Water pollution caused by hexavalent chromium [Cr-(VI)] ions has attracted increasing attention because Cr(VI) ions are highly toxic and carcinogenic, which may cause serious harm to aquatic organisms and human health. More and more research has focused on the sensing or adsorption of Cr(VI) ions. However, so far, it is still a challenge to prepare advanced materials that can simultaneously detect and adsorb Cr(VI) ions. Herein, we present a facile and effective strategy to prepare a chitosan−sulfur quantum dots (CS-SQDs) composite hydrogel with both excellent sensing and uptake capability toward Cr(VI) ions. The CS-SQDs show excellent fluorescence stability against pH variation, high ionic strength, UV−light irradiation, and long-term storage. Moreover, the CS-SQDs exhibit sensitive and selective fluorescence responsiveness to Cr(VI) ions. The detection limit can reach 176.2 nM. Additionally, the CS-SQDs also show high uptake capability and favorable reusability for the adsorptive removal of Cr(VI) ions with a maximum adsorption capacity of 186.22 mg g −1 . The adsorption behavior is spontaneous, and the adsorption process conforms to Langmuir isotherm and pseudosecond-order kinetic models. This work provides an effective strategy for the preparation of multifunctional hydrogels with the potential to simultaneously monitor and remove water contaminants.
Sulfur nanoparticles (SNPs) have shown good potential in numerous fields due to their unique composition and properties. However, the direct utilization of abundant and inexpensive elemental sulfur for the large‐scale fabrication of high‐quality SNPs is still in its infancy. Herein, a simple one‐pot approach for the preparation of SNPs is presented, and gram‐scale SNPs can be readily prepared in one batch in the laboratory. By adding elemental sulfur‐ethylenediamine precursor to the acidic chitosan (CS) solution, chitosan‐capped sulfur nanoparticles (CS‐SNPs) can be formed immediately. Benefiting from the capping of CS, CS‐SNPs simultaneously possess small and uniform size with an average diameter of 19 nm, good aqueous dispersibility and stability, and favorable antioxidant capability against 2,2′‐azino‐bis (3‐ethylbenzothiazoline‐6‐sulfonic acid) free radicals. Moreover, CS‐SNPs also exhibit fine antibacterial activity against Staphylococcus aureus, and the minimum and optimal inhibitory concentrations are 256 and 512 µg mL−1, respectively. Considering the easy fabrication process and attractive attributes of CS‐SNPs, this investigation not only offers an effective method for the scalable fabrication of robust SNPs but also provides a feasible way for the value‐added utilization of elemental sulfur.
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