Search

[Display omitted] • MnCo 2 O 4 doped g-C 3 N 4 nanosheets were successfully synthesized. • Excellently degradation performance of pollutants was reached in PMS/vis system. • The degradation mechanism of MnCo 2 O 4 /g-C 3 N 4 /PMS/vis system was proposed. • A possible tetracycline hydrochloride degradation pathway was analyzed. Peroxymonosulfate (PMS) activation by heterogeneous transition metal oxides is an effective approach for treating emerging pollutants in water. However, the low PMS activation efficiency associated with the valency conversion rate of transition metals has been a major challenge to sulfate radical-based oxidation. In this work, manganese cobaltate (MnCo 2 O 4) nanoparticles anchored on graphitic carbon nitride (g-C 3 N 4) flakes (MnCo 2 O 4 /g-C 3 N 4) were successfully prepared and showed high PMS activation efficiency under visible (Vis) light. The obtained catalysts degraded 96.1% of the tetracycline hydrochloride (TCH) through the synergistic effect of PMS and photocatalysis. The reaction rate constant (0.2505 min−1) was 5.3 and 1.8 times higher in the MnCo 2 O 4 /g-C 3 N 4 /PMS/Vis system than in the pristine g-C 3 N 4 (0.0471 min−1) and MnCo 2 O 4 (0.1435 min−1) systems, respectively. The characterization results verified that g-C 3 N 4 , which functions as the electron donor in the photocatalytic heterojunction system, could transmit numerous photogenerated electrons to MnCo 2 O 4 , thereby increasing the cyclability of divalent-trivalent metal ions. The composites also showed good stability, cycling capability, and cation/anion tolerance. Tentative degradation mechanism and reaction pathways were proposed based on the reactive species and degradation products. [ABSTRACT FROM AUTHOR]

In this work, the ternary hybrid photocatalyst composed of ZnO nanorods with BiOI and Pt NPs (denoted as Pt@BiOI/ZnO) was fabricated by a simple three-step method. The as-prepared samples were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–Vis diffuse reflectance spectrometry (DRS) and X-ray photoelectron spectroscopy (XPS), which proved the strong interaction has occurred among the Pt, BiOI and ZnO. The phenol degradation test showed that the Pt@BiOI/ZnO ternary hybrid composite exhibited the maximum photodegradation efficiency of phenol (99.9%) under UV irradiation within 30 min compared to Pt/BiOI, BiOI/ZnO binary composites as well as Pt/ZnO. Additionally, the transient photovoltage (TPV), steady-state PL spectra and time-resolved PL spectra were used to investigate the possible mechanism for photocatalytic performance. Our results elaborated that the enhanced photocatalytic activity was mainly attributed to the synergetic effect of Pt/ZnO and BiOI/ZnO interfaces. Conversely, the interfacial interaction of Pt/BiOI is little contribution, indicating that the effective interfaces design is very important for the degradation of phenol in the preparation process of ternary hybrid photocatalyst. These findings will contribute to developing high efficiency photocatalysts for application in environmental remediation. [ABSTRACT FROM AUTHOR]

In this paper, a series of BiOI/ZnO photocatalysts containing various BiOI contents were prepared by a facile two-step synthetic method. The structure and crystal phase, morphology, surface element analysis, optical property of as-prepared samples are measured by X-ray diffraction (XRD), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and UV–Vis diffuse reflectance spectrometry (DRS). BiOI/ZnO photocatalytic activities of the prepared photocatalysts were evaluated by photocatalytic degradation of phenol under simulated light irradiation. The phenol degradation rate reached 99.9% within 2 h under simulated solar light irradiation. The probable photocatalytic mechanism of composites photocatalysts is discussed by active species trapping experiments, the surface photovoltage (SPV), the transient photovoltage (TPV) and photoluminescence (PL) measurements. The results manifest that the superior photocatalytic activity of BiOI/ZnO composites is derived from the strong internal electric field between BiOI and ZnO, which is beneficial for the effective separation and transfer of photogenerated charges in ZnO. Moreover, the loading of BiOI on the surface of ZnO inhibited the recombination of photogenerated charge carriers in ZnO, resulting in excellent photocatalytic activity. On the contrary, the effect of an extension of the light absorption range induced by the introduction of BiOI on the phenol degradation activity is not significant. [ABSTRACT FROM AUTHOR]

Abstract: The phase inversion temperature (PIT) method is generally used to prepare nonionic surfactant stabilized nano-emulsions because of its low energy and surfactant consumption. The emulsion droplets are usually negatively charged because of the selective adsorption of OH− onto the droplet surfaces. In this work, positively charged oil/water nano-emulsions were prepared by adding a cationic surfactant to the system. The cationic molecules change the spontaneous curvature of the surfactant layers and raise the PIT above 100°C. The PIT can be depressed by addition of NaBr, as shown by conductivity measurements and equilibrium phase behavior. Therefore, these nano-emulsions can be prepared by the PIT method. We found that the formation of the nano-emulsions did not require a cross-PIT cycle. The mechanism of the emulsification is the formation of mixed swollen micelles that can solubilize all the oil above a “clearing boundary”, followed by a stir-quench to a temperature where these droplets become metastable emulsions. The zeta potential of the emulsion droplets can be easily tuned by varying the cationic surfactant concentrations. Due to electrosteric stabilization, the resulting nano-emulsions are highly stable, thus could find significant applications in areas such as pharmaceuticals, cosmetics and food industries. [Copyright &y& Elsevier]