Photocatalytic degradation is a promising method to solve the problem of ceftriaxone sodium wastewater. In this paper, Ag/TiO 2 @C composite materials with different Ag molar contents, where cellulose-derived carbon beads used as the carrier, were successfully prepared by the One-Pot method. In Ag/TiO 2 @C composite photocatalyst, Ag nanoparticles were deposited on TiO 2 particles to form a metal-semiconductor structure, where charge carriers were effectively separated under the Surface Plasmon Resonance effect of Ag nanoparticles, thereby extending the lifetime of charge carriers. Ag/TiO 2 @C has been found of higher photocatalytic degradation performance compared to pure TiO 2 and pure carbon beads. Among all, Ag (0.5%)/TiO 2 @C has the best catalytic performance. According to the Langmuir-Hinshelwood model, the photodegradation rate followed first-order kinetics, with the highest apparent rate of 0.0091 min −1 . According to the results of mass spectrometry, ceftriaxone sodium was degraded into small molecules and eventually degraded into CO 2 , H 2 O, and we proposed possible pathways and photocatalytic mechanism accordingly.
Jianhua Yang,Lu Fang,Zhengkui Li,Guanhua Meng,Yong Jia,Yongbin Jiang,Jianjun Lian,Xinhong Gan
At present, the researches on photocatalysis were mainly focused on the design, improvement and development of catalysts, and less attention was paid to the existing characteristics of environmentally persistent free radicals (EPFRs) during the process of photocatalytic oxidation. In this study, A flower-like Z-type heterojunction ZnO/ZnIn 2 S 4 (ZnO/ZIS) and typical antibiotic ceftriaxone sodium (CS) were taken as study objects, concentrating on the generation characteristics of EPFRs during the degradation of CS by ZnO/ZIS, and clarifying the degradation mechanism of CS in which EPFRs participated. The results showed that the degradation efficiency of 10 mg/L CS by 0.40 g/L ZnO/ZIS reached 85.3% in 150 min under the irradiation of 500 W xenon lamp . It was clear that ·O 2 − and h + play major roles in CS degradation by ZnO/ZIS under visible light, and ·OH plays an auxiliary role. Furthermore, the formation mechanism of EPFRs during photocatalytic degradation processes of CS by ZnO/ZIS were first investigated thoroughly via experimental analysis and density functional theory (DFT) calculations. The concentration level of EPFRs centered on oxygen atoms is 10 11 spin/mm 3 , which were generated in the process of degradation of CS by ZnO/ZIS under visible light. The production of EPFRs chiefly includes two procedures: chemical adsorption and transfer of electrons. The adsorption energy of precursor P8 on ZnIn 2 S 4 side is −1.91 eV, the electrons transferred from precursor P8 and P11 to ZnO/ZnIn 2 S 4 heterojunction. Surprisingly, EPFRs have little negative effects on the degradation process of CS by ZnO/ZIS. The study was not only a key field in the development of photocatalysis technology , but also a new way to study the removal mechanism of antibiotics.
Antibiotics can easily enter the water environment through direct or indirect approach, causing environmental pollution and endangering the health of organisms. Therefore, development of highly efficient adsorbent materials to adsorb and remove antibiotics is necessary. Here, cobalt oxide and nickel oxide are uniformly and tightly bonded on the surface of porous boron nitride fibers (PBNFs-NiCo), increasing the number of functional groups (B–O and N–H) and hydrogen bond receptors within PBNFs. The total pore volume and specific surface area of resulting PBNFs-NiCo can reach up to 0.48 cm3 g−1 and 720.3 m2 g−1, respectively. Encouraged by the unique micromorphology and chemical composition mentioned above, PBNFs-NiCo exhibits excellent ceftriaxone sodium (CS) adsorption ability, showing the adsorption capacity and removal efficiency up to 410.9 mg g−1 and 96.5%, respectively. Chemical adsorption plays an important role in their adsorption behavior, abiding by Langmuir adsorption theory and pseudo-second-order kinetic equation. Importantly, PBNFs-NiCo exhibits fascinating adsorption effects in surroundings with pH ranging from 4 to 6, 25 °C and varying salt concentrations. This work would establish a practical and feasible foundation for the practical application of PBNFs-NiCo for CS adsorption in aqueous solution.
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