Hydrolysis Of Lignocellulose By Combination Of Ball Milling, Dilute Citric Acid, Fungus Penicillium Simplicissimum And Ultrasonic Treatment At Room Temperature

The conflicts between the increasing dependence on fossil fue ls in the industryand the limitio n of fossil resource impact serious ly on the country’s energy security.Converting bio mass to biofue l can significantly reduce the country’s dependence oncrude oil imports, enhance nationa l security. Therefore, the use of lignocellulosic toproduce fue l etha nol in China has important economic and socia l significance.The lignocellulose resources in China is very ric h, but the utilization is very low,mostly in d irect use as a fue l, not only wasting resources and pollut ing theenvironme nt serious ly. So the develop ment of using lignocellulose to product fue lethano l in China has broad prospects and important practica l significance. In thisthesis, in order to investigate the degradation process of natura l lignocellulose, wheatstraw and birch wood chips were chosen to be as representive raw materia ls ofherbaceous and woody plants.In order to investigate the effect on the degradatio n of the natura l lignocellulos icsubstrates (wheat straw and birc h wood chips) with the phys ical degradation method(ball milling and ultrasonic treatme nt), chemica l acid hydro lys is method, bio logica ldegradatio n method, and the synergy between these three methods, the wheat strawand birch wood chips were hydrolyzed by wet ball milling, d ilute c itric ac id,Penicillium simplicissimum H5and ultrasonic treatme nt. Exp lore the feas ib ility o fdegradatio n of natura l lignocellulos ic substrates (wheat straw and birch wood chips)under norma l temperature and pressure. It is expected that there is a simp le, andenvironme nta lly friend ly approach for hydrolyzing wheat straw and birc h wood chipsto sugar. Firstly, the wheat straw and birch wood chips were hydrolyzed by thecomb ination o f wet ball milling and d ilute c itric acid, to research the e ffect of the pHvalue on the hydrolys is of wheat straw and birc h wood chips. Secondly, Penicilliumsimplicissimum H5was used to improve the hydro lys is, us ing its enzyme productioncharacteristics. The wheat straw and birch wood chips were hydrolyzed by thecomb ination of wet ball milling, dilute citric acid and Penicillium simplicissimum H5,to research the effect of the Penicillium simplicissimum H5on the hydro lys is of wheatstraw and birch wood chips. At last, the ultrasound was introduced into the reactionsystem. The birch wood chips was pretreated by ultrasonic treatment, the n werehydro lyzed by the comb inatio n of wet ball milling, dilute c itric acid and Penicillium simplicissimum H5, to research the effect o f ultrasonic treatment a nd the pH va lue onthe hydro lys is of wheat straw and birch wood chips.In the first p lace, the wheat straw and birch wood chips can be hydro lyzed by thecomb ination of wet ball milling and dilute c itric acid, under norma l te mperature andpressure.(1) The sugar production of wheat straw and brich wood were186.9mg/gand120.5mg/g.(2) The addition o f commerc ia l cellulase can not form a goodsynergy with the wet ball milling-dilute c itric acid treatme nt. The sugar productionwas even lower than s ingle the wet ball milling-dilute citric ac id treatment withoutce llulase.(3) Ball milling with dilute ac id treatme nt exerted significant differentinflue nce on the different hydro lysates. The yie ld of glucose increased with extend ingball milling time in the hydrolys is of wheat straw and wood chip s, otherwise the yie ldof xylose decreased with exte nd ing ball milling time. The hydrolys is of wood can alsobe influe nced by the pH va lue of d ilute acid. The sugar production in c itrate solve nt(pH=5,6) were higher tha n in c itrate solvent (pH=3,4).(4) With the extend ing ballmilling time, the pH va lue of wheat straw and wood chips’ hydrolyzate offset to thealkaline direction and reach equilibrium after24hours. Finally rema ined substantia llywithin the neutral ra nge.(5) As was shown in the XRD a nd ESEM pattern, ballmilling disrupted the long-range crystalline structure of cellulose. It made wheatstraw and wood chips more accessib le to citrate, which enab ling convers ion ofcarbohydrate polymers into sugar.(6) The FT-IR and UV spectroscopy ind icated thatthe ball milling treatme nt in citrate solvent present a dramatic increase in ligninhydro lys is. As the connection between the lignin and carbohydrates serious ly impededto the hydro lys is of lignocellulos ic, the degradation of lignin make cellulasehydro lyzed more easily and reach higher sugar production. Compared with trad itiona lindustria l high-temperature and high-pressure acid hydrolys is, the comb ination of wetball milling and dilute citric acid treatment can hydrolyze natura l lignocellulose undernorma l te mperature and pressure. Although the saccharification is not high, thereactio n is mild and basica lly non-polluting.Secondly, the hydrolyzation of wheat straw and birc h wood chips can besignifica ntly promoted by the comb inatio n of wet ball milling,dilute citric acid andPenicillium simplicissimum H5, under norma l te mperature and pressure and reachhigher sugar yie ld.(1) The sugar production o f wheat straw and brich wood were216.9mg/g and245.3mg/g. The addition of Penicillium simplicissimum H5couldsignifica ntly pro mote the hydrolys is o f wheat straw and wood chips.(2) The add itionof Penicillium simplicissimum H5can form a good synergy with the wet ball milling and dilute citric acid treatment. The enzyme activity and surviva l of fungi ma inta in24hours under ball milling treatment.(3) Ball milling-dilute acid-fungi treatme ntexerted significant different influe nce on the differe nt hydro lysates. The yie ld ofglucose increased with extend ing ball milling time in the hydrolys is of wheat strawand wood chips, otherwise the yie ld of xylose decreased with e xtend ing ball millingtime. The hydro lys is of wood can also be influenced by the addition of Penicilliumsimplicissimum H5. The sugar production in citrate solve nt (pH=4,5) were higher tha nin citrate solvent (pH=3,6).(4) With the extend ing ball milling time, the pH va lue ofwheat straw and wood chips’ hydrolyzate offset to the alka line d irection a nd reachequilibrium a fter24hours. The pH va lue o f t he best degradatio n syste m o f straw andwood chips were6.5and7.5after ba ll milling48hours.(5) As was shown in the XRDand ESEM pattern, ball milling-dilute acid-fungi treatment disrupted the lo ng-rangecrystalline structure of cellulose. At milling short time, the degree of crysta llinity ofthe straw and wood chips improved, as the addition of Penicillium simplicissimum H5decomposed amorphous cellulose for priority. With the extending ball milling time,the crystallinity decreased. It made wheat straw and wood chips more accessib le tocitrate, whic h enabling convers ion of carbohydrate polymers into sugar.(6) The FT-IRand UV spectroscopy ind icated that the ba ll milling treatme nt in c itrate solve ntpresent a dramatic increase in lignin hydrolysis. The addition o f Penicilliumsimplicissimum H5Promoted the degradatio n of lignin in the wheat straw and woodchips.As the connection between the lignin and carbohydrates serious ly impeded tothe hydrolys is of lignocellulosic, the degradatio n of lignin make cellulase hydrolyzedmore easily a nd reach higher sugar production. Overall the additio n of Penicilliumsimplicissimum H5Significant promoted the degradatio n of ce llulose and lignin o fwheat straw and wood chips, reach higher saccharification. The reactio n is mild andbasica lly non-po lluting, low cost with microbia l and ease for ind ustrialization.Fina lly, birch wood chips was pretreated by ultrasonic treatment, then werehydro lyzed by the comb ination of wet ball milling, dilute c itric acid and Penicilliumsimplicissimum H5, and the hydrolyzation can be significa ntly promoted by thepretreatment of ultrasonic wave, and reach higher sugar yie ld.(1)The sugarproductio n of wood chips was126.84mg/g with the ultrasonic pretreatme nt.(2) Theadditio n of ultrasonic pretreatment could s ignificantly promote the hydrolys is ofwood chips, and reach higher saccharification rate. The sugar production of woodchips was311.16mg/g wood at ball milling for36hours, compared with245.3mg/gwood at ball milling for48hours obtained without the ultrasonic pretreatme nt.(3) Ultrasonic pretreatment could promote the d issolution o f both glucose and xylose.(4)After pretreated by the ultrasonic wave, with the extend ing ball milling time, the pHvalue of wood chips’ hydro lyzate offset to the alka line direction and reachequilibrium after12hours. The pH va lue of the best degradatio n system of woodchips were7.0after ball milling48hours.(5) As was shown in the XRD and ESEMpattern, ball milling-dilute acid-fungi treatment disrupted the long-range crystallinestructure of cellulose. The ultrasonic pretreatment s lightly decreased the degree ofcrystallinity of wood chips. At milling short time, the degree of crystallinity of thewood chips improved, with the addition of ultrasonic pretreatme nt. With theextend ing ball milling time, the crysta llinity decreased. It made wood chips moreaccessib le to citrate, which enabling convers ion of carbohydrate polymers into sugar.(6) The FT-IR and UV spectroscopy indicated that the ball milling treatment in citratesolve nt with H5present a dramatic increase in lignin hydrolys is. The additio n ofultrasonic pretreatment promoted the degradation of lignin in the wood chips. As theconnectio n between the lignin and carbohydrates serious ly impeded to the hydrolys isof lignocellulosic, the degradatio n of lignin make cellulase hydrolyzed more easilyand reach higher sugar production. Overall the additio n of ultrasonic pretreatme ntsignifica nt promoted the degradation of ce llulose and lignin of wood chips, reachhigher saccharification. The reactio n is mild and basically no n-polluting, low costwith microbia l and ease for industria lization.In summary, in this thes is the natura l lignocellulose wheat straw and birchwood chips were hydrolyzed by the comb ination o f wet ball milling, dilute c itric acid,Penicillium simplicissimum H5and ultrasonic treatment, reach high saccharificationrate. The reactio n is mild and basically non-polluting, low cost with microbia l andease for industria lization, and provides a clean, effic ient and new way for conversio nof bio mass into ethano l.