DSpace Repository :: Browsing by Author "Gentile, Guillermina J."

Browsing by Author "Gentile, Guillermina J."

Now showing 1 - 6 of 6

Enhanced retention of bacteria by TiO2 nanoparticles in saturated porous media
(2016) Gentile, Guillermina J.; Fidalgo de Cortalezzi, María M.
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.
Enhancement of the fouling resistance of zwitterion coated ceramic membranes
(2020) Storms, Max; Kadhem, Abbas J.; Xian, Shuting; Bernards, Matthew; Gentile, Guillermina J.; Fidalgo de Cortalezzi, María M.
Ceramic membranes suffer from rapid permeability loss during filtration of organic matter due to their fouling propensity. To address this problem, iron oxide ultrafiltration membranes were coated with poly(sulfobetaine methacrylate) (polySBMA), a superhydrophilic zwitterionic polymer. The ceramic-organic hybrid membrane was characterized by scanning electron microscopy (SEM) and optical profilometry (OP). Membranes with and without polySBMA coating were subjected to fouling with bovine serum albumin solution. Hydraulic cleaning was significantly more effective for the coated membrane than for the non-coated one, as 56%, 66%, and 100% of the fouling was removed for the first, second, and third filtration cycle, respectively. Therefore, we can highlight the improved cleaning due to an increased fouling reversibility. Although some loss of polymer during operation was detected, it did not affect the improved behavior of the tested membranes.
Interparticle effects in the cotransport of viruses and engineered nanoparticles in saturated porous media
(2021) Gentile, Guillermina J.; Blanco Fernández, María D.; Fidalgo de Cortalezzi, María M.
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.
Molecularly imprinted polymers (MIPs) in sensors for environmental and biomedical applications : a review
(2021) Kadhem, Abbas J.; Gentile, Guillermina J.; Fidalgo de Cortalezzi, María M.
Molecular imprinted polymers are custom made materials with specific recognition sites for a target molecule. Their specificity and the variety of materials and physical shapes in which they can be fabricated make them ideal components for sensing platforms. Despite their excellent properties, MIP-based sensors have rarely left the academic laboratory environment. This work presents a comprehensive review of recent reports in the environmental and biomedical fields, with a focus on electrochemical and optical signaling mechanisms. The discussion aims to identify knowledge gaps that hinder the translation of MIP-based technology from research laboratories to commercialization.
Nanotechnology and the environment
(2019) Gentile, Guillermina J.; Fidalgo de Cortalezzi, María M.
This chapter presents different phenomena that arise when nanomaterials reach the environment, with emphasis in water systems. Transformations on the surface of nanomaterials and nanoparticles because of adsorption of macromolecules and metals cations, as well as biological interactions alter their colloidal stability, originating in some cases homoaggregation or heteroaggregation, which in turn affects their fate and transport. Some engineering applications of nanomaterials are highlighted: as adsorbents, as enhancers of water filtration, providing antifouling, catalytic, and antibacterial activity, and as catalysts, giving special attention to photoactivity and to the removal of indoor air contaminants as volatile organic compounds.
Virus removal by iron oxide ceramic membranes
(2014) Fidalgo de Cortalezzi, María M.; Gallardo, María V.; Yrazu, Fernando; Gentile, Guillermina J.; Opezzo, Oscar; Pizarro, Ramon; Poma, Hugo R.; Rajal, Verónica B.
Nanoporous iron oxide ceramics were studied for the removal of virus contamination from water. Supported and unsupported iron oxide nanostructured hematite was fabricated by a green chemistry route from ferroxane nanoparticles. The material had a surface area of approximately 30 m2 /g and a mean pore size of 65 nm. Bacteriophage P22 was chosen as a model for human virus. The kinetics and equilibrium of the attachment process was investigated. P22 adsorption isotherms on iron oxide were described by the Freundlich equation. Batch experiments resulted in 1.5 LRVs. Removal proceeded rapidly for the first 7 h; next, a diffusion-limited stage occurred. Dynamic attachment experiments demanded extensive recirculation to achieve significant reduction levels. Up to 3 LRV were observed. The enhanced performance can be explained by the higher iron oxide area available and the facilitated access to inner porosity sites that were previously unavailable due to slow diffusion. The role of electrostatic interactions in the attachment mechanisms was confirmed by the dependence of the isotherm on the ionic strength of the suspension medium. P22 bacteriophage is expected to attach to the iron oxide by electrostatic forces up to a pH of 6.5. DLVO theory predicts moderately well the interaction energies between P22 particles themselves and between the phage and the ceramic. However, a slight underestimation of the P22–P22 repulsive forces was evident by comparison to the experimental data.

Browsing by Author "Gentile, Guillermina J."

Results Per Page

Sort Options