Simultaneous determination of polymetallic ions by ratio second derivative ultraviolet spectrophotometry

Abstract

Zinc hydrometallurgy is the main zinc smelting process, and the wastewater after its production contains a variety of metal ions, which must be detected and strictly controlled in real time. Aiming at the problem that it is difficult to simultaneously detect multiple metal ions in zinc hydrometallurgy wastewater due to serious spectral overlap and low resolution, a ratio second derivative spectroscopy based on continuous wavelet transform is proposed for simultaneous detection of multiple metal ions. The continuous wavelet transform is found suitable for second order linear derivation to avoid distortion and noise drying. The ratio second derivative method is used to quickly screen out the characteristic wavelength of each metal ion to be detected, and establish a high-precision and low-error analysis model suitable for simultaneous detection of zinc, nickel, cobalt and copper. The linear detection ranges are 10–100 mg/L for zinc, 0.6–6.0 mg/L for nickel, 0.3–3.0 mg/L for cobalt and 0.5–5.0 mg/L for copper. The average relative deviation for zinc, nickel, cobalt and copper was 2.83%, 3.21%, 2.28% and 2.79%, respectively. The work reported here provides a new idea for ion detection of zinc smelting industrial wastewater based on ultraviolet visible spectroscopy, and lays a foundation for online detection of polymetallic ions.