Ionic Liquid Based Silica Tuned Silver Nanoparticles: Novel Approach for Fabrication

Nanomaterial Synthesis in Ionic Liquids and Their Use on the Photocatalytic Degradation of Emerging Pollutants

The unique properties of ionic liquids make them suitable candidates to prepare nanoscale materials. A simple method that uses exclusively a corresponding bulk material and an ionic liquid—in this case, [P_6,6,6,14]Cl—was used to prepare AgCl nanoparticles and AgCl@Fe₃O₄ or TiO₂@Fe₃O₄ magnetic nanocomposites. The prepared nanomaterials were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet–visible spectroscopy, and X-ray photoelectron spectroscopy. The photodegradation of atenolol as a model pharmaceutical pollutant in wastewater was investigated under ultraviolet–visible light irradiation using the different synthesized nanocatalysts. In the presence of 0.75 g·L⁻¹ AgCl nanoparticles, a practically complete degradation of 10 ppm of atenolol was obtained after 30 min, following pseudo-first-order reaction kinetics. The effect of different variables (concentrations, pH, oxidant agents, etc.) was analyzed. The recyclability of the nanocatalyst was tested and found to be successful. A degradation mechanism was also proposed. In order to improve the recovery stage of the nanocatalyst, the use of magnetic nanocomposites is proposed. Under the same experimental conditions, a slightly lower and slower degradation was achieved with an easier separation. The main conclusions of the paper are the suitability of the use of ionic liquids to prepare different nanocatalysts and the effectiveness of these at degrading an emerging pollutant in wastewater treatment.

Printable nanocomposites of polymers and silver nanoparticles for antibacterial devices produced by DoD technology

Silver nanoparticles (Ag-NPs) are known for their efficient bactericidal activity and are widely used in industry. This study aims to produce printable antibacterial devices by drop-on-demand (DoD) inkjet technology, using Ag-NPs as the active part in complex printable fluids. The synthesis of this active part is described using two methods to obtain monodisperse NPs: chemical and microwave irradiation. The synthesized NPs were characterized by UV-VIS, STEM, TEM, DLS and XRD. Two printable fluids were produced based: one with Ag-NPs and a second one, a polymeric nanocomposite, using silver nanoparticles and polyvinyl butyral (Ag-NPs/PVB). Cellulose acetate was used as a flexible substrate. The ecotoxicity analysis of fluids and substrate was performed with Artemia franciscana nauplii. Optimized electric pulse waveforms for drop formation of the functional fluids were obtained for the piezoelectric-based DoD printing. Activity of printed antibacterial devices was evaluated using the Kirby-Bauer method with Staphylococcus aureus and Escherichia coli. The results show that the printed device with Ag-NP fluids evidenced a bacterial inhibition. An important advantage in using the DoD process is the possibility of printing, layer by layer or side by side, more than one active principle, allowing an interleaved or simultaneous release of silver NP and other molecules of interest as for example with a second functional fluid to ensure effectiveness of Ag activity.

Improvement of Cochineal Extract (Dactylopius coccus Costa) Properties Based on the Green Synthesis of Silver Nanoparticles for Application in Organic Devices

The UV-Vis absorption and conductivity properties of the organic sample cochineal (Dactylopius coccus Costa) were modified by using it as a reducing agent in the biosynthesis of silver nanoparticles. This was done in a straightforward way in order to allow its possible application in organic devices. The biosynthesized solution exhibited a hybrid material with a UV-Vis absorbance range from 205 to 650 nm. The sizes of silver nanoparticles of the hybrid material were between 5 and 10 nm. X-ray diffraction (XRD) revealed silver structures, when samples were dried at 100°C. At 40°C, the structures detected were chlorargyrite (AgCl) and silver oxide (Ag2O). The nucleation and subsequent growth of the hybrid thin film on the substrates indicated an increase of clusters and roughness in comparison to thin films made solely from cochineal. The thin films of hybrid materials showed an improvement of 40% in their electrical potential. The stability at room temperature demonstrated that the hybrid material could be useful as a potential candidate for photoactive thin films in organic devices.