Optimized Pretreatment And Fermentation Of Sargassum Horneri Based Ethanol

As one important part of the biomass energy, bioethanol possesses very excellent significance for the alleviation of the increasingly serious energy and environmental problems. Containing large amounts of carbohydrate, the macroalgae plays a pretty role in being converted to bioethanol by varieties of microorganisms such as bacteria or saccharomycetes, which is considered as a hotspot nowadays. Moreover, compared with corps which need vast areas, the macroalgae has many advantages such as having short vegetative cycle and rich resources in the sea. As a kind of macroalgae with excellent environmental remediation ability, Sargassum Horneri was employed to prepare bioethanol in this paper. On the basis of the analysis of its component, the hydrolysis pretreatment of Sargassum Horneri with the dilute sulfuric acid was deeply studied. Besides, based on the optimized condition acquired from the process of the pretreatment, NSSF (Nonisothermal simultaneous saccharification and fermentation) applied in the bioethanol preparation from Sargassum Horneri was studied systematically. The results are shown as follows:(1)The cellulose content of Sargassum Horneri is close to the land lignocellulosic, and it is suitable to prepare bio-ethanol due to lower lignin contained. The model compound which was constructed in accordance with the content of cellulose, hemicellulose and lignin, could reflect its preparation laws to a certain extent.(2)The effect of the pretreatment with dilute sulfuric acid on the yield of sugar levels obeys the following deseending order:sulfuric acid concentration, hydrolysis temperature, hydrolysis time, liquid to solid ratio. The optimum pretreatment conditions presented as follows:the concentration of sulfuric acid is4%, the hydrolysis temperature is120℃, the hydrolysis time is2.0h, the liquid to solid ratio is20mL:g. Under this condition, the yield of reducing sugar is22.1%, the hydrolysation rate of cellulose and hemicellulose is18%and83%, respectively. And the lignin can hardly be hydrolyzed. During this process pretreated by dilute sulfuric acid combined with hydrolysised by collulase, the yield of ethanol fermentated from the samples could reach0.068g/g DW, which is much higher than the value of0.013g/g DW obtained from the single pretreatment of dilute sulfuric acid and0.033g/g DW form the pretreatment of hydrolysis by the collulase.(3)The NSSF offers a solution to solve the temperature problem of fermentation and hydrolysis. The results showed that the influence degree decreased as follows:the temperature of fermentation, the cellulase hydrolysis time, the fermentation time. The optimum condition is that the fermentation temperature of36℃, the cellulase hydrolysis time of3h, the cellulase dosage of25IU/g, the fermentation time of5d. And the yield of ethanol can achieve0.078g/g DW under this condition.(4)During the fermentation process, acetic acid played a role as the main inhibitor. And the research of production kinetics of acetic acid and ethanol indicated that they matched well with Boltzmann model.(5)A11the results indicated that the technology of comprehensive utilization of preparatation from Sargassum Horneriat and the by-product is feasible.