An integrated electrolysis-microfiltration-ion exchange closed-loop system for effective water softening without chemicals input and spent regenerant discharge

Ba, Xuchen; Chen, Jinghua; Wang, Xuesong; Xu, Hui; Sun, Junqiang; Qi, Yuanfeng; Li, Yifan; Wang, Juan; Jiang, Bo

doi:10.1016/j.desal.2023.116481

Cited by 15 publications

(6 citation statements)

References 41 publications

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“…Although the long-term stability of a Ti tubular anode for boundary layer abstraction might suffer from pore clogging by finely dispersed particles and suspended matters, this clogging phenomenon can be effectively solved by employing the conventional backwashing strategy to restore the water flux of a porous Ti tubular anode. Simultaneously, in softening applications, the fouling caused by filter cake accumulation on the filter surface can be effortlessly solved by periodically applying a positive potential on the Ti filter. , As for the fouling on the cathode after a long-term operation process, the strategies such as pickling, ultrasonic cleaning, and mechanical scraping may be required to maintain the electrochemical water softening process. Moreover, the cylindrical geometry of the present electrolytic cell has a higher surface-to-volume ratio, which is favorable in terms of the volumetric power density and industrial scalability.…”

Section: Resultsmentioning

confidence: 99%

“…Simultaneously, in softening applications, the fouling caused by filter cake accumulation on the filter surface can be effortlessly solved by periodically applying a positive potential on the Ti filter. 52,53 As for the fouling on the cathode after a long-term operation process, the strategies such as pickling, ultrasonic cleaning, and mechanical scraping may be required to maintain the electrochemical water softening process. Moreover, the cylindrical geometry of the present electrolytic cell has a higher surface-to-volume ratio, which is favorable in terms of the volumetric power density and industrial scalability.…”

Section: Water Softening Applicationmentioning

confidence: 99%

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Anode Boundary Layer Extraction Strategy for H⁺–OH^– Separation in Undivided Electrolytic Cell: Modeling, Electrochemical Analysis, and Water Softening Application

Ba,

Chen,

Wang

et al. 2023

ACS EST Eng.

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To promote the application of the electrolysis process for in situ pH adjustment of wastewaters with complex matrices, a robust, industrially scalable, and undivided electrolytic cell featuring the abstraction of H + from the anode boundary layer was developed in this study, where a tubular Ti porous membrane was used as the anode. Modeling, electrochemical analysis, and COMSOL simulation results show that abstracting H + from the anode boundary layer could effectively inhibit the transfer of H + into the bulk solution with the decrease in the anode double-layer thickness and electric double-layer capacitance. Increasing the current density from 6 to 22 mA cm −2 and the influent rate from 330 to 11,100 mL min −1 deteriorated the H + −OH − separation performance, owing to the enhanced electro-migration of H + into the bulk solution and turbulence state near the anode surface, respectively. The H + −OH − separation performance showed a volcanic type change trend with the acid extraction rate with the optimal value at 50 mL min −1 , specifically the separation efficiency of 10%−72% and 16%−94% for H + and OH − in the acidic and alkaline effluents, respectively, at an influent rate of 500 mL min −1 and a current density of 6−22 mA cm −2 . Importantly, the present undivided electrolytic cell showed better H + −OH − separation performance than that of the widely studied membrane-based divided system. The feasibility of this undivided electrolytic cell was also validated by water softening experiments, where the Ca hardness removal efficiency was 42%−92% with energy consumption of 1.2−4.6 kWh (kgCaCO 3 ) −1 at a current density of 6−22 mA cm −2 . In general, this new undivided electrolytic cell opened a new pathway for in situ electrochemically regulating wastewater pH.

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Section: Resultsmentioning

confidence: 99%

Section: Water Softening Applicationmentioning

confidence: 99%

Anode Boundary Layer Extraction Strategy for H⁺–OH^– Separation in Undivided Electrolytic Cell: Modeling, Electrochemical Analysis, and Water Softening Application

Ba,

Chen,

Wang

et al. 2023

ACS EST Eng.

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“…Within this system, as the current density increases from 20 A/m 2 to 100 A/m 2 , the precipitation rate of CaCO 3 increases from 975 g/h/m 2 to 348.8 g/h/m 2 , with energy consumption rising from 0.68 kWh/kg CaCO 3 to 1.88 kWh/kg CaCO 3 . Ba et al [42] developed an electrolytic cell that extracts H + from the anode boundary layer to enhance hardness removal efficiency and combined it with microfiltration and ion exchange for scale removal. In this system, the effluent from the electrolytic cell was intercepted by a porous tubular titanium microfilter in the crystallizer and further treated with ion exchange resin.…”

Section: Electrodeposition-microfiltrationmentioning

confidence: 99%

“…Electrochemical descaling is an innovative, eco-friendly process that offers no need for additional chemicals, pollution-free operation, easy regulation, simple process structure, and the potential for automation [41,42]. During electrochemical descaling, water decomposition near the anode produces oxygen and an acidic environment, while hydrogen and an alkaline environment are created near the cathode.…”

Section: Introductionmentioning

confidence: 99%

Research Progress on Novel Electrochemical Descaling Technology for Enhanced Hardness Ion Removal

Wang,

Zhou,

Chang

et al. 2024

Water

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In recent years, electrochemical descaling technology has gained widespread attention due to its environmental friendliness and ease of operation. However, its single-pass removal efficiency could be higher, severely limiting its practical application. To overcome the limitations of traditional electrochemical descaling processes, this paper first focuses on the separation efficiency of H+ and OH− in the scale removal process based on numerous recent research papers. It mainly emphasizes how innovative cathode design can enhance the efficiency and stability of electrochemical descaling. Furthermore, this paper explores the coupling of electrochemical processes with different water treatment technologies, such as the combination of electrodeposition with electrocoagulation, filtration crystallization, microfiltration, and electrodialysis, and how these methods synergistically enhance descaling effects. Additionally, this paper discusses potential future directions for electrochemical descaling technology, including innovations in scale expansion, material updates, process optimization, system integration, and automation. Finally, this paper analyzes the practical challenges of electrochemical descaling technology, such as cost, energy consumption, equipment durability, and environmental impact, and proposes solutions. The implementation of these strategies is expected to promote the commercialization of electrochemical descaling technology, making it more aligned with the sustainability requirements of industry and the environment.

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“…Recently, electrochemical-induced precipitation has been proposed as a sustainable alternative, avoiding the addition of reagents and the discharge of concentrated brine. Compared with chemical precipitation, electrochemical-induced precipitation can reduce 67–84% of waste solids, and the outlet pH remains moderate with no need for further neutralization, which has attracted great research interest in various water-softening scenarios. − Moreover, benefiting from the easy automation and potential to be powered by renewable energy, electrochemical-induced precipitation shows a huge potential in point-of-use tap-water softening.…”

Section: Introductionmentioning

confidence: 99%

Coupling of Electric and Flow Fields to Enhance Ion Transport for Energy-Efficient Electrochemical Tap-Water Softening

Li,

Xu,

Tao

et al. 2024

Environ. Sci. Technol.

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Electrochemical-induced precipitation is a sustainable approach for tap-water softening, but the hardness removal performance and energy efficiency are vastly limited by the ultraslow ion transport and the superlow local HCO 3 − /Ca 2+ ratio compared to the industrial scenarios. To tackle the challenges, we herein report an energy-efficient electrochemical tap-water softening strategy by utilizing an integrated cathode−anode−cathode (CAC) reactor in which the direction of the electric field is reversed to that of the flow field in the upstream cell, while the same in the downstream cell. As a result, the transport of ions, especially HCO 3 − , is significantly accelerated in the downstream cell under a flow field. The local HCO 3 − /Ca 2+ ratio is increased by 1.5 times, as revealed by the finite element numerical simulation and in situ imaging. In addition, a continuous flow electrochemical system with an integrated CAC reactor is operated for 240 h to soften tap water. Experiments show that a much lower cell voltage (9.24 V decreased) and energy consumption (28% decreased) are obtained. The proposed ion-transport enhancement strategy by coupled electric and flow fields provides a new perspective on developing electrochemical technologies to meet the flexible and economic demand for tap-water softening.

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An integrated electrolysis-microfiltration-ion exchange closed-loop system for effective water softening without chemicals input and spent regenerant discharge

Cited by 15 publications

References 41 publications

Anode Boundary Layer Extraction Strategy for H⁺–OH^– Separation in Undivided Electrolytic Cell: Modeling, Electrochemical Analysis, and Water Softening Application

Anode Boundary Layer Extraction Strategy for H⁺–OH^– Separation in Undivided Electrolytic Cell: Modeling, Electrochemical Analysis, and Water Softening Application

Research Progress on Novel Electrochemical Descaling Technology for Enhanced Hardness Ion Removal

Coupling of Electric and Flow Fields to Enhance Ion Transport for Energy-Efficient Electrochemical Tap-Water Softening

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An integrated electrolysis-microfiltration-ion exchange closed-loop system for effective water softening without chemicals input and spent regenerant discharge

Cited by 15 publications

References 41 publications

Anode Boundary Layer Extraction Strategy for H+–OH– Separation in Undivided Electrolytic Cell: Modeling, Electrochemical Analysis, and Water Softening Application

Anode Boundary Layer Extraction Strategy for H+–OH– Separation in Undivided Electrolytic Cell: Modeling, Electrochemical Analysis, and Water Softening Application

Research Progress on Novel Electrochemical Descaling Technology for Enhanced Hardness Ion Removal

Coupling of Electric and Flow Fields to Enhance Ion Transport for Energy-Efficient Electrochemical Tap-Water Softening

Contact Info

Product

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Anode Boundary Layer Extraction Strategy for H⁺–OH^– Separation in Undivided Electrolytic Cell: Modeling, Electrochemical Analysis, and Water Softening Application

Anode Boundary Layer Extraction Strategy for H⁺–OH^– Separation in Undivided Electrolytic Cell: Modeling, Electrochemical Analysis, and Water Softening Application