Preparation of the orgamomodified cellulose acetate membranes for adsorption of the ions Cu(II), Cd(II), Mn(II) AND Ni(II)

Cellulose acetate polymeric membranes had been prepared by a procedure of two steps, combining the method of phase inversion and the technique of hydrolysis-deposition. The first step was the preparation of the membrane, and together was organomodified with tetraethylortosilicate and 3-aminopropyltrietoxysilane. Parameters that exert influence in the complexation of the metallic ion, as pH, time of complexation, metal concentration, had been studied in laboratory using tests of metal removal. The membranes had presented resistance mechanics and reactivity to cations, being able to be an alternative for the removal, daily pay-concentration or in the study of the lability of metals complexed

Self-sterilizing ormosils surfaces based on photo-synzthesized silver nanoparticles

Medical device-related infections represent a major healthcare complication, resulting in potential risksfor the patient. Antimicrobial materials comprise an attractive strategy against bacterial colonizationand biofilm proliferation. However, in most cases these materials are only bacteriostatic or bactericidal,and consequently they must be used in combination with other antimicrobials in order to reach theeradication condition (no viable microorganisms). In this study, a straightforward and robust antibac-terial coating based on Phosphotungstate Ormosil doped with core-shell (SiO2@TiO2) was developedusing sol-gel process, chemical tempering, and Ag nanoparticle photoassisted synthesis (POrs-CS-Ag).The coating was characterized by X-ray Fluorescence Spectroscopy (XRF), Field Emission ScanningElectron Microscopy (FE-SEM), Atomic Force Microscopy (AFM) and X-ray Photoelectron Microscopy(XPS). The silver free coating displays low antibacterial activity against Staphylococcus aureus and Pseu-domonas aeruginosa, in opposition to the silver loaded ones, which are able to completely eradicate thesestrains. Moreover, the antimicrobial activity of these substrates remains high until three reutilizationcycles, which make them a promising strategy to develop self-sterilizing materials, such as POrs-CS-Ag-impregnated fabric, POrs-CS-Ag coated indwelling metals and polymers, among other materials.Fil: Gonçalves, Lidiane Patrícia. Universidade de Sao Paulo; BrasilFil: Miñan, Alejandro Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Benítez, Guillermo Ignacio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Fernandez Lorenzo, Monica Alicia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Vela, Maria Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Schilardi, Patricia Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Ferreira Neto, Elias Paiva. Universidade de Sao Paulo; BrasilFil: Noveletto, Júlia Cristina. Universidade de Sao Paulo; BrasilFil: Correr, Wagner Rafael. Universidade de Sao Paulo; BrasilFil: Rodrigues Filho, Ubirajara Pereira. Universidade de Sao Paulo; Brasi

Estudos em compositos de celulose e acetato de celulose com oxido de zirconio (IV)

Orientador: Yoshitaka GushikemTese (doutorado) - Universidade Estadual de Campinas, Instituto de QuimicaDoutorad

Sintese e caracterização de complexos de pentacianoferrato (II) na superficie da silica gel organomodificada

Orientadores : Yoshitaka Gushikem, Eduardo StadlerDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de QuimicaMestrad

Thermal Transformations and Proton Species in 12-Phosphotungstic Acid Hexahydrate Studied by ¹H and ³¹P Solid-State Nuclear Magnetic Resonance

The hydration environments around the heteropolyanion in 12-phosphotungstic acid (PW₁₂O₄₀H₃, HPW) were analyzed as a function of temperature in the hexahydrated form (HPW·6H₂O). Samples were obtained drying HPW·<i>n</i>H₂O with <i>n</i> ∼ 22 at 358 K for 2 h in a furnace with either uncontrolled air atmosphere or saturated with N₂. The existence of a phase transition in HPW·6H₂O and the change in the thermal balance of hydrated species were tested using a set of multinuclear NMR techniques: high-resolution ³¹P and ¹H NMR, ³¹P­{¹H} spin–echo double resonance, and {¹H}-³¹P cross-polarization. Differences in the proton dynamics were also probed measuring the spin–lattice relaxation time in the rotating frame (¹H-<i>T</i>_1ρ), using direct excitation of all ¹H species or selecting only those in the neighborhood of the polyanion with cross-polarization techniques. Experiments were conducted between 223 and 358 K to induce appreciable variations in the dynamic equilibrium of hydrated species. Although XRD and TGA showed the same results for both samples, consistent with HPW·6H₂O, structural differences were detected with NMR, indicating that the material obtained from the drying process under N₂ is more compatible with the hexahydrate. ¹H NMR confirmed the existence of an equilibrium balance between hydration species as a function of temperature: H₅O₂⁺ ↔ H₃O⁺ + H₂O ↔ H⁺ + 2H₂O. Proton exchange was detected in H₃O⁺ and also in hydrogen bonds in H₅O₂⁺ at a very fast rate, even at low temperatures. No evidence of a structural phase transition was found in this sample. For the sample dried in uncontrolled atmosphere, the presence of mobile water in clusters was detected. Heating from room temperature, the hydrated species undergo a transformation at 318 K, related to rearrangement/removal of interstitial H₂O. A complex sequence of metastable states and hysteresis effects is observed when this sample is cooled down to room temperature. These results indicate that the transformation at 318 K is not an intrinsic property of the HPW hexahydrate structure, but it is related to the rearrangement of interstitial H₂O