Abstract Silsesquioxane 3-n-propylpyridinium chloride (SiPy+Cl-) is a water-soluble polymer that can be used as a promising material with remarkable biological effects. SiPy+Cl- can form thin films on substrate surfaces and shows suitable adhesiveness. Besides, it has high affinity for metal ions. Considering this effect as exchanger polymer and the well-known antimicrobial and cytotoxic features of copper, the aim of this study was to perform the copper functionalization of silsesquioxane 3-n-propylpyridinium chloride Cu-SiPy+Cl-. The SiPy+Cl- was obtained by the sol-gel processing method and the incorporation of copper (II) chloride was carried out by immobilization. Its characterization was performed by spectroscopic methods of Fourier-transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). The FTIR spectrum of SiPy+Cl- showed symmetric and asymmetric stretching of Si-O-Si group and also exhibited vibrational bands of pyridinium ring. The FTIR spectrum of Cu-SiPy+Cl- assigned typical bands displacements of the metal coordination to nitrogen atoms. Spectroscopic data recorded by 13C and 29S NMR confirmed the chemical structures of SiPy+Cl- and Cu-SiPy+Cl-. Concerning to the in vitro susceptibility assay, the antimicrobial activity against Staphylococcus aureus, Escherichia coli and Streptococus mutans was achieved by the agar-well diffusion method. Cu-SiPy+Cl- showed similar cytotoxicity than SiPy+Cl- against Calu-3 and 3T3 cell lines by the MTT colorimetric assay. Further studies are required to investigate the use of Cu-SiPy+Cl- as a novel dental material.

Os compósitos obtidos a partir de fibras de bagaço de cana-de-açúcar e polímeros reciclados (PEAD e PS) foram obtidos através da técnica de extrusão a quente e o planejamento fatorial possibilitou a análise dos fatores que influenciam a obtenção dos compósitos. As amostras contendo polietileno de alta densidade (PEAD), tanto com 30% como com 50% de fibras, mostraram-se mais impermeáveis na presença da água que as amostras obtidas com poliestireno (PS). Os compósitos obtidos com PEAD apresentaram resistência à flexão com uma tensão máxima aplicada de 45 MPa (50% de fibra) e de 39MPa (30% de fibra), esses valores são maiores que os apresentados pelos materiais obtidos com PS. Compósitos de polímeros e madeira (com 60% de serragem) apresenta resistência à flexão de aproximadamente 32 MPa e o MDF apresenta uma resistência à flexão de 36 MPa, esses resultados mostram que os compósitos obtidos possuem uma boa resistência a flexão.

The composites were obtained through hot extrusion of a mixture of recycled polymers (HDPE and PS) and sugar cane fibers. The extrusion technique resulted in homogeneous materials with good mechanical properties and the factorial design allowed the analysis of the factors that influence the process. Samples containing high density polyethylene (HDPE), both with 30% and 50% fibers were shown to be significantly more effective compared to polystyrene (PS) aiming at impermeability in the presence of water. The composites obtained with HDPE showed bending resistance, with 45 MPa (50% fiber) and 39MPa (30% fiber) maximum applied stress, these values are higher than those presented in the composites obtained with PS. Composites of polymers and wood (60% of sawdust) provide bending resistance of about 32 MPa and MDF has a bending resistance of 36 MPa, these results show that the compounds obtained have a good bending resistance.

Neste trabalho, a degradação de cânfora em solução aquosa foi avaliada utilizando-se processos fotocatalíticos mediados por suspensões e formas imobilizadas de TiO2 e ZnO. Os catalisadores suportados (TiO2/anéis de vidro, TiO2/alginato de cálcio e ZnO/alginato de cálcio) foram caracterizados por microscopia eletrônica de varredura com espectroscopia de energia dispesiva de raios X (SEM/EDX), difratometria de raios X (XRD), fluorescência de raios X por energia dispersiva (EDXRF) e espectroscopia Raman, técnicas que permitiram confirmar a elevada porosidade dos materiais, assim como as fases cristalinas características (anatase e wurtzita). A eficiência de degradação dos fotocatalisadores suportados foi comparada com a dos semicondutores em suspensão, observando-se resultados comparáveis entre TiO2 Degussa P25 e TiO2 imobilizado em anéis de vidro. Por outro lado, o uso de esferas de alginato de cálcio propiciou menores eficiências de degradação, provavelmente em decorrência da significativa redução da área superficial nos sistemas imobilizados.

In this work, the degradation of aqueous solution of camphor by heterogeneous photocatalysis was study using suspended and supported TiO2 and ZnO. The supported catalysts (TiO2/borosilicate reaching ring, TiO2/calcium alginate and ZnO/calcium alginate) were characterized by scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/EDX), X-ray diffractometry (XRD), energy dispersive X-ray fluorescence (EDXRF) and Raman spectroscopy, techniques that permitted to confirm the porosity of the material as well as the characteristic crystalline forms (anatase and wurtzite). The degradation efficiency of the supported photocatalysts was compared with the performance of free TiO2 and ZnO, observing comparable results between conventional Degussa P25 TiO2 and TiO2 immobilized in glass-rings. On the other hand, the use of calcium alginate beads leads to lower degradation efficiency probably due to the significant area reduction observed in immobilized systems.

Different parameters of carbon ceramic electrodes (CCE) preparation, such as type of precursor, carbon material, catalyst amount, among others, significantly influence the morphological properties and consequently their electrochemical responses. This paper describes a 2³ factorial design (2 factors and 3 levels with central point replicates), which the factors analyzed were catalyst amount (HCl 12 mol L-1), graphite/precursor ratio, and precursor type (TEOS - tetraethoxysilane and MTMOS - methyltrimetoxysilane). The design resulted in a significant third order interaction for peak current values (Ipa) and a second order interaction for potential difference (ΔE), between thefactors studied, which could not be observed when using an univariated study.

In this work the preparation and characterization of a supported catalyst intended for degradation of reactive dyes by Fenton-like processes is described. The photocatalyst was prepared by immobilization of Fe3+ into the molecular sieve (4A type) surface and characterized by x-ray diffractometry and infrared, Mössbauer and EPR spectroscopy. The solid containing 0.94% (w/w) of ferric ions was used in degradation studies of aqueous reactive-dyes samples with really promissory results. Generally, Vis-assisted photochemical processes leads to almost total decolorization of all tested dyes at reaction times lower than 30 min. It was also observed that the iron-molecular sieve matrix can be reused.

A new mixed material was obtained through the combination of the suspensions of iron oxy-hydroxide and bentonite clay, denoted BFe. Analysis of its structure (XRD, Mossbauer and TGA) and composition (AAS) suggests the maintenance of the layer structure of the clay and an increase in the thermal stability of the BFe. Electrochemical studies performed in different electrolytes show that only in an alkaline medium it is possible to observe the redox peaks relative to the processes involving Fe+2/Fe+3 pair. Tests that evaluated the potential use of the photo-Fenton process showed an efficient degradation process of the dyes in significantly reduced reaction times.