Examinando por Materia "DIOXIDO DE TITANIO"
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- Artículo de Publicación PeriódicaComparative assessment of oxygen uptake rate of activated sludge and Escherichia coli exposed to nanomaterials(2022-08) Aude Luppi, Vergenie E.; Oppezzo, Oscar J.; Fidalgo de Cortalezzi, María Marta"The adverse effects of engineered nanomaterials (ENMs) on bacterial populations found in wastewater treatment plants (WWTPs) or natural systems have been studied for more than a decade, but conflicting evidence on the matter still makes it a subject of considerable concern. In this paper, the short-term exposure impact of titanium dioxide nanoparticles (nTiO2), carboxyl-functionalized multiwall carbon nanotubes (f-MWCNT), and zero-valent iron nanoparticles (nZVI) toward activated sludge and Escherichia coli (E. coli) was investigated through respiration inhibition experiments. Microorganisms were exposed to nanoparticle concentrations of 50, 100 and 200 mg/L (nTiO2, f-MWCNT) and 20, 50 and 100 mg/L (nZVI). The experiments showed that nTiO2 produced no inhibition in activated sludge or E. coli; up to 100 mg/L of nZVI did not inhibit the activated sludge respiration but 50 mg/L inhibited 24 ± 3% the respiration of E. coli and damaged its cell membrane. Activated sludge respiration was inhibited 17 ± 3% with 200 mg/L of f-MWCNT while for E. coli the inhibition was 36 ± 15% and the cell membrane was damaged with a 100 mg/L dose. Transmission electron microscopy (TEM) showed nTiO2-bacteria and nZVI-bacteria surface interaction while bacteria appeared punctured by f-MWCNT. E. coli was more susceptible than activated sludge to the nanomaterials and nZVI was more toxic than f-MWCNT for E. coli. These results demonstrated the absence of acute toxicity effects of the studied nanomaterials at those concentrations expected to occur in activated sludge facilities, and it would only be a concern in case of extremely high inputs, underscoring the resilience of WWTPs biological treatment."
- Artículo de Publicación PeriódicaEnhanced retention of bacteria by TiO2 nanoparticles in saturated porous media(2016-08) Gentile, Guillermina José; Fidalgo de Cortalezzi, María Marta"The simultaneous transport of TiO2 nanoparticles and bacteria Pseudomonas aeruginosa in saturated porous media was investigated. Nanoparticle and bacterium size and surface charge were measured as a function of electrolyte concentration. Sand column breakthrough curves were obtained for single and combined suspensions, at four different ionic strengths. DLVO and classical filtration theories were employed to model the interactions between particles and between particles and sand grains. Attachment of TiO2 to the sand was explained by electrostatic forces and these nanoparticles acted as bonds between the bacteria and the sand, leading to retention. Presence of TiO2 significantly increased the retention of bacteria in the sand bed, but microorganisms were released when nanomaterial influx ceased. The inclusion of nanomaterials in saturated porous media may have implications for the design and operation of sand filters in water treatment."
- Ponencia en CongresoEstudio de la influencia de fuerza iónica, pH y materia orgánica natural en la agregación de nanopartículas de dióxido de titanio(2019-08) Barboni, Tomás; Devoli Díaz, Juan Gabriel; Mujica, Clara; Peralta, Mateo; Gentile, Guillermina José"El objetivo general del presente trabajo fue investigar cómo la agregación de las nanopartículas de dióxido de titanio (TiO2) y su carga de superficie, son influenciadas por el pH, la fuerza iónica y la presencia de materia orgánica natural (MON). Los resultados obtenidos evidenciaron que las nanopartículas de TiO2 sufren un rápido proceso de agregación y en ningún caso fue posible tenerlas en su tamaño primario de 21 nm. Dentro de los resultados más relevantes, se puede mencionar que la influencia de los iones divalentes, como el Ca2+, así como elevados valores de fuerza iónica, 10 mM, tuvieron un gran aporte en la desestabilización de las nanopartículas. La influencia del pH se vio muy marcada en las suspensiones donde había solamente iones indiferentes y en baja concentración. En todos los casos, la adición de MON provocó una gran disminución de los valores de potencial zeta, obteniéndose valores muy negativos y, en consecuencia, se logró aumentar notablemente la estabilidad de las nanopartículas. La forma y estructura de los agregados, así como su tamaño y el de las partículas primarias se pudo también observar por medio de microscopía electrónica de barrido (SEM)."
- Artículo de Publicación PeriódicaInterparticle effects in the cotransport of viruses and engineered nanoparticles in saturated porous media(2021-10) Gentile, Guillermina José; Blanco Fernández, María Dolores; Fidalgo de Cortalezzi, María Marta"The effects of P25 TiO2 nanoparticles on the transport in saturated porous media of the bacteriophage PP7 was investigated. Two levels of ionic strength were considered, given by monovalent and divalent cations, Na+ and Ca2+. The viruses and the P25 particles were characterized with respect to size and surface charge, by dynamic light scattering and electron microscopy. The breakthrough curves were obtained for suspensions of each particle and both combined, using UV absorbance to quantify P25 and RT-qPCR for PP7. In the single transport experiments, P25 was retained, while the viruses mostly eluted the sand bed. However, in the cotransport experiments, retention increased for the virus and decreased for the TiO2 nanoparticles under high viral content, due to heteroaggregation among the colloids in the incoming suspension, electrostatic interactions, and ripening. The interparticle interactions were modeled by DLVO theory, resulting in agreement with the experimental observations, which highlights the electrostatic nature."
- Artículo de Publicación PeriódicaPreparation and characterization of nanoencapsulated synthetic soybean oil derivative-an abundant and environmentally friendly phase change material-heat transfer analysis and applications(2020-10) Bergamo, Jorge; Rossi, Ezequiel; Maffi, Juan M.; De Angelis, Laura; Errea, María Inés"The thermal properties of a phase change material (PCM), together with its environmental health risks and natural abundance are important aspects to consider when choosing one for a domestic application. In this work, a soybean oil derivative, which comes from one of the most abundant crops on Earth, is proposed as PCM. A heat transfer model was developed to compare the performance of the proposed PCM, under the same boundary and initial conditions, with other materials reported in literature that have well-known disadvantages in terms of flammability, renewability, abundance and environmental care. Results showed that its performance was as good as theirs. Nanocapsules of the PCM coated with TiO2 were prepared and characterized physical, thermal and morphologically. Thermal studies were carried out in a device designed and constructed simulating a water heater, and a reduction of about 70% of the PCM phase thermal resistance due to the TiO2 shell was observed. Furthermore, the calculated thermal energy stored in the device filled with nanoencapsulated PCM was 10.6% higher with respect to the blank, and the total cooling time of the water was increased by over 18% thanks to the PCM."