Ultrahigh Capacity and Rapid Selective Recycling of Gold Ions by Organic Intercalated and Exfoliated Few-Layer Ti₃C₂T_x Nanosheets

Abstract

For the sustainable development of the ecological environment in gold recycling, it is urgently desired to develop a more efficient and highly selective process for gold ions from ewaste or mineral lixivium. As a kind of emerging two-dimensional nanomaterials, Ti 3 C 2 T x has emerged as a rapidly developing novel water treatment material. Herein, the preparation of few-layer Ti 3 C 2 T x nanosheets and their performance for recycling of gold ions were studied. Notably, it exhibits an impressive capacity of 2973.57 mg/g at room temperature, almost 124 times that of commercially available activated carbon (24 mg/g), and an exciting selectivity for Au(III) in the presence of competing ions due to perfectly weak reduction caused by the removal of the Al layer. The Langmuir isotherm and pseudo-second-order kinetic model can accurately depict the rapid adsorption process. Additionally, it can be regenerated effectively by thiourea and exhibits excellent reutilization. A critical mechanism involves an adsorptive−reduction pathway between Au(III) and active Ti sites. Excellent performance in real lixiviums from e-waste and gold-bearing sludge is also exhibited, demonstrating great potential for Au(III) recycling. It may be a sustainable direction for the capture and separation of Au(III) and also lays the foundation for the interface control of Ti 3 C 2 T x and Au NPs as a catalyst and other functional materials.

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).…”