Turning waste into resource: Metal framework-scale composite cathode overcomes limitations of low efficiency and cathode failure in electrochemical water softening

IF 11.4 1区环境科学与生态学 Q1 ENGINEERING, ENVIRONMENTAL

Water Research Pub Date : 2025-03-28 DOI:10.1016/j.watres.2025.123549

Jie Zhou , Yuexin Chang , Weijia Li , Mingtao Li , Duowen Yang , Liu Yang , Bo Jiang , Wei Yan , Hao Xu , Xing Xu

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Abstract

Despite years of development, electrochemical water softening continues to face challenges in achieving high softening efficiency and maintaining long-term cathode stability. To address these issues, this study builds upon the characteristics of membrane-free electrochemical water softening and prior research by employing a large-pore stainless steel filter as the cathode. During extended operation, a fluffy, porous scale layer gradually forms on the cathode surface, transforming the stainless-steel filter into a metal framework-scale composite (MF-S) cathode. This composite cathode enhances OH⁻ enrichment and extraction, improving water softening efficiency. Additionally, the soft scale deposited on the cathode's pores and surface can be partially removed through simple backflushing, extending system's operational lifespan. Experimental results indicate that using a stainless-steel cathode with 15×10 mm pore size, the effluent pH exceeds 11.0 after 18 h of operation, with a Ca²⁺ hardness removal rate of over 97 %. To prevent clogging of the cathode pores during extended operation, backflushing is conducted every 25 h to remove scale. Remarkably, after 700 h of continuous operation, there is no observed decline in hardness removal efficiency, and the cathode remains functional, allowing the water softening process to continue. Electrochemical tests and finite element simulations reveal that the composite cathode significantly outperforms the stainless-steel filter cathode in generating and enriching OH⁻. The proposed composite cathode demonstrates strong practical potential, offering a new perspective for applying membrane-free, high-efficiency electrochemical water softening processes.

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来源期刊

Water Research 环境科学-工程：环境

CiteScore

20.80

自引率

9.40%

发文量

1307

审稿时长

38 days

期刊介绍： Water Research, along with its open access companion journal Water Research X, serves as a platform for publishing original research papers covering various aspects of the science and technology related to the anthropogenic water cycle, water quality, and its management worldwide. The audience targeted by the journal comprises biologists, chemical engineers, chemists, civil engineers, environmental engineers, limnologists, and microbiologists. The scope of the journal include: •Treatment processes for water and wastewaters (municipal, agricultural, industrial, and on-site treatment), including resource recovery and residuals management; •Urban hydrology including sewer systems, stormwater management, and green infrastructure; •Drinking water treatment and distribution; •Potable and non-potable water reuse; •Sanitation, public health, and risk assessment; •Anaerobic digestion, solid and hazardous waste management, including source characterization and the effects and control of leachates and gaseous emissions; •Contaminants (chemical, microbial, anthropogenic particles such as nanoparticles or microplastics) and related water quality sensing, monitoring, fate, and assessment; •Anthropogenic impacts on inland, tidal, coastal and urban waters, focusing on surface and ground waters, and point and non-point sources of pollution; •Environmental restoration, linked to surface water, groundwater and groundwater remediation; •Analysis of the interfaces between sediments and water, and between water and atmosphere, focusing specifically on anthropogenic impacts; •Mathematical modelling, systems analysis, machine learning, and beneficial use of big data related to the anthropogenic water cycle; •Socio-economic, policy, and regulations studies.