optimization of the total reducing sugars yield from dilute acid hydrolysis and bioethanol production from moringa oleifera seeds husk

Abstract

The objective of this thesis is bioethanol production from moringa oleifera seeds husk, which is in effects to minimize energy cost and substituting non-renewable energy by renewable resources. Moringa oleifera is a plant with various benefits to mankind from its root until leaves, from food to biofuel applications, all parts are useful. Moringa oleifera seeds husk, which is an agricultural waste with no appreciable value to industries and competitive use as a food. This study involved the optimization of the total reducing sugars yield from dilute acid hydrolysis and bioethanol production from moringa oleifera seeds husk. The production process was carried out in four main steps, pretreatment, hydrolysis, fermentation and distillation. The husk was hydrolysis using acid hydrolysis which is dilute sulfuric acid and fermented using saccharomyces cerevisiae yeast. The experiment was designed by Response Surface Methodology (RSM) using central composite design (CCD) to investigate the effect of acid concentration (2-3%), reaction time (20-30min) and temperature (120-140ºC) of hydrolysis parameters using Design expert® version 11 software. The optimum combination of temperature, time and acid concentration was determined. High yield of total reducing sugar 44.83% (average) at the optimum parameters, temperature of 130ºC, 25 min reaction time, and 2.5% acid concentration. This process investigates the parameters which produce optimum total reducing sugar yield. Acid concentration, temperature and time have a statically significant effect on the yield with p-value 0.0029, 0.0007 and 0.0394 respectively. However, high acid concentration, temperature as well as increasing hydrolysis time causes a decline in the total reducing sugar yield. The statistical analysis also showed that the total reducing sugar yield of (44.98 %) and 3.71 ml/40g bioethanol yield was obtained at optimization variables of 2.72 % acid concentrations, 132.38 º C temperatures, and at a time 27.18 minutes. From this, it can conclude that a good agreement with the observed values of the total reducing sugar yield (44.83). Chemical characterization of the bioethanol produced was performed by FTIR. The result shows that, the ethanol produced contains O-H, C-O,- CH2 and CH3 functional groups which indicates the presence of ethanol in the product.