With the rapid development of industrialization, the wastewater treatment problems generated by electroplating industry have become increasingly prominent, especially nickel electroplating (ENP) wastewater, which contains nickel (Ni), phosphorus (P) and chemical oxygen demand (COD) and other pollutants, posing a serious threat to the environment and ecosystem. Although the traditional treatment method has some effect, it often has some problems such as low efficiency, high cost and difficult resource recovery. In recent years, the emergence of three-dimensional electrodialysis (3D ED) technology has provided a new solution to this problem, realizing the dual goals of efficient removal of pollutants and resource recovery, and showing the great potential of electrochemical technology in the field of wastewater treatment.

Nickel and its compounds are abundant in ENP wastewater due to its wide range of industrial applications, but at the same time, the addition of sodium hypophosphite (NaH2PO2) during electroplating leads to extremely high concentrations of Ni-organic complexes and H2PO2- in wastewater, and these negatively charged pollutants are concentrated in the anode chamber, increasing the difficulty of recovery. Although the traditional 2D electrodialysis (2D ED) technology can recover Ni to a certain extent, its treatment capacity is inadequate in the face of complex and changeable waste water composition.

Under this background, three-dimensional electrodialysis (3D ED) technology came into being, which significantly improved the removal efficiency of Ni, P and COD by introducing a third electrode - graphite particle electrode into the system and using the electrooxidation reaction on the particle electrode. This innovative technology not only solves the limitations of traditional 2D ED in the treatment of complex pollutants, but also realizes the efficient removal of Ni2+, total phosphorus (TP) and COD by optimizing the process conditions, such as dilution coefficient, voltage, treatment time and particle electrode addition amount, with the removal rates as high as 95.8%, 97.7% and 91.8%, respectively.

It is particularly worth mentioning that 3D ED technology also realizes the effective recovery of resources in the process of treating ENP wastewater. The decomposed Ni2+ is successfully recovered in the form of Ni(OH)2, which not only reduces environmental pollution, but also brings economic benefits to the enterprise, in line with the concept of sustainable development.

In order to further explore the mechanism of 3D ED technology to enhance ENP wastewater treatment, the researchers also carried out detailed analysis of the solid-liquid products before and after treatment by means of scanning electron microscopy-energy scattering spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS). These results not only provide a solid theoretical basis for the application of 3D ED technology in ENP wastewater treatment, but also provide a scientific basis for further optimization of process conditions and improvement of treatment efficiency.

Three-dimensional electrodialysis (3D ED) technology has shown broad application prospects in the treatment of nickel-free electroplating wastewater due to its advantages of high efficiency, environmental protection and resource recovery. The successful application of this technology has not only injected new vitality into the in-depth development of electrochemical technology in the field of wastewater treatment, but also provided new ideas and insights for realizing resource-saving wastewater treatment and environmentally friendly electroplating industry. In the future, with the continuous progress and improvement of technology, 3D ED technology is expected to play an important role in more fields, contributing to environmental protection and sustainable development.