Purpose Soil salinization is a limiting factor in the sustainable development of agricultural production systems. Electrokinetic (EK) remediation mobilizes saline ions in compacted highly saline soils, and conventional systems can induce extreme soil pH polarization (anode acidification/cathode alkalization), limiting post-remediation soil utilization. In this study, we evaluate an innovative EK configuration that integrates anion/cation exchange membranes (AEM/CEM) to efficiently remove salt-based ions, eliminate detrimental soil pH polarization, and reduce energy consumption. Materials and methods Experiments were performed under a constant voltage (20 V) in an EK reactor for 15 days using various AEM or CEM strategies. The electrical current, electroosmotic flow, soil pH and electric conductivity (EC) distribution, the removal efficiency of saline ions, the exchangeable sodium percentage (ESP), and energy consumption were then analyzed. Results and discussion The findings revealed that positioning an AEM near the anode effectively impeded the migration of H+ ions into the soil, while a CEM near the cathode restricted OH− ions. This membrane configuration mitigated extreme pH fluctuations, leading to a more uniform pH distribution across the soil. Specifically, the AEM-treated soil exhibited a pH range of 8.17–8.92, outperforming other treatments (7.67–9.07). The soil EC and ESP both decreased by approximately 90% following the EK treatment. The saline ion removal efficiencies followed the order AEM treatment > CEM treatment > control treatment. Notably, the AEM treatment achieved removal rates of 97.68% for Na+, 95.88% for Cl−, and 93.48% for SO42− after 15 days. An energy consumption analysis revealed that the enhanced EK system that incorporated ion exchange membranes achieved a 26.3–38.8% reduction in energy consumption (119.3–124.3 kW·h/m3) while delivering a superior desalination performance. The operational efficiency was due to the membrane-mediated prevention of competing electrolysis reactions and optimized ion transport. Conclusions This ion exchange membrane-enhanced EK technology resolved critical pH imbalance challenges and improved the ionic removal efficiency and energy economy. These results provide a technical foundation for the development of sustainable land utilization practices in China’s salinization-affected agricultural regions.

Mitigating pH polarization and enhancing ion migration: Energy-Efficient electrokinetic soil desalination via ion exchange membrane integration

期刊论文
发表日期：

2025年9月27日

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Yifan Li,
Yuan Zhao,
Chenfeng Wang,
Ruihan Chen,
Long Cang

摘要

Purpose

Soil salinization is a limiting factor in the sustainable development of agricultural production systems. Electrokinetic (EK) remediation mobilizes saline ions in compacted highly saline soils, and conventional systems can induce extreme soil pH polarization (anode acidification/cathode alkalization), limiting post-remediation soil utilization. In this study, we evaluate an innovative EK configuration that integrates anion/cation exchange membranes (AEM/CEM) to efficiently remove salt-based ions, eliminate detrimental soil pH polarization, and reduce energy consumption.

Materials and methods

Experiments were performed under a constant voltage (20 V) in an EK reactor for 15 days using various AEM or CEM strategies. The electrical current, electroosmotic flow, soil pH and electric conductivity (EC) distribution, the removal efficiency of saline ions, the exchangeable sodium percentage (ESP), and energy consumption were then analyzed.

Results and discussion

The findings revealed that positioning an AEM near the anode effectively impeded the migration of H⁺ ions into the soil, while a CEM near the cathode restricted OH⁻ ions. This membrane configuration mitigated extreme pH fluctuations, leading to a more uniform pH distribution across the soil. Specifically, the AEM-treated soil exhibited a pH range of 8.17–8.92, outperforming other treatments (7.67–9.07). The soil EC and ESP both decreased by approximately 90% following the EK treatment. The saline ion removal efficiencies followed the order AEM treatment > CEM treatment > control treatment. Notably, the AEM treatment achieved removal rates of 97.68% for Na⁺, 95.88% for Cl⁻, and 93.48% for SO₄²⁻ after 15 days. An energy consumption analysis revealed that the enhanced EK system that incorporated ion exchange membranes achieved a 26.3–38.8% reduction in energy consumption (119.3–124.3 kW·h/m³) while delivering a superior desalination performance. The operational efficiency was due to the membrane-mediated prevention of competing electrolysis reactions and optimized ion transport.

Conclusions

This ion exchange membrane-enhanced EK technology resolved critical pH imbalance challenges and improved the ionic removal efficiency and energy economy. These results provide a technical foundation for the development of sustainable land utilization practices in China’s salinization-affected agricultural regions.