摘要
在木质纤维素的生物降解和转化过程中,木质纤维素的复杂结构和木质素组分限制了碳水化合物的高效酶水解。过氧化氢预处理可以通过破坏木质纤维素的物理化学结构并氧化降解部分木质素,从而改善原料的酶水解效率。过氧化氢预处理主要有过氧化氢-酸、过氧化氢-碱、活化过氧化氢这3类预处理方法。笔者主要归纳了不同预处理过程中的木质素降解机理,总结了过氧化氢预处理强化木质纤维原料酶水解的效果,探讨了预处理对木质纤维原料降解产物的影响,评价了各类过氧化氢预处理的可行性和优缺点。最后,根据过氧化氢预处理的特点分析了过氧化氢预处理的研究策略,展望了过氧化氢预处理的发展趋势。从安全性和经济可行性的角度来看,低试剂用量、低温和低压的预处理条件是未来过氧化氢预处理的主要研究方向。
In the process of biomass conversion,the intricate structure and the presence of lignin in lignocelluloses hinder the saccharification of carbohydrate components through enzymatic hydrolysis.Pretreatment can remove lignin and destroy the physical and chemical structures of lignocelluloses,thus achieving efficient conversion of biomass to monosaccharide.Hydrogen peroxide is widely used in the pretreatment of lignocelluloses because of its strong oxidative degradation ability to lignin.Hydrogen peroxide pretreatment methods mainly consist of hydrogen peroxide-acid,hydrogen peroxide-alkali,and hydrogen peroxide-activator pretreatments.This review summarized the mechanism of lignin degradation in these hydrogen peroxide pretreatments.In acidic media,hydrogen peroxide acts as an electrophilic reagent by forming hydronium ion.The aromatic hydroxylation of hydronium ion by substitution/addition reaction is the main reaction for degradation of lignin in acidic media of hydrogen peroxide.In alkaline medium,some active reaction substances(hydrogen peroxide anion,hydroxyl group radical,and superoxide anion radical)are formed by the decomposition of hydrogen peroxide.The alkene and carbonyl groups of the side chain of lignin can be attacked by those active reaction substances with a nucleophilic reaction.In hydrogen peroxide-activator systems,hydrogen peroxide can be activated by transition metal ions to enhance the oxidation ability of the hydrogen peroxide for the lignin degradation.The improvements of enzymatic hydrolysis of lignocelluloses through hydrogen peroxide pretreatments were summarized.In the hydrogen peroxide pretreatment,hydrogen peroxide-acid pretreatment shows the strongest lignin removal ability and the higher improvement on the enzymatic hydrolysis of lignocelluloses.The main lignin degradation products in hydrogen peroxide pretreatment were organic carboxylic acids and phenolic compounds.The advantages and disadvantages of various hydrogen peroxide pretreatments were compared.The feasibility of various hydrogen peroxide pretreatment methods was evaluated by economic analysis.Hydrogen peroxide-alkali pretreatment shows the lowest economic cost in those three hydrogen peroxide pretreatment methods.Gramineous plants are suitable for hydrogen peroxide-alkali pretreatment and wood materials are suitable for the hydrogen peroxide-acid pretreatment.Finally,the development trend of hydrogen peroxide pretreatment was predicted and prospected based on the characteristics of these pretreatment methods.The decomposition of hydrogen peroxide,the design of reaction equipment,the safety of pretreatment systems,and the utilization of degradation products of lignocelluloses are the main research directions of hydrogen peroxide pretreatment in the future.In conclusion,hydrogen peroxide pretreatments with low reagent dose,low temperature,and low system pressure were the main research direction of hydrogen peroxide pretreatment in the future.The objective of this work was to comprehensively review various hydrogen peroxide pretreatment methods and offer insights into potential research directions in the field of hydrogen peroxide pretreatment.
作者
张军华
文沛瑶
林子贺
应文俊
ZHANG Junhua;WEN Peiyao;LIN Zihe;YING Wenjun(College of Chemical Engineering,Nanjing Forestry University,Nanjing 210037,China)
出处
《林业工程学报》
CSCD
北大核心
2024年第2期1-13,共13页
Journal of Forestry Engineering
基金
国家自然科学基金(32171731)
南京林业大学科研启动基金(GXL2018036)。
关键词
过氧化氢预处理
木质素氧化
降解产物
经济分析
研究策略
hydrogen peroxide pretreatment
oxidation of lignin
degradation product
economic analysis
research strategy
