Recovering Platinum Black Nanoparticles via Photodeposition for Industrial Catalysis

During the Cu or Ni smelting process, carbonylation slag is subjected to pressurized leaching. The resulting leachate typically contains low concentrations (<20 mg/L) of precious metals such as Pt and Au. Therefore, there is an urgent need to develop efficient methods for extracting these low-concentration precious metals. This article introduces an environmentally friendly method for recovering and preparing nanoplatinum black from a solution with a low concentration of Pt ions by using the photodeposition technique. The nano tungsten oxide (WO 3 ) was prepared by calcination as a photocatalyst to achieve efficient recovery of Pt in a low-concentration precious metal Pt ion solution through ultraviolet (UV) irradiation. The study showed that the optimal experimental conditions were an ethanol concentration of 0.2 M, WO 3 concentration of 0.5 g/L, and pH of 1.0, with a Pt reduction efficiency up to 99.75% after 20 min of illumination. The applicable range for Pt ion concentration is 0.01–10.0 mM. Further alkali leaching treatment yielded high-purity nano Pt black particles with an average particle size of 3.5 nm, a purity of 99.9%, and a total extraction efficiency of 96.75%. Under ultraviolet light, WO 3 generated electrons captured by surface platinum ions. These ions were reduced to Pt nanoparticles, which deposited onto the WO 3 surface. Nanoplatinum black was then separated by dissolving WO 3 in alkaline conditions. This method is efficient, environmentally friendly, and nonpolluting, providing theoretical guidance and technical support for recovering and extracting Pt from low-concentration noble metal solution.