Studies On The Pretreatment Of Sugarcane Bagasse By Fenton Reaction Combined With Sodium Hydroxide Extraction

With the gradual exhaustion of the fossil fuels like coal,petroleum and natural gas on the earth,people had to find alternative energy.There was a massive amount of lignocellulose on the earth,from which bioethanol could be produced.Sugarcane bagasse(SCB)was an important kind of lignocellulosic resource.However,due to its compact structure which made it very hard to be degraded,pretreatment was required.Pretreatment could interrupt the surface structure of SCB,partially degraded the hemicellulose and lignin to some extent,so that the embedded cellulose could expose to the outside,thus the SCB became very easy to be degraded.In recent years,using Fenton reaction to pretreat lignocellulose had attracted the attention of researchers because of its low cost and mild pretreatment conditions as well as green and eco-friendly.Fenton reaction worked by generation of radicals like hydroxyl radicals and oxygen radicals to oxidize lignocellulose from the reaction of ferrous ions and hydrogen peroxide.As a result,the surface structure was interrupted,most lignin was removed,therefore,the embedded cellulose was completely exposed to cellulase in the surroundings to make it easily enzymatically hydrolyzed.Here,the feasibility of Fenton reaction combined with NaOH extraction to pretreat SCB had been explored.The pretreatment performance was evaluated by the biological methods such as enzymatical hydrolysis and simultaneous saccharification and co-fermentation(SScF).Besides,a series of physical methods such as scanning electronic microscope(SEM),X-ray diffraction(XRD)and chemical component analysis had been introduced to further investigate the pretreatment mechanism.Moreover,performance of simultaneous saccharification and co-fermentation(SScF)under high solid loading had been investigated.Finally,fed-batch SScF had been fully studied to further enhance the ethanol concentration.Fenton’s reagents,pretreatment pH,temperature and time had been optimized as 10%(w/w)of H2O2,20 mM of Fe2+,pH 2.5,pretreatment time 6 h,and pretreatment temperature55℃.Fenton pretreatment followed by NaOH extraction under the optimized conditions had the highest efficiency of 64.7% and 108.3% for enzymatical hydrolysis and simultaneoussaccharification co-fermentation(SSc F).The surface structure of pretreated SCB was significantly interrupted and the lignin removal rate reached 59.8% as well as the crystallinity index(CrI)was significantly enhanced to 55.9% from 33.7%.The SScF performance with different feeding modes under high solid loadings of10%(w/v),14%(w/v),20%(w/v)and 30%(w/v)were compared.Besides,pre-saccharification SSCF was also investigated.The results showed that enzyme feeding or substrate feeding and pre-saccharification could not enhance the final ethanol concentration compared with the batch mode in the SSCF.Under the high solid loading of 30%(w/v),ethanol concentrations of above 80 g/L were both obtained in the batch mode and enzyme feeding mode which suggested that the pretreated SCB got an excellent fermentation performance.Compared with the other control groups,the enzyme feeding mode exhibited a more prominent fermentation performance with a final ethanol concentration and productivity of 84.04 g/L and 1.23 g/L/h,respectively.The enzyme feeding mode was further found to decrease the enzyme loading by40%,with a final enyzme loading of 9 FPU/g SCB.