Industrial TiO2 based nacreous pigments as functional building materials: Photocatalytic removal of NO

In this paper, the photocatalytic activity of industrial titanium dioxide (TiO₂) based nacreous pigments was researched as functional building materials for photocatalytic NO remove. Three industrial TiO₂ based nacreous pigments were selected to estimate the photocatalytic activity for NO remove. This study is a good proof that pearlescent pigments can eliminate NO, and its performance is positively correlated with its titanium dioxide content. And this research will widen the application of nacreous pigments in functional building materials, and provide a new way to eliminate in door nitric oxide pollution.     

Photocatalytic oxidation of NO x over visible-light-responsive nitrogen-doped TiO2

In order to utilize visible-light in photocatalytic conversion of NO _x , nitrogen atoms were doped in commercially available photocatalytic TiO₂ powders by impregnating method. The crystal structures of TiO₂ were not changed after calcination process. Analysis by X-ray photoelectron spectroscopy (XPS) indicated that N atoms were incorporated in the bulk phase of TiO₂ as N-Ti-O linkages. A significant shift of the absorption edge to a lower energy and a higher absorption in the visible-light region were observed. These N-doped TiO₂ powders exhibited photocatalytic activity of the oxidation of NO _x under visible-light irradiation. The sample mixed with 20 wt% ammonium carbonate and calcined in 600 °C showed best photocatalytic activity and its activity can be restored by rinsing with water after long-term operation.     

Printing nano TiO2 on large-sized building materials: Technologies,surface modifications and functional behaviour

The industrial feasibility of large-sized, photocatalytic building materials was assessed by the adoption of suitable, fast and environmental friendly technological solutions. Nanostructured TiO₂ coatings can be realized by ink-jet or roller printing of nano-anatase suspensions by modifying, in one single step, the chemistry and microstructural features of products. Functional coatings must be consolidated through additional thermal steps, which necessarily entail modifications of the current production cycles of ceramic tiles. This is due to the fact that the direct functionalization of unfired ceramics is detrimental to the photocatalytic performance. The microstructure of coatings depends on deposition technologies and processing conditions. However, photoactive materials that also display superhydrophilic behaviour can be obtained by employing much lower amounts of TiO₂ than 1.0 g m^?2, and by annealing at temperature as low as 400–500 °C. A limited increase of the cost of products is involved, especially in the case of large-sized elements.     

Photocatalytic NOx abatement by calcium aluminate cements modified with TiO2: Improved NO2 conversion

Photocatalytic activity of TiO₂ was studied in two types of calcium aluminate cement (CAC) under two different curing regimes. The effect of the TiO₂ addition on the setting time, consistency and mechanical properties of the CACs was evaluated. The abatement of gaseous pollutants (NO_x) under UV irradiation was also assessed. These cementitious matrices were found to successfully retain NO₂: more abundant presence of aluminates in white cement (w-CAC, iron-lean) helped to better adsorb NO₂, thus improving the conversion performance of the catalyst resulting in a larger NO_x removal under UV irradiation. As evidenced by XRD, SEM, EDAX and zeta potential analyses, the presence of ferrite in dark cement (d-CAC, iron-reach) induced a certain chemical interaction with TiO₂. The experimental findings suggest the formation of new iron titanate phases, namely pseudobrookite. The reduced band-gap energy of these compounds compared with that of TiO₂ accounts for the photocatalytic activity of these samples.     

纳米二氧化钛光催化材料治理工业废水的研究

工业废水是环境污染最广泛、最严重的领域之一,为能有效降解废水中有机污染物,文章通过调节pH,以水热合成法制备了纳米TiO_2光催化材料。利用X射线衍射仪、扫描电子显微镜、激光粒度仪及紫外-可见光光度计进行了检测与表征。结果表明:当pH=3时,获得由锐钛矿和板钛矿组成的双相纳米二氧化钛光催化材料,晶粒尺寸为12.6 nm,比表面积为278.4 m~2/Kg,光催化剂的降解率为96%,能彻底降解以甲基橙模拟的污染物。     

三氧化二铁包膜云母钛珠光颜料的研制

采用沸腾水解法制备三氧化二铁包膜云母钛珠光颜料。通过实验,考察了不同工艺条件,即ｐＨ值、沉积量、反应时间等产品质量的影响。并以ＸＲＤ和ＳＥＭ技术检测产品的物相及微观结构。最佳工艺条件为：ｐＨ值２～４,反应时间１～１．５ｈ,焙烧温度６７０℃,三氧化二铁沉积是不同,可得到不同颜色的珠光颜料。     

二氧化钛光催化降解塑料研究进展

从提高二氧化钛(TiO2)光催化效率及太阳光利用率的各种改性及TiO2固相光催化降解的机理等方面综述了近年来国内外TiO2光催化降解塑料的研究进展,探讨了光催化降解塑料的应用前景及存在的问题。     

Photocatalytic degradation of iron–cyanocomplexes by TiO2 based catalysts

The removal of iron–cyanocomplexes in industrial effluents is a difficult process, due to the resistance of these compounds to conventional treatments for cyanide wastewater detoxification. The mechanism of both the homogeneous photolysis of these compounds and their heterogeneous photocatalytic oxidation with Degussa P25 TiO₂ and silica-supported TiO₂ photocatalysts has been investigated. The activities of the tested catalysts for complexed cyanide degradation were found to be different from those observed for free cyanide photo-oxidation. The best activity was found for the photocatalyst synthesized by supporting 20 wt.% of TiO₂ on SBA-15 silica as compared with the commercial catalyst Degussa P25 and the other supported catalysts tested. On the basis of detected intermediate species, a mechanism for iron–cyanocomplexes photodegradation is suggested. The influence of the textural properties of the support and titania loading on the process is discussed. The results point out that the high activity observed, when SBA-15 is used as support of TiO₂, seems to be related to the microporosity of the material acting as molecular sieve, which avoids the deactivation of the semiconductor. The porous structure of the SBA-15 material limits the access of the iron–cyanocomplexes to the TiO₂ particles whereas the free cyanides homogeneously released can reach the semiconductor surface, being subsequently oxidized to cyanate.     

Atomically dispersed Pd on nanostructured TiO2 for NO removal by solar light

Reducing the particle size of noble metals on ceramic supports can maximize noble metal performance and minimize its use. Here Pd clusters onto nanostructured TiO₂ particles are prepared in one step by scalable flame aerosol technology while controlling the Pd cluster size from a few nanometers to that of single atoms. Annealing such materials at appropriate temperatures leads to solar photocatalytic NO_x removal in a standard ISO reactor up to 10 times faster than that of commercial TiO₂ (P25, Evonik). Such superior performance can be attained by only 0.1 wt.% Pd loading on TiO₂. Annealing these flame‐made powders in air up to 600 °C decreases the amorphous TiO₂ fraction and increases its crystal and particle sizes as observed by x‐ray diffraction (XRD) and N₂ adsorption. The growth of single Pd atoms to Pd clusters on TiO₂ prepared at different Pd loading and annealing conditions was investigated by scanning transmission electron microscopy and XRD. The single Pd atoms and clusters on TiO₂ are stable up to, at least, 600 °C for 2 h in air but at 800 °C they grow into PdO nanoparticles whose fraction is comparable with the nominal Pd loading. Hence, most of Pd atoms are on the TiO₂ surface where at 800 °C they diffuse and coalesce. Diffuse reflectance infrared Fourier transform spectroscopy reveals NO adsorption on single, double, three and fourfold coordinated Pd atoms depending on their synthesis and annealing conditions. The peak intensity of NO adsorption sites involving multiple Pd atoms is substantially lower in TiO₂ containing 0.1 wt.% than 1 wt.% Pd but that intensity from single Pd atoms is comparable. This indicates the dominance of isolated Pd atoms compared to clusters in Pd/TiO₂ containing 0.1 wt.% Pd that match or exceed the photocatalytic NO_x removal of Pd/TiO₂ of higher Pd contents. © 2016 American Institute of Chemical Engineers AIChE J, 63: 139–146, 2017     

Photocatalytic Properties of Silica-supported TiO2

TiO₂ supported on SiO₂ surface is effective on the recovery of photocatalyst, morphological control, and coating on the substrate. Furthermore, it shows much higher photocatalytic activity than pure TiO₂. The silica support is quite influential on the surface properties of TiO₂ supported on SiO₂. The enhanced photocatalytic activity of TiO₂–SiO₂ could be explained by the effects of surface area, adsorption, band-gap energy and local structure. However, it is difficult to say which one is the most important factor responsible for the photocatalytic property of TiO₂–SiO₂. For example, the reduction of particle size could effect on both of the surface area and band-gap energy. And, Ti–O–Si bonds could modify the band-gap energy and local structure. Therefore, the photocatalytic properties of TiO₂–SiO₂ should be expressed by sum of many factors such as surface area, adsorption, band-gap energy and local structure.     

Synergetic catalytic removal of Hg0 and NO over CeO2(ZrO2)/TiO2

A series of CeO₂(ZrO₂)/TiO₂ monolith catalysts were investigated for catalytic oxidation of Hg⁰ and NH₃-SCR of NO. Effect of flue gases components on catalytic oxidation of Hg⁰ was mainly studied. Results showed that the CeO₂(ZrO₂)/TiO₂ catalyst exhibited high efficiency for catalytic oxidation of Hg⁰ at 240–400 °C without adding other oxidant, and its catalytic performance for NH₃-SCR of NO was not affected. NH₃ had slight inhibitory effect while SO₂ and NO had no influence on catalytic oxidation of Hg⁰, but O₂ obviously improved catalytic oxidation of Hg⁰ for its oxidation susceptibility.     

纳米TiO2光催化降解工业污水的因素权重评价

对于光催化氧化降解处理工业污水的工艺条件或因素的权重评价是达到优良处理效果的关键性技术之一。将模糊数学中的模糊综合评判法与信息工程学中的熵权结合而建立地熵权模糊综合评判法来对光催化氧化降解过程的影响因素权重进行评价,结果表明,该种方法的评价结果和参考文献中的评价结果基本吻合。因此,熵权模糊综合评判法在光催化降解因素分析中具有一定的可靠性和可参考价值。     

TiO2光催化剂研究进展

TiO2具有光催化效率高、稳定性好、不容易产生二次污染和成本低等特点，在众多半导体光催化材料中表现优异，并在抑菌抗癌、制备氢气、废水处理、太阳能电池、防晒、自清洁等方面有着非常广泛的应用。本文综述了近年来国内外TiO2光催化材料的研究现状与进展，并从TiO2的光催化反应机理出发详细探讨了TiO2光催化剂的活性影响因素，进而系统地综述了目前TiO2光催化剂的改性方法，阐述了改性过程中所面临的问题，并对未来发展给出了合理的建议。     

Pd-doped TiO2@polypyrrole core-shell composites as hydrogen-sensing materials

A core-shell composite consisting of polypyrrole (PPy) nanofibers and TiO₂ was synthesized by using PPy nanofibers as the core and TiO₂ as the shell. The TiO₂@PPy composite substrate was doped with Pd nanoparticles via chemical reduction. The resulting Pd–TiO₂@PPy nanocomposite was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Brunauer–Emmett–Teller (BET) adsorption analysis before it was utilized to fabricate a hydrogen sensor. Compared with sensors based on TiO₂@PPy or PPy, the Pd–TiO₂@PPy sensor was highly sensitive and selective to hydrogen gas, exhibiting a fast response time in air at room temperature. The Pd–TiO₂@PPy-based sensor exhibited a sensitivity of 8.1% toward 1 vol% of H₂ gas, which is much larger than the sensitivities of sensors based on only TiO₂@PPy and PPy nanofibers. The excellent reproducibility, stability and selectivity of the Pd–TiO₂@PPy nanocomposite make it a high potential candidate for hydrogen sensors.     

Photocatalytic oxidation of ethane over TiO2

The photocatalytic oxidation of ethane has been studied at room temperature using a specially designed stirred reactor. The effect on the rate of ethane oxidation, of the partial pressure of reactants, the UV light intensity, the amount of catalyst and the residence time has been evaluated. Running the experiments according to a factorial plan permitted to deduce from a limited amount of experimental data the complete kinetic model corresponding to the steady state adsorption mechanism. On the basis of the experimental critical mass of the catalyst (1.5 g), an expression permitting calculation of the critical mass of the catalyst (TiO₂) for any type of photocatalytic reactor has been derived.     

TiO2光催化薄膜的制备法

介绍了溶胶凝胶法制备ＴiＯ２光催化薄膜的特点,源理和方法,并对ＴiO2在非耐热基材表面的低温涂膜技术作了简要评述。     

提高二氧化钛光催化性能的途径

本文介绍了TiO2的光催化特性,对如何提高其光催化性能及材料的实用性作了简要评述.     

Photocatalytic Degradation of Polyethylene Plastic with Polypyrrole/TiO2 Nanocomposite as Photocatalyst

The photocatalytic degradation of polyethylene (PE) plastic was carried out directly under the sunlight irradiation with polypyrrole/TiO₂ (PPy/TiO₂) nanocomposite as photocatalyst, which prepared by sol-gel and emulsion polymerization methods. The photocatalytic degradation efficiency was determined by weight loss monitoring, gel permeation chromatography (GPC), atomic force microscopic (AFM) and FT-IR analysis. The photocatalytic degradations of PE plastic with pure TiO₂ and PPy were also investigated and compared with that of PPy/TiO₂. It was noticed that irradiating the PE plastic for 240 h by sunlight reduced its weight up to 35.4% and 54.4% of M _w, respectively. The AFM images showed the formation of cavities on PE plastic surface. FT–IR spectroscopic studies indicated that a strong interaction existed between the interface of PE and PPy/TiO₂ and caused the degradation of PE. The photocatalytic degradation mechanism was also discussed briefly.     

二氧化钛光催化降解硝基苯废水

用紫外灯作为光源,以锐钛型TiO2为催化剂降解硝基苯。探讨了光照时间、初始pH值、初始浓度、催化剂用量和载铜TiO2复合催化剂对光催化降解的影响。结果表明,TiO2用量为3.0 g/L,pH为3,硝基苯初始浓度为40.6 mg/L,室温条件下,光照6 h硝基苯降解率为80.6%;掺杂1%Cu2+(摩尔分数)的TiO2复合催化剂,光催化活性高于纯TiO2,其光催化降解率较TiO2提高14.5%。