Photocatalysis of methylene blue on titanium dioxide nanoparticles synthesized by modified sol-hydrothermal process of TiCl4

Titanium dioxide nanoparticles were synthesized by the hydrolysis and condensation of TiCl₄, an economic titanium precursor, in a mixed solvent of iso-propyl alcohol and water. As-prepared powders were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FE-SEM), energy filtering transmission electron microscopy (EF-TEM). To examine the photocatalytic activity of the as-prepared TiO₂, the photodegradation of MB which is a typical dye resistant to biodegradation has been investigated on TiO₂ powders in aqueous heterogeneous suspensions. The photocatalytic activity of TiO₂ powders prepared by the hydrolysis of TiCl₄ in the mixed solutions of iso-PrOH/H₂O exceeded that of commercial TiO₂ powders. The apparent first order rate constants (k _app) for the photodegradation of methylene blue (MB) showed a good correlation with the absorbance area obtained by UV-VIS DRS on wavelength in the limits of used lamp emission 300∼420 nm.     

Original antifouling strategy: Polypropylene films modified with chitosan-coated silver nanoparticles

A new coating strategy of polypropylene (PP) films with silver nanoparticles (AgNPs) is proposed to obtain surfaces with antifouling properties. As a first step, the photograft polymerization is used to produce polyacrylic acid-grafted PP (PAA-grafted PP) films. A green AgNP synthesis is used by thermal reduction of AgNO₃ with amino groups of chitosan (CS), which controls ion diffusion and stabilizes nanoparticles. AgNP/CS complexes are adsorbed on PAA-grafted PP by electrostatic interactions, yielding AgNP/CS-coated PP films. These films show an excellent antimicrobial activity, even for AgNP contents as low as 0.08 wt %, reducing more than 4 log units in the viable Staphylococcus aureus concentration or inducing Escherichia coli death. This trend is consistent with an adequate amount of small AgNP adsorbed in an organized manner within a thin surface layer. Therefore, the antimicrobial activity of this film seems to be more than promising, used as an active surface for a wide range of applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48448.     

Cellulose fibers modified by silicon dioxide nanoparticles

The sol–gel method is one of the most suitable ways for producing glasses, glass films, glass fibers, and glass nanoparticles. The relatively mild reaction conditions and simplicity of the sol–gel method make it an excellent tool for producing substances with precisely tailored properties. This technique opens the possibility for the synthesis of various new compounds, including pH sensors, ion sensors, bioactive nanoparticles, dyes carriers, and so forth. An attempt was made to combine the sol–gel technique with the advanced technology in the production of cellulose fibers in order to obtain fibers with new and unique properties. Cellulose fibers were prepared with N‐methylmorpholine‐N‐oxide as the direct solvent. The obtained fibers contained up to 30% (w/w) silicon dioxide nanoparticles. In order to observe the influence of the modifier on the fibers, their mechanical properties were examined. Modified fibers were also examined by means of thermogravimetry, wide‐angle X‐ray scattering, and ²⁹Si‐NMR solid‐state spectroscopy. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1793–1798, 2005     

The toxicity in vitro of titanium dioxide nanoparticles modified with noble metals on mammalian cells

The aim of the presented work was to evaluate the effect of modification of titanium dioxide nanoparticles with noble metals and their oxides on selected mammalian cells. The in vitro cytotoxicity studies of titanium dioxide (TiO₂) nanoparticles modified with Au, Ag, Pd, Ag₂O, and PdO with reference to the unmodified TiO₂ nanoparticles were presented. The evaluation of cytotoxic activity of the tested nanocomposite particles was carried out using three cell lines: Caco-2 colorectal epithelial adenocarcinoma cells, BJ normal human skin fibroblasts, and L929 mouse fibroblasts. The in vitro studies included determination of cell viability after 24 and 48 hours of exposure to the nanocomposite particles, using the MTT assay, as well as flow cytometry with Annexin V-FITC staining. Our results indicate that irrespectively of the kind of cell line and assay used, nanoparticles of unmodified titanium dioxide as well as those with addition of gold and palladium have a slight impact on cell viability at the investigated concentration range (10-200 μg/mL). Nanoparticles with addition of silver (Ag and Ag₂O), were found to have significantly higher toxic effect, the level of which varied depending on the cell line and assay used.     

载银二氧化钛光催化杀菌性能的研究

以偏钛酸为前驱体,浸渍一定浓度的硝酸银溶液,用热沉积法制备出载银二氧化钛。用XRD测定载银二氧化钛的结构,扫描电镜观测形貌,研究了载银量、光强、二氧化钛浓度、细菌浓度对光催化杀菌的影响。结果表明:制备的粉体为超细锐钛矿型二氧化钛,颗粒为均匀的类球形,粒度约为100～200nm。在二氧化钛颗粒上负载约1.6%的银可以扩展光源利用范围至可见光,光催化作用与银协同杀菌;但银量过高,则主要体现银的杀菌效果。光强增加,杀菌效果提高;二氧化钛的浓度为1.5g/L时杀菌效果最好;细菌浓度低于106细胞/mL时,载银二氧化钛杀菌率可以达到90%以上。     

聚苯胺改性负载型纳米二氧化钛的研究

采用悬浮聚合法制备聚苯乙烯微珠载体,通过矿化接枝技术将溶胶-凝胶法制备的纳米二氧化钛负载在微珠载体上,制成负载型纳米二氧化钛光催化剂。利用导电聚苯胺对负载型纳米二氧化钛光催化剂进行可见光改性研究,通过XRD,SEM等方法对负载型纳米二氧化钛光催化剂进行表征;通过光催化降解甲基橙实验评价了导电聚苯胺改性负载型纳米二氧化钛光催化剂在可见光条件下的光催化活性。实验结果表明：导电聚苯胺对负载型纳米二氧化钛光催化剂的改性,可有效改善负载型纳米二氧化钛光催化剂在可见光条件下的光催化性能,降解率提高了24.5%。     

Lysozyme-coated silver nanoparticles for differentiating bacterial strains on the basis of antibacterial activity

Lysozyme, an antibacterial enzyme, was used as a stabilizing ligand for the synthesis of fairly uniform silver nanoparticles adopting various strategies. The synthesized particles were characterized using UV-visible spectroscopy, FTIR, dynamic light scattering (DLS), and TEM to observe their morphology and surface chemistry. The silver nanoparticles were evaluated for their antimicrobial activity against several bacterial species and various bacterial strains within the same species. The cationic silver nanoparticles were found to be more effective against Pseudomonas aeruginosa 3 compared to other bacterial species/strains investigated. Some of the bacterial strains of the same species showed variable antibacterial activity. The difference in antimicrobial activity of these particles has led to the conclusion that antimicrobial products formed from silver nanoparticles may not be equally effective against all the bacteria. This difference in the antibacterial activity of silver nanoparticles for different bacterial strains from the same species may be due to the genome islands that are acquired through horizontal gene transfer (HGT). These genome islands are expected to possess some genes that may encode enzymes to resist the antimicrobial activity of silver nanoparticles. These silver nanoparticles may thus also be used to differentiate some bacterial strains within the same species due to variable silver resistance of these variants, which may not possible by simple biochemical tests.     

Catalytic hydrogen oxidation using zeolite RHO modified by silver nanoparticles

Catalytic activity of zeolite RHO modified by silver ions and nanoparticles is studied by way of example of the hydrogen oxidation reaction. It has been ascertained that incorporation of silver nanoparticles in the zeolite RHO structure provides significant enhancement of its catalytic activity and hydrogen oxidation at a temperature as low as 200°C rather than 450°C in case of nonmodified zeolites.     

Photoelectrocatalytic and photocatalytic disinfection of E. coli suspensions by titanium dioxide

This paper reports studies of the photoelectrocatalytic and photocatalytic disinfection of E. coli suspensions by titanium dioxide in a sparged photoelectrochemical reactor.

Two types of titanium dioxide electrode have been used. ‘Thermal’ electrodes were made by oxidation of titanium metal mesh; ‘sol–gel’ electrodes were made by depositing and then heating a layer of titania gel on titanium mesh. Cyclic voltammetry was used to carry out an initial characterisation and optimisation of both electrode types. The best ‘thermal electrodes’—i.e. those with the highest photocurrents—were prepared by heating titanium mesh at 700 °C in air. For sol–gel derived electrodes, optimum performance was obtained by heating at 600 °C. These electrodes were then used, in a gas sparged reactor, to disinfect E. coli suspensions with an initial concentration of 10⁷ colony forming units (cfu) ml⁻¹. Films prepared by the oxidation of titanium metal were shown to be superior to sol–gel derived films. Direct experimental comparison demonstrates that the photoelectrochemical system is more efficient than photocatalytic disinfection effected by slurries of Degussa P25 titanium dioxide.

Since in practical systems the TiO₂ would be exposed to a variety of species additional to those that are targeted, we also examined the effects of H₂PO₄⁻ and HCO₃⁻ ions on the measured disinfection rates. Phosphate addition poisons both the electrode and particulate-slurry systems and is only partially reversible. By contrast, although bicarbonate addition affects all three systems, the effects are reversible.     

复合二氧化钛负载膜降解十二烷基苯磺酸钠的研究

以玻璃珠为载体,用溶胶-凝胶法制备二氧化钍和三氧化二钕复合二氧化钛膜对水溶液中的十二烷基苯磺酸钠进行了固定相光催化氧化实验。研究了复合膜的紫外-可见光透过性能和二氧化钍与三氧化二钕的掺杂量、十二烷基苯磺酸钠水溶液的pH值等因素对光解率的影响。结果表明,二氧化钍和三氧化二钕复合二氧化钛负载膜的光催化活性显著提高且组分质量比存在最佳值。当二氧化钍与二氧化钛的质量比为0.02,三氧化二钕与二氧化钛的质量比为0.01时,最高光解率分别为同样条件下二氧化钛的2.3倍和1.6倍。     

Applied studies on immobilized titanium dioxide films ascatalysts for the photoelectrochemical detoxification of water

Preliminary results are presented on the photochemical and photoelectrochemical degradation of aqueous organic solutions by anodic, thermal and sol–gel TiO2 films. The films were tested in a photochemical falling film reactor, and a photochemical/photoelectrochemical vortex reactor, and preliminary results are presented on the degradation of a range of model organics using these reactors. The former showed the best mass transport characteristics and most efficient light usage, whilst the latter reactor clearly showed the efficacy of the electric field enhancement effect. The results on the vortex reactor effectively represent a proof-of-concept of the electric field enhancement approach in large scale photoelectrochemical reactors. From time to time it is necessary to recoat the substrates, and the importance of the procedure adopted to remove old TiO2 films prior to the fabrication of new films is highlighted, as well as the mode of operation of the sol–gel films, and problems encountered in reactor design.     

二氧化钛改性硅酮建筑密封胶的研究

以水性聚苯丙乳液为基料,气相白炭黑为填料,自制TiO_2为抗菌防污剂,邻苯二甲酸二丁酯为消泡剂和增塑剂,KH-550(γ-氨丙基三乙氧基硅烷)为偶联剂,制备抗菌防污型硅酮建筑密封胶。着重探讨了胶液的稳定性、黏度、色度、抗紫外线,以及胶膜的抗菌防污性、耐水性、耐老化等性能。研究结果表明:改性后的硅酮建筑密封胶胶膜性能符合国家标准,具有良好的抗菌防尘防污性和自清洁效果。     

负载硅钨杂多酸纳米银修饰电极的电化学性质研究

以硅钨杂多酸作为光催化还原剂制备了纳米银(SiW12-NS)。用PVP作偶联剂,将SiW12-NS修饰到玻碳电极表面,用循环伏安法(CV)研究其电化学行为。结果表明,修饰电极具有良好的电化学响应和电极稳定性,对BrO3-,NO2-具有良好的电催化还原性能。     

纳米二氧化钛强化的相变储能研究进展

近年来,随着一次能源紧缺,能源利用效率的重要性日益提升,相变储热可有效提升能源利用效率,人们开始将相变材料同其他物质相结合以进一步拓展其应用范围。纳米二氧化钛具有低成本、无毒、高导电性、高化学稳定性、高热稳定性等优点,现已被广泛研究用于相变储热领域。本文综述了纳米二氧化钛在相变储能领域中的研究进展,从纳米二氧化钛在复合相变材料中的功能出发,主要分为两个部分：（1）纳米二氧化钛在定型相变材料中的应用研究现状;（2）纳米二氧化钛在其他功能相变材料中的应用研究进展。旨在为纳米二氧化钛在相变储能领域的进一步应用提供理论依据与参考。     

Polyaniline modified mesoporous titanium dioxide that enhances oxo‐biodegradation of polyethylene films for agricultural plastic mulch application

Mesoporous titanium dioxide (M‐TiO₂) nanoparticles were successfully prepared followed by chemical modification with different contents of polyaniline (PANI/M‐TiO₂) and were used to accelerate the photo‐oxidation and biodegradation process of low‐density polyethylene (LDPE) film. The influence of these additives as a pro‐oxidant additive on the accelerated degradation of LDPE was investigated by photocatalytic oxidation under UV light irradiation and biodegradation with fungal strains. It was found that the as‐prepared PANI modified M‐TiO₂ particles exhibited an obvious light response from 400 to 800 nm which can improve the utilization of solar light. Compared with M‐TiO₂, PANI/M‐TiO₂ exhibited better photocatalytic performance when irradiated under UV light and the subsequent biodegradation efficiency was enhanced. Enhancement of the photocatalytic performance of PANI/M‐TiO₂ could be attributed to good dispersibility and compatibility of PANI/M‐TiO₂ in the LDPE matrix, a narrow band gap, effective separation of photogenerated electron–hole pairs and the chromophoric group of PANI which was used as a photosensitizer in the LDPE/PANI/M‐TiO₂ composite film. © 2019 Society of Chemical Industry     

Controlled multilayer films of sulfonate-capped gold nanoparticles/thionine used for construction of a reagentless bienzymatic glucose biosensor

A novel reagentless bienzymatic sensor for the determination of glucose in the low working potentials without interference is proposed. The bienzymatic sensor was fabricated by covalently attachment of periodate-oxidized glucose oxidase (IO₄⁻-GOx) and horseradish peroxidase (HRP) on controlled multilayer films of sulfonate-capped gold nanoparticles/thionine (SCGNPs/TH). Using the layer-by-layer method (LBL), SCGNPs and TH were deposited alternately on the gold electrode through the electrostatic and covalent interactions. SCGNPs could greatly enhance the amount of immobilized TH and ensure the good conductivity of the whole structure. UV-vis absorption spectroscopy and electrochemical methods showed that the resulting multilayer films were tridimensional conductive and porous, and TH incorporated in LBL configuration had well electroactive performance. Such superstructures can thus provide an ideal matrix for the construction of bienzymatic sensor, where TH molecules acted as a mediator for electron transfer. After IO₄⁻-GOx and HRP were covalently attached to the multilayer precursor film, the resulting biosensor exhibited good electrocatalytical response toward glucose and that the electrocatalytical response increased with the number of TH layers. This suggested that the analytical performance such as sensitivity and detection limit of the bienzymatic sensors could be tuned to the desired level by adjusting the number of deposited SCGNPs/TH bilayers. Furthermore, because of the low working potentials, the interference from other electro-oxidizable compounds (such as uric acid, ascorbic acid and acetaminophen) was avoided, which improved the selectivity of the biosensors. The biosensor constructed with six bilayers of SCGNPs/TH showed a good performance of glucose detection with a fast response less than 20 s, acceptable sensitivity of 3.8 μA mM⁻¹ cm⁻² and the detection limit of 3.5 × 10⁻⁵ M.     

Effect of titanium dioxide nanoparticles on polydimethylsiloxane/polyethersulfone composite membranes for gas separation

Introducing inorganic nanoparticles into the structure of polymeric membranes is an interesting approach for the enhancement of physical, chemical, and separation properties of the membranes. In this article, the performance of a two‐layer nanocomposite membrane for gas separation was studied. Three different methods for embedding titanium dioxide (TiO₂) nanoparticle were employed for the membrane preparation. The techniques include blending TiO₂ in the polydimethylsiloxane (PDMS) coating layer, blending TiO₂ in the polyethersulfone (PES) support and dip coating of PES support with TiO₂ accompanied by PDMS coating. The aim of the current research was finding the optimum technique for introducing TiO₂ into the membrane to obtain superior performance for gas separation. The results indicated that PES support containing TiO₂ nanoparticles possessed favorable effect on gas separation capability. The optimum performance was obtained by PDMS‐coated membranes prepared with 7 wt% TiO₂‐embedded PES support. Carbon dioxide (CO₂) permeance, CO₂/nitrogen, and CO₂/methane selectivity were obtained as 188.7 GPU, 8.6, and 3.4, respectively. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers     

多元改性二氧化钛的制备及其性能研究

采用浸渍法制备了铁-钐-镱-二氧化钛改性光催化剂,以苯酚为目标降解物,讨论了影响光催化剂性能的因素和提高光催化剂性能的方法。通过FE-SEM、XRD、UV-Vis等表征手段初步探讨了共掺杂提高二氧化钛光催化活性的机理。实验结果表明：常温、常压下,质量浓度为20 mg/L的苯酚废水（pH=7）,当催化剂加入量为 2.5 g/L、焙烧温度为550 ℃、金属（铁、钐、镱）掺杂量各为0.5%（质量分数）时,经4 h紫外光照其对苯酚的去除率可达90%以上。改性后的二氧化钛光催化剂在可见光下也能够显示出很好的活性。     

Surface modification of titanium dioxide nanoparticles by polyaniline via an in situ method

BACKGROUND: Nanoparticulate titanium dioxide (TiO₂) has the advantages of high chemical stability, high photocatalytic activity to oxidise pollutants in air and water, relatively low price and non‐toxicity. However, its high surface energy leads to the aggregation of nanoparticles. In addition, the wide band gap of TiO₂ (3.2 eV) only allows it to absorb ultraviolet (UV) light (<387 nm), which represents just a small fraction (3–5%) of the solar photons. These factors have limited its use in many fields. In this study, nanoparticulate TiO₂ was modified by polyaniline (PANI) in order to enhance its photoactivity under UV light and sunlight illumination. RESULTS: TiO₂ nanoparticles were modified by PANI via a chemical oxidative method. The introduction of small amounts of PANI enhanced the dispersion of TiO₂ nanoparticles and improved the photocatalytic activity under UV light. In addition, the band gap energies of all PANI/TiO₂ nanocomposites were lower than that of neat TiO₂ nanoparticles, so the PANI/TiO₂ nanocomposites can be excited to produce more electron–hole pairs under sunlight, which could result in higher photocatalytic activities. CONCLUSION: The modification of nanoparticulate TiO₂ by PANI can increase its photoactivity in the process of phenol degradation under UV light and sunlight illumination. Copyright © 2008 Society of Chemical Industry     

溶胶-凝胶法制备KH-570改性纳米二氧化钛及其表征

以钛酸丁酯(TBOT)为前驱物,盐酸为催化剂,γ-甲基丙烯酰氧基丙基三甲氧基硅烷(KH-570)为改性剂,采用溶胶-凝胶法原位制备了KH-570改性的纳米二氧化钛,研究了KH-570用量对纳米二氧化钛表面改性效果的影响,并采用红外光谱(FT-IR)、X射线衍射(XRD)、粒径分析等手段对纳米二氧化钛进行了表征。结果表明:KH-570接枝到纳米二氧化钛表面,纳米二氧化钛为锐钛矿型;随着KH-570用量的增大,接枝率先上升然后稍有下降,当KH-570用量为TBOT质量的14.57%时,接枝率达到25.6%;与未加KH-570制备的二氧化钛相比,KH-570改性纳米TiO2的平均粒径减小且分布变窄,亲油性得到明显提高。