Estudos da atividade antiespumante de ésteres etílicos derivados de óleos vegetais / Estudo da atividade antiespumante de ésteres etílicos derivados de óleos vegetais

AUTOR(ES)

Walter Hugo Venturelli

DATA DE PUBLICAÇÃO

2008

RESUMO

Gas-liquid foams are colloidal systems formed by air bubbles separated by a liquid thin film stabilized by surfactants, which are often found in many industrial processes. It becomes often necessary the use of antifoams to avoid loses of material or loses in the processs efficiency caused by a large foam production. The foaming mixtures utilized in this work were aqueous solutions of sodium dodecyl sulfate, SDS, and sodium dioctylsulfosuccinate, AOT, besides a mixture of sugar syrup and yeast in conditions compared to that used in fermentation process. The commercial antifoams usually comprise silicones and polyethers petrol derivatives, so the use of natural derivative oils can be very interesting since they are biodegradable and are obtained of natural sources. This dissertation presents results of the antifoam effect of ethylic esters with different saturation degree (animal fatty, soy oil, and coconut oil derivatives) in the presence and the absence of hydrophobic silica. Two methods are employed for foam characterization: the Barstch and Bikerman tests. The parameters utilized to evaluate the antifoam efficiency are the foam volume, foam stability and drainage rate of the liquid. In a general way, the results show that there is not a rationalization about the different saturation degree and the antifoam efficiency, but they all present a good effect in the foam prevention, exhibiting a synergistic effect in the presence of hydrophobic silica indicating that upon an additional study they can become a market alternative for antifoams, since their effect are comparable or in some cases better than those measured for commercial formulations. In the particular case of the sugar syrup the effect of the esthers upon foam drainage follows the trend: soya

ASSUNTO(S)

Ésteres etílicos antiespumantes gas-liquid foams ethylic esters espumas gás-líquido antifoams

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