Fluorine-doped carbon dot (CD)-modified enrichment chromogenic membrane and use thereof in detection of three perfluorinated compounds (PFCs)

A method for preparing a fluorine-doped carbon dot (CD)-modified enrichment chromogenic membrane, comprising:

• preparation of a substrate membrane:
• modifying polyvinylidene fluoride (PVDF) to produce αAA-PVDF;
• dissolving the αAA-PVDF and polyvinylpyrrolidone in N,N-dimethylformamide (DMF), stirring at 60° C. to 70° C. for 10 h to 12 h, and allowing to stand for 10 h to 18 h to produce a mixed solution;
• pouring the mixed solution on a scrape-coating machine, and scrape-coating to form the substrate membrane;
• and soaking the substrate membrane in deionized water for later use;
• preparation of a tannic acid solution:
• dissolving a tannic acid powder in a phosphate buffer to produce the tannic acid solution;
• dispersing a fluorine-doped CD and UiO-66-F4 in deionized water, and conducting an ultrasonic treatment to produce a dispersion of the UiO-66-F4 and the fluorine-doped CD;
• and
• cutting the substrate membrane, and subjecting a cut substrate membrane to a static immersion in the tannic acid solution for 20 min to 60 min and then to a static immersion in the dispersion of the UiO-66-F4 and the fluorine-doped CD for 20 min to 60 min to produce the enrichment chromogenic membrane,
• wherein the PVDF is modified through the following steps:
• step (1), dispersing a PVDF powder in a KOH solution at 50° C. to 60° C., adding ethanol, and stirring for 20 min to 60 min;
• and conducting suction filtration to collect an initial α-PVDF powder, washing the initial α-PVDF powder with deionized water until neutral to produce a wet α-PVDF powder, and drying the wet α-PVDF powder to produce a dry α-PVDF powder for later use;
• and
• step (2), adding the dry α-PVDF powder obtained in the step (1) to DMF, introducing nitrogen to expel oxygen for 20 min to 40 min, and stirring for dissolution;
• adding acrylic acid and 2,2′-azobis(isobutyronitrile), stirring at a constant temperature of 55° C. to 70° C. to allow a reaction for 8 h to 12 h;
• and adding methanol for precipitation to produce a precipitate, washing the precipitate with deionized water to produce a wet αAA-PVDF powder, and drying the wet αAA-PVDF powder to produce a dry αAA-PVDF powder for later use.