二氧化钛光催化氧化-离子色谱法测定液晶材料中的氟含量

建立了TiO2光催化氧化-离子色谱法测定液晶材料中氟含量的方法。利用TiO2光催化氧化技术作为预处理手段对含氟液晶化合物进行有机破坏,使碳氟键断裂,生成的F-用离子色谱法测定。结果表明,TiO2催化剂用量为0.1g/L时,可达到最佳的光催化降解效果,最佳降解时间为50min。F-峰面积与其含量在0.005～1mg/g范围内呈良好的线性关系,检出限为2.1μg/g。测得3种液晶材料的氟含量分别为7.6,18.1及28.4mg/g,不同浓度的加标回收率为86.0%～118.0%,相对标准偏差RSD(n=5)在3.2%～5.7%之间。本方法不仅适用于有机氟体系,同时也为需经有机破坏后进行测定的有机化合物体系提供了新方法。

二氧化钛光催化氧化-离子色谱法测定液晶材料中的氟含量

以二氧化钛光催化氧化为预处理手段,测定液晶材料中氟含量该方法是否可行。利用二氧化钛光能够有效处理含氟有机化合物,并使其完全降解的机理,以二氧化钛作为预处理手段对含氟液晶化合物进行有机破坏,使碳氟键断裂,在对生成的F-用离子色谱法进行测定。二氧化钛催化剂用量为0.1g/L时,可达到最佳的光催化降解效果,最佳降解时间为50分钟。F-峰面积与其含量在0.005至1mg/g范围内呈良好的线性关系,检出限为2.1μg/g。测得3种液晶材料的氟含量分别为7.6,18.1及28.4mg/g,不同浓度的加标回收率为86.0%至118.0%,相对标准偏差RSD(n=5)在3.2%至5.7%之间。该方法能够有效测定含氟有机物。

UV-TiO_2光催化氧化技术维护建筑景观水水质试验研究

采用UV／TiO2光催化氧化技术，利用动态试验方法和循环处理方式对模拟建筑景观水中难降解有机污染物的去除进行了研究，并与单-UV技术的处理效果进行了对比，重点考察了Uv、DOC和SUVA的去除效果。试验结果表明，UV／TiO2光催化氧化技术可以有效去除水中的腐殖酸，流量为0．5～1．0L／min时，UV254、DOC和SUVA的去除率随反应时间的增加而增加。UV／TiO2光催化氧化技术去除腐殖酸的效果明显好于单-UV技术，是一种有效的建筑景观水水质维护技朱，

Fe^(3+)掺杂TiO_2溶胶-凝胶法合成及其光催化性能研究

采用溶胶-凝胶法制备出锐钛矿型不同含量掺杂Fe3+的TiO2纳米材料,并用X射线衍射、透射电子显微镜等方法进行表征;通过对亚甲基蓝及腈纶污水中有机物的光降解分析,对其光催化性能进行了评价。结果表明:通过掺杂Fe能够显著提高TiO2的光催化效率。

光催化/活性炭/纳滤组合工艺处理二级出水及对膜污染的控制

污水的资源化与回用可作为城市和各类建筑的非传统水源,必须满足相关水质标准,其中有机物一直是广泛关注的重要指标.本文采用华北某市大型污水厂的二级出水,研究了二氧化钛光催化氧化(UV-TiO2)和颗粒活性炭(GAC)技术对溶解性有机物的去除特性以及对纳滤(NF)的膜污染控制特性,构建了UV-TiO2/GAC/NF组合工艺,评价了组合工艺的有机物去除效能和膜污染控制作用,解析了影响NF膜污染程度的有机物种类和相对分子质量分布特征.结果表明,UV-TiO2和GAC技术均可不同程度地缓解NF膜的不可逆污染、降低膜通量衰减速率;UV-TiO2/GAC联用的不可逆膜污染程度比单独UV-TiO2或GAC技术分别降低了48. 7%或61. 4%.类蛋白质和类腐殖质等有机污染物是不可逆膜污染的主要组分;相对分子质量为小于3×10^3和30×10^3~100×10^3的有机物是造成纳滤膜通量下降的主要因素. UV-TiO2/GAC/NF组合工艺的COD、DOC和UV254去除率为45. 7%、74. 5%和89. 2%,出水中COD、DOC和UV254等有机物指标均得到有效去除.研究成果为城市和各类建筑非传统水源的深度净化与多途径回用提供了技术支持.

Preparation of bismuth oxide/titania composite particles and their photocatalytic activity to degradation of 4-chlorophenol

Bismuth oxide/titania, one interfacial composite semiconductor with high photocatalytic activity under solar light, was prepared at low temperature. The structure was characterized by X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, brunauer-emmett-teller （BET）, X-ray photoelectron spectroscopy （XPS） and diffuse reflection spectra （DRS）. The results indicate that deposited titania nanoparticles on bismuth oxide surface have micro-nano structure, and this composite material exhibits porosity and increased surface hydroxyl groups. Furthermore, the as-prepared photocatalyst shows higher photocatalytic activity to the degradation of 4-chlorophenol than pure titania or P25 under sunlight.

Preparation and photocatalytic activity of neodymium doping titania loaded to silicon dioxide

Neodymium doping titania was loaded to silicon dioxide to prepare Nd/TiO2-SiO2 by sol-gel method and Nd/TiO2-SiO2 was characterized by X-ray diffractometry （XRD）, scanning electron microscopy （SEM）, Fourier transform-infrared spectroscopy （FT-IR） and diffuse reflectance spectra （DRS）. Photocatalytic activities of Nd/TiO2-SiO2 with different neodymium contents were evaluated by degradation of methyl orange. The light absorption of Nd/TiO2-SiO2 increased with increasing doping neodymium in a visible light range of 388-619 nm, and Nd doping was in favor of decreasing the recombination of photo-generated electrons with holes. Nd and SiO2 improved the photocatalytic activity of TiO2. The optimal molar fraction of Nd to Ti was 0.1%, and the optimum calcination temperature was 600 ℃. The highest degradation rate of methyl orange was 82.9% after irradiation for 1 h.

Multichannel charge separation promoted ZnO /P25 heterojunctions for the photocatalytic oxidation of toluene

The fabrication of multicomponent heterojunctions is an effective strategy to improve the performance of TiO2 based photocatalysts. We provide a new strategy for improving the charge separation and photocatalytic performance of ZnO /TiO2 composites by the formation of multichannel charge separated heterojunctions. ZnO /P25 composites were prepared by an incipient wetness impregnation method, and applied for the photocatalytic destruction of gaseous toluene. The ZnO /P25 composites consist of anatase TiO2（ATiO2）, rutile TiO2（RTiO2） and hexagonal zincite structures. The parasitic phase of ZnO in P25 leads to the formation of ZnO（002）/ATiO2（101）/RTiO2（110） heterojunctions that exhibit enhanced light absorption and improved multichannel electron/hole separation. ZnO /P25 heterojunctions can completely oxidize toluene into CO2 and H2O under ultraviolet light irradiation at room temperature, and show enhanced photocatalytic activity in comparison with P25 owing to the efficient electron-hole separation. Such a multichannel charge separated design strategy may provide new insight into the design of highly effective photocatalysts and their potential technological applications.

Efficient photocatalytic degradation of NO by ceramic foam air filters coated with mesoporous TiO_2 thin films

Ceramic foam air filters with three-dimensional（3D） porous structures and high surface areas were coated with mesoporous TiO 2 thin films by the reverse micellar method. The mesoporous TiO 2 thin films efficiently photocatalytically degraded nitrogen oxide（NO）. More than 92.5% of NO was degraded in a single pass for air filter samples containing different pore densities. The 3D porous structure of the ceramic air filters enhanced flow turbulence and mixing. This provided the catalytic system with excellent gas-dynamic properties,and sufficient contact between the reactant gas and catalyst surface. The higher pore density of the ceramic foam filters resulted in a higher photocatalytic rate. More adsorption sites for water vapor and the reactant and product gases improved the photocatalytic activity. The porous ceramic air filters coated with mesoporous TiO 2 had large surface areas,and thus high photocatalytic activity. This overcame the common disadvantages associated with using powdered TiO 2 photocatalysts on substrates. The 3D porous ceramic foam filters coated with mesoporous TiO 2 thin films exhibited a higher photocatalytic degradation rate of NO in air than the same thin film deposited on flat ceramic tiles. No deactivation was observed. A consistently high NO degradation rate was obtained between reaction cycles for the TiO 2-coated 3D porous ceramic filters.

Robust photocatalytic benzene degradation using mesoporous disk-like N-TiO2 derived from MIL-125(Ti)

N-doped anatase-rutile titanium dioxide(N-TiO2)is a classical semiconductor widely used in environmental remediation.Its photocatalytic performance is typically affected by its morphology,porous structure,and phase composition.Herein,disk-like mesoporous N-TiO2 was prepared by calcining MIL-125(Ti)and melamine matrix at different temperatures in air.The photocatalytic efficiency of the prepared mesoporous N-TiO2 for the photo-oxidation of gaseous benzene under visible-light irradiation was studied.With respect to light absorption and mass transfer,as-prepared N-TiO2 annealed at 500℃(MM-500)showed the best photocatalytic activity with corresponding photodegradation and mineralization efficiencies of 99.1%and 72.0%,respectively.In addition.MM-500 exhibited excellent reusability and stability in cyclic experiments,in which 84.8%of gaseous benzene could still be photodegraded after 10 experimental cycles.Furthermore,electron spin resonance analysis indicated that·OH and·O2-radicals were the dominating reactive oxygen species during the photo-oxidation process.Their excellent performance suggests that the as-prepared N-TiO2 photocatalysts can be used to eliminate volatile organic compounds.

Fe-TiO_2 and Fe_2O_3 quantum dots co-loaded on MCM-41 for removing aqueous rose bengal by combined adsorption/photocatalysis

Adsorption and photodegradation are promising approaches for removing organic pollutions.In this study,we combined these two processes by co-loading Fe-TiO2 and Fe2O3 quantum dots(QDs)on porous MCM-41,using a simple hydrolysis method.X-ray diffraction,high-resolution transmission electron microscopy,and X-ray photoelectron spectroscopy results indicated that Fe-TiO2 QDs are formed at low Fe precursor concentrations,while additional Fe2O3 QDs are formed at higher Fe precursor concentrations.The Fe2O3 and Fe-TiO2 QDs impart high adsorption capacity and high photoactivity to the porous MCM-41,respectively.Thus,their combination results in a synergic effect of the adsorption and photodegradation.The highest-performing sample exhibits excellent performance in removing rose bengal from aqueous solution.

Enhanced visible-light photocatalytic oxidation capability of carbon-doped TiO_2 via coupling with fly ash

A carbon‐doped TiO2/fly ash support(C‐TiO2/FAS)composite photocatalyst was successfully synthesized through sol impregnation and subsequent carbonization.The carbon dopants were derived from the organic species generated during the synthesis of the C‐TiO2/FAS composite.A series of analytical techniques,such as scanning electron microscopy(SEM),attenuated total reflection‐Fourier transform infrared(ATR‐FTIR)spectroscopy,X‐ray photoelectron spectroscopy(XPS),and ultraviolet‐visible diffuse reflectance spectroscopy(UV‐Vis DRS),were used to characterize the properties of the prepared samples.The results indicated that C‐TiO2 was successfully coated on the FAS surface.Coupling between C‐TiO2 and FAS resulted in the formation of Si–O–C and Al–O–Ti bonds at their interface.The formation of Si–O–C and Al–O–Ti bonds gave rise to a positive shift of the valence band edge of C‐TiO2 and enhanced its oxidation capability of photogenerated holes as well as photodegradation efficiency of methyl orange.Moreover,the C‐TiO2/FAS photocatalyst exhibited favorable reusability and separability.This work may provide a new route for tuning the electronic band structure of TiO2.

Facile synthesis of S-doped reduced TiO_(2-x) with enhanced visible-light photocatalytic performance

A different approach to synthesize visible‐light‐active sulfur(S)‐doped reduced titania(S‐TiO2‐x)using thiourea dioxide as both the S source and reductant was developed.The structure,morphology,and optical and electronic properties of the as‐prepared S‐TiO2‐x samples were examined by multiple techniques,such as X‐ray diffraction,transmission electron microscopy,X‐ray photoelectron spectroscopy,ultraviolet‐visible diffuse reflectance spectroscopy,Brunauer‐Emmett‐Teller and photocurrent measurements,and electrochemical impedance spectroscopy.The photocatalytic activity of S‐TiO2‐x was evaluated by photodegradation of organic Rhodamine B under visible‐light irradiation.The degradation rate of Rhodamine B by S‐TiO2‐x obtained by calcination was about31,2.5,and3.6times higher than those of pure TiO2,pristine TiO2‐x,and S‐doped TiO2,respectively.In addition,the as‐prepared S‐TiO2‐x exhibited long‐term stable photocatalytic performance in the degradation of Rhodamine B under visible‐light illumination.This report reveals a new approach to prepare stable and highly efficient solar light‐driven photocatalysts for water purification.

Visible-light photocatalytic selective aerobic oxidation of thiols to disulfides on anatase TiO2

This work presents the visible-light photocatalytic selective oxidation of thiols to disulfides with molecular oxygen(O2) on anatase TiO2. The high specific surface area of anatase TiO2 proved to be especially critical in conferring high photocatalytic activity. Herein, surface complexation between thiol and TiO2 gives rise to photocatalytic activity under irradiation with 520 nm green light-emitting diodes(LEDs), resulting in excellent reaction activity, substrate scope, and functional group tolerance. The transformation was extremely efficient for the selective oxidation of various thiols, particularly with substrates bearing electron-withdrawing groups(reaction times of less than 10 min). To date, the longest wavelength of visible light that this system can utilize is 520 nm by the surface complex of substrate-TiO2. Importantly, O2 was found to act as the electron and proton acceptor, rather than to incorporate into the substrates. Our findings regarding this surface complex-based photocatalytic system can allow one to understand the interaction between the conduction band electrons and O2.

3D flower-like heterostructured TiO_2@Ni(OH)_2 microspheres for solar photocatalytic hydrogen production

TiO2@Ni(OH)2 core-shell microspheres were synthesized by a facile strategy to obtain a perfect 3D flower-like nanostructure with well-arranged Ni(OH)2 nanoflakes on the surfaces of TiO2 microspheres;this arrangement led to a six-fold enhancement in photocatalytic hydrogen evolution. The unique p-n type heterostructure not only promotes the separation and transfer of photogenerated charge carriers significantly, but also offers more active sites for photocatalytic hydrogen production. A photocatalytic mechanism is proposed based on the results of electrochemical measurements and X-ray photoelectron spectroscopy.

Highly photoreactive TiO_2 hollow microspheres with super thermal stability for acetone oxidation

TiO2hollow microspheres(TiO2‐HMSs)have attracted much attention because of their high photoreactivity,low density,and good permeability.However,anatase TiO2‐HMSs have poor thermal stability.In this study,surface‐fluorinated TiO2‐HMSs were assembled from hollow nanoparticles by the hydrothermal reaction of the mixed Ti(SO4)2–NH4HF–H2O2solution at180°C.The effect of the calcination temperature on the structure and photoreactivity of the TiO2‐HMSs was systematically investigated,which was evaluated by photocatalytic oxidation of acetone in air under ultraviolet irradiation.We found that after calcination at300°C,the photoreactivity of the TiO2‐HMSs decreases from1.39×10?3min?1(TiO2‐HMS precursor)to0.82×10?3min?1because of removal of surface‐adsorbed fluoride ions.With increasing calcination temperature from300to900°C,the building blocks of the TiO2‐HMSs evolve from truncated bipyramidal shaped hollow nanoparticles to round solid nanoparticles,and the photoreactivity of the TiO2‐HMSs steady increases from0.82×10?3to2.09×10?3min?1because of enhanced crystallization.Further increasing the calcination temperature to1000and1100°C results in a decrease of the photoreactivity,which is ascribed to a sharp decrease of the Brunauer–Emmett–Teller surface area and the beginning of the anatase–rutile phase transformation at1100°C.The effect of surface‐adsorbed fluoride ions on the thermal stability of the TiO2‐HMSs is also discussed.

Effect of electron acceptors H_2O_2 and O_2 on the generated reactive oxygen species ~1O_2 and OH~· in TiO_2-catalyzed photocatalytic oxidation of glycerol

The effect of the electron acceptors H2O2 and O2 on the type of generated reactive oxygen species（ROS）,and glycerol conversion and product distribution in the TiO2-catalyzed photocatalytic oxidation of glycerol was studied at ambient conditions.In the absence of an electron acceptor,only HO^·radicals were generated by irradiated UV light and TiO2.However,in the presence of the two electron acceptors,both HO^· radical and ^1O2 were produced by irradiated UV light and TiO2 in different concentrations that depended on the concentration of the electron acceptor.The use of H2O2 as an electron acceptor enhanced glycerol conversion more than O2.The type of generated value-added compounds depended on the concentration of the generated ROS.

A review on TiO_2-based Z-scheme photocatalysts

TiO2‐based Z‐scheme photocatalysts have attracted considerable attention because of the low recombination rate of their photogenerated electron–hole pairs and their high photocatalytic efficiency.In this review,the reaction mechanism of Z‐scheme photocatalysts,recent research progress in the application of TiO2‐based Z‐scheme photocatalysts,and improved methods for photocatalytic performance enhancement are explored.Their applications,including water splitting,CO2reduction,decomposition of volatile organic compounds,and degradation of organic pollutants,are also described.The main factors affecting the photocatalytic performance of TiO2‐based Z‐scheme photocatalysts,such as pH,conductive medium,cocatalyst,architecture,and mass ratio,are discussed.Concluding remarks are presented,and some suggestions for the future development of TiO2‐based Z‐scheme photocatalysts are highlighted.

Photocatalytic Degradation of NOx Under Visible Light Irradiation Using Fe-Doped Titanium Dioxide

In order to utilize visible light in photocatalytic conversion of NOx, Fe atoms were doped in commercially available photocatalytic TiO2 powders by impregnating method. The crystal phase of TiO2 was not changed after calcination process. Analysis by both X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) indicated that Fe atoms were incorporated in TiO2 as Ti-O-Fe linkages. One significant shift of the absorption edge to a lower energy and a higher absorption in the visible light region were observed. The Fe-doped TiO2 powder exhibited photocatalytic activity for the degradation of NOx under visible light irradiation. The sample mixed with 0.2 at% Fe3+and calcined at 600 ℃ showed the best photocatalytic activity.

Preparation of TiO_2 photocatalyst loaded with V_2O_5 for O_2 evolution

TiO2 photocatalysts loaded with V2O5 were prepared via a modified hydrolysis process,and characterized by X-ray diffraction,transmission electron microscopy,Raman spectra and diffuse reflectance UV-Vis spectra measurements. The photocatalytic activity of V2O5/TiO2 was investigated by employing splitting of water for O2 evolution. The results indicate that V2O5 loading can pronouncedly improve the photocatalytic activity of TiO2 with Fe3+ as an electron acceptor under UV or visible light irradiation. The optimum mass fraction of the loaded V2O5 is 8%,and the largest speed of O2 evolution for 8%V2O5 (mass fraction) loaded TiO2 catalyst is 118.2 μmol/(L.h) under UV irradiation,and 83.7 μmol/(L.h) under visible light irradiation.