Fe 3+x-TiO2/Shell光催化剂的制备及其对石油的光催化降解

 以自制的贝壳基规整吸附体为载体,采用浸渍煅烧法制备了Fe ³⁺_x-TiO₂/Shell光催化剂。采用XRD、SEM-EDS和UV-Vis等技术对制备的Fe ³⁺_x-TiO₂/Shell光催化剂进行表征。以石油为降解对象,考察了Fe³⁺掺杂量、Fe ³⁺_x-TiO₂/Shell的负载次数及光照时间对Fe ³⁺_x-TiO₂/Shell光催化活性的影响。结果表明,Fe³⁺掺杂量为0.7%(m(Fe³⁺ )/m(TiO₂)×100%)、Fe ³⁺_0.7-TiO₂负载次数为4次时,制备的Fe ³⁺_0.7-TiO₂/Shell光催化剂的光催化活性最高,300 W碘钨灯照射16 h,石油的光催化降解率达76%。     

Effect of binder on the physical stability and bactericidal property of titanium dioxide (TiO2) nanocoatings on food contact surfaces

TiO₂ is a promising photocatalyst for use in food processing environment as an antimicrobial coating. The purpose of this study was to determine the effect of different binding agents on the physical stability and bactericidal property of TiO₂ nanocoatings created on stainless steel surfaces. A total of six different coating suspensions were prepared by mixing TiO₂ (Aeroxide^® P-25) nanoparticles (NPs) with three different types of binders (Shellac (A), polyuretahne (B), and polycrylic (C)) at a 1:4 to 1:16 NP to binder weight ratio. Bactericidal activity of these TiO₂ coatings against Escherichia coli O157:H7 (5-strain) was determined at three different UV-A light intensities (0.25, 0.50 and 0.75 mW/cm²) for 3 h. The type of binder used in the coating had a significant effect on the log reduction of E. coli O157:H7. TiO₂ coatings with binder C showed highest reduction (>4 log CFU/cm²) followed by TiO₂ coating with binder B and A. Increasing the binder concentration in the formulation from a 1:4 to 1:16 weight ratio decreased the log reduction of E. coli O157:H7. Increasing the UV-A light intensity from 0.25 to 0.75 mW/cm² increased the log reduction of bacteria for all the TiO₂ coatings. The physical stability of the TiO₂ coatings was determined using ASTM procedures. TiO₂ coatings with binder B showed highest adhesion strength and scratch hardness when compared to coatings with other binders. However, on repeated use experiments (1, 3, 5, and 10 times), TiO₂ coatings with binder C were found to be physically more stable and able to retain their original bactericidal property. The results of this study showed promise in developing durable TiO₂ coatings with strong photocatalytic bactericidal property on food contact surfaces using appropriate binding agents to help ensure safe food processing environment.     

Photocatalytic degradation of methylene blue and inactivation of Gram-negative bacteria by TiO2 nanoparticles in aqueous suspension

The photocatalytic degradation of methylene blue (MB) and inactivation of Gram-negative bacteria Escherichia coli (generic) and Pseudomonas aeruginosa by TiO₂ nanoparticles in aqueous suspension were studied. TiO₂ resulted in significant reduction in MB absorption and a shift of MB absorption peak from 664 nm to 658 nm after a short time of irradiation. The maximum degradation of MB was observed when the concentration of TiO₂ in the aqueous suspension was 0.5 g L⁻¹. TiO₂ was also very effective with inhibiting growth of both Gram-negative bacteria E. coli and P. aeruginosa, although it took more than 60 min to observe the inactivation effects. The photocatalytic inactivation toward E. coli and P. aeruginosa by TiO₂ showed a similar trend with much higher effectiveness toward E. coli under the same experimental conditions. The inactivation kinetic behaviors could be explained by the modified Langmuir–Hinshelwood model, and well fitted to a pseudo-first order kinetic equation. The reaction rate constant for E. coli and P. aeruginosa were 7.768 × 10⁶ cfu mL⁻¹ min⁻¹ and 5.655 × 10⁶ cfu mL⁻¹ min⁻¹, respectively. The adsorption equilibrium constant for E. coli was 1.053 × 10⁻⁸ mL cfu⁻¹, while it was 1.438 × 10⁻⁸ mL cfu⁻¹ for P. aeruginosa. These results further demonstrate that in an aqueous system, TiO₂ nanoparticles can effectively both degrade organic compounds and inhibit Gram-negative bacteria under UVA light. Compared with the degradation activity of TiO₂ toward organic compounds, its antimicrobial activity against Gram-negative bacteria would be delayed by 60 min. The antimicrobial activity of TiO₂ against Gram-negative bacteria could vary with bacterial species.     

双核磺化酞菁钴与硫化钠反应的伏安法研究

PDS脱硫法有效解决了氰化氢中毒问题,得到许多企业的青睐,但副盐问题仍然是目前整个脱硫行业十分关注的话题。采用循环伏安法对PDS脱硫体系中双核磺化酞菁钴(bi-CoPc)与硫化钠的反应过程进行了研究。结果表明:Na_2S和Na_2S_x在玻碳电极上的氧化反应是受浓度扩散控制的不可逆反应,且S~(2-)向S_8的转化并不是一步完成,而是先转化成S_x~(2-),进而再生成S_8。此外,参与反应的S~(2-)仅有20%转化为S_8。S_x~(2-)以S_2~(2-)～S_9~(2-)中的某两种形式为主要存在形式,且S_x~(2-)的存在形式可能对于S_8的生成速率和生成量有一定影响。bi-CoPc在水溶液中易与OH~-形成配合物,加入碳酸盐缓冲溶液,可降低配合物的形成能力,同时,Co~+/Co~(2+)的氧化还原反应更易发生。bi-CoPc与Na_2S反应先生成S_2~(2-),然后S_2~(2-)可转化为更长链的S_x~(2-),最终形成S_8。该研究结果有助于加深对脱硫机理的了解,同时,对降低副产物生成有一定的指导意义。     

Disinfecting efficacy of a plastic container covered with photocatalyst for postharvest

The simplification of the cleaning process of plastic containers used in the storage and/or distribution of fruits or vegetables is important. We coated a plastic container with an apatite-coated titanium dioxide photocatalyst (TiO₂–Ap container), and examined its disinfecting efficacy under UV irradiation from black light. The disinfecting efficacy of the TiO₂–Ap container on diluted drops evaporated from spinach (suspension) was examined. Changes in the microbial populations of the total aerobic bacteria, coliform bacteria, and moulds and yeasts in the TiO₂–Ap container were assayed at 25 °C for 24 h (UV-A intensity of 0.2 and 0.4 mW cm⁻²). The results showed that all of the microbial populations in the TiO₂–Ap container decreased with irradiation time and then reduced to uncountable levels. It was found that the increase in UV-A intensity enhanced the disinfecting efficacy.     

Effect of metal-doping of TiO2 nanoparticles on their photocatalytic activities toward removal of organic dyes

M-doped TiO₂ nanoparticles (M = Cu, Zn) were prepared by the sol–gel method. X-ray diffraction (XRD), scanning electron microscopy (SEM), FT-IR and UV–vis spectroscopy techniques were used to characterize the samples. Photocatalytic activities of samples for methyl orange (MO) degradation and the chemical oxygen demand (COD) were investigated. XRD results confirmed the formation of the anatase phase for the TiO₂ nanoparticles, with crystallite sizes in the range of 9–21 nm. The small crystallite size and doping ions (Cu and Zn) inhibited any phase transformation and promoted the growth of the TiO₂ anatase phase. The optical study showed that doping ions lead to an increase in the absorption edge wavelength, and a decrease in the band gap energy of TiO₂ nanoparticles. The doped TiO₂ nanoparticles in general showed higher photocatalytic activities than the pure ones. The Cu doped TiO₂ nanoparticles showed the best photocatalytic activity based on the measured COD values.     

Synthesis,characterization and comparative study of nano-Ag–TiO2 against Gram-positive and Gram-negative bacteria under fluorescent light

Currently, some of the major problems affecting the world are air pollution as well as microbial contamination. Every time we breathe, we are risking our lives by inhaling dangerous chemicals and biological contaminants that have found their way into the air. Therefore this work focuses on the antibacterial activity of Ag–TiO₂ to overcome the microbial contaminant and infectious disease. Ag–TiO₂ nanosolution were synthesized by sol–gel method and found to be an effective visible light driven photocatalyst. The nanosolutions were characterized by X-ray diffraction (XRD), transmittance electron microscopy (TEM), photoluminescence (PL) spectra, and X-ray photoelectron spectroscopy (XPS). At the concentration of 0.2–0.1 M, Ag–TiO₂ caused 100% inhibition of bacterial growth. The antibacterial efficacy of Ag–TiO₂ was evaluated with two kinds of bacteria; Gram-positive and Gram-negative. The colony count of Ag–TiO₂ against Gram-negative were evaluated with stain such as Escherichia coli, Pseudomonas aeruginosa and Shigella while for Gram-positive were investigated with Staphylococcus aureus, Bacillus subtilis, Bacillus cereus. Colony count results indicated that Ag–TiO₂ able to kill bacteria at the lowest concentration of 0.05 M that contains 0.06 mol % Ag. From the SEM and TEM observation, the survival of the Gram-positive was low and the decomposition was rapid as compared to Gram-negative bacteria.     

Performance and mechanism of standard nano-TiO2 (P-25) in photocatalytic disinfection of foodborne microorganisms – Salmonella typhimurium and Listeria monocytogenes

Under UV light, nano-TiO₂ is effective in photocatalytic disinfection. In this paper, we studied the disinfection effects of nano-TiO₂ on the two typical food-borne microorganisms, Gram-negative bacterium-Salmonella typhimurium and Gram-positive bacterium-Listeria monocytogenes, in meat products. Results show that nano-TiO₂ had a strong disinfecting activity against both Gram-negative and Gram-positive pathogens in a suspension under UV light. L. monocytogenes was more resistant to nano-TiO₂ treatment than Salmonella under UV light. Nano-TiO₂ concentrations and initial bacteria populations had significant influence on the photocatalytic disinfection effectiveness against S. typhimurium. The optimum concentration (1.0 g/L) was between 0.2 g/L and 1.5 g/L. Increasing S. typhimurium population from 10⁴ to 10⁷ CFU/mL resulted in reduced photocatalytic disinfecting effectiveness by nano-TiO₂. Electron microscope images revealed that nano-TiO₂ photocatalytic disinfection starts with damaging the cell walls of bacteria. With serious destructions of cell walls, cell components released or defused out of cell from the damaged areas, and finally the cells completely lost their integrity and dissolved. These results demonstrate that nano-TiO₂ is very effective against pathogens that can grow well on meat products and the effectiveness can be significantly influenced by nano-TiO₂ contents and pathogen populations. The findings by these experiments provide the essential information for further developing a nano-metal-based, antimicrobial packaging system to improve safety of meat products.     

A novel La3+–Zn2+–Al3+–MoO42− layered double hydroxides photocatalyst for the decomposition of dibenzothiophene in diesel oil

A new type of photocatalyst, La³⁺-Zn²⁺-Al³⁺-MoO₄^2? layered double hydroxide (LDH) (La:Zn:Al = 1:7:2), was prepared by a complexing agent-assisted homogeneous precipitation technique. The LDHs were used as catalysts for the desulfurization of diesel oil under UV irradiation. As revealed by the results, the catalyst showed superior desulfurization efficiency and recycling performance. Under UV irradiation, the desulfurization efficiency was 84% in 60 min. In La³⁺–Zn²⁺–Al³⁺–MoO₄^2? LDHs, the introduction of MoO₄^2? increased the interlayer space for promoting the adsorption of dibenzothiophene, and MoO₄^2? might act as the active sites for the oxidation of dibenzothiophene, resulting in the high desulfurization efficiency.     

NaAlO2溶液中铝酸根离子的微观结构

 应用IR、²⁷Al NMR 和UV3种波谱方法对不同方式配制的Al₂O₃浓度和苛性系数基本相同的四种NaAlO₂溶液进行了详细的表征。结果表明IR、²⁷Al NMR和UV3种光谱方法给出的信息可以相互补充支持,共同给出NaAlO₂溶液中铝酸根离子的微观结构。溶液配制方式对NaAlO₂溶液中铝酸根离子的微观结构具有显著影响,4种NaAlO₂溶液中铝酸根均以四配位[Al(OH)₄]^-为主体离子,可以排除六配位[Al(OH)₆]^3-的存在; 二聚[Al₂O(OH)₆]^2-含量因配制方式不同存在显著差别,在方式Ⅰ配制的溶液中二聚[Al₂O(OH)₆]^2-含量很少或不存在,在方式Ⅱ、Ⅲ、Ⅳ配制的溶液中显著存在二聚[Al₂O(OH)₆]^2-,在溶液Ⅱ、Ⅲ中还存在尚未确定结构的离子。     

硫化行为对Ni2P/SBA-15催化剂结构和加氢脱硫性能的影响

以介孔分子筛SBA-15为载体、硝酸镍为镍源、磷酸氢二铵为磷源,等体积浸渍法制备了Ni2P/SBA-15催化剂前驱体,然后在H2流中程序升温还原,得到Ni2P/SBA-15催化剂,再用CS2溶液对催化剂进行了硫化处理,制备出了硫化态xCS2-Ni2P/SBA-15催化剂。采用XRD、N2吸附-脱附、XPS对催化剂的结构进行了表征,对催化剂的二苯并噻吩加氢脱硫活性进行了评价,考察了硫化条件对催化剂结构和二苯并噻吩加氢脱硫催化活性的影响。结果表明,xCS2-Ni2P/SBA-15催化剂的物相有Ni2P、Ni12P5、Ni3S2,催化剂的比表面积随硫化溶液中CS2质量分数的增加有一定程度的增加,催化剂表面的Ni以Niδ+和Ni 2+形式存在,P以Pδ-和P5+形式存在。采用5%CS2硫化溶液硫化的催化剂对二苯并噻吩加氢脱硫具有最高的催化活性,380℃时二苯并噻吩的转化率可达99.3%。硫化过程形成的Ni3S2活性物相对二苯并噻吩的转化和直接脱硫都有利。     

Recycling of supported nanocomposites for hazardous industrial wastewater treatment via Solar photocatalytic process

Study of the photocatalytic activity of the synthesized polyvinylidene fluoride/multi-walled carbon nanotubes/titanium dioxide (PVDF/x%(MWCNTs/8%TiO2) nanocomposites using a simple modified solvent casting technique in decontamination of hazardous industrial wastewater and Reactive Yellow 145 dye as an industrial organic pollutant (local textile dye) were evaluated. Also, different MWCNTs/8%TiO₂ weight percentages in PVDF/x%(MWCNTs/8%TiO₂) nanocomposites were prepared and evaluated. The surface morphology and the structures of the synthesized samples were characterized using SEM, ATR-FTIR, DRS, XRD, and BET. The evaluated bandgap values for MWCNTs/xTiO₂ nanocomposites are from 2.38 to 2.69 based on the weight ratios (2%, 5%, and 8%). The results of the surface area of samples and the best optical behavior obtained at MWCNTs/8%TiO₂ are reported and its photodegradation rate raised to 10.22x10^?3S^?1. The photodegradation process of Reactive Yellow 145 dye by PVDF/x%(MWCNTs/8%TiO₂) nanocomposites was monitoring using chemical oxygen demand (COD). Also, the observed PL intensity for PVDF/MWCNTs/8%TiO₂ has high photonic efficiency and photocatalytic activity. The solar photocatalytic process efficiency for an Egyptian dying factory by repeating it 10 times using PVDF/10%(MWCNTs/8%TiO₂) nanocomposites as a supported photocatalyst for the industrial wastewater treatment was evaluated by the COD method and still under Egyptian environmental law allowed COD limit (1000 ppm).     

Photocatalytic TiO2 coating of plastic cutting board to prevent microbial cross-contamination

Kitchen cutting boards are one common source of microbial cross-contamination in foods. In this study, a method was developed to create an antimicrobial coating on HDPE cutting board using UV-activated TiO₂ nanoparticles (NPs). The antimicrobial efficacy of the developed coatings was tested against E. coli O157: H7 for 3 h at 0.5 ± 0.05 mW/cm² UVA light intensity. In addition, the effect of NP loading (0.0125, 0.0625, and 0.125 mg/cm²), and surface treatment of coatings by oxygen plasma for 1–15 min on the bactericidal efficacy was investigated. Further, the bactericidal efficacy of the TiO₂ coated cutting board on repeated use (i.e. 1, 2, 3 and 5 times) was also evaluated. The results showed that by increasing the NP loading from 0 to 0.125 mg/cm² has increased the log reduction from 0.37 to 1.18 CFU/cm². However, no significant difference (P > 0.05) in the reduction was observed between NP loadings at 0.0625 and 0.125 mg/cm². Oxygen plasma treatment of the coated surfaces for 5–15 min significantly increased (P ≤ 0.05) the log reduction compared to control sample without plasma treatment. Under the tested conditions, TiO₂ coating with 0.0625 mg/cm² NP loading followed by oxygen plasma treatment for 5 min was found to achieve the greatest reduction up to 2.67 log CFU/cm². Also, the coated-surfaces were found to retain the original bactericidal property even after up to 5 times washing treatment. The developed TiO₂ coating on cutting board showed promise to mitigate the risk of microbial cross-contamination by providing a stable antimicrobial activity for extended use. Plasma treatment further enhanced the bactericidal property of the developed coatings without affecting physical stability.     

Cu-N共掺杂改性纳米TiO2光催化剂制备及甲苯降解

以尿素、硝酸铜、钛酸四丁酯等为原料,采用溶胶-凝胶法,经Cu,N原子共掺杂制备出改性纳米TiO2光催化剂。采用 X射线衍射仪、扫描电子显微镜、紫外可见漫反射仪 、傅里叶变换红外光谱仪对其进行了分析表征。以甲苯气体为研究对象,考察了制备的TiO2光催化剂对甲苯的光催化降解性能。结果表明:共掺杂改性后的纳米TiO2光催化剂,在可见光400~550 nm处呈现出较强的吸收;当光催化反应120 min时,Cu-N-TiO2光催化剂对甲苯的催化降解转化率达到了38%,较纯纳米TiO2催化剂提高了近4倍。     

Yb-La共掺杂TiO_2光催化降解炼油废水

采用溶胶凝胶法制备了镱镧共掺杂TiO2(Yb-La/TiO2)催化剂,将其用于光催化降解炼油废水,优化了光催化反应条件,对反应动力学进行了研究,并利用XRD,IR,BET等手段对催化剂的结构进行了表征。实验结果表明,Yb-La/TiO2光催化降解炼油废水的最佳工艺条件为:催化剂用量4.0 g/L,体系pH=5,紫外光照射时间3 h。在此条件下,炼油废水的COD降解率(η)可达90.90%。光催化降解反应符合一级反应动力学特征,其反应速率方程为:ln[1/(1-η)]=0.808t-0.169 4(t为时间)。表征结果显示,镧镱共掺杂TiO2降低了颗粒粒径,增大了比表面积,提高了催化剂的活性,镧镱共掺杂具有协同效应。     

锐钛矿相TiO2纳米纤维制备与摩擦学性能

采用简便且可重复性较好的碱熔法制备锐钛矿相TiO2,采用简便的表面修饰技术对其进行表面改性,得到TiO2纳米纤维,并采用XRD、SEM和FT-IR方法对其进行表征。利用四球摩擦试验机考察其作为油品润滑添加剂的摩擦学性能。结果表明,所合成的TiO2纳米纤维为锐钛矿相结构,结晶度和纯度较高,而且在油品中具有良好的分散性;TiO2纳米纤维具有良好的抗磨减摩性能,并能够很好地提高油品承载能力,当其加入量为1.5%(质量分数)时,抗磨减摩以及提高承载能力的效果最好。这些特性使得锐钛矿相TiO2纳米纤维有望在未来成为绿色润滑油添加剂。     

Photocatalytic study of some synthesized MWCNTs/TiO2 nanocomposites used in the treatment of industrial hazard materials

Multi-walled carbon nanotubes/titanium dioxide nanocomposites were successfully synthesized by Sol-Gel method using new different ratios of tetrabutyl titanate and functionalized MWCNTs as the starting precursors. The synthesized Multi-walled carbon nanotubes/different titanium dioxide percentages (MWCNTs/3, 6 and 10%TiO₂) nanocomposites were characterized using XRD, SEM and N₂ Adsorption-Desorption techniques. The optical band gap was estimated for MWCNTs and MWCNTs with different TiO₂ percentages by Kubelka-Munk equation giving 3.72, 2.92, 2.83, 2.71 eV values respectively. The synthesized nanocomposites were used as photocatalyst for decontamination of two local textile Dianix Blue and Vat Green 1 Dyes which commonly used in dyeing manufacture in local market.     

Different outlet for preparing nano-TiO2 catalysts for the photodegradation of Black B dye in water

Two nano-titania catalysts were prepared using two economically varying titanium precursors: titanium tetrachloride (A) and titanium isopropoxide (B). The catalysts were calcined at temperatures of 500 °C, 600 °C and 700 °C and characterized using X-ray diffraction (XRD), electron diffraction (ED), BET surface properties and high resolution transmission microscopy (HRTEM). The calcined catalysts were found to differ markedly in their physical characters and TiO₂ phases produced as well as their photocatalytic activities. The anatase titania phase diminished from 100% to 83% in TiO₂A but from 64% to zero in TiO₂B via temperature increase from 500 °C to 700 °C, due to transforming anatase to rutile. The brookite TiO₂ phase only appeared (17%) in catalyst B500. In general, the catalyst of choice is A600 by virtue of many compositional, economical and catalytic advantages.     

Dibenzothiophene Hydrodesulfurization Activity of MoS2 Supported in Sol–Gel ZrO2–TiO2 Mixed Oxides

Abstract

In this work, we report the effect of support composition on the properties of MoS₂ impregnated in sol–gel ZrO₂–TiO₂ mixed oxides as dibenzothiophene hydrodesulfurization catalyst. The supports calcined at 500°C were characterized by N₂ physisorption and X-ray diffraction (electronic radial distribution function). The oxidic impregnated materials (2.8 Mo atoms/nm²) were sulfided at 400°C under a H₂S/H₂ stream. The sample impregnated on the equimolar support showed the highest activity per mass of catalysts whereas the one with TiO₂ carrier was superior in a per mass of Mo basis. Marked differences in products selectivity were observed by TiO₂ addition in the supports. The hydrodesulfurization route to partially hydrogenated compounds was favored over the mixed oxides-supported catalysts meanwhile the direct desulfurization (to biphenyl) was promoted on the ZrO₂-supported solid. It is suggested that among other properties the dispersion and morphology of the MoS₂ phase could influence that behavior.     

微波法合成TiO2及其光催化降解有机废水研究

以硫酸钦、聚乙烯毗咯烷酮(PVP)、乙二醇(EG)为原料,采用微波法制备了TiO2光催化剂.在间歇式光催化反应器内,用亚甲基蓝溶液模拟有机废水,在高压汞灯光照下,研究TiO2光催化剂对亚甲基蓝的光催化降解过程.利用X射线衍射(XRD)、扫描电子显微镜(SEM)和傅立叶变换-红外光谱(FT-IR)测试技术,对TiO2光催...