Challenges and opportunities in improving the production of bio-ethanol

Recent developments in pretreatment technologies on lignocellulosic biomass: Effect of key parameters, technological improvements, and challenges.

Enhancing cellulose accessibility of corn stover by deep eutectic solvent pretreatment for butanol fermentation.

The objective of this work is to provide update information about the recent progress on lignocellulose hydrogen conversion via dark fermentation. Therefore, in this review, the most important fields associated with lignocellulosic hydrogen fermentation are covered, firstly describing the problems associated with raw materials, followed by the discussion of pretreatment and hydrolysis methods assisting to achieve efficient hydrogen fermentation. Afterwards, issues related to fermentation inhibitors as well as advanced, integrated bioprocesses for hydrogen production purposes will be presented. Additionally, the paper gives future perspectives of lignocellulose biohydrogen.

Lignocellulose biohydrogen: Practical challenges and recent progress

The development and production of fossil fuel alternatives have become one of the main focal points in recent investigations. Lignocellulosic biomass is a renewable source of fermentable sugars for second-generation biofuels and chemicals via biotechnological pathways. However, the presence of lignin and hemicellulose in lignocellulosic biomass makes it difficult for the biomass to be hydrolyzed or digested during fermentation. Thus, effective biomass pretreatment is vital. The present review shows that chemical pretreatment is the current preferred method to obtain high sugar yields at low cost, with dilute acid and alkaline hydrolysis as the two most reported technologies. Dilute acid favours hydrolysis of the hemicelluloses whereas alkaline hydrolysis targets the lignin fraction. Both methods have merits and demerits, and have been combined with other treatments such as hydrothermal and enzymatic hydrolysis. Further investigation is required to improve the pretreatment processes and to ensure the economic viability of bioconversion.

Typical conversion of lignocellulosic biomass into reducing sugars using dilute acid hydrolysis and alkaline pretreatment

Bioconversion of biomass waste into high value chemicals.

In this study, mixed softwoods were pretreated with an ionic liquid, 1-butyl-3-methylimidazolium chloride ([Bmim]Cl), and the bioconversion efficiencies to fermentable sugars were estimated through the enzymatic hydrolysis. The cellulose crystallinity, surface morphology, structures and compositions of softwood were significantly changed after the ionic liquid pretreatment was carried out under a wide range of temperatures and reaction times. And, biomass digestibility significantly increased with increasing pretreatment temperature and reaction time. The enzymatic degradation of pretreated softwoods was remarkably improved at the pretreatment of high temperatures via the modification of crystalline cellulose I to a mixture of easily digestable cellulose II and amorphous structure, and partial removal of hemicellulose. The conversion of cellulose to glucose reached more than 90% at relevant conditions and the highest glucose yield was measured to about 78%. Through the study, it was clearly shown that ionic liquid pretreatment is one of the effective methods to produce high fermentable sugars without lignin dissolution from lignocellulosic biomass.

Ly Thi Phi Trinh

Papers

Bioconversion of biomass waste into high value chemicals.

Characterization of ionic liquid pretreatment and the bioconversion of pretreated mixed softwood biomass

Development of an integrated process to produce d-mannose and bioethanol from coffee residue waste.

Improvement of the fermentability of oxalic acid hydrolysates by detoxification using electrodialysis and adsorption

Aqueous acidified ionic liquid pretreatment for bioethanol production and concentration of produced ethanol by pervaporation