Enhancing Effect Of Long-chain Fatty Alcohols And Lignosulfonate On The Enzymatic Hydrolysis Of Cellulose And The Application

With the increasing demand for energy sources and the exhaustion of fossil fuels, theworld is facing with a serious energy source crisis. Producing biofuel and chemicals fromlignocelluloses by enzymatic hydrolysis and fermentation is considered as one of the effectiveways to relieve the crisis. Currently, the production of cellulosic biofuel is not commercialviable because of the high cost and slow rate of enzymatic hydrolysis of cellulose, which is akey step for conversion of lignocellulosic biomass to biofuel or chemicals.The enhancing effects of long-chain fatty alcohols (LFAs) on the enzymatic hydrolysis ofcellulose by two commercial Trichoderma reesi cellulase cocktails (CTec2and Celluclast1.5L) were studied. The results showed that n-Octanol, n-Decanol and n-Dodecanol hadstrong enhancement on enzymatic hydrolysis of crystalline cellulose in the buffer pH rangefrom4.0to6.0and the buffer ionic strength range from25mM to100mM, which couldincrease the substrate enzymatic digestibility (SED) of cellulosic substrates by6.6%~16.0%.LFAs have similar enhancement on the enzymatic hydrolysis of crystalline cellulose mixedwith lignin or xylan. Meanwhile, LFAs could improve the enzymatic hydrolysis of amorphouscellulose and cellobiose to glucose. LFAs not only could enhance the amorphogenesis, butalso could improve the enzyme activity of cellulases.The effect of the mixtures of anionic polymer surfactants and non-ionic surfactants on theenzymatic hydrolysis of cellulose was also investigated. It was found that the mixtures of SL3,SL4and LFAs had more significant enhancing effect on the enzymatic hydrolysis of cellulose,but there was no synergism between SL2and LFAs on the enzymatic hydrolysis of cellulose.Meanwhile, SL1inhibited the enzymatic hydrolysis of cellulose, and the additions of LFAscould reduce the negative effect. In addition, SL2and non-ionic surfactants also showedsignificant synergism on the enzymatic hydrolysis of cellulose.Recycling of the dilute acid pretreatment hydrolysate (DAL) by the addition of sodiumlignosulfonate was studied. It was found that DAL inhibited the enzymatic hydrolysis of purecellulose and lignocellulose. And the addition of sodium lignosulfonate could reduce theinhibition. By adding5.0g/L sodium lignosulfonate, the SED of microcrystalline cellulose and lignocellulose with DAL at72h increased by19.9%and28.2%, respectively. The recycleof DAL could reduce the loss of carbohydrates in the pretreatment hydrosate, and alsoreduced the consumption of water during the enzymatic hydrolysis process.