Titanium Dioxide Nanomaterials: Synthesis, Properties, Modifications, and Applications

TiO2 photocatalysis and related surface phenomena

Decontamination and disinfection of water by solar photocatalysis: Recent overview and trends

A one-step simple synthesis of silver colloid nanoparticles with controllable sizes is presented. In this synthesis, reduction of [Ag(NH3)2]+ complex cation by four saccharides was performed. Four saccharides were used:  two monosaccharides (glucose and galactose) and two disaccharides (maltose and lactose). The syntheses performed at various ammonia concentrations (0.005−0.20 mol L-1) and pH conditions (11.5−13.0) produced a wide range of particle sizes (25−450 nm) with narrow size distributions, especially at the lowest ammonia concentrations. The average size, size distribution, morphology, and structure of particles were determined by dynamic light scattering (DLS), transmission electron microscopy (TEM), and UV/Visible absorption spectrophotometry. The influence of the saccharide structure (monosacharides versus disaccharides) on the size of silver particles is briefly discussed. The reduction of [Ag(NH3)2]+ by maltose produced silver particles with a narrow size distribution with an average size of ...

Silver Colloid Nanoparticles: Synthesis, Characterization, and Their Antibacterial Activity

Generations Yi Ma,† Xiuli Wang,† Yushuai Jia,† Xiaobo Chen,‡ Hongxian Han,*,† and Can Li*,† †State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences and Dalian National Laboratory for Clean Energy, 457 Zhongshan Road, Dalian 116023, China ‡Department of Chemistry, College of Arts and Sciences, University of Missouri-Kansas City, 5100 Rockhill Road, Kansas City, Missouri 64110, United States

Titanium dioxide-based nanomaterials for photocatalytic fuel generations.

This study presents radio frequency plasma (RF-plasma), microwave plasma (MW-plasma), and vacuum-UV light irradiation as pretreatment of synthetic textile surfaces allowing the loading of TiO 2 by wet chemical techniques in the form of transparent coatings constituted of nano-particles of diverse sizes. These loaded textiles show a significant photo-oxidative activity under visible light in air under mild conditions, which discolors and mineralizes persistent pigment stains contained in wine and coffee. The mineralization of stains on the textile loaded with TiO 2 was monitored quantitatively to assess the appropriate surface pretreatment in conjunction with the most suitable deposition method of TiO 2 colloids, powders, or combination of both. Their photocatalytic activity allowed, in kinetically acceptable times, the almost complete discoloration of coffee and wine stains. The observed discoloration of colored stains seems to involve visible light sensitization of the stain pigment on the TiO 2 -loaded textile. The size of the particles obtained from colloidal precursors of TiO 2 varied between 5 and 25 nm.

Self-cleaning of wool-polyamide and polyester textiles by TiO2-rutile modification under daylight irradiation at ambient temperature

The bacterial inactivation efficiencies of silver metal and oxides and their combinations on textile fabrics was investigated to evaluate the disinfectant action on airborne bacteria. The inactivation performance was seen to depend on the amount of silver on the textile surface. The preparation of the polyester-polyamide Ag-loaded textiles was carried out by RF-plasma and vacuum-UV (V-UV) surface activation followed by chemical reduction of silver salts. The rate of bacterial inactivation by the silver loaded textile was tested on Escherichia coli K-12 and showed long lasting residual effect. Specular reflectance has been employed to assess the optical properties of the Ag-loaded fabrics. By elemental analysis it was found that levels of Ag loading >0.118% (w/w) for the vacuum-UV samples lead to complete inhibition of bacterial growth. X-ray photoelectron spectroscopy (XPS) shows that for textiles activated by RF or V-UV methods, the silver in the topmost layer increases with increasing concentration of the Ag used in the precursor solution. The exact determination of the oxidation state of the Ag-clusters on the textile is difficult because of the variation of particle size and electrostatic charging of the supported particles. Ag metal was found to be the main component of the Ag-clusters and not Ag2O and AgO as identified by the binding peak energies (BE). By transmission electron spectroscopy (TEM) it was seen that the Ag-clusters were deposited on the two polymer components of the textile fabric but having widely different sizes. (C) 2003 Elsevier Science B.V. All rights reserved.

Antibacterial textiles prepared by RF-plasma and vacuum-UV mediated deposition of silver

The photocatalytic activity of TiO 2 –SiO 2 -coated cotton textiles was investigated through the self-cleaning of red wine stains. It was shown that a TiO 2 –SiO 2 species could be produced at temperatures of 100 °C with acceptable photo-activity on non-heat resistant materials. The most suitable Ti-content of the coating was found to be 5.8% and for SiO 2 , the content was 3.9% (w/w). The discoloration of red wine led to CO 2 evolution that was more efficient for TiO 2 –SiO 2 -coated cotton for samples than of TiO 2 -coated ones. The reasons for these results are discussed. The textile surface did not show any change after several consecutive light-induced discoloration cycles of a red wine stain. By high-resolution transmission electron microscopy (HRTEM), the TiO 2 –SiO 2 layer thickness on the cotton fibers was detected to 20–30 nm. The TiO 2 and SiO 2 were both observed to have particle sizes between 4 and 8 nm. Further electron microscopy work coupled with energy dispersive spectroscopy (EDS) showed that the Ti-particles were always surrounded by amorphous SiO 2 and never alone by themselves. Infrared spectroscopy revealed that no modification of the cotton could be detected after photo-discoloration processes with TiO 2 –SiO 2 , taking a wine stain as model compound. The mixed TiO 2 and SiO 2 colloids lead during the dip-coating and subsequent thermal treatment on cotton to an organized structure of highly dispersed TiO 2 particles always surrounded by amorphous silica.

Self-cleaning cotton textiles surfaces modified by photoactive SiO2/TiO2 coating

This study shows that samples of bleached cotton (C 2 ) and of mercerized cotton (E) textiles can be activated by RF-plasma, MW-plasma and UV-irradiation introducing functional groups negatively charged to anchor TiO 2 on the textile surface. The preparation of the TiO 2 colloids and the cotton surface functionalization are described in a detailed way. The photo-discoloration and mineralization of stains of red wine, coffee, make up and grease were monitored following the CO 2 evolved upon daylight irradiation with 50% full solar light intensity (AM 1). For base treated cotton (C 2 ), UV activated textile followed by TiO 2 deposition from Degussa TiO 2 P25 was the most active sample during the discoloration of wine and coffee stains under daylight irradiation. In the case of the mercerized cotton samples (E), MW-plasma activation of the textile surface followed by TiO 2 deposition from a titanium tetra-isopropoxide (TTIP) colloid showed the most favorable discoloration kinetics. The images obtained by electron microscopy (TEM) and by (HRTEM) show 5–7 nm TiO 2 crystallites for the MW-plasma (E) cotton samples at time zero and for the same after 20 machine household washings. The coating of TiO 2 on the textiles presented variable thickness of 120–300 nm. The TiO 2 cluster size and distribution from sol–gel precursors after daylight induced stain discoloration did not vary with respect to the TiO 2 cluster size before irradiation. This is the evidence the stable nature of the TiO 2 cluster deposition on the cotton surface. X-ray evidence for rutile formation on the C 2 cotton fibers was obtained. Elemental analysis revealed Ti-loadings of 1–1.5% (w/w) for the TiO 2 attached by different techniques. The self-cleaning leading to the stain discoloration was quantified to assess the photo-activity of the TiO 2 clusters prepared under different experimental conditions. This process shows promise for the total removal of stains containing persistent colored pigments on the cotton fibers.

T. Yuranova

Papers

Self-cleaning of wool-polyamide and polyester textiles by TiO2-rutile modification under daylight irradiation at ambient temperature

Antibacterial textiles prepared by RF-plasma and vacuum-UV mediated deposition of silver

Self-cleaning cotton textiles surfaces modified by photoactive SiO2/TiO2 coating

Self-cleaning of modified cotton textiles by TiO2 at low temperatures under daylight irradiation

Synthesis, activity and characterization of textiles showing self-cleaning activity under daylight irradiation