Ion transport for simultaneous nickel electrodeposition and sulfuric acid recovery in single-membrane, dual-chamber electrolyzers

Abstract

This study introduces an effective single-membrane, dual-cell electrolysis system designed to overcome the limitations of conventional cloth-type membrane bag electrolysis, such as low current efficiency, high energy consumption, and poor product purity. The proposed process enables simultaneous recovery of nickel and sulfuric acid from nickel-rich wastewater. The ion transport behavior is elucidated by comparing the electrolytic performance of five different anion exchange membranes (IONSEP, LanRan, ACM, FAA, and AMV) and analyzing the dynamic changes in ion composition within the anode and cathode chambers. Scanning electron microscopy and X-ray diffraction techniques are employed to characterize the morphological and structural properties of the resulting nickel deposits. The findings reveal that the optimal electrolysis duration is 4 h. Among the tested membranes, the AMV membrane exhibits the best performance, achieving a cathodic current efficiency of 98.5%, energy consumption of 5945.8 kWh per tonne, and anodic sulfuric acid concentration of 38.1 g L⁻¹. The deposited nickel layer displays a smooth, dense, defect-free surface, with continuous and uniform grain growth. The XRD patterns of the nickel coating confirm a distinct preferred orientation along the (220) crystal plane, indicative of high crystallinity and purity. Overall, the single-membrane, dual-cell electrolysis technology improves resource recovery and offers a viable route for treating high-concentration nickel-containing wastewater.