Photocatalyst is the core of photocatalysis and directly determines photocatalytic performance. However, low quantum efficiency and low utilization of solar energy are important technical problems in ...the application of photocatalysis. In this work, a series of polyoxometalates (POMs) Hsub.3PWsub.12Osub.40 (PWsub.12)-doped titanium dioxide (TiOsub.2) nanofibers modified with various amount of silver (Ag) nanoparticles (NPs) were prepared by utilizing electrospinning/photoreduction strategy, and were labelled as x wt% Ag/PWsub.12/TiOsub.2 (abbr. x% Ag/PT, x = 5, 10, and 15, respectively). The as-prepared materials were characterized with a series of techniques and exhibited remarkable catalytic activities for visible-light degradation tetracycline (TC), enrofloxacin (ENR), and methyl orange (MO). Particularly, the 10% Ag/PT catalyst with a specific surface area of 155.09 msup.2/g and an average aperture of 4.61 nm possessed the optimal photodegradation performance, with efficiencies reaching 78.19% for TC, 93.65% for ENR, and 99.29% for MO, which were significantly higher than those of PWsub.12-free Ag/TiOsub.2 and PT nanofibers. Additionally, various parameters (the pH of the solution, catalyst usage, and TC concentration) influencing the degradation process were investigated in detail. The optimal conditions are as follows: catalyst usage: 20 mg; TC: 20 mL of 20 ppm; pH = 7. Furthermore, the photodegradation intermediates and pathways were demonstrated by HPLC-MS measurement. We also investigated the toxicity of products generated during TC removal by employing quantitative structure-activity relationship (QSAR) prediction through a toxicity estimation software tool (T.E.S.T. Version 5.1.2.). The mechanism study showed that the doping of PWsub.12 and the modification of Ag NPs on TiOsub.2 broadened the visible-light absorption, accelerating the effective separation of photogenerated carriers, therefore resulting in an enhanced photocatalytic performance. The research provided some new thoughts for exploiting efficient and durable photocatalysts for environmental remediation.
One of the main drawbacks of the application of photocatalysis for wastewater treatment is the use of dispersed photocatalysts, which are difficult to remove from effluent after the treatment process ...and may pose additional toxicity to the receiving bodies. As an alternative, immobilized catalysts can be applied; however, this strategy can increase the difficulties in mass and photo transfer. This work presents the development of an inert and highly porous support for TiOsub.2 immobilization. The produced materials have a high surface area and contribute to diminishing the difficulties in mass and phototransfer during photocatalysis. Different types of polymeric materials were tested as support, and a Taguchi experimental design with an L9 arrangement was used to optimize the immobilization process and evaluate the effect of TiOsub.2 content and the use of bidding agents, ultrasound, and thermic treatment. The grey automotive polyurethane foam proved to be the best support, using 5.0% of TiOsub.2 (wt.%) in the immobilization suspension with Triton X as the binding agent and heat treatment during immobilization. At the optimal conditions, it was possible to achieve total As(III) oxidation (below the analytical detection limit) in 240 min, with nearly 100% As(V) present in solution at the end of the reaction (almost no As adsorption on the catalyst surface). In addition, the catalytic bed was able to promote the As(III) complete oxidation in up to five consecutive cycles without significant leaching or deactivation of the immobilized TiOsub.2.
The adsorption-enhancing TiOsub.2-SBA-15 photocatalyst has been synthesized by an in situ etching displacement method, which possesses unique regular hexagonal pores and large specific surface area. ...The as-prepared TiOsub.2-SBA-15 can effectively adsorb and increase the concentration of pollutants in the photocatalyst and collision likelihood with the photogenerated radicals, thus improving the efficiency of photocatalytic organic degradation. The structure and morphology have been characterized by Nsub.2 adsorption isotherms, X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), and scanning electron microscopy (SEM). These characterizations confirm that TiFsub.4 alcohol solution prefers to react with the internal surface of SBA-15 because of the Siphon effect. Fourier transform infrared (FTIR) spectra demonstrate that a Ti-O-Si bond formed after the reaction of TiFsub.4 with SBA-15, which reveals a wonderful combination of TiOsub.2 and SiOsub.2 even at low temperatures. Through this function, the nanocomposite TiOsub.2-SBA-15 could obviously improve the efficiency of photocatalytical removal of toluene in the gas phase.
Keywords *OH radicals; beta particles; Lattice oxygen defects; *SO.sub.4 - radicals; Oxytetracycline Highlights * 1. beta particles were used to control the generation of oxygen defects and generate ...*O. * 2. Free state *O participated in the wet oxidation process of water to obtain *OH radicals. * 3. *OH activates SO.sub.4.sup.2- to produce *SO.sub.4.sup.- radicals and shorten the OTC degradation time. * 4. *OH radicals preferentially attack the unsaturated C = C in OTC to cause ring opening. * 5. The Bi.sup.0(0 0 3) crystal face makes the removal of OTC by Bi.sub.0.32@Bi.sub.1.68WO.sub.5.80 remain at 100%. beta particles were used to dissociate the Bi - O bond in layered microsphere-like Bi.sub.2WO.sub.6 to obtain Bi.sub.x@Bi.sub.2-xWO.sub.n with oxygen defects. Bi.sub.0.32@Bi.sub.1.68WO.sub.5.80 with Bi.sup.0 treated at 4.50 x 10.sup.15 MeV can realize the completely removal of oxytetracycline (OTC) within 20 min. Free radical scavenging experiments showed that the removal rate of OTC for Bi.sub.0.32@Bi.sub.1.68WO.sub.5.80 dropped to 11.39% after removing *OH radicals. Additionally, the LC-MS results revealed that the *OH radicals first oxidized the unsaturated C = C double bond and opened the hexatomic ring, making OTC easier to degrade. The DFT results confirm that the electron cloud density at the oxygen defect site has expand, thereby promoting the photocatalytic reaction. Bi.sub.0.32@Bi.sub.1.68WO.sub.5.80 with lowest O negative polarization rate verified that lattice oxygen defects produced by beta particles enhance the generation of *OH free radicals that activate SO.sub.4.sup.2- to produce *SO.sub.4.sup.- radicals. It is be confirmed that *OH radicals can activate SO.sub.4.sup.2- to form *SO.sub.4.sup.-.This work provides a new strategy for forming oxygen defects in photocatalytic. This work provided a new strategy for the efficient utilization of *OH radicals by beta-rays in the field of catalytic oxidation. Author Affiliation: (a) College of Science, Central South University of Forestry and Technology, Changsha 410004, China (b) School of Nuclear Technology and Chemistry & Biology, Hubei University of Science and Technology, Xianning 437100, China (c) College of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha, China * Corresponding authors. Article History: Received 22 November 2020; Revised 25 February 2021; Accepted 26 February 2021 Byline: Jing Wang (a), Wenlei Wang wenlei_wang@csuft.edu.cn (a,*), Juntao Wang (b), Kehui Xue (a), Yi Peng (a), Ying Yan (a), Yuanlan Wang (a), Hui Wang (c), Yiqiang Wu wuyiqiang@csuft.edu.cn (c,*)
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► GO was used as an adsorbent for tetracycline removal from the aqueous solution. ► Tetracyclines strongly deposited on GO via π–π interaction and cation–π bonding. ► The adsorption ...isotherms fit Langmuir model and Freundlich model well. ► The adsorption kinetics and effect of pH were studied in detail.
Significant concerns have been raised over pollution of antibiotics including tetracyclines in aquatic environments in recent years. Graphene oxide (GO) is a potential effective absorbent for tetracycline antibiotics and can be used to remove them from aqueous solution. Tetracycline strongly deposited on the GO surface via π–π interaction and cation–π bonding. The adsorption isotherm fits Langmuir and Temkin models well, and the theoretical maximum of adsorption capacity calculated by Langmuir model is 313mgg−1, which is approximately in a close agreement with the measured data. The kinetics of adsorption fits pseudo-second-order model perfectly, and it has a better rate constant of sorption (k), 0.065gmg−1h−1, than other adsorbents. The adsorption capacities of tetracycline on GO decreased with the increase in pH or Na+ concentration. The adsorption isotherms of oxytetracycline and doxycycline on GO were discussed and compared.
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•The novel 0D/2D Ag2WO4/WO3 Step-scheme heterojunction has been prepared successfully.•The formed internal electric field and band edge bending can induce charges separation ...efficiently.•The as-prepared heterojunctions show a superior photocatalytic degradation performance.•The S-scheme photocatalytic mechanism is well discussed.
The efficient photo-induced charges transfer/separation plays a critical role in enhancing photocatalytic performance of WO3. Herein, the novel visible-light-driven 0D/2D Ag2WO4/WO3 Step-scheme (S-scheme) heterojunction photocatalysts are synthesized by a facile hydrothermal method following with an in situ precipitation process. The special two-dimensional structure of WO3 not only acts as a suitable supporter for Ag2WO4 nanoparticles, but also shortens the transfer route of photo-induced charges. More importantly, the formed internal electric field as well as the band edge bending at the interface of Ag2WO4 and WO3 can further induce charges separation and retain the strong oxidation ability of holes on the VB of WO3. As a result, the obtained 0D/2D Ag2WO4/WO3 S-scheme heterojunction shows an excellent photocatalytic performance towards the degradation of oxytetracycline (OTC) and typical dyes, respectively. The specific degradation route based on the main intermediates of OTC and the possible mechanisms for this S-scheme heterojunction system are also investigated and discussed. This work provides the new insights into design of novel WO3-based S-scheme heterojunction photocatalysts for high-efficient antibiotic and dye degradation.
Efficient compositions for the selective detection of ethanol gas and the removal of organic contaminants were realized by codoping of (Gd, Nb) and (Gd, Mo) ions into TiOsub.2. TiOsub.2, ...Tisub.0.96Gdsub.0.01Nbsub.0.03Osub.2, and Tisub.0.96Gdsub.0.01Mosub.0.03Osub.2 samples were prepared by a coprecipitation method. For all compositions, a crystalline anatase phase of TiOsub.2 was detected. Compared to pure TiOsub.2, the absorption edges of Tisub.0.96Gdsub.0.01Nbsub.0.03Osub.2 and Tisub.0.96Gdsub.0.01Mosub.0.03Osub.2 samples were red-shifted, further broadening towards visible light. The morphological studies demonstrate that the grains of TiOsub.2 were more refined after (Gd, Nb) and (Gd, Mo) codoping. The photocatalytic efficiency of the Tisub.0.96Gdsub.0.01Mosub.0.03Osub.2 catalyst for degrading 20 mg/L reactive yellow 145, brilliant green, and amoxicillin was 98, 95, and 93% in 90 min, respectively. The reusability experiments indicate that the Tisub.0.96Gdsub.0.01Mosub.0.03Osub.2 catalyst had high stability during reuse. The high photocatalytic activity of the Tisub.0.96Gdsub.0.01Mosub.0.03Osub.2 catalyst was correlated to the broad visible-light absorption and effective separation of electron–hole pairs by Gdsup.3+ and Mosup.6+ cations. The gas sensing characteristic is reflected by the high sensitivity of the Tisub.0.96Gdsub.0.01Nbsub.0.03Osub.2 sensor to ethanol gas in the presence of different gases at 275 °C. The obtained results indicated that the (Gd, Mo) mixture could more effectively induce the photocatalytic properties of TiOsub.2 while (Gd, Nb) dopants were the best for reinforcing its sensing characteristics.
Utilization of semiconductor photocatalyst materials to degrade pollutants for addressing environmental pollution problems has become a research focus in recent years. In this work, a 2D/2D S-scheme ...crystalline carbon nitride (CCN)/BiOIOsub.3 (BOI) van der Waals heterojunction was successfully constructed for effectively enhancing the degradation efficiency of antibiotic contaminant. The as-synthesized optimal CCN/BOI-3 sample exhibited the highest efficiency of 80% for the photo-degradation of tetracycline (TC, 20 mg/L) after 120 min visible light irradiation, which was significantly higher than that of pure CCN and BOI. The significant improvement in photocatalytic performance is mainly attributed to two aspects: (i) the 2D/2D van der Waals heterojunction can accelerate interface carriers’ separation and transfer and afford sufficient active sites; (ii) the S-scheme heterojunction elevated the redox capacity of CCN/BOI, thus providing a driving force for the degradation reaction. The degradation pathways of TC for the CCN/BOI composite were investigated in detail by liquid chromatography-mass spectrometry (LC-MS) analysis. This work provides a design idea for the development of efficient photocatalysts based on the 2D/2D S-scheme van der Waals heterojunctions.
Introducción. El uso de plantas con fines etnoveterinarios son una opción para tratar trastornos de salud, debido a su amplia disponibilidad y menor precio comparado con los fármacos sintéticos ...(Cervantes, 2022). En este sentido, las especies arbóreas o arbustivas se pueden aprovechar para ser utilizados en la medicina veterinaria dado su contenido de metabolitos secundarios. Objetivo. Evaluar la actividad cicatrizante y antiinflamatoria de la harina de fruto de Caesalpinia coriaria (HFCc). Métodos. Se presentan dos casos clínicos, el primero en un macho de raza Merino, el cual tuvo una lesión traumática en la región dorsal del cuello, de aproximadamente 3 x 2 x 1cm largo, ancho y profundidad. Se limpió diariamente el área con solución salina y gasa estéril, posteriormente se aplicó la HFCc en el área afectada, durante 20 días de seguimiento. El segundo caso fue una borrega con problema de aborto espontáneo y retención placentaria. Se aplicó oxitetraciclina I.M. durante cinco días y se realizaron dos lavados intrauterinos con infusión de extracto acuosos al 10% de HFCc, estos se hicieron con dos días de diferencia. Resultados y discusión. En el primer caso se observó en cada limpieza que no se presentaron exudados que indicaran infección, los signos de inflamación disminuyeron, y el tejido de cicatrización cubrió la herida paulatinamente hasta cerrar por completo. En el segundo caso, en el residuo de los lavados no se presentó secreción purulenta y la expulsión de la placenta se dio con éxito al tercer día. Estos resultados se asocian a la presencia de taninos en C. coriaria, a los cuales se le atribuyen efectos antibacterianos (Olmedo-Juárez et al., 2019), antioxidantes (Janbandhu y Khan, 2022), cicatrizantes y astringentes (Sánchez-Carranza et al., 2017). Conclusión. Se registraron efectos antinflamatorios y cicatrizantes con el uso de la harina de fruto de C. coriaria en ovinos.
The synergy of adsorption and photocatalysis is a good method to remove organic pollutants in wastewater. In recent decades, persistent photocatalysis has gained considerable interest for its ability ...to sustain the catalytic degradation of organic pollutants in the dark. Herein, we report three different TiOsub.2 nanomaterials to remove tetracycline hydrochloride (TCH) in solution. We found that the removal ability of TiOsub.2, Ni-TiOsub.2, and Ag/Ni-TiOsub.2 is 8.8 mg/g, 13.9 mg/g and 23.4 mg/g, respectively, when the initial concentration of TCH is 50 mg/L. Chemical adsorption could be the rate-determining step in the TCH adsorption process. Moreover, Ag nanoparticles dispersed on Ni doped TiOsub.2 surface act as traps to capture photo-generated electrons upon illumination with indoor light. The holes in Ag/Ni-TiOsub.2 serve as critical oxidative species in TCH degradation under dark conditions. This work provides new insights into the design of persistent photocatalysts that can be activated by weak illumination and degrade organic pollutants in wastewater after sunset.
