Extração e purificação de cafeína da casca de café

AUTOR(ES)

Gislaine Fernandes

DATA DE PUBLICAÇÃO

2007

RESUMO

In 2006, Brazil consolidated its position as the world s largest producer and exporter of coffee, when were produced around 41.573.000 bags (60 kg) of benefited coffee. During the processing of dry coffee fruit, a big amount of coffee husk mass is generated in accordance with coffee variety. Aiming at adding commercial value to coffee husk, this work deals of extration and refining of caffeine in the coffee husk. Caffeine extraction was done using a trademark coffee extractor - Polti. In order to analyze influence of the diameter of coffee husk in caffeine extraction, samples with several average diameter particle was carried out. In refining experiments, 5 grams of coffee husk roasted was extracted with water getting itself 150 mL of extract. Liquid-liquid extraction was done in four sequential stages, using 30 mL of chloroform for the removal of the caffeine. The chloroformic solution was submitted to refining using activated coal and potassium hydroxide solution (0.1 mol/L). To quantify the effective percentage of removed pigments from the solution, the samples had been analyzed in one spectrophotometer operating with wave length of 319 nm. Refining results using activated coal had been adjusted to Langmuir and Freundlich models. Results of the refining using potassium hydroxide had been adjusted by a similar equation of Freundlichs model. A study to get the most excellent refining conditions was done and the result of this operational optimization show that the treatment with 0.15g activated coal and 10mL of the extract, agitated by 7 minutes were the best conditions. With regard to potassium hydroxide treatment, it started using the solution previously treated and optimized with activated coal. Optimum result consisted of agitation time of 6.3 minutes and a potassium hydroxide volume of 17.84mL. It was proposed a kinetic study to explain possible reaction between impurities in chloroformic solution, that probably it can originate the color, and potassium hydroxide solution. The model considered for the chemical reaction did not represent this refining process, by the following reasons: it presented a high value for the order of the reaction, as well as an ample variation of the value of reaction rate constant.

ASSUNTO(S)

extração de cafeína purificação de cafeína caffeine extraction refining caffeine engenharia quimica coffee husk casca de café cafeína

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