Tailoring the Asymmetric Structure of NH₂‐UiO‐66 Metal‐Organic Frameworks for Light‐promoted Selective and Efficient Gold Extraction and Separation

Abstract

Designing adsorption materials with high adsorption capacities and selectivities is highly desirable for precious metal recovery. Desorption performance is also particularly crucial for subsequent precious metal recovery and adsorbent regeneration. Herein, a metalorganic framework (MOF) material (NH 2 -UiO-66) with an asymmetric electronic structure of the central zirconium oxygen cluster has an exceptional gold extraction capacity of 2.04 g g À 1 under light irradiation. The selectivity of NH 2 -UiO-66 for gold ions is up to 98.8 % in the presence of interfering ions. Interestingly, the gold ions adsorbed on the surface of NH 2 -UiO-66 spontaneously reduce in situ, undergo nucleation and growth and finally achieve the phase separation of highpurity gold particles from NH 2 -UiO-66. The desorption and separation efficiency of gold particles from the adsorbent surface reaches 89 %. Theoretical calculations indicate that -NH 2 functions as a dual donor of electrons and protons, and the asymmetric structure of NH 2 -UiO-66 leads to energetically advantageous multinuclear gold capture and desorption. This adsorption material can greatly facilitate the recovery of gold from wastewater and can easily realize the recycling of the adsorbent.

Selective Production of CO from Organic Pollutants by Coupling Piezocatalysis and Advanced Oxidation Processes

“…The charge density difference (Figure 6c) was calculated to investigate the charge transfer at the Co 3 S 4 / MoS 2 interfaces. [26] 0.892 e À was transferred from MoS 2 to the Co 3 S 4 surface. The blue and yellow isosurfaces represented charge depletion and accumulation, respectively.…”

Selective and Light-Enhanced Au(III) Recovery by a Porphyrin-Based Metal–Organic Framework: Performance and Underlying Mechanisms

“…The higher ζ-potential of PCN-224 in light led to relatively stronger repulsion to positive nonprecious metal ions, thus showing enhanced selectivity. In summary, we found that visible light largely promoted the Au recovery performance of PCN-224 and made it superior to other materials in terms of recovery capacity ( q max ) and selectivity ( K d ), including UiO-66, COFs, − polymers, ,,, and 2D materials ,, (Figure S9).…”

“…We also noted that visible light enhanced the selectivity of Au by both increasing the recovery of Au(III) and decreasing the uptake of nonprecious metals. Under light irradiation, the uptake of Zn and made it superior to other materials in terms of recovery capacity (q max ) and selectivity (K d ), including UiO-66, 57 COFs, 58−61 polymers, 37,38,62,63 and 2D materials 33,64,65 (Figure S9).…”

Combing Hollow Shell Structure and Z-Scheme Heterojunction Construction for Promoting CO2 Photoreduction

“…The prosperity of modern civilization is based on the consumption of a large amount of fossil fuels. However, the consumption of fossil fuels is usually accompanied by the release of a large amount of CO 2 , which has resulted in serious energy and environmental problems. − CO 2 photoreduction taking the use of clean solar energy to convert CO 2 into valuable fuels has been considered as one of the most potent means to achieve carbon neutralization without creating new carbon emissions in the whole reaction process. − However, the limited light utilization efficiency of pristine photocatalysts and poor charge separation greatly restrict the efficiency of CO 2 photoreduction. , Hitherto, many efforts to enhance the light utilization and charge separation of photocatalysts have been made. − …”