Modification of carbon-coated TiO2 by iron to increase adsorptivity and photoactivity for phenol

Carbon-coated TiO(2) modified by iron, were prepared from TiO(2) of anatase structure and PET modified by FeC(2)O(4). Catalysts were prepared by mixing powders of TiO(2) and modified PET and heating at different temperatures, from 400 to 800 degrees C under flow of Ar gas. High adsorption of phenol was observed on the catalyst heated at 400 degrees C, confirmed by FT-IR analysis. On this catalyst, fast rate of phenol decomposition was achieved by addition of small amount of H(2)O(2) to the reaction mixture. Phenol decomposition proceeded mainly through the direct oxidation of phenol species adsorbed on the catalyst surface due to the photo-Fenton reaction. Iron-modified carbon-coated TiO(2) catalysts heated at 500-800 degrees C showed almost no phenol adsorption or oxidation.     

一种光催化体系光催化降解苯胺的研究

以钛酸丁酯为原料．以膨润土为载体,用酸性溶胶法合成TiO2纳米复合物,并利用该复合物作催化剂,在H2O2存在下进行光催化降解苯胺溶液。结果表明,该催化剂在UV／H2O2系统中对苯胺溶液有很好的光催化降解效果,其效果优于纯TiO2;H2O2的存在提高了苯胺光催化降解速率,在本实验条件下其最佳摩尔浓度是5mmol／L;溶液pH是影响反应速率的重要因素．pH在中性范围内具有更强的光催化活性;该体系中苯胺能够有效地被降解,其光催化反应遵循一级反应动力学规律。     

微乳法制备Fe-TiO_2纳米晶复合体及光催化性能

采用微乳法制备铁掺杂TiO2纳米晶（Fe-TiO2）复合体,通过热重-差热（TG-DTA）、X射线衍射（XRD）、扫描电镜（SEM）和紫外漫反射光谱（DRS）等对其结构和形态进行表征;以亚甲基蓝溶液（MB）为标准模拟降解物,对Fe-TiO2,纯TiO2和P25光催化降解性能进行评价。结果表明,Fe-TiO2的光催化活性明显〉P25,原因是Fe掺杂不仅能抑制TiO2晶粒生长,提高TiO2的热稳定性和比表面积,而且能够拓展TiO2的吸收波长范围至可见光区,提高了Ti3＋离子浓度,降低了光生载流子的复合几率。     

模拟室内环境下掺杂TiO2纳米晶体的光催化性能

采用环境测试舱模拟可见光下的室内环境,以甲醛气体的光催化降解为探针反应,评价了通过溶胶-凝胶法分别制备的8种(银Ag、铜Cu、铁Fe、钨W、铈Ce、镧La、硫S和氯C1)掺杂TiO2纳米晶体的光催化活性及对甲醛气体的去除效果.用X射线衍射、激光粒度分析和紫外-可见分光光谱表征了掺杂钠米TiO2的微晶尺寸、晶体结构与光学性能.结果表明,Cu掺杂可以提高TiO2对氧的吸附能力,减少纳米粒子表面光生电子与光生空穴的复合,使TiO2的光吸收带边发生红移且有利于对可见光的吸收,从而使Cu掺杂TiO2在模拟室内环境下光催化甲醛气体的能力得到明显提高.     

Superior pillared clay catalysts for selective catalytic reduction of nitrogen oxides for power plant emission control

Fe(3+)-, Cr(3+)-, Cu(2+)-, Mn(2+)-, Co(2+)-, and Ni(2+)-exchanged Al2O3-pillared interlayer clay (PILC) or TiO2-PILC catalysts are investigated for the selective catalytic reduction (SCR) of nitric oxide by ammonia in the presence of excess oxygen. Fe(3+)-exchanged pillared clay is found to be the most active. The catalytic activity of Fe-TiO2-PILC could be further improved by the addition of a small amount of cerium ions or cerium oxide. H2O and SO2 increase both the activity and the product selectivity to N2. The maximum activity on the Ce-Fe-TiO2-PILC is more than 3 times as active as that on a vanadium catalyst. Moreover, compared to the V2O5-WO3/TiO2 catalyst, the Fe-TiO2-PILC catalysts show higher N2/N2O product selectivities and substantially lower activities (by approximately 85%) for SO2 oxidation to SO3 under the same reaction conditions. A 100-hr run in the presence of H2O and SO2 for the CeO2/Fe-TiO2-PILC catalyst showed no decrease in activity.     

Photocatalytic degradation of mixed gaseous carbonyl compounds at low level on adsorptive TiO2/SiO2 photocatalyst using a fluidized bed reactor

An adsorptive silica-supported titania photocatalyst TiO(2)/SiO(2) was prepared by using nanosized titania (anatase) immobilized on silica gel by the sol-gel technique with the titanium tetra isopropoxide as the main raw material and acetic acid as the acid catalyst. Meanwhile the structure and properties of the TiO(2)/SiO(2) photocatalyst were studied by means of many modern analysis techniques such as TEM, XRD, and BET. Gas-solid heterogeneous photocatalytic decomposition of four carbonyl compounds mixture at low concentration levels over ultraviolet irradiated TiO(2)/SiO(2) photocatalyst were carried out with high degradation efficiencies in a coaxial triple-cylinder-type fluidized bed photocatalytic reactor, which provided efficient continuous contact of ultraviolet photons, silica-supported titania photocatalyst, and gaseous reactants. Experimental results showed that the photocatalyst had a high adsorption performance and a good photocatalytic activity for four carbonyl compounds mixture. Some factors influencing the photocatalytic decomposition of the mixed carbonyl compounds, i.e. the gas flowrate, relative humidity, concentration of oxygen, and illumination time, were discussed in detail. It is found that the photocatalytic reaction rate of four carbonyl compounds decreased in this order: propionaldehyde, acetone, acetaldehyde and formaldehyde.     

模拟室内环境下掺杂TiO_2纳米晶体的光催化性能

采用环境测试舱模拟可见光下的室内环境,以甲醛气体的光催化降解为探针反应,评价了通过溶胶-凝胶法分别制备的8种（银Ag、铜Cu、铁Fe、钨W、铈Ce、镧La、硫S和氯C l）掺杂TiO2纳米晶体的光催化活性及对甲醛气体的去除效果。用X射线衍射、激光粒度分析和紫外-可见分光光谱表征了掺杂钠米TiO2的微晶尺寸、晶体结构与光学性能。结果表明,Cu掺杂可以提高TiO2对氧的吸附能力,减少纳米粒子表面光生电子与光生空穴的复合,使TiO2的光吸收带边发生红移且有利于对可见光的吸收,从而使Cu掺杂TiO2在模拟室内环境下光催化甲醛气体的能力得到明显提高。     

Performance of photocatalytic reactors using immobilized TiO2 film for the degradation of phenol and methylene blue dye present in water stream

TiO2 thin film photocatalyst was successfully synthesized and immobilized on glass reactor tube using sol-gel method. The synthesized TiO2 coating was transparent, which enabled the penetration of ultra-violet (UV) light to the catalyst surface. Two photocatalytic reactors with different operating modes were tested: (a) tubular photocatalytic reactor with re-circulation mode and (b) batch photocatalytic reactor. A new proposed TiO2 synthesized film formulation of 1 titanium isopropoxide: 8 isopropanol: 3 acetyl acetone: 1.1 H2O: 0.05 acetic acid (in molar ratio) gave excellent photocatalytic activity for degradation of phenol and methylene blue dye present in the water. The half-life time, t1/2 of photocatalytic degradation of phenol was 56 min at the initial phenol concentration of 1000 microM in the batch reactor. In the tubular photocatalytic reactor, 5 re-circulation passes with residence time of 2.2 min (single pass) degraded 50% of 40-microM methylene blue dye. Initial phenol concentration, presence of hydrogen peroxide, presence of air bubbling and stirring speed as the process variables were studied in the batch reactor. Initial methylene blue concentration, pH value, light intensity and reaction temperature were studied as the process variables in the tubular reactor. The synthesized TiO2 thin film was characterized using SEM, XRD and EDX analysis. A comparative performance between the synthesized TiO2 thin film and commercial TiO2 particles (99% anatase) was evaluated under the same experimental conditions. The TiO2 film was equally active as the TiO2 powder catalyst.     

The preparation of Zn2+-doped TiO(2) nanoparticles by sol-gel and solid phase reaction methods respectively and their photocatalytic activities

The photocatalytic oxidation of the organic pollutants with TiO(2) as photocatalyst has been widely studied in the world, and many achievements have been made. The degradation of pollutants is highly related to the photocatalytic activity of TiO(2). It is demonstrated that doping ions to TiO(2) is one way to enhance the photocatalytic activity of TiO(2). In this paper, Zn(2+)-doped TiO(2) nanoparticles were prepared through sol-gel and solid phase reaction methods, characterized by means of X-ray diffraction (XRD) and transmission electron microscopy (TEM). The photocatalytic activity of the elaborated powders was studied following the degradation of Rhodamine B. The results showed that the photocatalytic activity of Zn(2+)-doped TiO(2) prepared by sol-gel method is close to that of pure TiO(2) particles, however, the photocatalytic activity of Zn(2+)-doped TiO(2) prepared by solid phase reaction method is much higher than that of pure TiO(2) particles. The most efficient degradation of Rhodamine B was found with TiO(2) particles doped with 0.5% Zn(2+) in mole and calcined at 500 degrees C. Also the reason for the enhancement of the photocatalytic activity of TiO(2) by Zn(2+) doping through solid phase reaction method was discussed.     

The role of ferrous ion in Fenton and photo-Fenton processes for the degradation of phenol

The efficiency of different Fenton-related oxidative processes such as Fenton, solar-Fenton and UV-Fenton were examined using phenol as a model compound in simulated and industrial wastewater. A batch study was conducted to optimize parameters like pH, hydrogen peroxide concentration and ferrous ion concentration governing the Fenton process. At optimum conditions, different Fenton-related processes were compared for the degradation of phenol. Increased degradation and mineralisation efficiency were observed in photo-Fenton processes as compared to conventional Fenton process. The maximum mineralising efficiency for phenol with Fenton, solar and UV-Fenton processes were 41%, 96% and 97% respectively. In Fenton process, carboxylic acids like acetic acid and oxalic acid were formed as end products during the degradation of phenol while in photo-Fenton processes, both these ions were identified during the early stages of phenol degradation and were oxidized almost completely at 120 min of the reaction time. In photo-Fenton processes (solar and UV light) complete degradation were observed with 0.4 mM of Fe2+ catalyst as compared to 0.8 mM of Fe2+ in conventional Fenton process. In Fenton and solar-Fenton processes, an iron reusability study was performed to minimize the amount of iron used in treatment process. The efficacy of Fenton and solar-Fenton processes was applied to effluent from phenol resin-manufacturing unit for the removal and mineralisation of phenol.     

Radiolysis of aqueous phenol solutions with nanoparticles. 1. Phenol degradation and TOC removal in solutions containing TiO2 induced by UV,gamma-ray and electron beams

Aqueous phenol solutions containing TiO(2) nanoparticles were irradiated with ultraviolet (UV), gamma-ray and electron beams. Organic compounds were fully removed by each type of radiation in the presence of the particles. The absorbed energy of the ionizing radiation (gamma-ray and electron beams) needed for removal was much lower than that of UV photocatalysis. Phenol was decomposed by the ionizing radiation in the absence of the nanoparticles and the addition of TiO(2) had no significant effect on phenol decomposition rate. Instead, total organic carbon (TOC) removal using the ionizing radiation was accelerated drastically by TiO(2). It is suggested that TiO(2) particles affect the intermediate compounds produced through the decomposition of phenol. The amount of removed TOC per absorbed energy were compared in the absence and the presence of TiO(2) nanoparticles. Radiolysis with the nanoparticles showed consistently high rate and high efficiency of TOC removal.     

负载TiO2/Fe3+的玻璃纤维反应器光催化苯酚

以玻璃纤维为载体,将TiO2负载到其表面形成了空间玻璃纤维反应器,引入Fe3+作为掺杂改性离子,形成了负载TiO2/Fe3+的空间玻璃纤维光催化反应器,并以高压汞灯为光源进行了光催化降解水中苯酚的实验研究,考察了影响苯酚光催化降解的因素,确定了在UV365～250 W光源照射下,pH为3～5,O2通入量1.0 L/(min.L),反应器内上升流速为0.7 m/min等实验条件下,初始浓度为30 mg/L的苯酚废水经120 min光催化反应后,降解率可达到85%,矿化率可达80%。     

Photocatalytic degradation of dyes on a magnetically separated photocatalyst under visible and UV irradiation

A novel kind of magnetically separable photocatalyst of TiO2/SiO2/gamma-Fe2O3 (TSF) is prepared. Scanning tunnel microscope (STM) and X-ray diffractometer (XRD) were used to characterize the structure of the photocatalyst. In the TSF photocatalyst, a TiO2 shell is for photocatalysis, a gamma-Fe2O3 core as a carrier is for separation by the magnetic field and a SiO2 membrane between the TiO2 shell and the gamma-Fe2O3 core is used to weaken the adverse influence of gamma-Fe2O3 on the photocatalysis of TiO2. Three kinds of dyes, Fluoresein, Orange II and Red acid G, were used to examine the photocatalytic activity of TSF. Due to strong UV adsorption of the gamma-Fe2O3, the photocatalytic activity of TSF was lower than that of the pure TiO2. Deducting the light absorption of the gamma-Fe2O3 particles, the photocatalytic activity of TSF was found to be higher than that of the P25 under UV irradiation. On the other hand, the photocatalytic activity of TSF under visible irradiation was much lower than that of the P25 TiO2 even deducting the visible light absorption of the gamma-Fe2O3 particles. Differences in the photocatalytic mechanisms under UV and visible irradiation lead to the differences in the photodegradation characteristics of dyes on TSF. The recycled TSF exhibited a good repeatability of photocatalytic activity.     

TiO_2/AC复合催化剂的制备及其对六氯苯的光催化降解性能研究

以颗粒活性炭（AC）和钛酸丁酯为原料,采用微波辐射法制备TiO2/AC复合光催化剂,并对制备的催化剂进行了表征;采用该催化剂对六氯苯进行光催化降解,确定了六氯苯降解的最佳工艺条件,并就几种外加试剂对TiO2/AC光催化降解六氯苯的强化作用进行了探讨。结果表明,制备的催化剂中TiO2均匀分布在活性炭表面、呈单一的锐钛矿晶型,晶粒生长完善。该催化剂催化降解六氯苯的最佳工艺条件为：pH值为5、TiO2负载量为18.2%、TiO2/AC投加量为0.4 g/L、反应时间为60 min。在此条件下,六氯苯降解效率达90.3%。添加适量的H2O2、AgNO3、K2S2O8、KIO4和KMnO4均能提高TiO2/活性炭对六氯苯的光催化降解效率。5种外加试剂的适宜添加量分别为0.3%、1.0、1.0、0.1和0.1 mmol/L,对TiO2/AC光催化效率的强化作用大小顺序为：H2O2〉AgNO3〉K2S2O8〉KMnO4〉KIO4。     

Photocatalytic oxidation of pesticide rinsate

Pesticide rinsate has been considered as one of the major threats for the environment. In this study, photocatalysts such as TiO2 and O3 were used to promote the efficiency of direct UV photolysis to prevent such wastewater pollution. Carbofuran (a carbamate pesticide) and mevinphos (an organophosphate pesticide) with a concentration of 100 mg/L were selected as the test pesticide rinsates. Parent pesticide compound, COD, and microtoxicity analysis were employed to investigate the effect of photocatalyst on the degradation efficiency of pesticide in rinsate. It was found that the photocatalytic oxidation process (UV/O3, UV/TiO2) showed much higher COD removal and microtoxicity reduction efficiency for pesticide rinsate than did direct UV photolysis under the imposed conditions, suggesting that photocatalytic oxidation processes such as UV/O3 and UV/TiO2 could be a better alternative to treat pesticide rinsate. In addition, it was noted that increasing the initial pH of mevinphos rinsate to a basic level was required to reach higher COD removal efficiency and positive microtoxicity reduction efficiency while it was not necessary for the treatment of carbofuran rinsate.     

Comparison of advanced oxidation processes and identification of monuron photodegradation products in aqueous solution

The photodegradation of monuron (3-(4-chlorophenyl)-1,1-dimethylurea) in aqueous solutions under simulated solar irradiation has been conducted by different advanced oxidation processes (UV/H(2)O(2), UV/H(2)O(2)/Fe(2+), UV/H(2)O(2)/TiO(2), UV/TiO(2), dark H(2)O(2)/Fe(3+)). The degradation rates were always higher for the homogeneous catalysis in photo-Fenton reactions (UV/H(2)O(2)/Fe(2+)) compared to the heterogeneous photocatalytic systems (TiO(2)/UV and UV/H(2)O(2)/TiO(2)). Optimal concentrations of Fe(2+) and H(2)O(2) for the abatement of the herbicide in the photo-Fenton system were found to be 1 mM Fe(II) and 10 mM H(2)O(2). Several intermediary products were identified using large volume injection micro-liquid chromatography with UV detection (mu-LC-UV), mu-LC-MS and GC-MS techniques and a degradation mechanism has been proposed.     

石英棒负载TiO2光催化膜的制备、表征与降解性能

利用浸涂法在石英光导棒上制得了TiO2光催化膜.用扫描电镜(SEM)、X射线衍射(XRD)等方法对膜的形貌和晶相组成进行了表征,以苯酚为模型污染物考察了膜的活性.结果表明,所制得的TiO2膜催化剂主要由锐钛矿和金红石2种晶相组成;光催化降解苯酚的效果明显优于直接光解;当苯酚初始浓度为0.98 mg/L时,反应2.5 h后的降解率为86%.     

Photo-oxidation of cork manufacturing wastewater

Several photo-activated processes have been investigated for oxidation of a cork manufacturing wastewater. A comparative activity study is made between different homogeneous (H2O2/UV-Vis and H2O2/Fe2+/UV-Vis) and heterogeneous (TiO2/UV-Vis and TiO2/H2O2/UV-Vis) systems, with degradation performances being evaluated in terms of total organic carbon (TOC) removal. Results obtained in a batch photo-reactor show that photo-catalysis with TiO2 is not suitable for this kind of wastewater while the H2O2/UV-Vis oxidation process, for which the effect of some operating conditions was investigated, allows to remove 39% of TOC after 4 h of operation (for C(H2O2)=0.59 M, pH=10 and T=35 degrees C). The combined photo-activated process, i.e., using both TiO2 and H2O2, yields an overall TOC decrease of 46% (for C(TiO2)=1.0 gl(-1)). The photo-Fenton process proved to be the most efficient, proceeds at a much higher oxidation rate and allows to achieve 66% mineralization in just 10 min of reaction time (for C(H2O2)=0.31 M, T=30 degrees C, Fe2+:H2O2=0.12 (mol) and pH=3.2).     

Iron-impregnated zeolite catalyst for efficient removal of micropollutants at very low concentration from Meurthe river

In this paper, for the first time, faujasite Y zeolite impregnated with iron (III) was employed as a catalyst to remove a real cocktail of micropollutants inside real water samples from the Meurthe river by the means of the heterogeneous photo-Fenton process. The catalyst was prepared by the wet impregnation method using iron (III) nitrate nonahydrate as iron precursor. First, an optimization of the process parameters was conducted using phenol as model macro-pollutant. The hydrogen peroxide concentration, the light wavelength (UV and visible) and intensity, the iron loading immobilized, as well as the pH of the solution were investigated. Complete photo-Fenton degradation of the contaminant was achieved using faujasite containing 20 wt.% of iron, under UV light, and in the presence of 0.007 mol/L of H₂O₂ at pH 5.5. In a second step, the optimized process was used with real water samples from the Meurthe river. Twenty-one micropollutants (endocrine disruptors, pharmaceuticals, personal care products, and perfluorinated compounds) including 17 pharmaceutical compounds were specifically targeted, detected, and quantified. All the initial concentrations remained in the range of nanogram per liter (0.8–88 ng/L). The majority of the micropollutants had a large affinity for the surface of the iron-impregnated faujasite. Our results emphasized the very good efficiency of the photo-Fenton process with a cocktail of a minimum of 21 micropollutants. Except for sulfamethoxazole and PFOA, the concentrations of all the other microcontaminants (bisphenol A, carbamazepine, carbamazepine-10,11-epoxide, clarithromycin, diclofenac, estrone, ibuprofen, ketoprofen, lidocaine, naproxen, PFOS, triclosan, etc.) became lower than the limit of quantification of the LC-MS/MS after 30 min or 6 h of photo-Fenton treatment depending on their initial concentrations. The photo-Fenton degradation of PFOA can be neglected. The photo-Fenton degradation of sulfamethoxazole obeys first-order kinetics in the presence of the cocktail of the other micropollutants.     

Effect of ZnFe2O4 doping on the photocatalytic activity of TiO2

The photocatalytic oxidation of the organic pollutants with the TiO2 as photocatalyst has been widely studied in the world, and many achievements have been got. The degradation of pollutants is highly related with the photocatalytic activity of TiO2. It is demonstrated that doping ions or oxides to TiO2 is one way to enhance the photocatalytic activity of TiO2. In this paper, the ZnFe2O4-doped TiO2 nanoparticles were prepared from butyl titanate by a sol-gel method and characterized by means of X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results showed that when TiO2 was doped with ZnFe2O4, its particle size will decrease and its crystal structure will partly transform from anatase to rutile. The photocatalytic activity of the elaborated powders was studied following the degradation of Rhodamine B. The results showed that doping ZnFe2O4 to TiO2 will enhance the photocatalytic activity of TiO2 and that ZnFe2O4-doped TiO2 in the coexistence of anatase and rutile has higher efficiency for the degradation of Rhodamine B than that in the anatase phase alone. Also the different role of O2 in the direct photolysis and photocatalysis of Rhodamine B was discussed.