Low cost and rapid fabrication of copper sulfides nanoparticles for selective and efficient capture of noble metal ions

Abstract

Transition-metal dichalcogenides (TMDCs) present great potential in the area of noble metals recovery and separation. Herein, a one-pot solvothermal method was carried out to fabricate CuS nanoparticles (CuS NPs). The morphology structure and physical properties of the CuS NPs were characterized by scanning electron microscope (SEM), transmission electron microscopy (TEM), high-resolution TEM (HRTEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption, and thermogravimetric analysis. Successful attempts to apply CuS NPs to the noble metal capture were firstly made. CuS NPs demonstrated highly selective binding and extremely efficient capture of Au3+, Pd2+ and Pt4+. The selectivity and capture capacity order were Au3+ > Pd2+ > Pt4+ > other metal ions. The enormous capacities for Au3+ (2.92 mmol g−1, 574.7 mg g−1), Pd2+ (1.13 mmol g−1, 222.2 mg g−1), and Pt4+ (0.72 mmol g−1, 142.9 mg g−1), and high distribution coefficients (Kd) of Au3+ (3.12 × 106 mL g−1), Pd2+ (2.24 × 106 mL g−1), and Pt4+ (6.220 × 103 mL g−1) placed the CuS NPs at the top known for such capture. Sorption isotherm of Au3+, Pd2+ and Pt4+ accorded with the Langmuir model suggesting homogeneous adsorption sites. The sorption kinetics for Au3+, Pd2+ and Pt4+ followed a pseudo-second-order model and the capture process was endothermic driven. The adsorption may occur by the reduction reaction of Au3+ and Pd2+ with CuS NPs as a captor in the hydrochloric systems, while it may occur by electrostatic interaction and electron-mediated coordination interaction for Pt4+. After the capture of noble metals, the crystallites of the CuS NPs retained the original shape, suggesting good stability and reversibility. This work proposes a new strategy to capture and recover noble metals and further expands the applications of TMDCs in pollution control.