SILVA, R. A.; http://lattes.cnpq.br/7145504826879112; SILVA, Rebeca de Almeida.
Resumo:
With the current worldwide search for renewable sources, the use of lignocellulosic
biomass waste has a very promising perspective for ethanol production. The process
derives from the fermentation of sugar from hemicellulose and cellulose origin,
fractions of lignocellulosic materials, by a suitable pre-treatment and enzymatic
hydrolysis of cellulose. The waste of acerola is constituted by 40 % of the processed
volume, and 24,7 % of cellulose, 19,27 % of hemicellulose and 28,37 % of lignin. The
aim of this work was to study the kinetics of enzymatic hydrolysis of acerola’s waste in
natura and waste pretreated, and also to evaluate the effect of this pretreatment on the
hydrolysis. Initially, a lignocellulosic characterization was made with the waste in
natura and waste pretreated, and microstructural characterization by means of XRD and
SEM analysis. To the waste of acerola, an acid pretreatment was applied, followed by
alkaline pretreatment. Then, the enzymatic hydrolysis of waste in natura and pretreated
was performed. Commercial enzymes Celluclast 1.5L (Novozyme) and beta-glucosidase
(Proenzyme) were used. As a tool to evaluate the variables that influence the process, a
factorial design 22 was used with three central points, and the analyzed variables were
enzymatic load and ratio of dry weight of waste per volume of reaction. This
lignocellulosic characterization showed that the waste of acerola is a viable substrate for
obtaining fermentable sugars and its subsequent conversion to ethanol. The acid
pretreatment followed by the alkaline showed to be very effective in concentrating the
cellulose, by the removal of part of the hemicellulose and lignin, causing an increase of
the cellulose from 25 % to 50 %. The crystallinity of waste of acerola was evidenced by
X-ray Diffraction and the modification in the morphology of waste, verified by
Scanning Electron Microscopy. Through the kinetics of enzymatic hydrolysis of waste
of acerola in natura and pretreated, yields of 100 % were obtained, in the conversion of
cellulose to glucose. The best glucose production was 22,3 g/L, reached in 36 hours of
hydrolysis of waste of acerola pretreated, which occurred in the best conditions of
enzyme load and dry weight of waste per reaction volume ratio.