Synthesizing a high value-added composite photocatalyst using waste capacitors combined with PANI by a mechanical chemistry method

Abstract

The main components of waste capacitors are BaTiO₃, Ag, Pd, Sn, Ni, Nb, and Pb, which are valuable to recycle. At present acid leaching is applied to separate metals from capacitors. However, the process is complex and will cause secondary pollution to the environment. In this work, we have broken through the traditional method of only recovering metals and converted waste capacitors into a Nb–Pb co-doped and Ag–Pd–Sn–Ni loaded BaTiO₃ photocatalyst through a simple ball milling method. To further improve its photocatalytic activity, polyaniline (PANI) was added during the ball milling to form a composite photocatalyst. The results showed that the specific surface area of the composite photocatalyst was 21.11–40.27 m² g⁻¹, and the particle size was 100–500 nm. The photocatalytic hydrogen production rate of the optimal composite photocatalyst was enhanced to 686.4 µmol g⁻¹ h⁻¹, which was 3.72 times that of the Nb–Pb co-doped and Ag–Pd–Sn–Ni loaded BaTiO₃ photocatalyst. Furthermore, the composite photocatalyst showed excellent photocatalytic stability and can be recycled by magnetic separation due to the Ni composition. These excellent photocatalytic performances were attributed to the addition of PANI which enhanced the visible light absorption and charge separation of the composite photocatalyst. This study utilizes the multi-component characteristics of waste capacitors to prepare high value-added composite photocatalysts, which provides a new idea for resource utilization of electronic waste.