A novel strategy for preparing metal-organic framework as a smart material for selective detection and efficient extraction of Pd(II) and Au (III) ions from E-wastes

The authors describe the synthesis of a novel nanocollector for detecting and extracting very low concen-trations of Pd(II) and Au(III) ions with remarkable specificity and capability. A new strategy was used to prepare the nanocollector (azo-HNTA-MIL-101(Al) sensor). It depends on preparing the azo dye first, then using this azo dye as a linker for preparing the (Al) metal-organic framework (MOF). The new strategy guaranteed the functionalization of all the amino groups of the 2-aminoterephthalic acid. Successful preparation of the azo-HNTA-MIL-101(Al) sensor was corroborated by nitrogen adsorption-desorption isotherms, TEM, SEM, XRD, FT-IR, and XPS spectral analysis. In particular, the novel azo-HNTA-MIL-101 (Al) sensor had a reasonable fluorescence due to the linker emission and outstanding sensing capability in detecting Pd(II) and Au(III) ions. With linear correlation values of 0.999 and 0.997, Beer's law was observed throughout a wide range of Pd(II) and Au(III) ions concentrations, respectively. A possible mech-anism for fluorescence quenching was investigated. High sensitivity for extremely low concentrations up to 1.50 x 10-8 molL-1 (1.59 ppb for Pd(II)) was demonstrated by the innovative nanosensor. In addition, it works as an excellent sensor for the efficient detection and extraction of Pd(II) and Au(III) ions from aqueous media. The capacities of adsorption were 84.7 and 77.4 mg of Pd(II) and Au(III) per gram of the azo-HNTA-MIL-101(Al) sensor, respectively. The approach was employed with effectiveness in extracting and determining the Pd(II) and Au(III) ions in cell phone scrap motherboards. (c) 2022 Elsevier B.V. All rights reserved.

Automated summary

The authors synthesized a new nanocollector capable of detecting and extracting very low concentrations of Pd(II) and Au(III) ions with high specificity. The novel azo-HNTA-MIL-101(Al) sensor was prepared by a new strategy involving the synthesis of an azo dye as a linker for a metal-organic framework (MOF). The sensor showed reasonable fluorescence and excellent sensing capability, as well as high adsorption capacities for Pd(II) and Au(III) ions.