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Abstract The difficulty in treating organic effluents and increasing the resistance of microorganisms to conventional treatments promotes the development of new materials for these applications. In this work, it was obtained ZnO co-doped with Fe3+ and Pb2+ (ZnO:xFe:yPb, with x and y varying between 0, 1, 3 and 7 mol%) by microwave-assisted hydrothermal method with a reaction temperature of 140 °C for 30 min. The powders were characterized by X-ray diffraction (XRD), field-scanning electron microscopy (SEM), Brunauer-Emmett-Teller method (BET), ultraviolet diffuse reflectance spectroscopy (DRS-UV), X-ray fluorescence analysis (XRF) and Fourier transform infrared spectroscopy (FTIR). Photocatalytic properties were estimated by the degradation of the methylene blue dye when subjected to UV radiation. The antimicrobial properties were investigated by the formation of inhibition halos against E. coli and S. aureus bacteria. The XRD patterns show that there was no formation of secondary phases, obtaining only the ZnO phase, with hexagonal structure. Through the XRD, it can be seen that the intensity of the characteristic peaks is also reduced as the dopant concentration increases, indicating the appearance of defects in the crystalline lattice. SEM images show that an increase in the dopant concentration promotes a loss in the morphology of ZnO nanoparticles, accompanied by a reduction in their mean size. The co-doping reduces the photocatalytic activity of ZnO against the methylene blue dye, but increases the antimicrobial activity against E. coli and S. aureus bacteria. [ABSTRACT FROM AUTHOR]

Abstract: This study describes the use of cassava starch acetate (CSA) to impregnate Kraft paper and its influence on the water vapor permeability (K w). This barrier property depends on the water vapor diffusion coefficient (D eff) and the material hygroscopicity properties (adsorptivity, β). The influences of D eff and β on the K w value were studied. Kraft paper samples were impregnated at atmospheric pressure and under vacuum. The results showed an important decrease on the K w values, which was associated with two factors: (a) the partial filling of the Kraft paper superficial and internal pores by the impregnated CSA, reducing the K w; (b) as CSA is much less hygroscopic than paper, its adsorptivity is reduced significantly by impregnation. This paper demonstrates that CSA impregnation of Kraft paper is an interesting alternative for the improvement of the hygroscopic properties and water vapor permeability of the Kraft paper. [Copyright &y& Elsevier]

A fibrous residue rich in non-extracted starch (bagasse) obtained from the industrial production of cassava starch was used to obtain a composite that is similar to cardboard, through a technique used in small scale artisan production of recycled paper. A mixture of 90% cassava bagasse and 10% of Kraft paper was used for the production of these composites. Kraft paper was added as a source of long fibres, in order to improve the mechanical properties of the material. The prepared material has similar characteristics to the molded fibre packaging made using recycled paper, as used in egg boxes. However, cassava bagasse has advantages over recycled paper, in view of the fact that it is obtained from known and renewable sources. The impregnated and non-impregnated materials were submitted to tests of tensile strength and to direct contact with water by complete immersion of the samples. The cassava bagasse-Kraft paper composites obtained had a slight resistance to direct contact with water. The water mass absorbed by the materials impregnated with starch acetate was approximately half that of the materials without impregnation. However, the impregnation had little influence on the tensile strength of the tested samples. Starch acetate is therefore an attractive additive for use in the manufacture of waterproof materials, such as disposable trays. [Copyright &y& Elsevier]