Highly efficient and fast adsorption of Au(III) and Pd(II) by crosslinked polyethyleneimine‐glutaraldehyde

Abstract

An adsorbent (PEI‐GA) is prepared by crosslinking polyethyleneimine with glutaraldehyde. PEI‐GA shows outstanding adsorption performance towards Au(III) and Pd(II). PEI‐GA presents large adsorption capacity towards Au(III) in a wide application pH range from 1 to 9. The adsorption capacities of PEI‐GA for Au(III) and Pd(II) at 25°C reach 2575 and 497 mg/g, respectively. Au(III) and Pd(II) can be adsorbed completely within 10 min for 8.3 mg/L Au(III) and 20 min for 9.7 mg/L Pd(II). The adsorption equilibrium time required for 523.9 mg/L Au(III) and for 565.6 mg/L Pd(II) is 2 and 9 h, respectively. The Sips model is the most suitable to describe the adsorption isotherms which leads to more realistic adsorption capacities for both metals. PEI‐GA also exhibits high selectivity and repeatability towards Au(III) and Pd(II). The adsorption mechanism involves redox, chelation coordination, and electrostatic interactions for Au(III), and coordination and electrostatic interactions for Pd(II).

Efficient extraction of gold from e-waste using functional guanidinium ionic liquids

“…The results from slope method, Job's method, UV-vis, and 13 CNMR indicate that the extraction of Au (III) by the two guanidinium ILs follow the process of anion exchange. Then, the extraction equation can be obtained as follows：…”

“…The concentration of metals in aqueous solution was analyzed by flame atomic absorption spectrometer (AA-6880, Shimadzu, Japan) and ICP-Ms (ICAP-7850, Agilent, America). The structures, aqueous solubility and purities of ILs were characterized by 1 H NMR and 13 C NMR using a NMR spectrometer (Bruker AV 400, Bruker Scientific Instruments, Germany).…”

“…This further proves that AuCl4 − and the ILs are combined at a ratio of 1:1, which was consistent with the slope method. In order to further investigate the extraction mechanism, we also analyzed the ILs and the extracted species using 13 C NMR. As display in Figure 7B, compared to the pure ILs before extraction, the signal peak of the extracted species at 120ppm vanish, while the other peaks remain basically unchanged.…”

“…LLE is an effective method for the recovery of Au(III) due to its large amount of single recovery, simple device and strong practicability. [12][13][14][15] However, most extractants have low selectivity and some toxicity. 16 Therefore, it is of great significance to develop low-toxicity, green, highly selective and reusable extractants to recover gold from e-waste.…”

Rapid and Selective Gold Stripping from Electronic Waste with Yolk–Shell-Structured Ion-Imprinted Magnetic Mesoporous Nanorobots for Efficient Water Decontamination

“…To date, various recovery techniques such as chemical precipitation, electrochemical techniques, solvent extraction, ion exchange, photocatalysis, membrane filtration, and adsorption have been developed to achieve gold recovery. Among them, adsorption has been recognized as a feasible and environmentally friendly strategy due to its easy operation, low cost, high efficiency, and green process . Recently, numerous novel gold adsorbents with high capacities have already been explored, such as metal–organic frameworks (MOFs), − porous organic polymers (such as covalent organic frameworks, porous aromatic frameworks, , porous organic polycarbene, and porous porphyrin polymer , ), functionalized silicas, polysaccharides, chelating resins, and modified fibers .…”