Extending Ag Nanoparticles as Colorimetric Sensor to Industrial Zinc Electrolyte for Cobalt Ion Detection

The direct and rapid determination of trace cobalt ion (Co(2+)) in the electrolyte of zinc smelting plants is urgently needed but is impeded by the severe interference of extremely high-concentration zinc ions in the solution. Herein, colorimetric detection of Co(2+) by the polyvinylpyrrolidone functionalized silver nanoparticles (PVP-AgNPs) is realized in solutions with the Zn/Co ratio being high, up to (0.8–5) × 10(4), which is located within the ratio range in industrial solution. The high concentration of Zn(2+) induces a strong attenuation of Co(2+)-related signals in ultraviolet-visible (UV-vis) extinction spectra; nevertheless, a good linear range for detecting 1–6 mg/L Co(2+) in 50 g/L Zn(2+) solution is still acquired. The strong anti-interference toward other metal ions and the mechanism understanding for trace Co(2+) detection in such a high-concentration Zn(2+) solution are also revealed by systematic analysis techniques. The results extend the AgNPs as colorimetric sensors to industrial solutions, providing a new strategy for detecting trace-metal ions in industrial plants.