Development of choline-based deep eutectic solvents for efficient concentrating of hemicelluloses in oil palm empty fruit bunches

Efficient Separation of Poplar Lignin Using a New Carboxylic Acid-Based Deep Eutectic Solvents - Choline Chloride/Malonic Acid

Separation of lignin by pretreatment is an important step in biomass refining. This study investigated how a novel dicarboxylic acid-based deep eutectic solvent (DES) - choline chloride (ChCl)/malonic acid (MA) - affected the process of separating lignin from poplar. At 140 °C for 3.0 h, with a ChCl: MA molar ratio of 1: 3.5, the ideal pretreatment conditions were met, and 91.8 % lignin was obtained. Even after five DES reuses, the consistent and effective separation efficiency of 77.9 % remains unchanged. The hydrolysate contained 92.4 % of the recovered lignin, with a purity of 94.6 %. Moreover, the regenerated lignin obtained through the new DES pretreatment exhibited a high phenolic hydroxyl content of 1.9 mmol g-1 and a low polydispersity index of 1.4. The results showed efficient and selective separation of lignin using the new binary carboxylic acid-based DES pretreatment was achieved. This research offers a novel approach to effectively separate wood fiber biomass and extract valuable lignin.

Deep eutectic solvents microbial toxicity: Current state of art and critical evaluation of testing methods

Deep eutectic solvents (DESs) were described at the beginning of 21st century and they consist of a mixture of two or more solid components, which gives rise to a lower melting point compared to the starting materials. Over the years, DESs have proved to be a promising alternative to traditional organic solvents and ionic liquids (ILs) due to their low volatility, low inflammability, easy preparation, and usually low cost of compounds used in their preparation. All these properties encouraged researchers to use them in diverse fields and applications e.g., as extractants for biomolecules and solvents in pharmaceutical and cosmetic industries. Nevertheless, despite undeniable potential of DESs, there is still controversy about their toxicity. Besides the low number of studies on this topic, there are also some contradicting reports on biocompatibility of these solvents. Such misleading reports could be mainly attributed to the lack of well design standard protocol for DESs toxicity determination or the use of out-off-purpose methodology. Thus, to better apply DESs in green and sustainable chemistry, more studies on their impact on organisms at different trophic levels and the use of proper techniques are required. This review focuses on DESs toxicity towards microorganisms and is divided into three parts: The first part provides a brief general introduction to DESs, the second part discusses the methodologies used for assessment of DESs microbial toxicity and the obtained results, and finally in the third part the critical evaluation of the methods is provided, as well as suggestions and guidelines for future research.

Key process parameters for deep eutectic solvents pretreatment of lignocellulosic biomass materials: A review

Deep eutectic solvent (DES) has been considered as a novel green solvent for lignocellulosic biomass pretreatment. The efficiency of DES pretreatment is affected by the synergy of various process parameters. The study of effect of DES physicochemical properties and pretreatment reaction conditions on the mechanism of lignocellulose biomass fractionation was of great significance for the development of biomass conversion. Form the view of process control, this review summarized recent advances in DES pretreatment, analyzed the challenges, and prospected the future development of this research field.