Abstract
Enzymatic and dilute acid processes were applied to study the orange bagasse hydrolysis. The moisture, ashes, lignin, cellulose, and hemicellulose contents, of the orange peels, were quantified. The xylanase and cellulase enzymes activities were quantified, as well as their optimum pH and temperatures. The pre dried orange peel biomass was pre-treated with calcium hydroxide, at preestablished conditions. The hydrolysis followed a central composite factorial 2³ design. The cellulase activity was 28.05x10-6 FPU (Filter Paper Units)/m3, the optimum pH was 4.8 and the temperature was 60°C. The results for xylanase were an activity of 199.58x10-3 U/Kg, pH 5.2, and temperature 50°C. The acid hydrolysis TRS (total reducing sugars) values varied from (9.328±0.68 mg)*10-3 TRS per Kg of biomass to (30.15±0.31)*10-3 mg TRS per Kg biomass, the most significant factor was the temperature and the least the time. The enzymatic hydrolysis TRS values varied from (77.33±3.82)*10-3 mg TRS per Kg biomass to (99.66±0.62)*10-3 mg TRS per Kg biomass, the most significant factor was the concentration of cellulase and the least the xylanase concentration.
Highlights
Biofuels are regarded as one of the most viable options for reduction of CO2 emissions in the transport sector [1]
Pretreatment is a fundamental step for refining biofuels and biobased products from the lignocellulosic biomass as the bioconversion of cellulose into fermentable monosaccharides [12]
Due to its complex structure, it requires pretreatment to improve the yield of reducing sugars in the hydrolysate during enzymatic hydrolysis from cellulose and hemicellulose [17]
Summary
Biofuels are regarded as one of the most viable options for reduction of CO2 emissions in the transport sector [1]. The orange bagasse contains approximately 16% of hemicellulose, 28% of cellulose and 9% lignin, showing to be a viable alternative to produce second generation ethanol. Due to its complex structure, it requires pretreatment to improve the yield of reducing sugars in the hydrolysate during enzymatic hydrolysis from cellulose and hemicellulose [17]. Most studies about the lignocellulosic ethanol production involve enzymes, besides that the hydrolysate volumes are insufficient to the following fermentation processes. Two types of hydrolysis, dilute acid and enzymatic, were evaluated For acid hydrolysis, it was studied the application of milder temperatures, to reduce energy costs as well as the generation of inhibitory compounds. A combination of cellulase and xylanase was studied, in order to increase the production of reducing sugars
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