Cr-Based MOF for Efficient Adsorption of Au at Low Concentrations

Abstract

The efficient enrichment and selection of Au are crucial for gold recovery. The adsorption technology is considered to have potential due to the advantages of operation simplicity and green processability. Nevertheless, the poor Au selectivity at low concentrations in complex solutions limits the further application of the adsorption technology. In this work, a novel Cr-based MOF adsorbent was successfully synthesized using 1,2,4-triazole and 4-aminobenzoic acid as ligands. Benefitting from the surface positive charge and extensive chelation and reduction sites, the novel Cr-based MOF exhibited a total adsorption capacity of up to 357 mg/g and excellent adsorption selectivity toward Au­(III) in the complex metal mixed solutions, such as simulated sewage ash waste liquid and actual e-waste leachate. Furthermore, the adsorption kinetics, isotherms, and thermodynamics were discussed in depth for investigating the adsorption mechanisms of the MOF. The PXRD and XPS analyses reveal that the adsorption process involves complexation, redox, and electrostatic interactions. We believe that this study of novel Cr-based MOF adsorbents for efficient Au adsorption is meaningful for further application in the gold recovery technology from e-waste.

Regulating the Interface Polarity Distribution of Zr-Based MOFs by Amino Acid-Like Ligand Functionalization Enables Efficient Recovery of Gold

“…The experimental data demonstrated that modified UKM-78 exhibits a significantly enhanced adsorption rate and efficiency, with a maximum adsorption capacity of 688.5 mg/g at pH 4.0. Compared to other reported materials for Au(III) adsorption (Figure 6c), 16,22,23 UKM-78 displayed a notably higher adsorption capacity. 24 To investigate the adsorption mechanism, we employed the Langmuir and Freundlich isotherm models, and their expressions are provided in S7 and S8.…”

“…Wang et al synthesized a Cr-based MOF using a one-pot method and achieved a high gold(III) adsorption capacity of 357 mg/g. 16 In contrast, postmodification entails attaching new organic ligands to the MOF precursors to enhance their functionality; however, this requires accessible modification sites on the MOF structure. 17 These strategies facilitate the introduction of specific functional groups, allowing the customization of MOFs with tailored properties.…”

“…Prefunctionalization involves the selection or modification of organic ligands before they are combined with metal ions to form MOFs. Wang et al synthesized a Cr-based MOF using a one-pot method and achieved a high gold(III) adsorption capacity of 357 mg/g . In contrast, postmodification entails attaching new organic ligands to the MOF precursors to enhance their functionality; however, this requires accessible modification sites on the MOF structure .…”

Efficiently improving the adsorption capacity of the Rhodamine B dye in a SO3H-functionalized chromium-based metal–organic framework

“…[39][40][41][42][43][44] Noteworthily, chromium-based MOFs have emerged as ultra-high water stable materials because of their robust metal-carboxylate bonds and rigid frameworks, leading to many applications of adsorption under practical conditions. 45,46 It should be noted that the molecular size of RhB exhibits unsimilarity with the pore size of traditional absorbents and a lack of strong attraction with the adsorption sites of the materials, resulting in a low adsorption efficiency of RhB. 47,48 Thus, it is necessary to incorporate negatively charged adsorption sites and achieve appropriate pore sizes within MOFs for significantly enhancing the adsorption capacity of the cationic RhB ions through efficient interactions.…”

“…39–44 Noteworthily, chromium-based MOFs have emerged as ultra-high water stable materials because of their robust metal-carboxylate bonds and rigid frameworks, leading to many applications of adsorption under practical conditions. 45,46…”