Extraction and detection of mercury in electronic waste using efficient modified MOF

Abstract

The harmful effects of heavy metal ions on human health and the ecosystem have made the detection of these ions in environmental samples increasingly important in recent years. There has been significant attention on the development of sensors that are selective and sensitive in detecting heavy metal ions. Due to their wide presence in the environment and high toxicity, the detection of Hg2+ ions is of great interest. MIL-101(Al)-N = 2NAPHT (2NAPHT = 3-hydroxy-2-naphthaldehyde, N = imine nitrogen) is a novel chemosensor that was solvothermally synthesized and characterized. A limit of detection of 5.48 ppb (2.73 ×10−8 M) was found for the chemosensor, which is highly selective and sensitive to Hg2+ ion detection. The fluorescence emission properties of MIL-101(Al)-NH2 were improved and more binding sites for analytes were introduced after functionalization with 2-hydroxy naphthaldehyde. The formation of the novel chemosensor was confirmed by using Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), TEM, SEM, thermogravimetric analysis (TGA), and X-ray diffraction (XRD). Moreover, this chemosensor showcased a regenerative emission feature, retaining its detection ability for six successive cycles. The study revealed that the sorbent had a considerable Hg2+ capacity, amounting to 133.2 mg per gram of MIL-101(Al)-N = 2NAPHT chemosensor. The chemosensor MIL-101(Al)-N = 2NAPHT was also assessed for its capability to identify Hg2+ ions in electronic waste samples (silver oxide button cells). According to the results mentioned above, the chemosensor exhibited a high degree of sensitivity and selectivity towards Hg2+ ions. The MIL-101(Al)-N = 2NAPHT chemosensor is an effective and promising technology for the detection and removal of mercury from electronic waste, in conclusion.