Photocatalytic degradation of azophloxine on porous La2Ti2O7 prepared by sol-gel method

Cetyltrimethyl ammonium bromide (CTAB) was used in a sol-gel route to synthesize porous lanthanum titanate. The materials are composed of perovskite La₂Ti₂O₇ in monoclinic system. The addition of CTAB does not cause phase transformation, but leads to a slight decreasing tendency of La₂Ti₂O₇ crystallite size. Both the pore volume and pore size distribution range are enlarged after using CTAB. The sample obtained with 4 g CTAB has the maximum BET specific surface area of 42.4 m²/g. When the amount of CTAB is less than 4 g, the increase in photocatalytic degradation efficiency is almost in linear relationship to the amount of CTAB. The reaction rate constants are 0.0032, 0.0116 and 0.0237 min⁻¹ on the La₂Ti₂O₇ samples obtained using 0, 2 and 4 g CTAB. The functional groups in azophloxine molecule are decomposed during photocatalytic oxidation with extending irradiation time.     

N-TiO2协同单过硫酸氢钾光催化降解氧氟沙星的研究

分别以尿素、钛酸四丁酯为氮源、钛源,利用溶剂热法制备氮掺杂二氧化钛光催化剂(N-TiO2),用XRD、SEM、IR、UV-vis DRS等对改性前后的催化剂进行表征.以LED灯为光源,氧氟沙星(OFX)为模型污染物,考察了N-TiO2协同单过硫酸氢钾(PMS)光催化降解OFX的性能.研究表明,当氮、钛摩尔比为0.6,O...     

The effects of cerium doping concentration on the properties and photocatalytic activity of bimetallic Mo/Ce catalyst

In this study, the characterization and photocatalytic activity of MoO₃ nanoparticles doped with various doping concentrations of cerium have been investigated. The Fourier transform infrared (FT-IR) spectra of the prepared catalysts confirmed that MoO₃ particles have been successfully doped by cerium. Field emission scanning electron microscopy (FESEM) was performed to visualize the surface morphology of the obtained catalysts. The XRD patterns suggested that the crystallinity of the sample with the lowest doping concentration of 15 mol % was higher in comparison with samples of higher doping concentrations. The volume-averaged crystal sizes of the obtained catalysts were calculated to be 25, 28, and 32 nm for 15, 35, and 60 mol % samples, respectively. The photocatalytic activity along with the reaction kinetics of Ce-doped MoO₃ nanoparticles have also been investigated through the dye degradation of methyl orange. The synthesized Ce-doped MoO₃ particles with the lowest dopant concentration of 15 mol % exhibited the highest photocatalytic activity for methyl orange dye degradation. It was observed that photo-degradation activity decreased with an increase in the doping concentration of cerium. The predicted rate constants for samples with 15, 35, and 60 mol % doping concentrations were found to be 0.0432, 0.035, and 0.029 min^–1, respectively.     

Separation of 97Ru from niobium target using PEG based aqueous biphasic systems

Separation of no-carrier-added (NCA) ⁹⁷Ru from bulk niobium target has been carried out for the first time using green analytical technique, aqueous biphasic system. 50 % (w/v) polyethylene glycol (PEG)-4000, against 2 M solutions of various salts such as Na-citrate, Na-tartarate, Na-malonate, Na₂CO₃, NaHSO₃, Na₂SO₄, Na₂S₂O₃ K₂HPO₄, K₃PO₄, K₂CO₃ and 4 M KOH were employed at room temperature for the extraction of NCA ⁹⁷Ru from bulk niobium. Influence of molecular weight of PEG rich phase as well as pH of some salt rich phase (e.g., Na-tartarate) on the extraction behaviour of NCA ⁹⁷Ru into PEG rich phase was also observed. In the presence of sodium-tartarate salt solution, when volume of PEG-4000: Na-tartarate was 3:1, 91 % of NCA ⁹⁷Ru was extracted into the PEG rich phase without any contamination of niobium target. Dialysis of PEG rich phase containing NCA ⁹⁷Ru was carried out against deionised water to obtained pure NCA ⁹⁷Ru.     

Synthesis of Bi-doped TiO2 Nanotubes and Enhanced Photocatalytic Activity for Hydrogen Evolution from Glycerol Solution

Bi‐doped TiO₂ nanotubes with variable Bi/Ti ratios were synthesized by hydrothermal treatment in 10 mol·L^?1 NaOH (aq.) through using Bi‐doped TiO₂ particles derived from conventional sol‐gel method as starting materials. The effects of Bi content on the morphology, textural properties, photo absorption and photocatalytic activity of TiO₂ nanotubes were investigated. The scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD) and X‐ray photoelectron spectroscopy (XPS) observations of the obtained samples revealed the formation of titanate nanotube structure doped with Bi, which exists as a higher oxidation state than Bi³⁺. Bi‐doping TiO₂ nanotubes exhibited an extension of light absorption into the visible region and improved photocatalytic activities for hydrogen production from a glycerol/water mixed solution as compared with pure TiO₂ nanotubes. There was an optimal Bi‐doped content for the photocatalytic hydrogen production, and high content of Bi would retard the phase transition of titanate to anatase and result in morphology change from nanotube to nanobelt, which in turn decreases the photocatlytic activity for hydrogen evolution.     

Preparation,Characterization and Photocatalytic Activity of Fe,La Co-doped Nanometer Titanium Dioxide Photocatalysts

A series of photocatalysts of un-doped, single-doped and co-doped nanometer titanium diox-ide (TiO₂) have been successfully prepared by template method using Fe(NO₃)₃·9H₂O, La(NO₃)₃·6H₂O, and tetrabutyl titanate as precursors and glucan as template. Scanning electron microscopy, X-ray diffraction, and N₂ adsorption-desorption measurement were em-ployed to characterize the morphology, crystal structure and surface structure of the samples. The photo-absorbance of the obtained catalysts was measured by UV-Vis absorption spec-troscopy, and the photocatalytic activities of the prepared samples under UV and visible light were estimated by measuring the degradation rate of methyl orange in an aqueous solu-tion. The characterizations indicated that the prepared photocatalysts consisted of anatase phase and possessed high surface area of ca. 163-176 m²/g. It was shown that the Fe and La co-doped nano-TiO₂ could be activated by visible light and could thus be used as an effective catalyst in photo-oxidation reactions. The synergistic effect of Fe and La co-doping played an important role in improving the photocatalytic activity. In addition, the possibil-ity of cyclic usage of co-doped nano-TiO₂ was also confirmed, the photocatalytic activity of codoped nano-TiO₂ remained above 89.6% of the fresh sample after being used four times.     

掺镁钛酸钡纳米棒的水热合成和光催化性能

用水热法制备掺镁钛酸钡(Ba1-xMgxTiO3(x=0,0.10,0.20,0.30,0.40),BMT)纳米粉体。运用X射线衍射仪(XRD)、场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)、紫外可见漫反射光谱技术(DRS)等手段对样品进行了表征,并在可见光照射下于溶液中考察了其光催化降解甲基橙反应活性。结果表明,通过控制氢氧根浓度可以得到不同形貌的纳米粉体。基于不同条件下制备的样品的微结构分析,提出了这些不同形貌的形成机制。制备出的BMT材料的带隙能约为2.61 eV。光催化反应结果表明BMT的光催化活性比掺氮TiO2高得多。OH-浓度为8 mol·L-1时制备的BMT纳米棒光催化效率最高,经可见光照射360 min,浓度为0.01 mmol·L-1甲基橙溶液的降解率可达到93.0%,且循环使用4次后,其光催化活性并没有明显降低,表明BMT是一种稳定有效的可见光催化剂.     

A credible role of copper oxide on structure of nanocrystalline mesoporous titanium dioxide

Copper oxide-titania catalysts with nanocrystalline mesoporous structure were prepared by sol-gel technique using tetra isopropyl ortho titanate (TiPT) as the inorganic precursor and amino-2 ethanol as the swelling agent. Characterization was performed using X-ray diffraction (XRD), fourier transformed infrared spectra (FTIR), scanning electron microscopy (SEM), diffuse reflectance UV-Vis spectroscopy (DRS), and N₂ adsorption-desorption measurements. It was found that CuO (0.025–0.1 mol ratio) has some effect on the particle size, surface area, pore-volume, pore-diameter, crystallinity of the particles, and crystalline phase of TiO₂ nanocrystalline. The results indicated that 0.1 CuO-TiO₂ had higher surface area and total pore volume among all CuO-TiO₂ samples. The SBET value of 0.1 mol ratio CuO-load TiO₂ sample is approximately similar to that of Degussa P25 while its pore volume (0.1198 cm³ g^?1) is larger than Degussa P25 due to production of large number of pores. Therefore, the physical property of 0.1 CuO-TiO₂ catalyst is comparable with Degussa P25.At 823K, the 0.1 mol ratio CuO-load TiO2 sample shows the phase transformation from anatase to rutile in the ratio of 1:1.1. The synthesized CuO-TiO₂ nanocrystalline will be able to show photocatalytic reaction under visible light.     

Coal Combustion Synthesis of Coal Cinder-Supported TiO<Subscript>2</Subscript> with Commendable Photocatalytic Activity

Coal cinder-supported TiO₂ photocatalysts were synthesized via a novel coal combustion method. As-obtained samples were characterized by XRD, SEM, EDS mapping, Raman spectra, FTIR and DRS, and their photocatalytic performances were evaluated by degradation of methylene blue (MB) and methyl orange (MO) under UV–Vis light illumination. The results revealed that mixed-phases TiO₂ with adjustable anatase–rutile ratio could be obtained by adjusting the amount of precursor tetrabutyl titanate, which was uniformly covered on the coal cinder. These coal cinder-supported TiO₂ photocatalysts exhibited commendable photocatalytic activity. Among them, the indexed CCT-7.5 sample presented the maximum of activity, which can be attributed to the optimal phase composition of TiO₂. The present work provided a novel synthetic route to fabricate immobilized photocatalysts, which might be extended to the preparation of other functional materials.     

Mesoporous titania photocatalyst: effect of relative humidity and aging on the preparation of mesoporous titania and on its photocatalytic activity performance

Mesoporous TiO₂ has been synthesized by the sol–gel method, using a nonionic triblock copolymer P123 as surfactant template under acidic conditions. The as-prepared samples were characterized by thermogravimetry–differential thermal analysis (TG–DTA), nitrogen absorption–desorption (BET), field emission scanning electron microscopy, and transmission electron microscopy. The photocatalytic activity of the mesoporous TiO₂ was evaluated by degradation of methylene blue under high-intensity UV light irradiation; the amount of methylene blue was measured by UV–visible spectroscopy. TG–DTA analysis revealed that the surfactant had been removed partly in as-synthesized samples. BET analysis proved that all the samples retained mesoporosity with a narrow pore-size distribution (4.5–6.3 nm) and high surface area (103–200 m²/g). All calcined mesoporous TiO₂ had high photocatalytic activity in the photodegradation of methylene blue.     

Structural,optical and photocatalytic activity of cerium doped zinc aluminate

Zinc aluminate and cerium-doped zinc aluminate nanoparticles are synthesised by co-precipitation method. Ammonium hydroxide is used as a precipitating agent. The synthesised compounds are characterised by powder X-ray diffraction (XRD), Fourier transform Infrared spectroscopy (FT-IR), Ultraviolet diffuse reflectance spectroscopy (UV-DRS), Thermogravimetric analysis (TGA), Scanning electron microscopy (SEM) and Surface area measurements. The photocatalytic activity of zinc aluminate and cerium doped zinc aluminate nanoparticles are studied under the UV light and visible light taking methylene blue as a model pollutant. The amount of catalyst, concentration of dye solution and time are optimised under UV-light. Degradation of methylene blue under the UV-light is found to be 99% in 20 min with 10 mg of cerium doped catalyst. Compared to visible light degradation, the degradation of dye under UV-light is higher. Cerium doping in zinc aluminate (ZnAl₂O₄:Ce³⁺) increased the photocatalytic activity of zinc aluminate.     

Preparation and Visible-Light Photocatalytic Activity of FeTPP-Cr-TiO2 Microspheres

Tetraphenyl-porphyrin iron (FeTPP) was chosen to sensitize Cr doped TiO₂ (Cr-TiO₂) nanoparticles, a novel multimodified photocatalyst FeTPP-Cr-TiO₂ with excellent visiblelight photocatalytic activity was successfully synthesized. The FeTPP-Cr-TiO₂ microspheres were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electronic microscopy, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectra and N₂ adsorption-desorption isotherms. The photocatalytic activity of FeTPP-Cr-TiO₂ was evaluated by degradations of methylene blue in aqueous solution under irradiation with Xe lamp (150 W). The results showed that the FeTPP-Cr-TiO₂ multimodified photocatalyst was anatase phase with high specific surface area (74.7 m²/g), and exhibited higher photocatalytic degradation efficiency than Cr-TiO₂ and FeTPP-TiO₂. The photocatalytic degradations of three quinolone antibiotics (lomefloxacin, norfloxacin, and ofloxacin) were further estimated for the feasibility of practical application of catalyst in wastewater treatment. It is desirable that photodegradation of antibiotics with FeTPP-Cr-TiO₂ achieved pretty high degradation rates and all followed the pseudo first-order reaction model, and the rate constants k of 3.02×10^-2, 2.81×10^-2, and 3.86×10^-2 min^-1 and the half-lifes t_1/2 of 22.9, 24.6, and 17.9 min were achieved respectively.     

Novel organic/inorganic PDI-Urea/BiOBr S-scheme heterojunction for improved photocatalytic antibiotic degradation and H2O2 production

The matched energy band structure and efficient carrier separation efficiency are the keys to heterogeneous photocatalytic reactions. A novel organic/inorganic step scheme (S-scheme) heterojunction PDI-Urea/BiOBr composite photocatalyst was constructed by simple solvothermal reaction combined with in-situ growth strategy. The composite photocatalyst not only has high chemical stability, but also can generate and accumulate a large number of active species (h⁺, ^?O₂^?, ^?OH, H₂O₂). PDI-Urea/BiOBr showed higher photocatalytic activity for the degradation of antibiotic such as ofloxacin (OFLO), tetracycline (TC) and the production of H₂O₂ in the spectral range of 400–800 nm. The apparent rate constant of 15% PDI-Urea/BiOBr for photocatalytic degradation of TC (or OFLO) was 2.7 (or 2.5) times that of pure BiOBr and 1.7 (or 1.8) times that of pure PDI-Urea. The H₂O₂ evolution rate of 15% PDI-Urea/BiOBr was 2.5 times that of PDI-Urea and 1.5 times that of BiOBr, respectively. This work has formed a mature S-scheme heterojunction design thought and method, which offers new visions for the development of heterogeneous photocatalysts.     

锌离子掺杂的二氧化钛介孔空心微球的制备及光催化性能

以二氧化硅为模板,钛酸四丁酯（TBOT）为钛源,硝酸锌为锌源,采用溶胶凝胶法制备了锌离子掺杂的介孔二氧化钛空心微球。采用X射线衍射（XRD）、比表面积（BET）、透射电镜（TEM）、扫描电镜（SEM）和X射线光电子能谱（XPS）等技术对样品进行表征,以亚甲基蓝（MB）的光催化降解为目标反应评价其光催化活性。结果表明,去核之后的复合微球为空心微球,壁厚为20nm左右。钛酸四丁酯溶液的滴加时间对微球的形貌影响较大,当滴加时间大于15min时,可以得到结构清晰的空心微球。用氢氧化钠溶液去除二氧化硅核,反应90min,二氧化硅可以被完全去除。X射线衍射表明,实验得到的掺杂锌离子的空心微球和没有掺杂锌离子的空心微球都是锐钛矿。当锌离子的摩尔分数为0.3%时,二氧化钛空心微球的晶粒尺寸最小,比表面积最大,催化亚甲基蓝降解的效率最高。     

锌离子掺杂的二氧化钛介孔空心微球的制备及光催化性能

以二氧化硅为模板,钛酸四丁酯(TBOT)为钛源,硝酸锌为锌源,采用溶胶凝胶法制备了锌离子掺杂的介孔二氧化钛空心微球。采用X射线衍射(XRD)、比表面积(BET)、透射电镜(TEM)、扫描电镜(SEM)和X射线光电子能谱(XPS)等技术对样品进行表征,以亚甲基蓝(MB)的光催化降解为目标反应评价其光催化活性。结果表明,去核之后的复合微球为空心微球,壁厚为20 nm左右。钛酸四丁酯溶液的滴加时间对微球的形貌影响较大,当滴加时间大于15 min时,可以得到结构清晰的空心微球。用氢氧化钠溶液去除二氧化硅核,反应90 min,二氧化硅可以被完全去除。X射线衍射表明,实验得到的掺杂锌离子的空心微球和没有掺杂锌离子的空心微球都是锐钛矿。当锌离子的摩尔分数为0.3%时,二氧化钛空心微球的晶粒尺寸最小,比表面积最大,催化亚甲基蓝降解的效率最高。     

Preparation of hollow nanospheres g-C3N4 loaded by Keggin type Cu mono-substituted heteropoly acid with enhanced visible-light harvesting and electron transfer properties for high-efficiency photocatalysis

Abstract

A series of heterojunction catalysts (CuCN-X) were successfully fabricated by loading the different amounts of Keggin type Cu mono-substituted heteropoly acid (HPW₁₁Cu) on the surface of hollow nanospheres g-C₃N₄ (HSCN). The HSCNs were prepared by using SiO₂ as a hard template. The chemical structure, porosity, morphology and electronic property of the prepared catalysts were investigated using XRD, SEM, N₂-absorption isotherm and XPS. The results indicated that the modified HSCN show prominent absorption in the visible light range and decrease the band gap. The greatly enhanced photocatalytic activity of obtained CuCN-X have been shown by the degradation of Rhodamine B (RhB), reduction of CO₂ and production of photocatalytic hydrogen under visible light irradiation. More significantly, CuCN-15 has shown significantly improved photocatalytic performance at 4.5, 3.5 and 3.3 times higher that of than HSCN for the degradation of RhB, reduction of CO₂ and production of photocatalytic hydrogen, respectively. Furthermore, the mechanism for the enhanced photocatalytic activity of CuCN-X is proposed to be due to the formation of heterojunction. The electrons can be rapidly transferred from HSCN to HPW₁₁Cu, in which facilitate charge separation and charge transfer.     

Passivation of zinc coatings in cerium-containing solutions

Process was developed for no-chromate passivation of zinc coatings in a solution containing 20-40 g L^-1 of cerium nitrate, 5-25 mL L^-1 H₂O₂, and 2-8 g L^-1 of an additive (8-10 g L^-1 of malic acid and 4-8 g L^-1 of sodium nitrate) at a temperature of 40-60°C and pH 2.5-3.5. It was shown that cerium-containing passivating coatings on zinc-plated steel articles compare well in corrosion resistance and protecting capacity with iridescent chromate coatings. It was found that cerium-containing coatings are capable of self-healing and sustain a thermal shock without degradation of their characteristics.     

金红石相TiO2纳米棒的氢化处理及其光催化活性

以钛酸四丁酯为钛源,通过盐酸调制的水热法制备出了具有棒状结构的金红石相纳米TiO₂,并进一步进行高温氢化处理. 采用X射线衍射（XRD）,透射电镜（TEM）,紫外-可见-近红外漫反射（UV-Vis-NIR DRS）,电子顺磁共振（EPR）和表面光伏（SPS）等测试手段对样品进行表征,以气相乙醛和液相苯酚为目标污染物考察催化剂的光催化活性. 结果表明：随着高温氢化处理时间的延长,TiO₂样品的可见光吸收逐渐增强,其颜色逐渐由白色转变成灰色,这主要与引入的Ti³⁺/氧空位缺陷有关. 表面光电压谱和羟基自由基测试表明,适当时间的氢化处理有利于光生电荷的分离. 在光催化氧化降解气相乙醛和液相苯酚过程中,经适当时间氢化处理的样品表现出高的可见光催化活性. 并且可见光催化活性的规律与紫外光下的是一致的. 这是因为氢化处理后在导带底下方引入了缺陷能级,拓展了可见光响应. 过度的氢化处理会在TiO₂导带下方引入较低的缺陷能级,使光生电荷的复合加剧,导致光催化活性降低.     

UV-assisted degradation of propiconazole in a TiO2 aqueous suspension: identification of transformation products and the reaction pathway using GC/MS

Photocatalytic degradation of propiconazole, a triazole pesticide, in the presence of titanium dioxide (TiO₂) under ultraviolet (UV) illumination was performed in a batch type photocatalytic reactor. A full factorial experimental design technique was used to study the main effects and the interaction effects between operational parameters in the photocatalytic degradation of propiconazole in a batch photo-reactor using the TiO₂ aqueous suspension. The effects of catalyst concentration (0.15–0.4 gL^?1), initial pH (3–9), initial concentration (5–35 mg L^?1) and light conditions were optimised at a reaction time duration of 90 min by keeping area/volume ratio constant at 0.919 cm² mL^?1. Photocatalytic oxidation of propiconazole showed 85% degradation and 76.57% mineralisation under UV light (365 nm/30 Wm^?2) at pH 6.5, initial concentration 25 mg L^?1 and constant temperature (25 ± 1 °C). The Langmuir–Hinshelwood kinetic model has successfully elucidated the effects of the initial concentration on the degradation of propiconazole and the data obtained are consistent with the available kinetic parameters. The photocatalytic transformation products of propiconazole were identified by using gas chromatography–mass spectrometry (GC/MS). The pathway of degradation obtained from mass spectral analysis shows the breakdown of transformation products into smaller hydrocarbons (m/z 28 and 39).     

Chalcogen-doped zinc oxide nanoparticles for photocatalytic degradation of Rhodamine B under the irradiation of ultraviolet light

In the present work, the chalcogen (Se²⁺)-doped ZnO nanoparticles (SeZO-NPs) were synthesized using sol-gel precipitation method and tested for photocatalytic degradation of Rhodamine B (RhB). X-ray diffraction pattern of SeZO-NPs showed the hexagonal wurtzite crystal structure regardless of Se concentration. The band edge and defect-level emissions of SeZO-NPs were determined by using the photoluminescence spectra with the excitation source of 370 nm. The bandgap, E_g, of SeZO-NPs was measured from diffused reflectance spectroscopy, which increased from 3.22 to 3.26 eV as Se concentration increased from 0 to 10 wt.%. The highest specific surface area and lowest pore size of 5-SeZO-NPs were observed to be 36.42 m²/g and 13.48 nm, respectively. The photocatalytic degradation of SeZO-NPs was measured under the illumination of ultraviolet (UV) light. The double donor (Se) played an important role toward photodegradation of RhB via reducing the recombination of charge carriers. The highest photocatalytic degradation (98.23%) and mineralization were achieved for the sample 5-SeZO (Se: 5 wt.%). The improved photocatalytic performance of 5-SeZO was attributed to the optimum Se dopant concentration for the production of more reactive oxygen species because of effective separation of charge carriers in UV light.