Amanda Alonso

Characterization of fibrous polymer silver/cobalt nanocomposite with enhanced bactericide activity

This manuscript describes the synthesis (based on the intermatrix synthesis (IMS) method), optimization, and application to bacterial disinfection of Ag@Co polymer-metal nanocomposite materials with magnetic and bactericidal properties. This material showed ideal bactericide features for being applied to bacterial disinfection of water, particularly (1) an enhanced bactericidal activity (when compared with other nanocomposites only containing Ag or Co nanoparticles), with a cell viability close to 0% for bacterial suspensions with an initial concentration below 10(5) colony forming units per milliliter (CFU/mL) after a single pass through the material, (2) capacity of killing a wide range of bacterial types (from coliforms to gram-positive bacteria), and (3) a long performance-time, with an efficiency of 100% (0% viability) up to 1 h of operation and higher than 90% during the first 24 h of continuous operation. The nanocomposite also showed a good performance when applied to water samples from natural sources with more complex matrices with efficiencies always higher than 80%.

Critical review of existing nanomaterial adsorbents to capture carbon dioxide and methane

Innovative gas capture technologies with the objective to mitigate CO2 and CH4 emissions are discussed in this review. Emphasis is given on the use of nanoparticles (NP) as sorbents of CO2 and CH4, which are the two most important global warming gases. The existing NP sorption processes must overcome certain challenges before their implementation to the industrial scale. These are: i) the utilization of the concentrated gas stream generated by the capture and gas purification technologies, ii) the reduction of the effects of impurities on the operating system, iii) the scale up of the relevant materials, and iv) the retrofitting of technologies in existing facilities. Thus, an innovative design of adsorbents could possibly address those issues. Biogas purification and CH4 storage would become a new motivation for the development of new sorbent materials, such as nanomaterials. This review discusses the current state of the art on the use of novel nanomaterials as adsorbents for CO2 and CH4. The review shows that materials based on porous supports that are modified with amine or metals are currently providing the most promising results. The Fe3O4-graphene and the MOF-117 based NPs show the greatest CO2 sorption capacities, due to their high thermal stability and high porosity. Conclusively, one of the main challenges would be to decrease the cost of capture and to scale-up the technologies to minimize large-scale power plant CO2 emissions.

Adsorption process of fluoride from drinking water with magnetic core-shell Ce-Ti@Fe3O4 and Ce-Ti oxide nanoparticles

Synthesized magnetic core-shell Ce-Ti@Fe3O4 nanoparticles were tested, as an adsorbent, for fluoride removal and the adsorption studies were optimized. Adsorption capacity was compared with the synthesized Ce-Ti oxide nanoparticles. The adsorption equilibrium for the Ce-Ti@Fe3O4 adsorbent was found to occur in <15min and it was demonstrated to be stable and efficient in a wide pH range of 5-11 with high fluoride removal efficiency over 80% of all cases. Furthermore, isotherm data were fitted using Langmuir and Freundlich models, and the adsorption capacities resulted in 44.37 and 91.04mg/g, at pH7, for Ce-Ti oxides and Ce-Ti@Fe3O4 nanoparticles, respectively. The physical sorption mechanism was estimated using the Dubinin-Radushkevich model. An anionic exchange process between the OH- group on the surface of the Ce-Ti@Fe3O4 nanomaterial and the F- was involved in the adsorption. Moreover, thermodynamic parameters proved the spontaneous process for the adsorption of fluoride on Ce-Ti@Fe3O4 nanoparticles. The reusability of the material through magnetic recovery was demonstrated for five cycles of adsorption-desorption. Although the nanoparticles suffer slight structure modifications after their reusability, they keep their adsorption capacity. Likewise, the efficiency of the Ce-Ti@Fe3O4 was demonstrated when applied to real water to obtain a residual concentration of F- below the maximum contaminated level, 1.5mg/L (WHO, 2006).

Intermatrix synthesis of monometallic and magnetic metal/metal oxide nanoparticles with bactericidal activity on anionic exchange polymers

In this communication, the synthesis of nanoparticles on anionic exchange polymers by the Intermatrix Synthesis method is reported. Monometallic (Ag) and core–shell metal/metal oxide (Ag@Fe3O4) nanocomposites were synthesized and characterized. Their magnetic and bactericidal activities were evaluated.

Phosphate removal and recovery from water using nanocomposite of immobilized magnetite nanoparticles on cationic polymer

ABSTRACT A novel nanocomposite (NC) based on magnetite nanoparticles (Fe3O4-NPs) immobilized on the surface of a cationic exchange polymer, C100, using a modification of the co-precipitation method was developed to obtain magnetic NCs for phosphate removal and recovery from water. High-resolution transmission electron microscopy-energy-dispersive spectroscopy, scanning electron microscopy , X-ray diffraction, and inductively coupled plasma optical emission spectrometry were used to characterize the NCs. Continuous adsorption process by the so-called breakthrough curves was used to determine the adsorption capacity of the Fe3O4-based NC. The adsorption capacity conditions were studied under different conditions (pH, phosphate concentration, and concentration of nanoparticles). The optimum concentration of iron in the NC for phosphate removal was 23.59 mgFe/gNC. The sorption isotherms of this material were performed at pH 5 and 7. Taking into account the real application of this novel material in real water, the experiments were performed at pH 7, achieving an adsorption capacity higher than 4.9 mgPO4–P/gNC. Moreover, Freundlich, Langmuir, and a combination of them fit the experimental data and were used for interpreting the influence of pH on the sorption and the adsorption mechanism for this novel material. Furthermore, regeneration and reusability of the NC were tested, obtaining 97.5% recovery of phosphate for the first cycle, and at least seven cycles of adsorption–desorption were carried out with more than 40% of recovery. Thus, this work described a novel magnetic nanoadsorbent with properties for phosphate recovery in wastewater. GRAPHICAL ABSTRACT

Bifunctional Polymer-Metal Nanocomposite Ion Exchange Materials

The unusual electrical, optical, magnetic, and chemical properties of metal colloids (better known in nowadays as metal nanoparticles, MNPs) have attracted increasing interest of scientists and technologists during the last decade. In fact, although Nanoscience and Nanotechnology are quite recent disciplines, there have already been a high number of publications that discuss these topics. [1-11] What is more, there are quite new high impact peer-reviewed journals especially devoted to these research fields and there is also a particular subject category “Nanoscience & Nanotechnology” in the Journal Citation Reports from Thomson Reuters.

Novel magnetic core–shell Ce–Ti@Fe3O4 nanoparticles as an adsorbent for water contaminants removal

Magnetic core–shell Ce–Ti@Fe3O4 nanoparticles were synthesized by coating cerium titanate on magnetite under mild experimental conditions. Combining magnetism, crystallinity, stability and adsorption capacity, it can be a promising nanomaterial as an adsorbent for anionic water contaminants, exhibiting high removal capacity, from 85% to 100%, for nitrates, phosphates and fluoride.

Ecologically Friendly Polymer-Metal and Polymer-Metal Oxide Nanocomposites for Complex Water Treatment

In this regard,polymeric supports play a very important role for several reasons including, the ease of their preparation in the most appropriate physical forms (e.g., granulated, fi‐ brous, membranes, etc.), the possibility to produce the macroporous matrices with highly developed surface area and some others. However, the immobilization of NPs on the appro‐ priate polymeric support represents a separate task [2] and thus, the incorporation of poly‐

Core–shell Au/CeO2 nanoparticles supported in UiO-66 beads exhibiting full CO conversion at 100 °C

Hybrid core–shell Au/CeO2 nanoparticles (NPs) dispersed in UiO-66 shaped into microspherical beads are created using the spray-drying continuous-flow method. The combined catalytic properties of nanocrystalline CeO2 and Au in a single particle and the support and protective function of porous UiO-66 beads make the resulting composites show good performances as catalysts for CO oxidation (T50 = 72 °C; T100 = 100 °C) and recyclability.

Self-oriented Ag-based polycrystalline cubic nanostructures through polymer stabilization.

This paper presents the study of the dynamics of the formation of polymer-assisted highly-orientated polycrystalline cubic structures (CS) by a fractal-mediated mechanism. This mechanism involves the formation of seed Ag@Co nanoparticles by InterMatrix Synthesis and subsequent overgrowth after incubation at a low temperature in chloride and phosphate solutions. These ions promote the dissolution and recrystallization in an ordered configuration of pre-synthetized nanoparticles initially embedded in negatively-charged polymeric matrices. During recrystallization, silver ions aggregate in AgCl@Co fractal-like structures, then evolve into regular polycrystalline solid nanostructures (e.g. CS) in a single crystallization step on specific regions of the ion exchange resin (IER) which maintain the integrity of polycrystalline nanocubes. Here, we study the essential role of the IER in the formation of these CS for the maintenance of their integrity and stability. Thus, this synthesis protocol may be easily expanded to the composition of other nanoparticles providing an interesting, cheap and simple alternative for cubic structure formation and isolation.