Nanotechnology: advantages and drawbacks in the field of construction and building materials

Nanotechnology seems to hold the key that allows construction and building materials to replicate the features of natural systems improved until perfection during millions of years. This paper reviews current knowledge about nanotechnology and nanomaterials used by the construction industry. It covers the nanoscale analysis of Portland cement hydration products, the use of nanoparticles to increase the strength and durability of cimentitious composites, the photocatalytic capacity of nanomaterials and also nanotoxicity risks

Nanotechnology in the cultural heritage - influence of nanospensions adopted by nanoparticles of TiO2 for cleaning the surface of historical plasters

The continuous development of nanostructure and the study of physico - chemical processes in the nanometer range lead to new methods that can slow down the degradation processes of a work of art, or even restore damage caused, for example, by an inappropriate restoration process. The use of nanosuspensions based on calcium hydroxide is probably the most widespread application of nanomaterials in heritage care, especially in the field of hardening of lime building materials (plaster, limestone, etc.). In combination with titanium dioxide, it should be a successful suspension in the fight against biological agents, surface contamination or in the protection of UV-resistant building materials.NAKI II [DG16P02M005

Aplicação da fotolise e fotocatalise heterogenea na desinfecção de aguas contaminadas com E.coli

Orientadores: Roberto Feijo de Figueiredo, Jose Roberto GuimarãesDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia CivilResumo: O desinfetante mais utilizado no mundo atualmente é o cloro, cuja aplicação apresenta vantagens como alta eficiência e custos baixos. A descoberta de subprodutos cancerígenos como os trihalometanos (THMs) resultantes da reação do cloro com a matéria orgânica presente na água, originou uma série de pesquisas buscando o desenvolvimento de métodos alternativos de desinfecção, que possam substituir o cloro com as mesmas vantagens e não induzam a formação de subprodutos indesejáveis. Dentre os novos processos que vêm sendo desenvolvidos a fotólise e a fotocatálise heterogênea têm se mostrado bastante eficientes. Neste trabalho realizou-se a desinfecção de águas preparadas em laboratório cujas características físico químicas são similares à água natural, contaminadas com concentrações conhecidas da Escherichia coli, com o objetivo de comparar a eficiência de desinfecção destes dois processos. Os resultados demonstraram que ambos apresentam alta eficiência de desinfecção, conseguindo desinfetar águas com alto teor de coliformes fecais em condições de cor e turbidez características de águas de abastecimento constituindo um processo promissor para novas tecnologias de desinfecção de águasAbstract: Chlorine is the most utilized disinfectant in the world, which application shows some advantages as high efficiency and low cost. The discovery of carcinogenics subproducts in the water, as THMs (trihalometanes) result of the reaction of chlorine free with organic matter in the water, originated several research works to find alternative methods of disinfection to substitute chlorine, maintaining the same advantages and avoiding the formation of carcinogenics subproducts. Two of the resulting processes, the ultraviolet radiation and the heterogeneous fotocata1ysis are very efficient and are object of this research. This paper shows the disinfection of a special water by ultraviolet radiation and heterogeneous fotocatalysis with the objective of comparing the efficiency the process. The water was prepared in the laboratory with the same characteristics of the natural water.The results showed that these processes were very efficient when using water with high color, turbidity, and coliforms. However, the heterogeneous fotocatalysis is more efficient for shorter operation time, and consequently is a promising technologyMestradoSaneamento e AmbienteMestre em Engenharia Civi

Utilização da fotocatalise heterogenea na destruição do cianeto : fase gasosa x fase aquosa

Orientador: Jose Roberto GuimarãesDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia CivilResumo: A fotocatálise heterogênea foi o processo utilizado neste trabalho, para desenvolver estudos de degradação do íon cianeto, em fase aquosa e gasosa. O reator fotocatalítico foi preparado fixando-se o fotocatalisador dióxido de titânio na superficie interna de um cilindro de vidro de borossilicato. As fontes de irradiação ultravioleta utilizada, foram as lâmpadas germicida e luz negra, de 30 W de potência. Para o monitoramento da concentração do íon cianeto, foi utilizado um eletrodo sensível ao íon em questão. Na primeira parte do trabalho, a degradação do cianeto foi realizada em fase aquosa, utilizando um sistema em recirculação. Os parâmetros avaliados durante o processo de degradação fotocatalítica foram: o uso de diferentes fontes de irradiação (luz germicida e luz negra), a variação da carga molar, e o uso de diferentes condições de aeração. Os resultados obtidos mostraram ser a luz germicida, mais eficiente na remoção do cianeto, em reação à luz negra, com 81% e 46% de remoção respectivamente. Com a variação da carga molar, uma maior remoção foi obtida para baixos valores de carga molar, sendo que para os valores 3,0, 7,7, 23,2 /lmol min-Abstract: In this work, the fotocatalysis was used to promote cyanide ion degradation studies, in on aqueous and gaseous phases. Titanium dioxide was fixed on the inner glass cylinder of the photocatalytic reactor inner glass surface of the glass cylinder. The source of irradiation used, were the germicide and black light lamps (30 Watts). The cyanide ion concentration was monitored using an eletrode sensible to the ion in study. The first step of this work, was the stydy of cyanide degradation in the aqueous phase, using a reciculation system. The parameters analyzed that influence the fotocatalytic process were: the use of different sources of irradiation (germicide and black light lamps), molar flow rate variation, and the use of different aeration conditions. The obtained results showed that the germicide lamp, is more efficient that black light while remotion of8l % while 46 % were obtained to the black light lamp. In the molar flow rate variation results, 3,0; 7,7; and 23,2 J.lmolL-I, where the remotion of 83, 80 and 50 %, respectively showing there to be a major disposition of active sites on the photocatalist surface, even to higher values as 239, 284, 372 J.lmolL-I, the obtained remotion was of63, 46 and 48,5 %, respectively, for occurring a active sites saturation on the titanium dioxide surface. The referent result to the medium aeration use, was got ITom a high efficiency whe utilized a photocatalytic reactor aeration, related to the aeration in the solution, and on the lack, being the results 99,2; 78,0 and 74,8 %, respectively. The second estep of this work, was the cyanide degradation in the gas phase, with a single pass though the reactor. The results obtained for concentration of 126, 168,264,63, 127, 101 and 99 ppmv, were 55, 33, 56, 55, 39 and 53 %, of degradation when the germicide lamp was used. When the black light, lamp was used, the remotion obtained were 25, 34 and 38 %, for concentrations of98, 147 and 145 ppmv, respectivelisMestradoSaneamentoMestre em Engenharia Civi

Nano TiO2 fotokatalizörün iç ve dış cephe inşaat boyalarında etkisinin araştırılması

Tez (yüksek lisans) - Anadolu ÜniversitesiAnadolu Üniversitesi, Fen Bilimleri Enstitüsü, İleri Teknolojiler Anabilim DalıKayıt no: 238876Fotokatalitik TiO? birçok uygulama alanında kullanılmaktadır. Bu çalışmanın amacı su bazlı boyalara fotokatalitik etkinin kazandırılması ile bakteriler uçucu organik bileşikler, hava dumanı gibi birçok çevresel sorunun önüne geçmek olacaktır. Modifiye ve orijinal TiO? toz alkol ve bağlayıcı içinde kararlı halde hazırlanmış ve boya yüzeyine püskürtme yöntemiyle uygulanmıştır. Bununla beraber modifiye TiO? toz su bazlı boya bünyesine katkılanmıştır. Elde edilen sonuçlardan modifiye TiO?’in orijinal TiO? ve referans boyaya göre daha iyi sonuç alındığı görülmüştür. Modifiye ve orijinal toz karakterizasyonu Zeta potansiyeli, enerji saçınımlı X ışınları spektrofotometresi (EDX), x ışınları difraktometresi (XRD) ile yapılmıştır. Su bazlı boya karakterizasyonu UV spektrofotometre, taramalı elektron mikroskobu (SEM), enerji saçınımlı x ışınları spektrofotometresi (EDX) ile yapılmıştır. Daha sonra fotokatalitik aktivite ölçümleri yapılmıştır

Photoactivity of nanocomposite for building materials

V rámci dizertační práce byly připraveny kompozity typu oxid křemičitý/TiO2 a kompozity typu vrstevnatý silikát/TiO2. K přípravě kompozitů byl jako prekurzor TiO2 využit titanylsulfát, který je meziproduktem při výrobě titanové běloby sulfátovým způsobem. Připravené kompozity byly následně tepelně zpracovány při vybraných teplotách. Připravené kompozity byly charakterizovány běžnými metodami chemické a fázové analýzy, byla určena jejich fotodegradační aktivita. Vybrané kompozity byly následně použity jako příměsi do past na bázi cementu a byl studován jejich vliv na mechanické vlastnosti těchto past. U vybraných past byla následně testována fotodegradační aktivita jejich povrchu, pro tyto testy byla použita metoda odbourávání Rhodaminu B naneseného na povrchu těchto vzorků a u vybraných vzorků byl proveden test odbourávání NO. Porovnáním výsledků bylo zjištěno, že nejvhodnějším fotokatalyticky aktivním plnivem je kompozit SiO2/TiO2 s obsahem 50 hm.% TiO2 kalcinovaný při teplotě 600 °C. Dále bylo také zjištěno, že nejvhodnějším latentně hydraulickým, fotokatalyticky aktivním plnivem je kompozit kaolin/TiO2 s obsahem 50 hm.% TiO2 kalcinovaný rovněž při 600 °C.The composites of silicon oxide/TiO2 and phyllosilicate / TiO2 were prepared within the frame of this dissertation. For the preparation of the composites, the titanylsulphate was used as the TiO2 precursor. The as synthesized composites were subsequently thermally treated at the given temperatures. Obtained samples were characterized using the selected methods of the chemical and phase analysis, their photodegradation activity was also evaluated. Selected composites were then used as the admixtures in the cement pastes ant their effect on the mechanical strength of hardened pastes was also tested. For the selected cement pastes the self-cleaning ability was tested using Rhodamine B, which was deposited on the surface of the tested samples, the photodegradation ability of the selected samples towards NO was also tested. The comparison of the samples showed that the most promising material is the calcined composite kaoline/TiO2.9360 - Centrum nanotechnologiívyhově

Preparation and Properties of Transition Metal Oxide Nanoparticles on the Kaolinite Matrix

Import 02/12/2011Příprava nanokompozitů kaolinit/TiO2 probíhala hydrolýzou směsi kaolinu s titanyl sulfátem, vybrané vzorky nanokompozitů kaolinit/TiO2 byly dopovány mědí. Postup přípravy nanokompozitů byl optimalizován z hlediska dosažení maximální fotokatalytické aktivity při minimální energetické a materiálové náročnosti. Poměr výchozích reaktantů byl zvolen tak, aby výsledný obsah oxidu titaničitého v takto připravených kompozitech představoval požadované množství TiO2. Fixací oxidu titaničitého na povrchu kaolinitu získáváme kompozit typu kaolinit/TiO2, jehož tepelnou úpravou získáváme kompozit metakaolinit/TiO2. Kompozity modifikované různými navrženými způsoby hydrolýzy byly následně charakterizovány použitím kombinací metod rentgenové fluorescenční spektrofotometrie, infračervené spektroskopie, Ramanovy spektroskopie, difúzně reflektanční spektroskopie, skenovací elektronové mikroskopie, rentgenové práškové difrakční analýzy. Molekulární modelování s využitím empirických silových polí v modelovacím prostředí „Materials Studio“ bylo použito jako doplňková metoda studia struktury a vlastností těchto nanokompozitů.Preparation of nanocomposites kaolinite/TiO2, using hydrolysis of titanyl sulfate in the presence of kaolin was addressed. Copper-doping has been carried out for selected samples of nanocomposites. The preparation procedure has been optimized in order to achieve the maximum photoactivity by minimum energy and material saving. A variable (kaolinite)/(titanyl sulfate) ratio has been used in order to achieve the desired TiO2 content in prepared nanocomposites. Calcination of the composites at 600 °C led to the transformation of the kaolinite to metakaolinite and to origination of metakaolinite/TiO2 composites. The prepared samples were investigated using X-ray fluorescence spectroscopy, X-ray powder diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy and diffuse reflectance spectroscopy in the UV-VIS region. Structural ordering of TiO2 on the kaolinite particle surface was modeled using empirical force field atomistic simulations in the „Materials Studio“ modeling environment. Photodegradation activity of the composites prepared was evaluated by the discoloration of Acid Orange 7 aqueous solution.Prezenční9360 - Centrum nanotechnologiívyhově

Raman characterization of polymer formation: first step to self-healing polymer coatings studies

Self-healing polymer coatings are a subdomain of the new smart materials which possess a build-in ability of repairing the damage of the primary structure. The present study reports on Raman spectroscopic investigations characterizing the polymer formation. Monitoring the reaction behavior has also validated a set of first steps on the analysis of the molecular structures. Moreover this study shows another approach for performing investigations, one that was able to expand the understanding of the self-healing mechanisms from a different perspective, from an angle that is more detailed oriented and one that could explain the chemical changes underlying microscopical insights of the processes.Selbstheilende Polymerbeschichtungen gehören zu den sogenannten „Smarten Materialien“ und besitzen die intrisische Eigenschaft Beschädigungen, an ihrer primären Struktur, selbst heilen zu können. Die vorliegende Arbeit beschäftigt sich mit der Raman-spektroskopischen Charakterisierung der Polymerbildung. Durch die Beobachtung des Reaktionsverhaltens konnten die ersten, nötigen Schritte zur Analyse der molekularen Strukturen validiert werden. Darüber hinaus verfolgt die vorliegende Studie einen Ansatz, der sich auf das detaillierte Verständnis der chemischen Prozesse konzentriert, die den mikroskopischen Prozessen zu Grunde liegen