ABSTRACT:Polypropylene (PP)/aluminum hydroxide (ATH) composites were prepared in a melt mixer with addition of polypropylene functionalized with vinyltriethoxysilane (VTES) as a coupling agent. The effects of ATH and PP-VTES on the melt flow indices (MFI), tensile properties, decomposition temperatures, and flame retardancy of composites were analyzed. It was verified that increased ATH concentration reduced MFI and tensile properties, but increased the decomposition temperature under oxidative atmosphere and improved the flammability properties. Addition of PP modified with VTES slightly improved tensile strength and maximum elongation and granted the best results for the flammability tests of the materials showing that it can be an effective coupling agent for PP/ATH composites.
A new activated biochar was produced by carbonizing Cássia fistula L. leaves and its characterization was performed. Scanning Electron Microscopic (SEM) images of the activated biochar showed morphology with numerous irregular cavities and pores. BET surface area and total pore volume of produced adsorbent were 192 m².g-1 and 0.108 cm3.g-1, respectively. Mean porous diameter of the produced biochar was 2.263 nm, characterizing a mesoporous material. Crystallinity and functional groups of the adsorbent were determined by X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy analyses, respectively. The pH of zero charge point (pHzcp) observed was equal to 10, demonstrating that the activated biochar has a negative surface, which facilitates the adsorption of positively charged compounds in water and wastewater treatment. Tree leaves of Cássia fistula L. represent a promising raw material for activated biochar production, given their availability and characteristics of the adsorbent produced. The use of tree leaves for activated biochar production can reduce the operational costs of adsorption process, besides providing the use of a residue for a more noble purpose.
Resumo O presente trabalho consistiu na aplicação da metodologia de avaliação de custo de ciclo de vida para estimar os custos de operação de um biorreator a membrana hipotético projetado para ser implementado em Santa Catarina/Brasil, visando à produção de água de reúso. Foram levantados dados de custo referentes à aquisição e troca de membranas, consumo energético, disposição final de lodo e funcionários para um biorreator a membrana dimensionado para tratar 6.060 m³d-1 (50.000 hab). Foram estimados valores equivalentes a R$0,63/m³ ou R$2,10 por kg de DBO removida, os quais vão ao encontro de outros estudos realizados abordando custos de biorreatores a membrana. O sistema proposto se apresentou competitivo para produzir água de reúso, apresentando custo de tratamento (R$/m³) inferior ao valor cobrado pela água potável. Palavras-chave: Biorreator a membrana. Avaliação econômica. Custo de operação. Avaliação de custo de ciclo de vida. Reúso. Lodos Ativados. Tratamento de esgotos.
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