Highly efficient nickel recovery from industrial wastewater via synergistic electrodeposition and electrocatalytic oxidation technique

Abstract

This study was conducted to address water pollution concerns entwined with electroless nickel plating (ENP) industry. Its principal endeavor centers on the development and application of an innovative single-compartment technique to proficiently treat spent ENP baths. The research demonstrated the recovery of Nickel (Ni) from wastewater through synergistic interactions between electrocatalytic oxidation and electrodeposition processes. Electrochemical tests used a direct current power supply in constant current mode, with the positive pole on IrO2/Ti mesh and negative pole on stainless steel. Zero-valent nickel recovered on the electrodes was conclusively identified via SEM, XRD, and EDS analyses. This work carefully examined the impact of initial pH, initial Ni ion concentration, and current density (CD) on electrochemical recovery efficiency. The findings suggest that higher current densities positively influence the Ni recovery ratio. Additionally, through meticulous experiments, the viability of this approach for treating spent ENP baths has been confirmed. An impressive 98.88% recovery of Ni was achieved under specific conditions: CD 4.5 mA cm−2, experimental time 180 min, pH 4.5, electrodes spacing 1.5 cm, temperature 55 °C, and a dilution factor 10 times. The study demonstrated the process for Ni recovering from ENP wastewater through direct oxidation and subsequent decomposition, leading to liberation of free Ni ions. The recovered substance, identified as zero-valent nickel, adheres to the electrodes. The method employed in this research is described by its cost-effectiveness, user-friendliness, and low energy consumption. As a result, this study makes valuable contributions to both wastewater remediation and the sustainable utilization of Ni resources.