Pure nano-TiO2 Research Articles

CdS quantum dots/nano-TiO2 incorporated wood as a long-term stable and easily separable photocatalytic adsorbent for efficient Cr(VI) removal

To address chromium pollution in water resources, a novel photocatalytic adsorbent, CdS quantum dots/nano-TiO2 incorporated wood (QNIW), was synthesized for efficient removal of Cr(VI), which displayed both long-term stability and easy separability. We extensively analyzed QNIW using a range of analytical techniques to investigate its morphology, structure, optical characteristics, as well as adsorption and photocatalytic properties. The adsorption experiments revealed QNIW's remarkable capacity for Cr(VI) adsorption in the absence of light, reaching a maximum value of 482.1 mg/g calculated using the Langmuir model. This value was 8.4 times greater than that of natural wood. The outcomes of adsorption and photocatalytic experiments showcased QNIW's superior performance. Specifically, the photocatalytic reaction rate coefficient of QNIW was measured to be 0.0661 ± 0.0078 min−1 under specific conditions: UV light intensity of 500 mW/cm2, adsorbent concentration of 0.25 g/L, pH of 2, initial Cr(VI) concentration of 20 mg/L, and temperature of 20 ℃. Remarkably, this coefficient exceeded that of pure nano-TiO2 by an impressive factor of 6.2. Importantly, QNIW exhibited exceptional stability, preserving 92.2 % of its initial removal efficiency after twelve weeks storage and maintaining 83.4 % efficiency even after undergoing five consecutive adsorption–desorption cycles. Thus, this study offers valuable insights into the progress of photocatalytic adsorbents characterized by high efficiency, enduring stability, and facile separability from treated wastewater.

Quantum dots TiO2 loaded amorphous SiO2 composite photocatalysts: Significant performance enhancement and the effect of SiO2 surface hydroxyl groups

Using amorphous SiO2 (A-SiO2) and tetrabutyl titanate (TBOT) as raw material, a composite photocatalyst with surface loaded quantum dot size TiO2 (A-SiO2/TiO2, AST) was prepared. The degradation of tetracycline hydrochloride as well as mechanism of performance improvement by A-SiO2 were investigated. The TiO2 on the composite was anatase with a content of 9.96 wt% and a size of 7–8 nm (quantum dot level). TiO2 was uniformly distributed and was closely bonded at the interface by chemical bonds. The degradation rate of AST was 95% after 60 min UV exposure, which was comparable to pure nano-TiO2. The particle size of TiO2 in AST was reduced from 20–50 nm to 7–8 nm comparing with pure nano-TiO2 and changed from a highly agglomerated to a well-dispersed state due to abundant hydroxyl groups on A-SiO2 surface. TiO2 bandgap width increased from 3.25 eV to 3.39 eV. These led to the exposing of active sites on TiO2 and significantly increased photogenerated carrier separation efficiency. This study provides a feasible and simple method to improve TiO2 nanoparticles’ photocatalytic activity, reduce the usage and achieve recycling to cut the application cost by surface coated.

Improved photocatalytic degradation of methylene blue under visible light using acrylic nanocomposite contained silane grafted nano TiO2

Removal of organic dyes from wastewater by photocatalytic oxidation (PCO) under visible light has attracted attention of many scientists. In this research, TiO2 nanoparticles were surface modified by aminopropyltriethoxysilane (APTES) at different concentrations (1, 3, 5, 7, and 10 wt%). The nanoparticles were applied to acrylic latex at 1, 3, and 5 wt% to prepare photocatalytic nanocomposite paints. The modified nanoparticles were evaluated for photocatalytic degradation of methylene blue in an aqueous solution as model-polluted wastewater. The modified nanoparticles showed 30, 29, and 22% enhancement in photocatalytic degradation of methylene blue compared to the pure TiO2 nanoparticles under UV, visible and solar lights, respectively. Using the modified nanoparticles in the acrylic film caused 31.6 and 56.3% improvement in the tensile strength and toughness compared to the pure nanoparticles containing sample. The modified nanoparticles considerably enhanced the light absorbance capacity of the acrylic paint. On this basis, the modified paints (at 3 wt% loading of nanoparticles) showed 29, 27, and 20% improvements in discoloration of methylene blue stain compared to the pure nano TiO2 containing nanocomposite under UV, visible, and solar lights, respectively.

PREPARATION AND PROPERTIES OF A NANO-TiO2 COMPOSITE PHOTOCATALYST SUPPORTED BY NATURAL QUARTZ

The goal of this paper is to improve the technical level of preparing composite photocatalysts with SiO2-supported nano-TiO2, expand the selection range of SiO2 carriers, reduce expenses and understand the influence of SiO2 crystallization behavior. Natural quartz (Q/SiO2) powder was used as a carrier to prepare a Q/SiO2-TiO2 composite photocatalyst by hydrolyzing a butyl titanate solution and performing high-temperature calcination of the hydrolysate. The performance, morphology, structure and mechanism were tested and characterized. In addition, the as-prepared photocatalyst was compared with other amorphous SiO2 carrier composite photocatalysts. The results showed that the Q/SiO2 surface of Q/SiO2-TiO2 contained a uniform load of TiO2 with a 26.98% proportion. Anatase-type TiO2 was mainly present, and the size was 5–10[Formula: see text]nm. Moreover, Q/SiO2 and TiO2 were firmly combined in the form of Si–O–Ti bonds between the interfaces. The degradation rate of Q/SiO2-TiO2 to methyl orange solution was 99.59% under UV irradiation for 60[Formula: see text]min, which was equivalent to that of pure nano-TiO2. The degradation performance remained stable after four cycles. Compared with other amorphous SiO2 carriers, Q/SiO2 exhibited a higher load of TiO2. Furthermore, Q/SiO2 played a more significant role in inhibiting the phase transition of TiO2 to rutile and improving the photocatalytic performance.

Performance of photocatalytic, carbonated calcium sulfoaluminate-belite cement

Carbonated and non-carbonated paste samples containing white Ordinary Portland Cement (OPC) or Calcium Sulfoaluminate-Belite (CSAB) cement with TiO2 were evaluated for NOx removal, optical properties, and CaCO3 polymorphs using chemiluminescence NOx analyzer, UV-Vis-NIR spectrophotometer, and X-Ray Diffraction, respectively. NOx removal of photocatalytic CSAB cement was 43% and 28% lower than white photocatalytic cement for non-carbonated and carbonated samples, respectively. Partially replacing the cements with fly ash decreased NOx removal in the non-carbonated state but reduced the negative impact of carbonation on photocatalytic efficiency. The decrease in NOx removal of carbonated samples were a combination of decrease in surface porosity, coverage of TiO2 sites by carbonation products, and decrease in activated TiO2 sites caused by a lower average diffuse reflectance in UV-A region despite an increase in photoconductance. All the TiO2-doped paste had a lower band edge energy than pure nano TiO2, and Urbach absorption tail, indicating presence of localized defects.

Hydrolytic Modification of SiO2 Microspheres with Na2SiO3 and the Performance of Supported Nano-TiO2 Composite Photocatalyst.

Modified microspheres (SiO2-M) were obtained by the hydrolytic modification of silicon dioxide (SiO2) microspheres with Na2SiO3, and then, SiO2-M was used as a carrier to prepare a composite photocatalyst (SiO2-M/TiO2) using the sol-gel method; i.e., nano-TiO2 was loaded on the surface of SiO2-M. The structure, morphology, and photocatalytic properties of SiO2-M/TiO2 were investigated. Besides, the mechanism of the effect of SiO2-M was also explored. The results show that the hydrolytic modification of Na2SiO3 coated the surface of SiO2 microspheres with an amorphous SiO2 shell layer and increased the quantity of hydroxyl groups. The photocatalytic performance of the composite photocatalyst was slightly better than that of pure nano-TiO2 and significantly better than that of the composite photocatalyst supported by unmodified SiO2. Thus, increasing the loading capacity of nano-TiO2, improving the dispersion of TiO2, and increasing the active surface sites are essential factors for improving the functional efficiency of nano-TiO2. This work provides a new concept for the design of composite photocatalysts by optimizing the performance of the carrier.

Enhanced photocatalytic reaction and mechanism for treating cyanide-containing wastewater by silicon-based nano-titania

The treatment of cyanide-containing wastewater is very important for the sustainable development of gold industry. Treating wastewater by nano-titania (nano-TiO2) has the advantage of adsorbing heavy metals and catalyzing the decomposition of cyanogen simultaneously. Since the catalysis is limited by solid-liquid diphase system, the photocatalytic and adsorption efficiency is relatively low. This study aimed to enhance catalytic process based on silicon-based nano-TiO2 composite functional material to treat deeply cyanide-containing wastewater. The characteristics of the silicon-based nano-TiO2 material were studied by Brunner−Emmet−Teller (BET) and field emission scanning electron microscopy (FESEM)/ energy dispersive spectrometer (EDS), which indicated that the material has excellent dispersibility and large specific surface area(146.6±2.4 m2·g−1). Further, the comparison of the treatment effects of cyanide wastewater with pure nano-TiO2 and silicon-based nano-TiO2 material demonstrates that the latter is more effective on cyanide degradation. Almost 99.8% of cyanide degradation was achieved by silicon-based nano-TiO2 material under light irradiation within 135 min. The mechanism and X-ray photoelectron spectroscopy (XPS) analysis. It was found that the final decompositions of Copper cyanide complex and zinc cyanide complex are CO2, NO2, Cu2+ and Zn2+.

Purification of automobile exhaust gas by activated carbon supported Fe3+ modified nano-TiO2 and its application on asphalt pavement

Automobile exhaust gas discharged into the air not only pollutes the environment but also seriously harms human health. Although pure nano-TiO2 has a purified effect on exhaust gas, it has a wide band-gap, a narrow response range of visible light, and is prone to agglomerate, leading to the lower catalytic efficiency. In this study, Fe3+ doping and activated carbon loading were used to compositely modify TiO2 to extend the spectral response range and dispersion performance of TiO2. Firstly, activated carbon supported Fe3+ modified nano-TiO2 (Fe-TiO2/AC) composite catalysts were prepared by sol–gel method. Then the specimens were characterised by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and ultraviolet–visible spectrophotometer (UV-Vis). The micro-structures were observed by scanning electron microscopy (SEM). Based on the self-developed exhaust gas test system, the effects of the activated carbon dosage, light source, temperature, catalyst dosage and other factors on the catalytic performance were investigated. Finally, the application method and effect of the catalyst in the asphalt pavement was explored. The results showed that with the increase of Fe3+ content, the grain size of nano-TiO2 decreases gradually, the band-gap narrows gradually, and the response range to visible light broadens gradually. The activated carbon loading not only increases the dispersibility of the nano-TiO2 but also increases the absorption of the exhaust gas. The Fe-TiO2/AC composite catalyst has the best degradation effect on CO, NO and HC exhaust gas, which is better than pure nano-TiO2 and Fe3+ modified TiO2. By using the spraying method, the catalytic performance of Fe-TiO2/AC photocatalyst combined with OGFC asphalt mixture reaches the maximum. With the increase of wear times, the degradation effect of the test specimen on the exhaust gas was reduced, the rate of decrease was fast, then slowly, and finally the degradation performance gradually tends to be stable.

Effect of calcination temperature on the structure and properties of SiO2 microspheres/nano-TiO2 composites

The silica microspheres surface-coated nano-TiO2 composite material (MS-SiO2/TiO2) was prepared by co-grinding the silica microspheres (MS-SiO2) and nano titanium dioxide soliquid (nano-TiO2-sol) in a stirring mill, and then calcining the above grinding products. The photocatalytic performance (methyl orange as the target pollutant) and surface photoinduced hydrophilicity of MS-SiO2/TiO2 calcined at different temperatures were tested, and their structure and morphology were characterized. The calcination temperature has a great effect on the structure and properties of MS-SiO2/TiO2 composites. The composite particles calcined at 300 °C (MS-SiO2/TiO2-300) have low photocatalytic efficiency because they are aggregated seriously and the crystalline phase of TiO2 in MS-SiO2/TiO2-300 has not formed. While, the MS-SiO2/TiO2-500 composite particles showed a good separation state. The TiO2 particles on MS-SiO2 were single anatase phase, and its particle size was about 10–20 nm, exhibiting a well dispersion state. The degradation rate of MS-SiO2/TiO2-500 under 90 min ultraviolet irradiation was 92%, and the water contact angle was 10°, which was better than pure nano-TiO2. In MS-SiO2/TiO2, the reduction of TiO2 particles aggregation, improvement of dispersion and the presence of a single anatase phase were important factors for MS-SiO2 to exert a synergistic effect, which led to the enhancement of nano-TiO2 functional efficiency.

Development of alcohol sensor using TiO2-Hydroxyapatite nano-composites

This work demonstrates successful utilization of thick films of hydroxyapatite (HAp), nano titanium dioxide (TiO2) and its composite coated on glass substrate using screen printing method for alcohol sensing application. Films of various compositions nano TiO2 in HAp were prepared via physical mixing 0.5, 1, 1.5 and 2 wt% of nano TiO2 in HAp. Gas sensing measurement of 1 wt% TiO2-HAp shows efficient sensing at operating temperatures of 33, 35 and 55 °C for methanol, ethanol and propanol gases, respectively, as compared with pure HAp, nano-TiO2 and other composite films. Fast response and recovery time were observed in 1 wt% TiO2-HAp for 10 ppm methanol (50 and 20 s), ethanol (170 and 20 s) and propanol (100 and 70 s), respectively, as compared with pure HAp, nano TiO2 and other composites. It is concluded that nano TiO2 and HAp composite film sensors can be efficiently used to detect alcohol vapors with their presence in ambient as low as 10 ppm concentration.

Investigation on the coating modification effect of nano-SiO2 particles on nano-TiO2 particles

TiO2 has received significant scientific attention as a highly operative, stable, and low-cost photocatalyst. However, the decomposition of organic matrices due to its photocatalytic action is considered to be one of the main drawbacks of TiO2 nanoparticles in its applications in inks. To overcome this problem, this study aims to coat the surface of the nano-TiO2 particles with a layer of nano-SiO2 particles through a sol-gel method. The nano-TiO2 powder was dispersed by polyvinylpyrrolidone (PVP) and 4-vinylpyridine (4VP). The effects of different concentrations of PVP and 4VP, molar ratios of silicon to titanium, and ammonia water dosage on the properties of the composite particles were investigated. Scanning electron microscopy (SEM) analysis showed that the coating effect is best when the PVP had a mass of 2 g, the 4VP had a volume of 2 ml, the ratio of titanium to silicon was 1:2, and the amount of ammonia was 5 ml. The transmission electron microscopy (TEM) images show that titania particles were successfully coated on the surface of nano-TiO2. The x-ray diffraction (XRD) patterns showed no change in the crystal structure of nano-TiO2 before and after coating with nano-SiO2. Comparing the Fourier-transform infrared (FT-IR) and x-ray photoelectron (XPS) spectra, it was found that the Ti–O–Si bond is present in the nano-TiO2/SiO2 composite particles, and the Si element is present in the TiO2 crystal in the form of Ti–O–Si. These results indicate that the nano-SiO2 was coated on the surface of the nano-TiO2 successfully, and the ultraviolet (UV) resistance of pure nano-TiO2 is effectively improved.

Evaluation of NO2-degradation by the rubber-titanium-aluminum ultrafine grained micro-surfacing material and its effect on pavement performance

The preparation of high degradation rate and recyclable photocatalytic material for automobile exhaust degradation is a hot and difficult issue in the field of automobile exhaust degradation. In this paper, a modified Rubber-Titanium-Aluminum(RTA) degradation material based on TiO2/Al2O3 composite carrier was prepared. The effects of particle size, RTA content, initial concentration of NO2, light source type, light intensity, ambient temperature and humidity on the degradation effect of RTA were studied by the self-designed indoor test equipment, and the skid resistance performance, noise reduction performance, durability, impermeability and repeatability of NO2-degradation of the RTA ultrafine grained micro-surfacing material were further studied. The results showed that compared with pure nano-TiO2, RTA had a higher degradation rate of NO2, and the smaller the particle size of RTA was, the higher the degradation rate was. With the increase of the RTA content, the NO2-degradation rate of the material also increased, but there was an upper limit. RTA could achieve the best effect of NO2-degradation under the appropriate temperature and suitable wavelength of the light source, but the air humidity and light illumination had little effect on the degradation rate of NO2. Moreover, the higher the initial concentration of automobile exhaust was, the smaller the degradation rate of NO2 was. In addition, the RTA ultrafine grained micro-surfacing material had good durability, which could improve the skid resistance performance, noise reduction performance and impermeability of the pavement. The effect of automobile wear on RTA’s ability of repeated NO2-degradation was not significant. With the skid resistance, degradation rate, durability and economic benefits taken into account, the optimum coating amount of RTA was 800 g.m−2.

Comparison of the photocatalytic performance of TiO2/AC and TiO2/CNT nanocomposites for methyl orange photodegradation.

To enhance the photocatalytic degradation efficiency of TiO2 on methyl orange (MO) removal, TiO2/AC (activated carbon) and TiO2/CNT (carbon nanotube) composites were synthesized. The prepared catalysts were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The photocatalytic performance of the obtained composites were investigated by the degradation of MO under UV irradiation (254 nm, 365 nm). The results revealed that the prepared nanocomposite showed higher MO degradation efficiency than pure nano-TiO2. Additionally, batch experiments of influencing factors, including H2O2 dosage, metal dopants, inorganic anions, chloride ion concentration and ultraviolet wavelength on the MO removal efficiency were also conducted. The results demonstrated that metal dopant and the presence of H2O2 significantly enhanced MO removal efficiency.

Effect of composite photo-catalysts prepared with recycled clay brick sands and nano-TiO2 on methyl orange and NOx removal

This research aims to develop a composite photo-catalyst using recycled clay brick sands (RCBS) and nano-TiO2. The RCBS was sourced from construction and demolition wastes (C&DW). For comparison, river sands (RS) were also used. Both RCBS and RS were soaked in 0%, 0.5%, 1.0%, 2.5%, and 5.0% (by weight) nano-TiO2 solutions to produce RCBS based composite and RS based composite photo-catalysts. The amount of nano-TiO2 absorbed by RCBS and RS was then determined. The photocatalytic methyl orange removal and NOx removal activities of the prepared composite photo-catalysts were investigated. The results showed that the amount of nano-TiO2 absorbed by RCBS and RS increased with increasing the concentration of nano-TiO2 solution. However, a non-linear relationship between the photocatalytic activities and the amount of TiO2 absorbed by RCBS and RS was observed. The highest methyl orange and NOx removal were observed on the composite photo-catalysts soaked in 1.0% nano-TiO2 solutions. Interestingly, the optimal RCBS based composite photo-catalysts were even superior to pure nano-TiO2 in terms of both methyl orange removal (60%) and NOx removal (50%) under the same conditions. Overall, the developed composite photo-catalysts not only possess an enhanced photocatalytic activity, but also generate value-added recycling of RCBS in construction materials.

Preparation of Nano-TiO₂-Coated SiO₂ Microsphere Composite Material and Evaluation of Its Self-Cleaning Property.

In order to improve the dispersion of nano-TiO2 particles and enhance its self-cleaning properties, including photocatalytic degradation of pollutants and surface hydrophilicity, we prepared nano-TiO2-coated SiO2 microsphere composite self-cleaning materials (SiO2–TiO2) by co-grinding SiO2 microspheres and TiO2 soliquid and calcining the ground product. The structure, morphology, and self-cleaning properties of the SiO2–TiO2 were characterized. The characterization results showed that the degradation efficiency of methyl orange by SiO2–TiO2 was 97%, which was significantly higher than that obtained by pure nano-TiO2. The minimum water contact angle of SiO2–TiO2 was 8°, indicating strong hydrophilicity and the good self-cleaning effect. The as-prepared SiO2–TiO2 was characterized by the nano-TiO2 particles uniformly coated on the SiO2 microspheres and distributed in the gap among the microspheres. The nano-TiO2 particles were in an anatase phase with the particle size of 15–20 nm. The nano-TiO2 particles were combined with SiO2 microspheres via the dehydroxylation of hydroxyl groups on their surfaces.

Synthesis of nano-TiO2 photocatalysts with tunable Fe doping concentration from Ti-bearing tailings

In this work, highly pure nano-TiO2 photocatalysts with varying Fe doping concentration were successfully synthesized from low-cost Ti-bearing tailings by an acidolysis-hydrothermal route. The effects of H2SO4 concentration, leaching temperature, acid/tailings ratio and leaching time on the recovery of TiO2 from the tailings were investigated. Synthesized samples were characterized by XRD, TEM, EDS, XPS, and UV–vis spectroscopy. The results showed that the material prepared is characteristic anatase with the average size of 20 nm and the Fe doping concentration in the synthesized nano-TiO2 is tunable. The photocatalytic activity of synthesized nano-TiO2 photocatalyst was also evaluated by the photodegradation of Rhodamine B under visible light and UV light irradiation. Our study demonstrates a low-cost approach to synthesize highly efficient and visible light responsive catalysts.

Preparation and photocatalytic properties of KH-550 modified nano-TiO2/graphene Composites.

KH-550 modified nano-TiO2/RGO composites were synthesized via a one-step hydrothermal method to improve the photocatalytic activity of nano-TiO2.The composites were characterized by X-ray Diffraction (XRD), Scanning Electron Microscope (SEM), Transmission Electron Microscope (TEM), Raman spectra, X-ray Photoelectron Spectroscopy (XPS). In addition, methyl orange solution was used in optical degradation to investigate the photocatalytic properties. The results showed that the photocatalytic degradation rate of KH-550 modified nano-TiO2/RGO composites was 57.32% while pure nano-TiO2, nano-TiO2/RGO was only degraded 28.83%, 46.68% during the same time and same mass ratio. Compared with nano- TiO2, the photocatalytic degradation rate of nano-TiO2/RGO and KH-550 modified nano-TiO2/ RGO composites were improved by 17.85%, 28.49% respectively. However, the composites displayed the best photocatalytic performance when the mass ratio of graphene and KH-550 modified nano-TiO2 was 8%.

Highly stabilized Ag2O-loaded nano TiO2 for hydrogen production from glycerol: Water mixtures under solar light irradiation

Nano TiO2 prepared by a hydrothermal method and silver-loaded nano TiO2 prepared by impregnation were studied for the photocatalytic production of hydrogen from glycerol:water mixtures. The structural characteristics were revealed using XRD, EDAX, DRS, TEM, XPS, BET surface area and Raman techniques. The photocatalytic hydrogen production has been investigated under solar light irradiation. Effects of nano TiO2 calcination temperature, silver loading, photocatalyst content, light source and Ag oxidation state on hydrogen production have been systematically studied. Maximum hydrogen production of 200 μmol h−1 g−1 is observed on 4wt% silver-loaded nano TiO2 catalyst in pure water and the maximum hydrogen production of 7030 μmol h−1 g−1 is observed on 3wt% silver-loaded nano TiO2 catalyst in glycerol: water mixtures. Silver-loaded nano TiO2 reduced and photodeposited catalysts show similar hydrogen production activities in glycerol: water mixtures under solar irradiation. The optimum catalyst modified with conducting carbon materials (graphene oxide, graphene, carbon nanotubes) by a solid-state dispersion method were also studied for hydrogen production under solar light irradiation. Compared with pure nano TiO2, a 3wt% silver-loaded nano TiO2/graphene composite exhibited an approximately 17-fold enhancement of hydrogen production leading to hydrogen production rates of 12,100 μmol h−1 g−1. Based on the characterization results and hydrogen production activity on these catalysts, a structure–activity correlation has been proposed wherein the interacting Ag2OAg phases on the surface of nano TiO2 play an important role in maintaining a high hydrogen production activity under solar irradiation.

Preparation and Photocatalytic Performance of MWCNTs/TiO2Nanocomposites for Degradation of Aqueous Substrate

In this study, multiwalled carbon nanotubes (MWCNTs)/TiO2nanocomposites were obtained by constant volumetric wet impregnation processes. The prepared catalysts were characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The effect of reaction conditions on photocatalytic performance of the catalysts was investigated by the degradation of methyl orange (MO) under UV irradiation, in a new type of reactor with unique structure. The results showed that the prepared nanocomposite exhibited higher MO degradation efficiency than that of pure nano-TiO2. Besides, in batch experiments of influencing factors, including ionic strength, oxidant amount, and response times, the presence of H2O2would contribute to increasing the MO degradation rate of MWCNTs/TiO2samples. Ionic concentration and long reaction times are adverse to the MO degradation in the processes.

Oxidative desulfurization of model fuels with pure nano-TiO2 as catalyst directly without UV irradiation

In this study, different crystalline forms of nano-TiO2 were prepared using the sol–gel method. The TiO2 particles were characterized by X-ray diffraction, transmission electron microscopy, and nitrogen adsorption/desorption measurements. The prepared nano-TiO2 was directly used as a catalyst to remove dibenzothiophene (DBT) from an octane solution without UV irradiation and with H2O2 aqueous solution as an oxidant. Results showed that anatase TiO2 nanoparticles have excellent catalytic oxidative activity because conversions as high as 100% were obtained within 50s under the experimental conditions; by contrast, conversion rates obtained from anatase–rutile and amorphous nanoparticles reached only 48.1% and 25.7%, respectively. The effects of stirring rate, reaction temperature, initial DBT concentration, catalyst amount, and oxidant content were also investigated in detail. Based on the results, a reaction kinetic model implying a first-order reaction with an activation energy of 56kJ/mol was established. The nano-TiO2 particles were used to catalyze 4,6-dimethyldibenzothiophene, and the effects of reaction temperature and amount of oxidant used on this reaction were investigated.