The main objective of this work was to investigate the enzymatic production of ethyl esters in continuous mode coupled to an ultrasound bath. For esterification reactions soybean free fatty acids (FFA) and ethanol were used as substrates, and Novozym 435 and Lipozyme TL IM, as catalysts. The experimental system consisted of a packed bed glass reactor immersed in an ultrasound bath and the following variables were studied: ethanol to FFA molar ratio of 1:1, 1:3 and 1:6, substrates flow rate of 2.5 and 5 mL/min, at 65 °C and 132 W ultrasound power output. It was noticed that the excess alcohol favored the esterification reaction with the best conversions observed, 95%, at 6 min reaction for 1:6 FFA to ethanol molar ratio, 2.5 mL/min feeding flow rate. Increasing the substrates feeding flow rate decreased the conversion down to 87% and replacing the Novozym 435 by Lipozyme TL IM no satisfactory conversions were achieved. This type of reactor demonstrated good performance for ethyl esters production, opening promising perspectives for use in the production of other types of esters such as those aromatic and others with high value.
RESUMO -Hidrólise é um processo pelo qual se podem obter diversos produtos de interesse na indústria. A utilização de enzimas para esse processo possibilita a produção de ácidos graxos em temperaturas mais amenas e a obtenção de um produto mais limpo. O ultrassom permite que não seja utilizado emulsificante para a formação de emulsões e fornece a agitação necessária para que a reação ocorra. As reações foram realizadas com agitação de 300 rpm em um frasco de vidro com potência ultrassônica de 132W , o uso de 10% de enzima Lipozyme TL IM (em relação a massa do substrato) e uma razão de óleo:água de 1:20 a 40 °C, variando somente o tempo de cada reação. Observou-se que após que o tempo de 2h o meio reacional se mantinha estável, e que a enzima poderia ser reutilizada com 50% de eficiência.
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