酶解木质素吸附脱除糠醛和5-羟甲基糠醛等发酵抑制物的研究

Removal of Furfural and 5-Hydroxymethylfurfural using Enzymatic Hydrolysis Lignin

摘要:

木质纤维素通过酶解发酵转变成燃料乙醇的过程中，酸法预处理法具有成本低、可发酵糖得率高等优点，但其预处理液中不仅含有糖份，还含有糠醛（Furfural）和5-羟甲基糠醛（5-HMF）等发酵抑制物。将木质纤维素燃料乙醇过程残留的酶解木质素（EHL）用作吸附剂，系统研究了吸附时间、固液比、pH等因素对糠醛和5-羟甲基糠醛在酶解木质素上吸附的影响规律，测定吸附等温线，并对其吸附热力学进行分析，最后研究了酶解木质素对两种酸法预处理液中的糠醛和5-羟甲基糠醛的吸附脱除效果。结果发现酶解木质素对糠醛和5-羟甲基糠醛都具有较好的吸附脱除能力；吸附过程均符合Freundlich模型，为放热过程；对糠醛吸附能力强于对5-羟甲基糠醛的吸附。结果表明，将酶解木质素用于吸附脱除酸法预处理液中的糠醛和5-羟甲基糠醛是可行的。

Abstract:

Because of low cost and high yield of fermentable sugars, acid-based pretreatment methods have been proven to be efficient in conversion of lignocelluloses to fuel ethanol by microbial fermentation. However, some of the byproducts including furfural and 5-hydroxymethyl furfural（5-HMF) in the acidic prehydrolysates were the inhibitors in the fermentation process. Meanwhile, large amounts of enzymatic hydrolysis lignin (EHL) residue were produced as another byproduct. To explore the application of this lignin residue for detoxification of acidic prehydrolysates, EHL was applied to decrease the concentration of furfural and 5-HMF through adsorption. The effects of contact time, lignin dose, pH on the adsorption of furfural and 5-HMF on EHL and adsorption isotherms were investigated. EHL was used to remove furfural and 5-HMF in two acidic prehydrolysates of corn stover. The results showed that the adsorption was a spontaneous exothermic process, and good fit was obtained by Freundlich model. Furfural was easier to be removed than 5-HMF through adsorption by EHL. The results indicated EHL could be the adsorbent to remove furfural and 5-HMF in acidic prehydrolysates.