Tetracycline cannot be effectively degraded in wastewater treatment. Therefore, the development of excellent photocatalysts is of significant importance for environmental protection. In this study, a β-Bi2O3/BiOCl heterojunction photocatalyst with hollow flower-like microspheres was successfully synthesized by the in-situ reaction of HCl and β-Bi2O3 hollow spheres. The prepared samples are characterized by Scanning electron microscopy, Transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, N2 physical adsorption, UV-vis diffuse reflectance spectroscopy, and Photoluminescence. Then, research on the photocatalytic performance for the degradation of tetracycline hydrochloride was conducted. The results show that the photocatalytic performance of the β-Bi2O3/BiOCl composite is significantly better than the β-Bi2O3 and BiOCl. The increase in photocatalytic activity is due to the formation of a heterojunction between β-Bi2O3 and BiOCl, which effectively promotes the separation of photogenerated electron-hole pairs. Additionally, the heterojunction nanocomposite demonstrated the outstanding photocatalytic stability after five cycles, which indicates that the material can be used for water environment purification. This paper provides assistance for studying the photocatalytic mechanism of heterojunction photocatalytic materials.
In this study, a magnetically separable Fe3O4/CeO2 (Fe/Ce) nanocomposite is synthesized by sol-precipitation method and characterized by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy dispersive spectrometer , vibrating sample magnetometer, atomic absorption spectrometer, and zeta potential measurements. The Fe/Ce is used as sorbent to adsorb anionic dye of Acid Black 210 (AB210) from aqueous solutions, and the maximum adsorption capacity is about 90.50 mg/g, which is six times higher than that of the commercial CeO2. Dependence of absorption performance on essential factors, such as initial dye concentration, temperature and initial pH, are experimentally examined. The result shows that the adsorption kinetic of Fe/Ce follows pseudo-second-order model and the adsorption isotherm is well described by the Langmuir adsorption model. Furthermore, the thermodynamic analysis indicates that the adsorption of Fe/Ce for AB210 is spontaneous and endothermic.
Amino-functionalized spherical mesoporous silica (ASMS) materials were successfully prepared via a convenient treatment method by using 3-aminopropyltrimethoxysilane (APTES), which was used in different concentrations in the process of spherical mesoporous silica (SMS) synthesis. The adsorption performances of ASMS were evaluated by taking toluene as a simulated pollutant and the adsorption mechanism was also studied. A variety of characterization methods were adopted, including scanning electron microscopy, small-angle X-ray diffraction and Fourier-transform infrared spectroscopy techniques and nitrogen adsorption-desorption analyses, which led to a better understanding of the performance of the materials. It was found that the SMS has a good adaptability due to the amino functionality, the pore structure still remains in the modified samples even when the mass ratio of APTES/TEOS is up to 3, and the chemical properties of the material surface are significantly improved by the amino functionality. The results show that the capacities of the toluene adsorption follow the order of SMS < ASMS-1 < ASMS-3 < ASMS-2. ASMS-2 has the highest toluene adsorption capacity (98.1 mg g À1 ) and the saturated adsorbent can be easily regenerated by thermal desorption, which has a stable adsorption capacity after 4 adsorption cycles. These experimental data indicated that amino functionalization could affect both the pore structure and surface chemical properties of SMS, making ASMS a promising material for the reduction of industrial volatile organic compound emissions in air treatment.
Ordered mesoporous carbons (OMCs) were synthesized in this study through a soft template method and then activated by employing different mass ratios of KOH/OMCs to obtain KOH-activated ordered mesoporous carbons (KOMCs) with hierarchical pore structures. To verify the adsorption capacity, the KOMCs have been subjected to toluene emission-reduction experiments. The KOMCs were characterized by TEM, XRD, N2 adsorption-desorption isotherms, and Raman spectroscopy. The pore structure of OMCs was found to be effectively optimized by the activation with KOH, with the BET-area and total pore volume values reaching as high as 2661 m2 g−1 and 2.14 cm3 g−1 respectively. Then, the dynamic adsorption capacity of toluene on KOMCs was investigated via breakthrough curves, which can be well described by the Yoon and Nelson (Y-N) model. The dynamic adsorption capacities of toluene exhibit the following order: OMC < KOMC-1 < KOMC-5 < KOMC-3. The sample activated by KOH/OMC with a mass ratio of 3:1 (KOMC-3) demonstrated the highest toluene adsorption capacity of 355.67 mg g−1, three times higher in comparison with the untreated carbon (104.61 mg g−1). The modified hierarchical porous carbons also exhibited good recyclability. The KOMCs with rich pore structure, high toluene adsorption capacity, and superior reusability thus display a huge potential for volatile organic compound (VOC) elimination.
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