New Cu-doped dual-emission carbon dots (D-CDs) were synthesized rapidly and simply via a one-pot solvothermal method, and its special photoluminescence mechanism was studied. D-CDs have two fluorescence (FL) emission peaks under one-wavelength excitation and can be used as dual-signal sensor which is usually designed with two or more substances. The prepared CDs show excellent water solubility, photostability, salt tolerance, oxidation resistance, and special optical properties. The raw material ratio, solvent, pH, time, and synthesis temperature were optimized. The characterizations of CDs including transmission electron microscopy, X-ray photoelectron spectroscopy, inductively coupled plasma spectroscopic analysis, X-ray diffraction assignation of phases, thermogravimetric analysis and differential scanning calorimetry, Fourier transform infrared (FTIR) spectroscopy, FL spectrum, and ultraviolet-visible spectrum (UV-vis) were conducted. The investigation on mechanism indicates that the unique dual-emissive property is mainly caused by the energy-level gaps generated by the surface defects of CDs. The prepared D-CDs have good potential in dual-signal analysis and visualization sensing. To demonstrate the practical application, ferric ions, vitamin A acetate, and pH have been determined successfully.

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As a persistent organic pollutant, perfluorooctane sulfonate has drawn a worldwide attention. In this contribution, a novel molecularly imprinted polymer based on mesoporous silica nanoparticles was prepared for efficient separation and enrichment of perfluorooctane sulfonate in water samples. The polymer was characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, X‐ray diffraction, and N2 adsorption/desorption experiments. The static adsorption experiments and the adsorption kinetic tests were conducted. The results showed that the adsorbents had high adsorption capacity (21.10 mg/g) and short adsorption equilibration time (25 min). Meanwhile, the effect of mesoporous silica nanoparticles on the adsorption capacity was investigated. The results indicated that the mesoporous structure helped to increase the adsorption capacity of adsorbent to adsorbate. Besides, the adsorbents show good specificity and good reusability with the adsorption capacity of adsorbent toward perfluorooctane sulfonate decreasing <5% after five adsorption–desorption cycles. The mesoporous silica nanoparticles molecularly imprinted polymer has been used successfully for the removal of perfluorooctane sulfonate in environmental water samples with relative standard deviation ≤4.64%.

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