Selective recovery of precious metals through photocatalysis

Abstract

Precious metals such as gold and platinum are valued materials for a variety of important applications, but their scarcity poses a risk of supply interruption. However, the dissolution and recovery of precious metals using the current methods are limited by associated serious environmental pollution and high energy consumption. Here, we show a photocatalytic process that allows one to selective retrieve 7 kinds of precious metal elements (Ag, Au, Pd, Pt, Ru, Rh and Ir) (with dissolution efficiency of 99%) from waste circuit boards, ternary automotive catalysts and even ores. Precious metals is recovered with high purity (≥98%) through a simple reductive method. The whole process only needs light and catalyst without strong acid, strong base and highly toxic cyanide. It has an environmentally friendly, scalable and efficient way, in which the catalyst has been recycled more than 100 times under normal temperature and pressure without performance degradation. It has successfully realized the scale of dissolution from grams to kilograms, and it is expected to realize large-scale recovery of precious metals in industrial application. This general approach provides an unprecedent technology for recycling resources on earth.

Photocatalytic Materials Obtained from E-Waste Recycling: Review, Techniques, Critique, and Update

“…Additionally, other techniques such as vacuum metallurgy separation [21], bioleaching [22], and supercritical fluids oxidation-extraction [23] processes can also be used. Recently, Chen et al [24] introduced a novel photocatalytic technique that can selectively recycle seven precious metals, including Ag, Au, Pd, Pt, Rh, Ru, and Ir, from various e-wastes. One of the advantages of this method is that it does not need the utilization of any strong acids or bases or toxic cyanide: it only requires light and photocatalysts such as TiO2.…”

“…One of the advantages of this method is that it does not need the utilization of any strong acids or bases or toxic cyanide: it only requires light and photocatalysts such as TiO2. In addition, it can recycle more than 99% of the targeted elements of the e-waste after a simple reduction reaction, resulting in high purity (≥98%) [24]. Niu et al [25] successfully converted multilayer ceramic capacitors (MLCCs) (mainly composed of BaTiO3, Ag, Pd, Ni, and Sn) into a highly efficient photocatalyst through a one-step ball milling procedure, producing an Nb-Pb-co-doped and a Ag-Pd-Sn-Ni-loaded BaTiO3 nano-photocatalyst with superior photocatalytic efficiency.…”

Visible light-initiated aerobic oxidation of amines to imines over TiO2 microspheres with TEMPO+PF6−

“…15–19 However, developing new TiO 2 -related materials is ponderable for enhanced photocatalytic performance. 20–25 Self-assembly of TiO 2 nanocrystals into porous microspheres merits special attention on account of their fascinating optical properties and ease of recycling in practical applications. 26–28 Specifically, the porous nature and high specific surface areas of TiO 2 microspheres are favorable for increasing the density of active sites with good approachability and the diffusion of substrates and products.…”

Fabrication of conductive silver paste recovered from leaching of waste catalyst using hydrochloric acid

“…However, it has been proved that each leaching agent is effective for only one or two PMs. 16,17 Therefore, it is needed to improve the performance of the leaching agent.…”