Advances on lignocellulose pretreatment by choline chloride-based deep eutectic solvents
To achieve the goal of carbon neutrality,utilization of renewable resources and energies has gained world-wide interest.In this contest,the abundant,cheap and renewable lignocellulosic biomass has great potential to be an alternative to fossil resources for producing valuable chemicals and functional materials because the utilization of ligno-cellulosic biomass has shown the unique"net-zero carbon emission"nature,thus making its utilization become a hots-pot in chemical community.However,the natural resistance to degradation of lignocellulosic biomass seriously restricts its effective utilization.Therefore,it is essential to break the natural anti-degradation barrier of lignocellulose by pretreatment to achieve better utilization of lignocellulose.To date,various strategies have been developed to pre-treat lignocellulose,including physical methods(e.g.,grinding),chemical methods(e.g.,alkalis,acids,organic solvents,ionic liquids,deep eutectic solvents and enzymatic hydrolysis),and the combination of both physical and chemical methods(e.g.,wet oxidation and hydrothermal cracking).Of these developed strategies,pretreatment of lignocellulosic biomass using deep eutectic solvents(DESs,a newly developed functional green solvents)is consi-dered as an emerging technology,which has shown good applications in the pretreatment of lignocellulosic biomass.This study discussed the progress on the pretreatment of lignocellulosic biomass using choline chloride(ChCI)-based DESs in recent years.The correlation between the pretreatment performance and the physical and chemical properties(i.e.,density,viscosity,ionic conductivity and polarity)of the ChCl-based DESs was reviewed.Moreover,the ap-plications of ChCl-based DESs with various carboxylic acids,alcohols,aminos or amides as hydrogen bond donors in lignocellulosic biomass treatment were systematically analyzed and discussed.Especially,the influence of various pa-rameters,i.e.,pretreatment temperature,pretreatment time,the structure of hydrogen bond donors and its molar ratio with ChCl,and solid-to-liquid ratio,on the pretreatment performance were discussed in detail.Additionally,the per-formance of combining ChCl-based DESs and other auxiliary technologies(i.e.,microwave,ultrasonic sound,addi-tives,hydrothermal,extrusion,and bio-pretreatment)on biomass pretreatment,the techniques(i.e.,anti-solvents,extraction,and membrane filtration)for the recovery of ChCl-based DESs,and the regeneration of lignocellulose components from the pretreatment systems were reported.Finally,an outlook was provided to highlight the challenges and opportunities associated with the pretreatment of lignocellulosic biomass by utilizing DESs,and several key prob-lems to be addressed in future works were discussed based on the authors'knowledge.According to the discussions in this review,it is no doubt that the utilization of DESs as the efficient solvents for the pretreatment of lignocellulosic biomass is highly promising.We believe that this review could provide useful information for the readers working in this interesting and important area.
deep eutectic solventbiomass pretreatmentlignocelluloselignincholine chloride
国家科技期刊平台
NSTL
万方数据
维普
