient, citric acid concentration in the electrolyte, and polarity reversal frequency on the removal efficiency by EKR of Cd and the optimization conditions were investigated. The migration and accumulation mechanisms of Cd were explored by analyzing the changes in electrokinetic process parameters, experimental phenomena, and X-ray diffraction (XRD) analysis. The results showed that the maximum removal efficiency of Cd reached 82.26%. The optimal conditions were determined by fitting the RSM model using the BBD design. In the EKR experiment with polarity reversal, Cd accumulated mainly in the middle part of the soil, attributed to the formation of chemical precipitation focusing area caused by soil pH transition, ion-induced potential gradient well trapping effect (IIPGWTE), or soil compaction induced by water loss. In conclusion, the various parameters have cross-impacts on the EKR of Cd-contaminated soil, and efficient in-situ removal of Cd from the contaminated soil can be achieved by adjusting the parameter conditions.
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Ceballos-Escalera A, Pous N, Balaguer MD, Puig S. Electrochemical water softening as pretreatment for nitrate electro bioremediation. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 806:150433. [PMID: 34560446 DOI: 10.1016/j.scitotenv.2021.150433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 09/06/2021] [Accepted: 09/14/2021] [Indexed: 06/13/2023]
Abstract
Electro bioremediation is gaining interest as a sustainable treatment for contaminated groundwater. Nevertheless, the investigation is still at the laboratory level, and before their implementation is necessary to overcome important drawbacks. A prevalent issue is the high groundwater hardness that generates scale deposition on electrodes that irreversibly affects the treatment effectiveness and their lifetime. For this reason, the present study evaluated a novel and sustainable approach combining electrochemical water softening as a preliminary step for electro bioremediation of nitrate-contaminated groundwater. Batch mode tests were performed at mL-scale to determine the optimum reactor configuration (single- or two-chambers) and the suitable applied cathode potential for electrochemical softening. A single-chamber reactor working at a cathode potential of -1.2 V vs. Ag/AgCl was chosen. Continuous groundwater softening under this configuration achieved a hardness removal efficiency of 64 ± 4% at a rate of 305 ± 17 mg CaCO3 m-2cathode h-1. The saturation index at the effluent of the main minerals susceptible to precipitate (aragonite, calcite, and brucite) was reduced up to 90%. Softening activity plummeted after 13 days of operation due to precipitate deposition (mostly calcite) on the cathode surface. Polarity reversal periods were considered to detach the precipitated throughout the continuous operation. Their implementation every 3-4 days increased the softening lifetime by 48%, keeping a stable hardness removal efficiency. The nitrate content of softened groundwater was removed in an electro bioremediation system at a rate of 1269 ± 30 g NO3- m-3NCC d-1 (97% nitrate removal efficiency). The energy consumption of the integrated system (1.4 kWh m-3treated) confirmed the competitiveness of the combined treatment and paves the ground for scaling up the process.
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Han Y, Li W, zhi R, Ma G, Gao A, Wu K, Sun H, Zhao D, Yang Y, Liu F, Gu F, Guo X, Dong J, Li S, Fu L. MiR-30c suppresses the proliferation, metastasis and polarity reversal of tumor cell clusters by targeting MTDH in invasive micropapillary carcinoma of the breast. Heliyon 2024; 10:e33938. [PMID: 39071710 PMCID: PMC11279262 DOI: 10.1016/j.heliyon.2024.e33938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2024] [Revised: 06/30/2024] [Accepted: 07/01/2024] [Indexed: 07/30/2024] Open
Abstract
Purpose Invasive micropapillary carcinoma (IMPC) of the breast has a high propensity for lymphovascular invasion and axillary lymph node metastasis and displays an 'inside-out' growth pattern, but the molecular mechanism of invasion, metastasis and cell polarity reversal in IMPC is unclear. Methods and Patients: Cell growth curves, tumor sphere formation assays, transwell assays, mouse xenograft model and immunofluorescence were evaluated to investigate the effects of miR-30c and MTDH. Dual luciferase reporter assays was performed to confirm that the MTDH (metadherin) 3'UTR bound to miR-30c. MiRNA in situ hybridization (ISH) and immunohistochemistry (IHC) were carried out on IMPC patient tissues for miR-30c and MTDH expression, respectively. Results We found miR-30c as a tumor suppressor gene in cell proliferation, metastasis and polarity reversal of IMPC. Overexpression of miR-30c inhibited cell growth and metastasis in vitro and in vivo. MiR-30c could directly target the MTDH 3'UTR. MiR-30c overexpression inhibited breast cancer cell proliferation, invasion and metastasis by targeting MTDH. Moreover, miR-30c/MTDH axis could also regulate cell polarity reversal of IMPC. By ISH and IHC analyses, miR-30c and MTDH were significantly correlated with tumor size, lymph nodule status and tumor grade, the 'inside-out' growth pattern, overall survival (OS) and disease-free survival (DFS) in IMPC patients. Conclusions Overall, miR-30c/MTDH axis was responsible for tumor proliferation, metastasis and polarity reversal. It may provide promising therapeutic targets and prognostic biomarkers for patients with IMPC.
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Cournoyer A, Bazinet M, Clément JP, Plante PL, Fliss I, Bazinet L. How peptide migration and fraction bioactivity are modulated by applied electrical current conditions during electromembrane process separation: A comprehensive machine learning-based peptidomic approach. Food Res Int 2025; 200:115417. [PMID: 39779161 DOI: 10.1016/j.foodres.2024.115417] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2024] [Revised: 10/23/2024] [Accepted: 11/19/2024] [Indexed: 01/11/2025]
Abstract
Industrial wastewaters are significant global concerns due to their environmental impact. Yet, protein-rich wastewaters can be valorized by enzymatic hydrolysis to release bioactive peptides. However, achieving selective molecular differentiation and eventually enhancing peptide bioactivities require costly cascades of membranes. In this study, a complex porcine cruor hydrolysate, containing 150 well-characterized peptides and demonstrating only an antifungal activity, was used as a model solution to evaluate the impact of current modes (continuous electrical current (CC), pulsed electric field (PEF) and polarity reversal (PR)) and the combination of pulse/pause-reversal pulse duration (10 s/1 s and 1 s/1 s) during peptides separation by an electromembrane process. The data analysis was assisted by a machine learning (ML)-based peptidomic approach to identify which of the 45 physicochemical characteristics of the peptides explain migration, or lack thereof, during electrodialysis with filtration membrane, a generic electromembrane process. The results demonstrated, for the first time, that electric current conditions modulate the population of recovered peptides and their associated fraction bioactivities. ML models identified the main features correlated to peptide migration, allowing tentative explanations of the underlying peptide selective migration phenomena. For CC-PEF 10 s/1 s-PR 10 s/1 s, isoelectric point (pI) (importance of 63.1%) and molecular weight (MW) (17.7%) were most important. For PEF 1 s/1 s, pI (53.9%), MW (23%) and GRAVY score (6.2%) played major roles. Finally, for PR 1 s/1 s, MW (82.5%), GRAVY score (5.5%) and tyrosine content (1.1%) were the key features. In addition, CC, PEF 10 s/1 s and PR 10 s/1 s allowed the production of two reusable fractions, an antibacterial recovery fraction and a feed fraction retaining antifungal activity, which aligns with the concept of circular economy.
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