Screening of hydrogen bond acceptor for the synthesis of low transition temperature mixtures with malic acid

Abstract

Biomass exploitation emerges to be the most probable and practical alternative in solving the global depletion of fossil fuels. Nevertheless, the components in lignocellulosic biomass are assembled in a complex three-dimensional structure which leads to difficulty in hydrolyzation and resistance against chemicals. In this context, low transition temperature mixtures (LTTMs) tend to be the promising green solvents to delignify lignocellulosic biomass. This research focused on customizing the physicochemical behaviour of LTTMs by a prudent selection of hydrogen bond acceptor (HBA) in which malic acid is used as the hydrogen bond donor (HBD). LTTMs with carbohydrates as HBA could be formed in the temperature range of 60 to 100 o C. On the other hand, LTTMs with organic and inorganic salts as HBA could only be formed in the temperature range of 100 to 180 o C. Besides, no crystallization of starting materials was observed for LTTMs prepared from carbohydrates when they are cooled to room temperature. This phenomenon was due to the hydrogen bonding and van der Waals interactions formed between the starting materials. Based on Fourier transform infrared spectroscopy (FTIR) analysis, the representative peak of carboxylic acid group of malic acid turned broader. The peaks involved in the H-bonding as a result of the formation of LTTMs shifted and became broader by the combination of malic acid and carbohydrates. Keywords: hydrogen bond acceptor, hydrogen bond donor, low transition temperature mixtures (LTTMs), Fourier transform infrared spectroscopy, hydrogen bond.

Natural deep eutectic solvents pretreatment as an aid for pectin extraction from apple pomace

“…Moreover, consistent with other reports (Fisher & Kunz, 2014;Hou et al, 2008)), the three NADES were non-Newtonian with a shear-thinning behavior (data not shown Similarly, the highest pectin yield was attained from pomelo peels with NADES (Choline chloride : glucose : water; 5:2:5) at 60 °C for 2h (Elgharbawy et al, 2019). The disparity from our result may lie in different water content in NADES extraction system (water : NADES=8.5% (v/v), considering 68% of water content in raw pomace), as it affected the extraction ability of DES (Passos, Tavares, Ferreira, Freire, & Coutinho, 2016;Yiin, Yusup, Quitain, & Uemura, 2015). In contrast, the yield of the water fraction after CC:LA pretreatment was at least 6 times higher than that of corresponding NADES fraction.…”

Low Transition Temperature Mixtures (LTTM) Containing Sugars as Potato Starch Plasticizers

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