A seawater softening pretreatment method based on cation membrane electrolysis

By improving the structure and fluid parameters of the electrolyzer, and by adopting cation membrane electrolysis and optimizing the anode reaction, the problems of difficult by-product treatment and environmental friendliness in seawater softening pretreatment have been solved. This has enabled efficient removal and resource utilization of calcium and magnesium ions, while reducing energy consumption and environmental risks.

CN122254680APending Publication Date: 2026-06-23DALIAN UNIV OF TECH
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2026-03-30
Publication Date
2026-06-23

AI Technical Summary

Technical Problem

Existing seawater softening pretreatment technologies suffer from difficulties in handling byproducts and are environmentally unfriendly. Traditional chemical methods generate large amounts of precipitated solid waste that is difficult to separate, while seawater electrolysis methods have problems such as low current efficiency, toxic waste acid, and chlorine hazards.

Method used

The method employs a cation exchange membrane electrolysis approach. By improving the structure and fluid parameters of the electrolyzer, the cathode and anode regions are separated using a cation exchange membrane. The anode reaction of sodium sulfate solution with calcium carbonate powder is used to eliminate acid-base neutralization side reactions, thereby achieving stepwise precipitation and resource utilization of calcium and magnesium precipitates. A nylon mesh electrolyzer is used for disinfection pretreatment.

Benefits of technology

It achieves a high calcium and magnesium ion removal rate of nearly 100%, a current efficiency of nearly 100%, zero solid waste and liquid discharge, is environmentally friendly, reduces energy consumption and improves resource utilization, and avoids the risks of sedimentation blockage and equipment corrosion.

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Abstract

The present application belongs to the technical field of seawater pretreatment and resource recovery, and relates to a seawater softening pretreatment method based on cation membrane electrolysis. Seawater is first acidified in the anode region of a nylon net electrolytic cell to remove bicarbonate ions, and then deacidified in the cathode region of the nylon net electrolytic cell. Then, the seawater enters an ion membrane electrolytic cell, seawater is introduced into the cathode region, and a sodium sulfate solution containing calcium carbonate is introduced into the anode region. After electrochemical reaction, magnesium ions in the seawater are precipitated. Then, the seawater enters a centrifugal separation device, the precipitated magnesium hydroxide is collected and dried to serve as a product with certain industrial value. Then, sodium carbonate or carbon dioxide is added to the seawater to precipitate calcium ions. The solution after the reaction enters a filtration separation unit, the precipitated calcium carbonate is intercepted and recovered to serve as a neutralizing agent for the anode region of the electrolytic cell. The effluent after the reaction can be used for seawater desalination, chlor-alkali industry or hydrogen production industry.
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Citation Information

Patent Citations

  • Electrochemistry-based graded extraction process for calcium and magnesium in saline water

    CN120483428A