By hydrothermal reaction, the hydrangea-like ZnS/ZnIn 2 S 4 microspheres were prepared in the presence of thioacetamide. X-ray photoelectron spectroscopy and high resolution transmission electron microscopy confirmed that the ultra-long nanowires are composed of ZnS and ZnIn 2 S 4 . Scanning electron microscopy showed the morphology of ultra-thin nanosheets with an average thickness of 8.5 nm cross from inside to outside, forming ZnS/ZnIn 2 S 4 microspheres with a porous diameter of about 2.8 μm. Nitrogen adsorption desorption isotherm determined that the BET specific surface area of the microspheres was 109.19 m 2 /g which showed that they have a large specific surface area. The obtained ZnS/ZnIn 2 S 4 microspheres showed broad absorbance ranging from UV (200 nm) to visible (520 nm) with low indirect band gaps of 2.08 eV. It leads to outstanding visible-light-driven photocatalysis for the degradation of xylenol orange (XO) and thymol blue (TB) in water, and the two dyes were almost completely degraded after 60 and 135 min, respectively. This provides new potential to explore nanomaterials for efficient photo-driven degradation of organic dyes under visible light irradiation.
To further enhance the safety and energy efficiency of the Fe3O4preparation experiment, we proposed a strategy for synthesizing monodisperse Fe3O4microspheres through a one-step solvothermal process. In this environmentally friendly synthesis method, stable FeCl3∙6H2O was utilized as the sole raw material, while ethylene glycol, characterized by its high boiling point and favorable safety profile, served as the solvent. Additionally, inexpensive and readily available urea was selected to function either as a mineralizer or surfactant. Through this one-step solvothermal reaction, the target product of Fe3O4could be obtained without subsequent calcination under reducing or inert atmospheres, thereby enhancing experimental safety and promoting energy conservation. By controlling the amount of urea added, it became feasible to produce monodisperse magnetic Fe3O4microspheres characterized by complete crystallinity and high yield. Utilizing the as-synthesized Fe3O4as a catalyst, we investigated its photocatalytic activity against xylenol orange organic dyes along with its regeneration characteristics. When 40 mmol of urea was incorporated into the reaction mixture, the resulting Fe3O4sample exhibited optimal photocatalytic performance; a 20 mg/L xylenol orange solution became colorless and transparent after just 1.5 h of UV light irradiation. Furthermore, during five consecutive regeneration cycles, its catalytic activity could be restored to its initial level. Importantly, Fe3O4demonstrated excellent magnetic sensitivity properties that facilitated rapid targeted separation under an external magnetic field, providing convenience for recovery and collection purposes.
To enhance the adsorption performance, chitosan microspheres (CS–MSs) were grafted with polyethylenimine (PEI), a cationic compound with abundant amine groups. The resulting PEI-grafted CS–MSs (PEI–CS–MSs) were used for the adsorption of xylenol orange (XO), an anionic dye. The results show that PEI–CS–MSs were in regular spherical shape without porous structure. XO molecules were adsorbed onto the amine groups of PEI–CS–MSs through electrostatic interaction. The maximum adsorption capacity of XO onto PEI–CS–MSs was 816.33 mg/g at 303 K, being much higher than that onto CS–MSs. The adsorption process could be properly described by the pseudo-second-order kinetic and Langmuir models. The adsorption of XO was a spontaneous process with exothermic nature. In addition, the adsorption capacity only decreased by 0.52 % after seven cycles of adsorption-desorption, indicating the excellent reusability of PEI–CS–MSs.
Rui Jiang,Jinfeng Wang,Bin Feng,Panpan Mou,Shuo Zhou,Xianbo Zhang,Yan Zhou,Guosong Chen,Donghai Lin
We have developed a novel fluorescence sensor based on upconversion nanoparticles (UCNPs) for the rapid and sensitive detection of trace aluminum ions (Al³⁺). The sensor utilizes the inner filter effect (IFE) between the UCNPs and the xylenol orange-aluminum complex (XO-Al³⁺), resulting in significant fluorescence quenching at 543 nm upon Al³⁺ binding. This quenching correlates directly with the Al³⁺ concentration, allowing for quantitative detection within a range of 0–30 µM and achieving an ultra-low detection limit of 0.19 µM. Selectivity of the sensor is enhanced by the incorporation of ascorbic acid, which masks interfering Fe³⁺ ions, thus ensuring accurate determination of Al³⁺ even in the presence of other metal ions. The UCNPs-XO sensor exhibits excellent stability, reproducibility, and minimal interference from commonly co-existing substances. This makes it suitable for the detection of Al³⁺ in various matrices, including food products and environmental water samples. Our work offers a significant advancement in Al³⁺ detection, with potential applications in food safety, environmental monitoring, and public health.
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