Search

Copyright of Revista ION is the property of Universidad Industrial de Santander and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Veterinaria is the property of Universidad Nacional del Nordeste and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Lemongrass (Cymbopogon citratus) is a leaf that has been used throughout the years for medicinal and food purposes. Currently, other uses have been added in the chemical industry since its infusion helps the process of synthesis of TiO2 nanoparticles, generating by-products such as cellulose and other compounds that have great potential for reuse. For this reason, in the present research an exergetic analysis of the process of TiO2 nanoparticle production from lemongrass and titanium isopropoxide is performed. From this analysis it is possible to know which process stages require improvements and to evaluate the overall efficiency of the process. This process is an academic research conducted by the University of Cartagena. The simulation was performed on the specialized Aspen Plus V10 TM software. It was observed that with approximately 32675 ton/year of lemongrass and 5724 ton/year of titanium isopropoxide, 1496 ton/year of TiO2 nanoparticles are produced, with an overall exergetic efficiency of 0.2366%. In addition, a sensibility analysis was done to propose improvements that would increase the overall efficiency of the process. [ABSTRACT FROM AUTHOR]

Lemongrass (Cymbopogon citratus) is a leaf that has been used throughout the years for medicinal and food purposes. Currently, other uses have been added in the chemical industry since its infusion helps the process of synthesis of TiO2 nanoparticles, generating by-products such as cellulose and other compounds that have great potential for reuse. For this reason, in the present research an exergetic analysis of the process of TiO2 nanoparticle production from lemongrass and titanium isopropoxide is performed. From this analysis it is possible to know which process stages require improvements and to evaluate the overall efficiency of the process. This process is an academic research conducted by the University of Cartagena. The simulation was performed on the specialized Aspen Plus V10 TM software. It was observed that with approximately 32675 ton/year of lemongrass and 5724 ton/year of titanium isopropoxide, 1496 ton/year of TiO2 nanoparticles are produced, with an overall exergetic efficiency of 0.2366%. In addition, a sensibility analysis was done to propose improvements that would increase the overall efficiency of the process. [ABSTRACT FROM AUTHOR]

Copyright of Iteckne is the property of Universidad Santo Tomas, Division de Ingenierias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article discusses the need to evaluate the effects of sunscreens on aquatic ecosystems. Studies have been conducted on the safety of sunscreen components for human use, but the risks to marine organisms have not been taken into account. Experiments with pond shrimp showed that certain components of sunscreens caused body opacity and lethal consequences. The toxicity of cream D, which contains zinc oxide in the form of nanoparticles, is highlighted, and the pollution and adverse effects of titanium dioxide are mentioned. It is concluded that detailed studies and regulations are needed to protect human health and the marine environment. [Extracted from the article]

The development of ceramic nanomaterials with self-cleaning properties is an important field of research since they can be used in different sectors such as the textile, aerospace, automotive and biomedical protection elements. The objective of the work is to analyze and identify world trends in research, level of innovation, as well as emerging technologies in the development of TiO2/ZnO nanoparticles with antibacterial and self-cleaning properties; based on the technological monitoring of patents and Scholarly works using bibliometric methods using Lens bibliometric analysis software. The stages of technological development were estimated through the logistic model using the Loglet Lab4 software and the Yoon parameters, the Technological Maturity Rate (TMR), the potential patents to appear (EPP), the remaining lifetime (ERL) were calculated. four indicators were used: Granted patents (i1), patent applications (i2), scholarly Works (i3) and human capital (i4). The technological trend of patents for the first period focused on the development of catalysis processes, while in period II on technology for the manufacture of cosmetics and disinfectants. In period III, nanotechnology applied in cosmetics and disinfection processes appeared, finally, in period IV a trend towards disinfection and coating processes was observed, as well as the number of patent applications for this period. This technology of self-cleaning surfaces registered an average maturity rate of 72.3%, which is in a stage of maturity, being a technology classified as "leading technology" with the possibility of investment in the development of new products and processes. [ABSTRACT FROM AUTHOR]

Nanocomposites are multiphase structures with at least one phase dimension of nanometric order size. Polymer-based materials mixed with low proportions of titanium dioxide nanoparticles (NPs-TiO2) are a versatile alternative in different industrial applications, considering the optimization of mechanical and thermal properties with respect to pure polymers and conventional materials. In this work, the synthesis and thermal characteristics measurement of a nanocomposite formed by anatase phase Nps-TiO2 of 5 nm particle size in a polyurethane matrix is reported. The polymeric matrix was obtained through the reaction between the self-condensation of castor oil and diphenylmethane diisocyanate (MDI), while sol-gel technique was used in the synthesis of NPs-TiO2, using titanium (IV)-bis(acetylacetonate) diisopropoxide as precursor. Specific heat (Cp) of the samples was measured by means of the thermal relaxation method and thermal diffusivity (α) was determined with the photoacoustic technique. Cp of the nanocomposite increased by 12.98 % due to addition of the NPs, while α decreased by 98.63 %, compared to corresponding values of the polyurethane matrix. With a concentration of 3 wt % of NPs-TiO2 in the matrix, these thermal parameters were found below average values of conventional plastics. [ABSTRACT FROM AUTHOR]

The objective was the evaluation of color as a proxy for soil contamination by heavy metals in Mexico City. The concentrations of heavy metals were measured by X-ray fluorescence, and the color was determined with the Munsell Tables and colorimeter using Red Green Blue (RGB) system. From the Hue, Value and Croma values, five soil groups were formed by color: I, Dark reddish brown, 5YR 4/2; II, Dark gray, 7.5YR 4/1; III, Olive gray, 5Y 5/2; IV, Gray, 5YR 5/1; V, Pinkish gray, 7.5YR 6/2. With the Red Green Blue colorimetric values, three color indexes were calculated: Hue index, Redness index and saturation index. Validation of soil groups was greater with color indexes than with heavy metals. Groups I and II of dark color had the highest concentrations of Cr, Cu, Pb and Zn; they also had the highest percentages of Fe2O3, MnO, and TiO2. Light colored groups IV and V had the highest percentages of Al2O3, MgO and SiO2. Group III had intermediate values of Cr, Cu, Pb, Zn, Fe2O3, MnO, and TiO2. For the first time, it is reported that the color of the urban soil of Mexico City can be used as a rapid analysis technique to identify sites contaminated with heavy metals. [ABSTRACT FROM AUTHOR]

Photodynamic therapy (PDT) has become an important alternative for the treatment of different types of cancer, due to its great advantages over conventional methods. In this field, TiO2 nanoparticles are one of the most widely studied photosensitizers due to their high photocatalytic activity, high absorption of UVA light and high biocompatibility. Although there are several successful studies related to PDT treatment, using TiO2 nanoparticles, for different types of adherent cancer cells, there are few reports of PDT applied to non-adherent cancer cells, due to the challenges related to blood volume and light penetration. To address this challenge, modified TiO2 nanoparticles (TiO2-m) were deposited on glass substrates to study the cytotoxic effect of PDT on Molt4, non-adherent cells, using these coatings. The shaping of uniformed coatings on substrates was proved by standard deviation of transmittance in the UVA range at different points. Different experimental PDT tests of Molt4 cells on TiO2-m coatings were performed and the treatment cytotoxic effect was evaluated by LDH concentration. The results demonstrated the possibility of generating cytotoxic effect on non-adherent cancer cells with only 20 min of contact and 40 min of UVA radiation. This result is the first step for the possible development of new methodologies in the application of PDT on non-adherent cells using TiO2-m coatings. [ABSTRACT FROM AUTHOR]

Copyright of Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales is the property of Academia Colombiana de Ciencias Exactas, Fisicas y Naturales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Introduction: in the search for new materials useful as thermoluminescent dosimeters (TL) alumina (α-Al2O3) has acquired great attention. The α-Al2O3 has a sensitivity TL that is perceptível to the concentrations of impurities and to the thermal conditions of the growth of its crystals, so finding new variations of the material will allow to increase its TL response. Objective: analyze the brightness curves of pure alumina matrices sintered under different calcination conditions and doped with cerium at a concentration of 0.1 % p/p (Al2O3:Ce), using the asymmetric logistic function, to calculate its thermoluminescent kinetic parameters and explain the behavior of the material. Materials and methods: boehmite alumina powder was used to prepare pure sintered samples of under different calcination conditions (NALO and ALO). The cerium was introduced by wet impregnation using cerium hexahydrate nitrate. The structural analysis of the matrices was carried out by X-ray diffraction. The TL reading was performed in a TLD 4500. Results: the deconvolution obtained in the brightness curves for the ALO and NALO groups evidences the presence of three and four TL signals respectively, and of six TL signals in the sample Al2O3:Ce. Conclusion: the applied heat treatments introduced a substantial change in the brightness curve of the material and its TL kinetics, in terms of the number of traps and the initial amount of charge carriers trapped. The introduction of cerium impurities produced a fundamental modification in the brightness curve of the alumina matrices. [ABSTRACT FROM AUTHOR]

Spinach is consumed for its valuable nutritional contributions. However, in Colombia, this crop has been of little interest in the research area due to its low production. On the other hand, the nanotechnology that can be used in agriculture to prevent or control diseases in crops through the application of nanoparticles (NPs) is emerging as a high potential subject in our country. In this work, the inoculation of suspensions of titanium dioxide NPs with the incorporation of silver (TiO2- Ag) in spinach seeds was evaluated. The NPs were synthesized through Sol-gel method and characterized by means of X-ray diffraction; suspensions of these powder samples of grain size between 7 and 26 nm were prepared at different concentrations for inoculation. In comparison with the control group (without inoculation), highest plant growth was obtained with NPs of the lowest size and 2 % concentration. It possibly due to the contribution in the photosynthesis process and antimicrobial role of incorporated TiO2-Ag. The photosynthetic activity of the plants from control and treated groups was measured by the photoacoustic technique and it was found that the plants treated with the smallest NPs suspension, at a concentration between 0.25 and 2 %, presented a rate of oxygen evolution similar to control group. These results indicate that the treatment with NPs of TiO2-Ag between 7 and 8 nm at low concentration can improve the growth without drastic alteration of the photosynthetic rate of spinach plants, which can be an efficient alternative for improvement in crop production. [ABSTRACT FROM AUTHOR]

Copyright of Bistua: Revista de la Facultad de Ciencias Básicas is the property of Facultad de Ciencias Basicas de la Universidad de Pamplona and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The synthesis and study of biomaterials possessing biomechanical and biocompatibility properties is a subject of continuous research by the scientific community. Compounds such as hydroxyapatite (HA) and brushite, which have interesting properties and are biocompatible, are being used as a barrier layer between materials such as 316L steel and biological media, thus reducing the iron ion flux from the steel to the Biological fluids. Although recent studies have presented advances regarding the adhesion of these materials to different metals, there are still open challenges to improve the adhesion of these materials to the desired metal. In this work, we have implemented coatings composed of brushite and titanium dioxide (TiO2) bilayers. Following are the protocols followed for synthesis of brushite, titanium dioxide and bilayer coatings on 316 L steel, as well as the structural characterization by infra-red spectrometry (FTIR), X-ray diffraction (XRD), electron microscopy of Scanning (SEM) and dispersive energy spectroscopy (EDS) of the coatings obtained. [ABSTRACT FROM AUTHOR]

The effect of adding functionalized and non-functionalized multiwall carbon nanotubes to nano-ceramic material by the sol-gel process of nanoceramic TiO2 were studied. The functionalization of multiwall carbon nanotubes using the method of carboxylation with HSO4-HNO3 and HCl was developed. Tetrabuthoxide Titanium, Ti(OBu)4, was the precursor used for the manufacture of TiO2. The hydrolysis and polycondensation reactions, in addition to the pre-calcined and calcined in the sol-gel process were followed and analyzed by Fourier Transform Infrared Spectroscopy (FTIR). TiO2 with multiwall carbon nanotubes mass fraction of 0.0%, 0.7%, 1.4% and 2.1% were obtained. For nanoindentation and microindentación tests increase in hardness of 39% and increase of two times in the Young's modulus were observed. Structural details establishing uniformity and reduction in the size of multiwall carbon nanotubes were studied by Transmission Electron Microscopy (TEM). [ABSTRACT FROM AUTHOR]

The optical properties of nanocrystalline and mesoporous titanium dioxide (TiO2) layers, obtained using the "doctor blade" technique, are analyzed. These layers are used in different sensitized solar cell types, as well as, in the novel perovskite solar cells. Transmittance and diffused reflection spectra of different layers deposited on optical glass are reported and compared. Using Swanepoel method, the refractive index is determined in the 600-800 spectral range from transmittance spectra. Feasibility of obtaining the spectral dependence of an effective absorption coefficient for mesoporous TiO2 is discussed and the spectra are reported. The use of the obtained optical constants to find the thickness of TiO2 films, similar to those studied, is discussed. [ABSTRACT FROM AUTHOR]

The work of photoelectrochemical sensors, based on the Ti/TiO2 electrode (being an example for the modeling the hydrazine sensor), was described mathematically and the respective model was analyzed by means of linear stability theory and bifurcation analysis. The best response condition for this sensor, as also, the oscillatory and monotonic instabilities requirements, were inferred, basing on the model´s analysis. [ABSTRACT FROM AUTHOR]

Copyright of Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales is the property of Academia Colombiana de Ciencias Exactas, Fisicas y Naturales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Medicina y Seguridad del Trabajo is the property of Escuela Nacional de Medicina del Trabajo - Instituto de Salud Carlos III and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista Colombiana de Ciencias Químico-Farmacéuticas is the property of Universidad Nacional de Colombia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Directive 2010/75/EU of the European Parliament and of the Council establishes rules on the prevention and control of industrial pollution. Its objective is to prevent, reduce, and eliminate pollution derived from industrial activities, following the principles of "polluter pays" and pollution prevention. The Directive applies to industrial activities that generate pollution, excluding research, development, and experimentation of new products and processes. Member States must implement the provisions of the Directive before January 7, 2013. The Directive came into force on January 6, 2011, and replaces several previous Directives related to the titanium dioxide industry, waste, and pollutant emissions. [Extracted from the article]

The quenching of the excited state of [Ru(deeb)(bpy)2] (PF6)2 where bpy is 2,2'-bipyridine and deeb is 4,4'-(COOEt)2-2,2'-bipyridine was studied in fluid acetonitrile solution and anchored to nanocrystalline titanium dioxide thin films. To quench the excited state, the cobaloximes [Co(py)(Cl)(dmgH)2] and [Co(py)(Bu)(dmgH)2] where py is pyridine, Bu is n-butyl and dmgH is dimethylglyoximate were used. These cobaloximes are efficient quenchers of the excited state both in fluid solution and when the ruthenium complex is bound to titanium dioxide. The quenching process can be adequately described using the Stern-Volmer model, which indicates that quenching is dominated by diffusion processes and is coherent with a photo induced electron transfer process. [ABSTRACT FROM AUTHOR]

Bio-coatings of TiO2 and biological hydroxyapatite (HA) doped with magnesium (TiO2/HA-Mg) were deposited on AISI 316L stainless steel by dip-coating technique, from suspensions of HA-Mg powders (which were obtained by hydrothermal treatment of bovine bone in solutions of Mg(NO3)2) in TiO2 sols. Biological hydroxyapatite powders doped with Mg were characterized by XRD and FT-IR analytical techniques, in order to evaluate the compositional changes. On the other hand, the coating's characteristics were evaluated by scanning electron and optic microscopies, adhesion force to the substrate, in vitro bioactivity in SBF and corrosion resistance. The bovine bone hydrothermally treated allowed to obtain hydroxyapatite with greater reactivity due to its doping with Mg, what was confirmed throughout the electrochemical characterization of the films. The modification of HA with Mg does not significantly affect the physical and mechanical properties of the TiO2/HA films. An increment in the bioactivity of the HA was only observed when it was modified with 10% Mg, so that during the immersion of this coating in SBF shows an initial stage of biomaterial dissolution and the subsequent stage of apatites formation on its surface. [ABSTRACT FROM AUTHOR]

Copyright of Iteckne is the property of Universidad Santo Tomas, Division de Ingenierias and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Mixed oxides SiO2-TiO2 were prepared of different compositions by the sol-gel method combined with hydrothermal treatment (HT), using tetraethylorthosilicate and titanium tetraisopropoxide as precursors of the sources silica and titanium, respectively. Hybrids obtained using the nonionic surfactant Triton X100, were carried out with TH for 48 hours at 120 °C, washed, dried at 70 °C/24 h, and calcined at 550 °C/2 h (heating rate 1 °C/min.). The mixed oxides were characterized by nitrogen physisorption, SEM, TEM, FTIR, XRD and TGA. The results indicate that the materials presented high specific surface area in the range of 190-805 m²/g, average pore diameter 4,0-6,5 ran, additionally, the silica-titania mixed oxides exhibits anatase phase desirable in photocatalytic reactions. [ABSTRACT FROM AUTHOR]

This paper reports studies on the 3.5- dinitrosalicylic acid (DNS) which is present in high concentrations in the waste produced in the practice of Physical Chemistry II Laboratory School of Chemistry at the Technological University of Pereira "Enzymatic Catalysis: Inversion of Sucrose" the process was found, after multivariate ANOVA analysis with different combinations of pH, H2O2 and TiO2 at pH 4, 300 ppm of H2O2 and 0.7 g / L of TiO2 provides the best primary degradation of the compound (96.7%) evaluated spectrophotometrically at 336 nm, the extrapolation of these conditions to heliofotocatalítico CPC reactor with waste collected in the laboratory gave a degradation of 53.37% in 450 minutes in a day of solar radiation 253.11 average W/m2; on the other hand, chemical tests show that during the degradation of other compounds isolated DNS produces substances which decrease the biodegradability of the waste, while the presence of other, the increase. [ABSTRACT FROM AUTHOR]

The soiling of in-service electrical insulators exposed to the atmosphere is a major problem in power transmission lines. Several inorganic and organic particulate materials are deposited on insulator surfaces forming a layer that could become conductive in the presence of moisture. This produces different phenomena that could deteriorate the insulating properties of the material and eventually lead to its rupture, affecting the electrical energy supply. Currently, a method based in the application of a titanium dioxide film is being developed. This method tries to minimize the pollution accumulation on the porcelain insulators without affecting their electrical properties. In this work the performance of two different thicknesses of the coating film on the porcelain insulators was evaluated by means of contact angle, adhesion, leakage current, dry-flashover voltage and erosion laboratory tests. Finally, the in-service behavior of coated and no-coated insulators installed in a power transmission tower was evaluated. The coated insulators showed a good performance in the laboratory tests. Moreover, before 5 months of exposure in the energized power line, a decrease in the soiling was observed. [ABSTRACT FROM AUTHOR]

Gold nanoparticles, Nano-Au, were prepared on different supports and used as CO oxidation catalysts. Synthesis of Nano-Au, supported on TiO2, CeO2 and γ-Al2O3 was done by precipitation in non-aqueous HAuCl4/ethylene-glycol in a Li2S/oxide/ethylene-glycol suspension in a minimum HClO4 volume. All the nano-structured systems were characterized by TEM, XPS, XRD, AE, ICP and UVVisible methods. The TEM images confirm Nano-Au/ oxide formation on all the supports. Particle size distribution analysis suggest different dispersions, being Au/Al2O3 (∼3,45 nm) the least dispersed system. XRD analysis shows the presence of Au/oxide, compared with the XRD standard, and crystal size was estimated using the Debye-Scherrer equation. UV-visible spectra shows a characteristic band near 520 nm, due to plasmon resonance in all the synthetized systems and there was no clear tendency between particle size and the absorption band displacement. XPS analysis shows two peaks with a slight displacement in bonding energy, assigned to the Au4f7/2 y Au4f5/2 transitions due to Au(0) and Au3+ from Au2S3. The CO oxidation catalytic activity of Nano-Au was done in a static bed reactor at low temperature, obtaining a 36% conversion with Au/TiO2. [ABSTRACT FROM AUTHOR]

Photocatalysts have opened the possibilities to many applications in science and medicine. The TiO2 in presence of ultraviolet UV-A is opening up space in the future treatment of various cancers. In this work we determined the effect of the composite photocatalytic TiO2 and TiO2-Au on cells of cervical cancer (HeLa) and healthy cells of Chinese hamster ovary (CHO) cell lines. Was varied compound concentration, the exposure time to UV-A and the presence or absence of UV-A. Was measured cytotoxicity of the compounds on HeLa and CHO cells with Lactatedeshydrogenase test (LDH). The highest cytotoxicity in HeLa cells was 43.2 %, while the cytotoxicity in CHO cells in all cases was negative. The compounds causes no cytotoxic effect on CHO cell lines. [ABSTRACT FROM AUTHOR]

We studied the synthesis of colloidal catalysts of Au, Ir and Au-Ir, supported on TiO2. The solids obtained were characterized by X ray diffraction (XRD), temperature programmed reduction (TPR), nitrogen physisorption, chemisorption of hydrogen and transmission electronic microscopy (TEM). The catalytic activity was evaluated in the selective hydrogenation of acrolein in gas phase. The results of characterization indicated that the metal particles were not completely reduced, so it was necessary a subsequent heat treatment of reduce at 773K. This treatment did not affect the particle size obtained by transmission electron microscopy. The addition of iridium to gold increased the dissociation capacity of hydrogen with respect to the monometallic gold catalyst and improved catalytic activity in the selective hydrogenation of C= O group of acrolein. [ABSTRACT FROM AUTHOR]

For this study were synthesized nanostructured materials of titanium dioxide by sol-gel method, at low temperature. The pH of gelation was set at 3 (TiO2-a), and 9 (TiO2-b), calcined at 500°C, to study the inluence of pH, in the electronic, optical, structural properties in the process of photodegradation. The results indicate that the semiconductors have particle sizes between 7 nm and 10 nm. The BET speciic surface areas of the samples are among TiO2-b 61 m²/g and TiO2-a 83 m /g higher than that of Degussa P25 titania (50 m²/g). The UV-vis spectroscopy of diffuse relectance was used to determine the (E ) bp band gap energy of the samples, where the values have the following order E bg (TiO2-a) < Ebg (TiO2-b)< Ebg (Degussa P25). The DRX indicate that the materials consist mainly of anatase phase. The TEM image shows that the TiO2-a presents smaller particle sizes (5 nm) compared to the other semiconductor. The photocatalytic activity for the prepared samples was tested in the 4-nitrophenol (4-NP) degradation. The mineralization of the contaminant up to 98% (TOC) was obtained with TiO2-a sample, exhibiting the highest photoactivity. [ABSTRACT FROM AUTHOR]

Copyright of Avances en Ciencias e Ingeniería is the property of Avances en Ciencias e Ingenieria and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This article discusses the viability of using agents such as niobium photocatalyst in decreasing higher energy of the band gap. To do so competitively with TiO2, the presence of oxidation helpers such as H2O2 and O3 could present surprising results in the catalytic performance due to higher generation of OH o radicals. Oxidation helpers are shown to assist in obtaining larger area oxides and textural properties different from commercial niobium oxide, and enhancing its catalytic activity in free cyanide removing. The article presents experimental results of cyanide photodegradation of 100mg/l with Degussa P- 25 TiO2 and Nb2O5 . 3H2O, using a type CPC photoreactor and sunlight as the radiation source. Taking an inclination equal to Cartagena latitude of 10,45°, the results show a clear effect of pH, catalyst type and oxidation auxiliar agent on photodegradation reaction. The ion cyanide reduction of polluted effluent was enhanced by oxidizing agent (O3 and H2O2) addition. This may suggest a greater susceptibility to free cyanide oxidation and cianate indirect oxidation due to higher hydroxyl radical generation, which was induced by H2O2 or O3 presence under solar radiation. The results showed free cyanide photocatalytic oxidation percentages between 64% and 72% using Nb2O5 . 3H2O and 67% and 71% using TiO2 Degussa P-25. The catalysts were characterized structurally by XRD, BET, Raman and FTIR, with the purpose of correlating morphological changes in catalytic performing. [ABSTRACT FROM AUTHOR]

Effectiveness of heterogeneous photocatalysis using TiO2 in the degradation of organic matter from an effluent of pharmaceutical industry was evaluated. The results show that the studied variables (initial pH, concentration of TiO2 and H2O2) affect the removal efficiency of organic matter. The highest levels of COD (70.4%), BOD (96.7%) and TOC (81.4%) removal were obtained using 340 mg/L of TiO2, 10.0 mM of H2O2 at pH initial 7.0 and an UV light exposure time of 5 hours. [ABSTRACT FROM AUTHOR]

The Pt/SiO2, Pt/Al2O3 y Pt/TiO2 catalysts through wet impregnation at 1% concentration in weigh metal were prepared. The resulting catalysts were characterized by X-ray diffraction (XRD), nitrogen physisorption (77 K) and hydrogen chemisorptions (298 K). Theses catalytic systems were employed in the reaction of m-dinitrobenzene hydrogenation toward m-phenylenediamine. The m-phenylenediamine is aromatic amine used in fine chemicals. The reactions were carried out in batch reactor to hydrogen pressure of 0.82 MPa, 343 K, using ethanol as solvent. The products resulting were analyzed by gas chromatography. The results showed that Pt/TiO2 catalyst had a high level of selectivity toward m-phenylenediamine (72.4 %) and level of conversion of m-dinitrobenzene (91.5 %). This behavior could be attributed to the strong metal-support interaction, as well as this catalyst is promising by production of m-phenylenediamine. [ABSTRACT FROM AUTHOR]

Different models of radiation scattering used to valuate its effect on the amount of radiant energy absorbed by a photocatalyst in the determination of quantum yields were analyzed. The radiation field in a heterogeneous photodecomposition of dichloroacetic acid catalyzed by particles of titanium dioxide was simulated using a one-dimensional model to evaluate the absorption and scattering of radiation in the reaction space. The results obtained by the different models of non- isotropic phase function with the isotropic phase function were compared. It was found that the scattering of isotropic radiation is a reasonable approximation for scattering produced by suspended particles of titanium dioxide. [ABSTRACT FROM AUTHOR]

Introduction. In this paper, an experiment made with the degradation of the Recoltive red dye with titanium dioxide, peroxide and phenton using the UV lamp as a medium, is presented. The tests made involved the variation of the quantities of these oxidants. Objective. To compare the treatments with titanium dioxide and phenton for colored waste water. Materials and methods. The equipment used consisted of a 41 cm x 25,5 cm x 20 cm glass bucket that contained 15L of sample; a MIGHTY PURE ultra violet lamp 60 Hz and a pump that drives a 0,047 L/s flow. The dye was added in the tank and then the concentration was 100 mg/L. The pH was continuously measured in order to adjust it in 5,0.When phenton and TiO2 were used, either acids or bases were required to measure the pH values, because they were more stable. Results. The best combination to treat water from textile industries with UV light lamp and titanium dioxide is 100 mg/L of TiO2 and 2% v/v of H2O2. The test with the optimal degradation of the color was that with phenton, 30 mg/L of FeCl3 and 1% v/v of H2O2. Conclusions. The use of advanced oxidation processes such as photo catalysis with TiO2 or photo phenton, had different results concerning the reduction of the dye's degradation percentage and higher reaction speeds. The photo phenton reaction was the one with the best percentages and reduction time periods (E13 with 30 mg/L FeCl3 and 1% v/v of H2O2). [ABSTRACT FROM AUTHOR]

The effect of pH on the photocatalytic degradation of natural organic matter in water from a lentic ecosystem using commercial titanium dioxide in suspension and a solar UV simulator was studied. The degradation monitoring and natural organic matter characterization was followed by size exclusion chromatography with dissolved organic carbon and ultraviolet detection at wave length λ=254 nm, and UV-Vis spectrophotometry. It was found that at pH below the isoelectric point of the photocatalyst, the kinetics of the reaction is high and with a pH above the isoelectric point the reaction kinetics decreases. Also, the photocatalysis is given by an alteration of the molecular weight distribution especially for the degradation of high molecular weight compounds to low molecular weight compounds, before their mineralization. [ABSTRACT FROM AUTHOR]

Heterogeneous photocatalysis is an advanced oxidation process applied in this work to determine the degradation and mineralization of bromocresol green indicator present in wastes from laboratories and environmental chemical analysis, commonly generated in Universities. In the treatment was used of titanium dioxide (Degussa P-25) as a catalyst, a Batch type reactor, and an artificial UV with a 360 nm wavelength. The degradation was quantified by UV-visible spectrophotometry, and the mineralization was evaluated by COD parameter. the optimum conditions for waste treatment are: 260ppm of TiO2 and 60 minutes of this shows that the heterogeneous photocatalysis process can be useful in the effluents treatment that has the presence of bromocresol green indicator. [ABSTRACT FROM AUTHOR]

The titanium dioxide, TiO2, is a material of technological importance for their physicochemical properties. Also is known that material properties depend of synthesis process used for their production, condition that is more demanding in new technologies, specifically in nanotechnology. In this work we used two methods of synthesis, sol-gel and polymeric precursor (Pechini), we realized a comparative analysis of the two processes. The synthesized powders were characterized using infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (TEM and SEM). With the results we determined the effect of the synthesis methods on the characteristics of the final product. The powders obtained presented nanometric size and primary anatase crystalline phase, from a temperature up of 450°C. The presence of AcacH complexing, in the system, reduced the size of the agglomerates and modified their morphology. [ABSTRACT FROM AUTHOR]

Copyright of Revista ION is the property of Universidad Industrial de Santander and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Objective. To determinate the effectiveness of the ionic toothbrush based on titanium dioxide compared to the Vitis Junior toothbrush in bacterial plaque removal in children of 8 to 10 years od at Weberbauer Schule School. Material and method. The study was carried out on a group of 30 children, whom behaved as a control and an experimental group, because they were evaluated in two different opportunities. In the first one, the circular technique of brushing was made with Vitis Junior for 3 minutes, registering bacterial plaque through O'Leary's index before and after it. Subsequently same procedures were made with the ionic toothbrush based on titanium dioxide and both test data were contrasted. Results. After analyzing the data using the T student test, significant differences in dental plaque reduction in maxilla, facial and lingual surfaces were found, improving those registered in the ionic toothbrush based on titanium dioxide against the one from the Vitis Junior toothbrush. Conclusion. The ionic toothbrush based on titanium dioxide is more effective in bacterial plaque removal compared to the Vitis Junior toothbrush. The first one removed 34.06% and the second 18.04% in average. [ABSTRACT FROM AUTHOR]

Introduction. The advance of heterogeneous photocatalysis as an advanced oxidation process has been used in the treatment of water contaminated with recalcitrant substances, which bring negative impacts to the environment and, in consequence, to human health. Given the urgent necessity of preserving water as a natural resource, heterogeneous photocatalysis was used in this research work to treat effluents generated in chemical and environmental research laboratories. Objective. To apply heterogeneous photocatalysis by the use of TiO2 to treat waste water with bromocresol green. Materials and methods. Batch type reactors were used in this process. Titanium dioxide (TiO2) Degussa P-25 was used as a catalyst and natural UV radiation was taken as the source to activate the photocatalytic method to generate the discoloration and mineralization of the bromocresol green indicator in the liquid effluents. The process was followed up by pH tests; Absorbance by the use of a spectrophotometer (418 nm wave length) and COD by the technique suggested by Standard Methods, every day during a five days period. Results. The comparison of the data obtained shows the feasibility of the technique, especially by the use of a 300 ppm concentration of catalyst, obtaining a 93,94% of degradation and a 72.22% of mineralization. Conclusion. With the results of degradation and mineralization percentages obtained, it is evident that heterogeneous photocatalysis, using sunlight, is an advanced oxidation process useful to treat waste water with bromocresol green indicator. [ABSTRACT FROM AUTHOR]

Copyright of Superficies y Vacío is the property of Sociedad Mexicana de Ciencia y Tecnologia de Superficies y Materiales and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The activity of 5%Pd/TiO2 and for the first time 5%Pd/TiO2-5%Na catalysts was evaluated in the liquid phase catalytic hydrodechlorination of chloroform at room temperature and 50°C, using isopropanol as solvent and hydrogen donor. 5%Pd/TiO2-5%Na catalyst showed the best catalytic performance at room temperature and 50°C, with the highest conversion at 50°C (32.5%) after 5 hours of reaction. The incorporation of sodium ions into the support favored both the dehydrogenation of isopropanol and the capture of chloride ions produced during the reaction, both positive for the hydrodechlorination of chloroform. The catalysts were characterized by AAS, mass titration, XRD, BET, hydrogen chemisorption, TPR and TGA. Na and Pd were loaded on the support practically without loss. and the anatase phase of titanium dioxide did not change with the addition of NaOH increased the catalyst's isoelectric point, indicating an increase in catalyst basicity. This can explain the improved activity of Na-containing catalysts. [ABSTRACT FROM AUTHOR]