Navegando por Autor "Gomes, Michelle Garcia"

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Pretreated sugarcane bagasse with citric acid applied in enzymatic hydrolysis.
(2020) Gomes, Michelle Garcia; Santos, Renata Vidal dos; Barreto, Elisa da Silva; Baffi, Milla Alves; Gurgel, Leandro Vinícius Alves; Baeta, Bruno Eduardo Lobo; Pasquini, Daniel
The objective of the study was to evaluate the pretreatment of sugarcane bagasse (SCB) with diluted citric acid solution in a pressurized system and its behavior when submitted to enzymatic hydrolysis using the Cellic CTec 3 enzyme complex, employing a Doehlert’s experimental design (23 ), with 5 central points (CP). The operating variables were temperature (T, °C), time (t, min) and percentage by weight of citric acid in relation to bagasse (PCA, wt%), ranging from 120 to 180°C for 20 to 90 min and 3 to 12 wt%, respectively. The pretreatments were effective in promoting changes in compositions of lignin, hemicellulose, and cellulose in all samples in relation to raw SCB. The concentrations of the glucose reached the maximum, 23.74 g/L, for the pretreated sample with temperature of 160°C, PCA 5.25 wt%, and reaction time of 20 min, while the xylose reached the maximum, 5.23 g/L, with the sample ob tained in the temperature of 150 C, PCA 7.5 wt% and 55 min.
Pretreatment of sugarcane bagasse using citric acid and its use in enzymatic hydrolysis.
(2020) Gomes, Michelle Garcia; Gurgel, Leandro Vinícius Alves; Baffi, Milla Alves; Pasquini, Daniel
This study evaluated the use of a renewable organic acid (citric acid) as homogeneous catalyst for the pretreatment of raw sugarcane bagasse (SB). A 22 central composite design with two factors (reaction time and citric acid concentration) was used to evaluate the effect of the factors on the chemical composition of the pretreated SB samples and enzymatic hydrolysis efficiency. The enzymatic hydrolysis experiments of the pretreated SB samples were performed using the enzymatic cocktail Cellic® CTec 3 and the total reducing sugars (TRS) released after enzymatic hydrolysis was determined. In addition, scanning electron microscopy and X-ray diffraction were used to examine the changes in the morphology and structure of the pretreated SB samples. The changes in the structure and chemical composition of the pretreated SB resulted in a high TRS concentration (28.2 g L 1 ) after enzymatic hydrolysis, for the pre treatment condition employing 6 wt% citric acid and 102.4 min, compared to the raw SB (3.06 g L 1 ). The pretreatment showed potential for application since a moderate conversion of polysaccharides in TRS was obtained, even though it was a pretreatment carried out under milder conditions. The pretreatment studied has the advantage of using weak and environmentally friendly acid catalyst, atmospheric pressure, and low temperature.
Pretreatment of sugarcane bagasse with dilute citric acid and enzymatic hydrolysis : use of black liquor and solid fraction for biogas production.
(2022) Gomes, Michelle Garcia; Paranhos, Aline Gomes de Oliveira; Camargos, Adonai Bruneli de; Baeta, Bruno Eduardo Lobo; Baffi, Milla Alves; Gurgel, Leandro Vinícius Alves; Pasquini, Daniel
This study evaluated the pretreatment of sugarcane bagasse (SCB) with dilute citric acid solution for biogas production. The black liquor (BL) from pretreatment and residual solid fraction (RSF) obtained after enzymatic hydrolysis were used as substrates for the biogas production. After saccharifications of the pretreated solid fractions performed with Cellic® CTec 3 cocktail, the highest concentration of total reducing sugars (TRS) was in the range of 10.7–184.8 g L−1 and the sugar yields were in the range of 3.5–88.8%. For BL, the contents of glucose, xylose, and arabinose were in the range of 1.9–8.9 g L−1, 4.0–24.7 g L−1, and 0.2–5.4 g L−1, respectively. Biogas production from BL and RSF resulted, respectively, in maximum values of 563.6 and 57.8 NmL gCOD−1, indicating the feasibility of using dilute citric acid pretreatment coupled to biogas production in biorefineries. Brief energy and economic assessment were carried out considering the energy balance (thermal energy generated by burning biogas - thermal energy spent in the pretreatment), as well as revenue from a possible sale of electricity generated in a combined heat and power system.