Covalent Organic Framework Isomers for Photoenhanced Gold Recovery from E-Waste with High Efficiency and Selectivity

Abstract

Gold recovery from electronic wastewater (e-waste) has attracted more and more attention because of the rapid increase of electronic waste, which is also significant for the economy and the environment. However, it remains a great challenge to design stable adsorbents for selective gold recovery from e-waste with large capacity and fast adsorption rate. Herein, three covalent organic framework (COF) isomers adopting different layer stacking models (named Tp-BTD-AA, Tp-BTD-AB, and Tp-BTD-ABC) were employed for gold adsorption. Interestingly, the adsorption rates and uptake amount of these COF isomers for gold were improved markedly under the irradiation of visible light. After optimizing the pH of aqueous solutions and the wavelength of the light source, Tp-BTD-AA exhibits the highest gold capacity of 3.0946 g/g at pH 5 and under irradiation with 460 nm light. The adsorption procedure conformed to the pseudo-second-order kinetic and Langmuir models. Moreover, Tp-BTD-AA showed high adsorption selectivity to gold and good recyclability, which could be used as a potential adsorbing material for the adsorption of gold from e-waste.

Economical synthesis of functional aromatic polythioamides from KOH-assisted multicomponent polymerizations of sulfur, aromatic diamines and dialdehydes

“…While it is of great economic and environmental significance to recycle precious metals from electronic waste, [28][29][30] aromatic polythioamides with abundant sulfur coordination sites to metal ions, especially to Au 3+ , 2 were then investigated for gold extraction from aqueous solutions. The metal coordination selectivity of the polythioamides among various metal ions was first studied.…”

Material Design Strategies for Recovery of Critical Resources from Water

“…[105] COFs are similar to MOFs, but instead of having metal-based nodes linked with organic ligands, the structure is fully comprised of covalent bonds to form pores in a cyclic manner. Metals like gold, [186] palladium, [187] and uranium [188] are typical targets for COF-based sorbents. Yue et al [187] synthesized a new sp 2 carbon-conjugated covalent organic framework containing a selenodiazole structure for selective Pd removal and achieved an ultrahigh adsorption capacity of 4578.6 mg g −1 .…”

“…COFs are similar to MOFs, but instead of having metal‐based nodes linked with organic ligands, the structure is fully comprised of covalent bonds to form pores in a cyclic manner. Metals like gold, [ 186 ] palladium, [ 187 ] and uranium [ 188 ] are typical targets for COF‐based sorbents. Yue et al.…”

Evaluation of the Oxygen Reduction Reaction Electrocatalytic Activity of Postsynthetically Modified Covalent Organic Frameworks

“…Thus, the most widespread strategy to obtain homogeneously doped carbons is the pyrolysis of organic precursors. Among them, covalent organic frameworks (COFs) stand out among the best candidates. ,,, COFs are a class of polymers with superior properties such as intrinsic crystallinities, large surface areas (in some cases up to 4000 m 2 /g), predesignability, and moldability of the networks which can be obtained via pre-synthetic (during the network formation) or post-synthetic (after the polymerization) approaches. − The structure of the COFs is proposed to template the pyrolysis to homogeneously doped carbons. , However, we envisaged that the MFE based on nonpyrolyzed COFs could produce an improvement on the performance yielded by these materials, avoiding the energetic costs associated with the pyrolytic process. Furthermore, during the pyrolytic process, the formation of the active sites is hardly controlled, and among all the functional groups produced, only some of them are the active ones .…”