Green synthesis of Ag nanoflowers using Kalanchoe Daigremontiana extract for enhanced photocatalytic and antibacterial activities.

The synthesis and applications of anisotropic nanostructures have attracted much attention in the last decade. The nanoflower-type structures are one of the nanomaterials with anisotropic structures most investigated because of owing to high densities of edges, corners, and stepped atoms present on their nano-petals. Here, silver nanoparticles obtained by a one-step green synthesis method using extract from Kalanchoe Daigremontiana´s leaves are reported. To identify the compounds responsible for reduction of silver ions, the functional groups present in plant extract were investigated by UV-vis and FTIR. Ag nanoparticles were characterized by UV-vis, XPS, ζ-potential, XRD, and SEM-EDS. Different solvents were used to eliminate agglomeration of the silver nanoparticles. These solvents produced nanoflower-like morphology with abundant nano-petals. This is the first report of the synthesis of Ag nanoflowers formed by green synthesis method using Kalanchoe Daigremontiana extract. The synthesized Ag nanoflowers are faced center cubic structure in nature with a petal thickness approximately of 25 nm. Photocatalytic activity of the different Ag nanostructures was evaluated through the degradation of methylene blue, where the degradation time as low as 1 min is reported. Furthermore these green synthesized Ag nanoflowers were found to show high antibacterial activity against Gram-negative bacteria Escherichia coli and Gram-positive Staphylococcus aureus.

Effluent Disinfection of Real Wastewater by Ag­TiO2 Nanoparticles Photocatalysis.

Currently pathogen microorganisms, presents in wastewater, are more resistant to conventional disinfection process, due to its constant change induced for the antibiotic for human diseases. One of the new options for the pathogen microorganisms is the heterogeneous photocatalysis, which has been used for remove microorganism, but never in real wastewater effluent. This paper shown the synthesis of Ag­TiO2 nanoparticles, its physical characterization was carried out by TEM, SEM, S-BET, XPS and band gap measurement by UV-vis spectroscopy showing that Ag­TiO2 are spherical particles with sizes around 50 nm with 1 and 10 %w of Ag, and a significant decrease in the band gap. The disinfection system was illuminated using the solar radiation of a spring day at Querétaro, Mexico, in lapses from 11:00 am to 03:00 pm; the microbiological tests were performed according to the Official Mexican Norm (NOM-003-SEMARNAT-1996), the results shows that after 3 hours of solar photocatalysis disinfection process the material 1 %w Ag­TiO2 at 0.2 gL⁻¹, removes the fecal and total coliform microorganisms from effluent, leaving Enterobacter, Escherichia, Citrobacter, Salmonella and Klebsiella microorganisms alive due to its capability of reactivation.

Characterization and degradation of functionalized chitosan with glycidyl methacrylate.

The synthesis, characterization and degradation of a hybrid chitosan (CTS)/glycidyl methacrylate (GMA) material are reported. These versatile materials (natural-synthetic materials) are potential candidates for dental restoratives. All materials were characterized by infrared spectroscopy (FT-IR), X-ray diffraction and thermal (DSC) analysis. Particular attention was paid to the thermal stability and chemical resistance of the hybrid CTS materials. From dynamical rheological tests, it was concluded that CTS-GMA solutions behave as physical hydrogels. These pH-sensitive gels are an example of stimuli-responsive polymers, also known as 'smart polymers'.