For the serious hazards to human and natural environment caused by the toxic Hg(II), a new MOF-based adsorption material, UiO-66-AHMT, was designed and synthesized by incorporating the 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole molecule into the UiO-66-NH 2 matrix and used for the removal of Hg(II) from aqueous media. As expected, UiO-66-AHMT exhibits rapid removal ability toward Hg(II) and maximum uptake capacity of 327.88 mg/g at 298 K and pH = 5, the adsorption capacity is improved significantly compared to the unmodified UiO-66-NH 2 and comparable in the excellent UiO-66 based adsorbents reported so far. The adsorption behaviors of UiO-66-AHMT conform well to the pseudo-second-order and Langmuir models, respectively, which indicate that the adsorption process is mainly monolayer chemisorption . Meanwhile, UiO-66-AHMT shows strong selectivity to Hg(II) in the coexistence of varieties of metal ions and outstanding recyclability characteristics. To investigate the adsorption mechanism, the Hg(II) loaded UiO-66-AHMT mainly analyzed by XPS suggests that the nitrogen- and sulfur-containing groups in grafted molecule have the synergistic complexation to Hg(II). Furthermore, the binding strength between different function sites and Hg(II) are quantified and the stable complexation patterns are obtained based on the DFT calculation. These results strongly confirm that UiO-66-AHMT is a potential adsorbent in the practical treatment of wastewater containing Hg(II).
This study developed a novel ratiometric electrochemical sensor for detecting formaldehyde content in food. For the first time, we innovatively utilized 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (AHMT), a traditional colorimetric probe that specifically reacts with formaldehyde, as an electrochemical probe to construct the electrochemical assay. The reaction product of AHMT with formaldehyde exhibits different redox potentials from AHMT, thereby enabling ratiometric detection of formaldehyde. We systematically investigated the electrochemical behavior of AHMT and its reaction product with formaldehyde. Under optimized conditions, this novel ratiometric electrochemical assay demonstrated high sensitivity and selectivity for formaldehyde, with a response linear range of 0.1–20 μM and a detection limit of 21 nM. Additionally, the sensor was successfully applied to detect formaldehyde in various mushrooms and fish, with measured concentrations of 1.34 μg g −1 in shimeji mushrooms, 0.80 μg g −1 in oyster mushrooms, 1.41 μg g −1 in enoki mushrooms, and 1.12 μg g −1 in king oyster mushrooms. For seafood, concentrations of 2.45 μg g −1 in cuttlefish and 0.83 μg∙g −1 in cutlassfish fish were detected. These results were validated against the standard method, underscoring the sensor's potential and reliability for practical applications. This study is anticipated to offer valuable insights for the development of innovative electrochemical sensors for food analysis.
The toxic volatile organic compounds (VOCs), especially formaldehyde (FA), released from decoration materials pose a great threat to human health. In this study, formaldehyde adsorption performance of the specially formulated nanocellulose/chitosan aerogel (CNFCA) was investigated in simulated atmosphere. The physicochemical property of the composite aerogel was characterized, which had a large specific surface area (153.67 m 2 /g), a rough surface and an ultra-thin and porous structure. The composite aerogel showed excellent adsorption capacity for the formaldehyde, its theoretical maximum adsorption capacity was as high as 83.89 mg/g, and the adsorption process was more in accordance with the pseudo-second-order kinetics. The chromogenic reaction between the 4-amino-3-benzo-5-mercapto-1,2,4-triazolium (AHMT) and CNFCA was found that the color of the composite aerogel was depended on the free formaldehyde concentration. Based on this phenomenon, a colorimetric card was proposed and built to detection the formaldehyde in the atmosphere. Moreover, the adsorption mechanism research was found that the CNFCA with a multilayer structure belonged to physicochemical complex adsorption.
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