Systematic Assessment of Precious Metal Recovery to Improve Environmental and Resource Protection

Abstract

Environmental pollution and resource shortage are two major challenges facing the world today, and resourcization of precious metals is one of the effective strategies to confront these problems. Precious metals, known for their high performance and scarcity, are indispensable our current lives. As nonrenewable resources, the demand and consumption of precious metals are increasing every year. Therefore, it is necessary to develop green and efficient precious metal recovery technologies to alleviate the environmental and resource crisis. This perspective summarizes various typical precious metal recovery strategies and pays attention to innovations from traditional technologies. We also evaluate and prospect the above methods based on secondary pollution and recovery efficiency.

Interfacial Coordination Bonding-Assisted Redox Mechanism-Driven Highly Selective Precious Metal Recovery on Covalent-Functionalized Ultrathin 1T-MoS2

“…DOS originated from the Mo 4d states and S 3p states are observed to pass through the Fermi level as shown in Figure c, which verifies previous report that PMs would be reduced by oxidation of Mo 4+ and S 2– of MoS 2 to MoO 4 2– and SO 4 2– . Unexpectedly, the pyridine of Py-MoS 2 also contributes to the DOS, confirming that the pyridine group can act as electron donation, which not only increases the selectivity toward PM ions but also increases the interfacial electron transport efficiency. , Theoretically, Py-MoS 2 could reduce PM ions into metallic with higher redox potentials (Figure d), including Au 3+ , Pd 4+ , Ag + , and Pt 4+ . In the practical recovery process, Au 3+ , Pd 4+ , and Ag + were indeed reduced into metallic, while platinum was atomically dispersed over Py-MoS 2 in the form of Pt 2+ .…”

“…51,52 Theoretically, Py-MoS 2 could reduce PM ions into metallic with higher redox potentials (Figure 4d), including Au 3+ , Pd 4+ , Ag + , and Pt 4+ . 53 In the practical recovery process, Au 3+ , Pd 4+ , and Ag + were indeed reduced into metallic, while platinum was atomically dispersed over Py-MoS 2 in the form of Pt 2+ . The different morphologies and surface statuses lead to distinct removal efficiency for PMs.…”

Operando Spectroscopic Observation of CO Oxidation on a Pt/TiO2 Catalyst in NO–CO Mixtures under Dark and UV Illumination

“…Hence, we further evaluated oxidation and reduction processes occurring at ambient temperature under photocatalytic conditions. Photocatalytic oxidation is one of the key technologies for diminishing environmental pollutants and preventing poisoning deactivation. − …”

Photocatalytic Dissolution of Precious Metals by TiO2 through Photogenerated Free Radicals

“…The changes occurring in solvent composition after photocatalytic dissolution of Au and Pt were analyzed by high-resolution nuclear magnetic resonance (NMR) spectroscopy. First, a background experiment was performed with deuterated chloroform (7.26 ppm in 1 H NMR and 77.16 ppm in 13 C NMR) as the test solvent, and the peak at 0 ppm was derived from the internal standard tetramethylsilane (TMS). For the MeCN system, an obvious peak at 1.97 ppm in the 1 H NMR spectrum was assigned to the hydrogens (H) on the methyl group (À CH 3 ) pf MeCN (Figures S4a and S5a).…”