Preparation of N-TiO2/SiO2 composites by solvothermal method and their photocatalytic properties

In order to improve the visible light catalytic activity of titanium dioxide (TiO2) and ensure its long-term stability on the surface of concrete, an N-TiO2/SiO2 composite was prepared using tetrabutyl titanate, nitric acid, and modified SiO2 nanospheres as the precursors by a solvothermal method. The effect of nitric acid on the phase composition, morphology and photoelectric properties of the synthesized photocatalytic composites was systematically studied by various characterization methods. The results show that the optimum nitric acid/butyl titanate volume ratio is 1/6. The nitrogen-doped TiO2 nanoparticles were uniformly dispersed on the surface of spherical SiO2 with a diameter of 200 nm. The degradation rate of simulated pollutants (RhB) with pH 5 and 7 exceeded 95% within 30 minutes and the catalytic effect remained excellent after five repetitions without much weakening. The excellent visible photocatalytic performance can be attributed to the doping of N replacing part of the oxygen atoms in TiO2, forming the energy level of N 2p at the O 2p energy level and reducing the TiO2 energy band gap to 2.99 eV. At the same time, the better dispersion of N-TiO2/SiO2 prepared by this new synthesis method also plays an important role in the improvement of visible light photocatalytic activity.

Catalytic Oxidation of Methylene Blue by Attapulgite/TiO2

Methylene blue (MB) is a common pollutant in wastewater of printing and dyeing industry. At present, ozone oxidation is commonly used in the treatment of printing and dyeing wastewater. Ozone is used for oxidation reaction directly and indirectly. However, the reaction rate is not fast enough. In this study, the attapulgite (ATP) was modified by tetrabutyl titanate-ethanol solution. The TiO2/ATP nanocomposite with high catalytic activity was prepared. The synthesized samples were subjected to characterized by X-ray diffraction (XRD) and Fourier Transform infrared spectroscopy (FTIR). The morphology and particle size of the particles were observed by scanning electron microscopy (SEM). The TiO2/ATP nanocomposite was calcined at 300°C for 2 h, and the degradation rate of 80 mg/L methylene blue was 99.8%. The experimental results show that the ozone, temperature and mass transfer factors are excluded, and the effects of temperature, MB concentration and pH on the degradation of methylene blue are investigated. The optimal reaction conditions are as follows: The ozone concentration is 0.067 g/min; the ozone flow rate is 0.15 NL/min; the stirrer rotation speed is 550 r/min; the catalyst is 0.1 g; the temperature is 50°C; Based on the results, the reaction mechanism was derived and the kinetic study of the experiment was carried out.

Synthesis of titania fibers by electrospinning and its photocatalytic degradation properties

The electrospinning precursor solution was prepared by dissolving polyvinyl pyrrolidone as template, tetrabutyl titanate as titanium source, and acetic acid as inhibitor. The TiO2 nanofilms were prepared by precursor solution electrospinning and subsequent calcination. Thermal gravimetric analysis (TG), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and transmission electron microscopy (TEM) were used to characterize and analyze the samples. The influence of technological parameters on spinning fiber morphology was also studied. The results indicate that the TiO2 nanofibers morphology is good when the parameters are as follows: voltage 1.4×104 V，spinning distance 0.2 m，translational velocity 2.5×10-3 m·s-1, flow rate 3×10-4 m·s-1, and needle diameter 3×10-4 m. The diameter of the fibers is about 150 nm. With the 1×10-4 mol·L-1 methylene blue solution used as simulated degradation target, the degradation rate is 95.8% after 180 minutes.

Controllable Synthesis of Enhanced Visible Light Responded Fe, N, Co Tri-TiO2@MCM-41 Nanocomposites and Its Photocatalytic Performance

A novel method for in situ synthesis of Fe, N, Co tri-TiO2 (DT) loading on MCM-41 composite photocatalyst was proposed. Fe, N, Co tri-TiO2@MCM-41 (DTM) with adsorption-degradation synergy was prepared by adjusting tetrabutyl titanate (TBOT) concentrations, the alcohol-water ratio in the atmosphere of the reaction chamber. The influence of preparation parameters on the texture structure, catalytic activity, and the synergism of adsorption and degradation of the DTM was discussed, the optimal parameters were determined. The DTM was characterized by XRD, TEM, BET, FT-IR, and UV-Vis. Besides, the DTM exhibited obvious redshift and visible catalytic activity compared with undoped TiO2@MCM-41 (TM), which possessed excellent performance in the degradation of gaseous and liquid pollutants. The degradation rate of methylene blue (MB) and nitric oxide (NO) was 96.39% and 56.75%, respectively. Furthermore, DTM photocatalyst exhibited excellent reusability. The degradation efficiency of MB and NO after five cycles decreased by 4.54% and 5.89%, respectively.

Facile synthesis of superhydrophobic MS/TiO2/PDMS sponge for efficient oil-water separation

In order to obtain a kind of superhydrophobic sponge with high oil and water selectivity, the MS/TiO2/PDMS sponge were prepared via a two-step hydrophobic fabrication based on the melamine sponge (MS), tetrabutyl titanate (TBOT) and polydimethylsiloxane (PDMS). The effects of modification time, the concentrations of TBOT and PDMS on the properties of the MS/TiO2/PDMS sponge were studied, and the separation mechanism was also discussed based on the interaction between the oil and the surface of the MS/TiO2/PDMS sponge. The results suggest that under optimal conditions, the MS/TiO2/PDMS sponge show superhydrophobicity. The contact angle and adsorption capacity for oil of the MS/TiO2/PDMS sponge are 149.2° and 98.5 g·g−1, respectively, and they can be recycled about 25 cycles after oil-water separation test. This study aims at preparing a new composite material with high oil-water selectivity, which lays a good foundation for the development and research of new oil adsorbent.

Octahedral Shaped PbTiO3-TiO2 Nanocomposites for High-Efficiency Photocatalytic Hydrogen Production

In this work, octahedral shaped PbTiO3-TiO2 nanocomposites have been synthesized by a facile hydrothermal method, where perovskite ferroelectric PbTiO3 nanooctahedra were employed as substrate. The microstructures of the composites were investigated systemically by using XRD, SEM, TEM and UV-Vis spectroscopy. It was revealed that anantase TiO2 nanocrystals with a size of about 5 nm are dispersed on the surface of the {111} facets of the nanooctahedron crystals. Photocatalytic hydrogen production of the nanocomposites has been evaluated in a methanol alcohol-water solution under UV light enhanced irradiation. The H2 evolution rate of the nanocomposites increased with an increased loading of TiO2 on the nanooctahedra. The highest H2 evolution rate was 630.51 μmol/h with the highest concentration of TiO2 prepared with 2 mL tetrabutyl titanate, which was about 36 times higher than that of the octahedron substrate. The enhanced photocatalytic reactivity of the nanocomposites is possibly ascribed to the UV light absorption of the nanooctahedral substrates, efficient separation of photo-generated carriers via the interface and the reaction on the surface of the TiO2 nanocrystals.

Facile preparation and photocatalytic performance of anatase TiO2/nanocellulose composite

Anatase TiO2/nanocellulose composite was prepared for the first time via a one-step method at a relatively low temperature by using cellulose nanofibers as carrier and tetrabutyl titanate as titanium precursor. The morphology, structure and element composition of the composite were characterized by SEM, EDS, TEM, XRD and XPS. The specific surface area and thermal stability of the composite were investigated by N2 adsorption-desorption and thermogravimetric analysis, respectively. In addition, the prepared composite was used for the photocatalytic degradation of methyl orange (aqueous solution, 40 mg·L-1). It was found that the composite had a good morphology and anatase crystal structure, and Ti-O-C bond was formed between TiO2 and nanocellulose. The specific surface area of composite was increased and the thermal stability was decreased compared with the cellulose nanofiber. Moreover, the degradation rate of methyl orange was achieved as 99.72% within 30 min, and no obvious activity loss was observed after five cycles. This work might give some insights into the design of efficient photocatalysts for the treatment of organic dye wastewater.

Enhanced Ultraviolet-Visible Photocatalysis of RGO/Equaixial Geometry TiO2 Composites on Degradation of Organic Dyes in Water

The reduced graphene oxide dopped equaixial geometry TiO2 (rGO/egTiO2) composite as photocatalyst was synthesized hydrothermally with various mass ratios of tetrabutyl titanate. The photocatalyst is considered to be rGO/equaixial geometry TiO2 in terms of modifying the combined reduced graphene Oxide and TiO2. The rGO plays a vital role in rGO/egTiO2 composite as photocatalysts were analyzed in methylene blue (MB) and rhodamine B (RhB) photocatalytic degradation under UV and simulated solar light irradiation. This synthesized catalyst was characterized by various analytical techniques such as XPS, XRD, SEM, BET and TEM. The rGO/egTiO2 composite exhibits enhanced photo-catalytic performance with degradation rate of 97.5 and 97% on RhB and MB for 60 min under UV radiation respectively, while the degradation rate of 94 and 92 % was observed on the same dyes for 6 h under the simulated sunlight radiation. The enhanced photocatalytic performance of the rGO/egTiO2 composite under ultraviolet irradiation source was owing to a high separation efficiency of the photo-induced electron-hole pairs, while the photocatalytic performance under simulated sunlight radiation was due to the photosensitive and charge separator behavior of rGO. This offers us an excellent potential of significant photo catalytic activity for the removal of organic contaminants from wastewater.

Porous Titanium Dioxide Spheres for Drug Delivery and Sustained Release

By hydrothermal method, porous TiO2 spheres with pompon morphology are successfully synthesized in the tetrabutyl titanate (TBT)–acetic acid (HAc) system with no other additives. The morphological, structural and textural properties of the specimen are figured out by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray powder diffraction (XRD), N2 adsorption/desorption, and fluorescence microscope. The results show the pompon-like morphology of porous TiO2 with high specific surface area and large pore volume, which can be used as a drug carrier. In this paper, doxorubicin hydrochloride (DOX) is chosen as drug model to understand the process of drug release. And results indicate that the porous TiO2 is biocompatible and can be used for continuing drug-release, which shows lots of possibilities in medical fields.