Influence of Dispersed TiO2 Nanoparticles via Steric Interaction on the Antifouling Performance of PVDF/TiO2 Composite Membranes.

Herein, the influence of various contents of polyethylene glycol (PEG) on the dispersion of TiO2 nanoparticles and the comprehensive properties of PVDF/TiO2 composite membranes via the steric hindrance interaction was systematically explored. Hydrophilic PEG was employed as a dispersing surfactant of TiO2 nanoparticles in the pre-dispersion process and as a pore-forming additive in the following membrane preparation process. The slight overlap shown in the TEM image and low TSI value (<1) of the composite casting solution indicated the effective dispersion and stabilization under the steric interaction with a PEG content of 6 wt.%. Properties such as the surface pore size, the development of finger-like structures, permeability, hydrophilicity and Zeta potential were obviously enhanced. The improved antifouling performance between the membrane surface and foulants was corroborated by less negative free energy of adhesion (about −42.87 mJ/m2), a higher interaction energy barrier (0.65 KT) and low flux declination during the filtration process. The high critical flux and low fouling rate both in winter and summer as well as the long-term running operation in A/O-MBR firmly supported the elevated antifouling performance, which implies a promising application in the municipal sewage treatment field.

Hydrothermal Preparation and Characterization of TiO2 /BiVO4 Composite Catalyst and its Photolysis of Water to Produce Hydrogen.

In the present work, bismuth vanadate composited photocatalysts were synthesized and characterized. X-ray diffractometry and Raman results showed that the particles were well crystallized, and formed by the complex of monoclinic BiVO4 and TiO2 . On electron microscopy, the photocatalyst exhibited high crystallization, agglutination and irregular shape, and was surrounded by numerous TiO2 particles. The study of surface areas showed that the specific surface area of 30-BiVO4 /TiO2 composited was 112 m(2) ·g(-1) , which was nearly 10 times that of pure BiVO4 . The ultraviolet-visible diffuse reflectance spectra indicated the composited photocatalyst were activated in visible light. The activity of photocatalytic water splitting was studied. The results showed that monomer BiVO4 photocatalyst was not able to produce hydrogen under any light source. BiVO4 /TiO2 composited photocatalysts, however, were capable of generating hydrogen. Under UV light irradiation for 120 min, 1 g catalyst dispersed in 50 mL deionized water produced almost 1 mL hydrogen, such that the productivity of hydrogen was higher than that of P25-TiO2 . Photocatalytic decomposition of water under visible light also confirmed that the BiVO4 /TiO2 composited photocatalyst had the ability of water splitting.

Microemulsion synthesis of nanosized TiO(2) particles doping with rare-earth and their photocatalytic activity.

Microemulsion is the easiest and cleanest of the popular methods of synthesizing nanomaterial. This work synthesized the nanosized La-TiO(2) and Ce-TiO(2) particles through the hydrolyzation of tetrabutyl titanate in a Triton X-100/n-hexanol/cyclohexane/water reverse microemulsion. The particles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform-infrared spectroscopy (FT-IR) and thermogravimetry (TG). The photocatalytic activity was evaluated by photocatalytic degradation of methyl orange (MO) under ultraviolet light and visible light irradiation. The results showed that reverse microemulsion produced the nanosized and well-separated particles, which are obviously in degrading MO. Comparing the pure TiO(2) with doping TiO(2) , the doping ones are smaller and have better photocatalytic activity, which was best at the molar content of 0.1% for La, whereas for Ce it was 0.5%.