Estudo de pré-tratamento e hidrólise ácida do bagaço do pedúnculo de caju para a produção de bioetanol hidratado de segunda geração.

Abstract

Currently, the cashew (Anacardium occidentale L.) is a fruit grown in Brazil, mainly in the States of Ceará, Piauí, Rio Grande do Norte, Maranhão, Bahia and Paraíba, but Ceará is the one responsible for greater domestic production. The cashew crop is expanding throughout Brazilian territory and the Northeast region is responsible for an area that plants around 1 million hectares. This way, from the stalk of cashews we get the pulp, juice clarified, cajuina, soda, vinegar, fermented wine, brandy and hydrated alcohol. The fermented cashew can be converted into hydrated alcohol of good quality, and may be an important product of this culture. The simple batch fermentation was conducted during 24 hours in a temperature between 28 and 32 °C with yeast S.cerevisiae. Fermentation processes were followed at intervals of 2 hours, monitoring the total acidity, pH, concentration of biomass and sugar and alcohol content. The fermentation parameters evaluated were fermentative efficiency (Ef), productivity (Qp), product yield in relation to substrate consumed (Yp/s) and biomass (Yx/s) and specific growth rate (|Ax). The volatile components of fermented and the alcohol of cashews (actual alcoholic strength, higher alcohols, esters, aldehydes and methanol) were characterized by gaseous chromatography. The analysis evaluated of the chemical composition of cashew bagasse were cellulose content (22%), polioses (20%), lignin (38%), extractives (12%), ashes (1.0%) and moisture (8.0%). In prehydrolysis acid process, the results of yield, lignin and holocellulose ranged from 87 to 52%, from 36 to 29% and from 28 to 34%, respectively. The results of cellulosic pulp yield of the pulping process (delignification) sodas ranged from 42 to 16%. In soda pulping kinetics, the residual lignin content ranged from 35 to 8% and the dissolved lignin reached an extension of delignification of 80% (considering pre-hidrolysed bagasse). For the acid hydrolysis process has run 23 factorial planning, the variables of dilute sulphuric acid concentration were of 1.0, 1.5 and 2.0%; of time ranging from 10, 15 and 20 min and temperature ranging from 150, 170 and 190°C, respectively. The response variables: levels of glucose, xylose, arabinose, furfural, HMF and acetic acid were quantified by high performance liquid chromatography (HPLC). After choosing the best point of hydrolysis of factorial planning, the fermentation process of hydrolyzed occurred satisfactorily.