Analysis of the efficiency of electromembrane purification of industrial solutions from nickel ions

Electrodialysis (ED) is a promising method for purifying wastewater from galvanic industries from heavy metal ions, in particular nickel (Ni²⁺). In this paper, we study the kinetics of the electrodialysis process using anion- and cation-exchange membranes (MA-41P and MK-40L) to remove Ni²⁺ from solutions with initial concentrations from 40 to 160 mg/l. It was found that the purification efficiency reaches 99.3%, which confirms the high selectivity of the method. The key factor affecting the speed and efficiency of the process is the current density. The optimal value of 20 A/m² ensures a balance between a high degree of purification and energy consumption. Increasing the current density above this value does not lead to a significant increase in efficiency, but significantly increases energy consumption. In addition, it is shown that at a high initial concentration of nickel (160 mg/l), the process slows down due to membrane saturation and possible sedimentation. An important aspect of the study was the analysis of the electrodiffusion permeability of membranes. It was found that with increasing current density, the permeability coefficient decreases by 55%, which is due to an increase in the concentration gradient and a change in the membrane properties under the influence of an electric field. Based on the experimental data, a process flow chart for cleaning industrial wastewater was proposed, including the stages of neutralization, electrodialysis, and concentrate utilization. Purified water can be returned to the production cycle, and nickel-containing concentrate can be recycled. The results of the work demonstrate the high efficiency of electrodialysis for cleaning wastewater from nickel and can be used to optimize industrial processes taking into account economic and environmental requirements.