(86b) Extraction of Carboxylic Acid from Aqueous Solution By Strong Hydrogen Bond Basicity Ionic Liquids

Extraction of carboxylic acid
from aqueous solution by strong hydrogen bond basicity ionic liquids

Yinge
Bai^1,2, Ruiyi Yan¹, Jianguo Qian^1,2, Xiangping
Zhang¹*, Suojiang Zhang¹*

¹Beijing Key Laboratory of Ionic
Liquids Clean Process, State Key Laboratory of Multiphase Complex Systems, Key
Laboratory of Green Process and Engineering, Institute of Process Engineering,
Chinese Academy of Sciences, 100190, Beijing, P. R. China

²School of Chemistry and Chemical
Engineering, University of Chinese Academy of Sciences, 100190, Beijing, P. R. China

*corresponding author: xpzhang@ipe.ac.cn (X. Zhang), sjzhang@ipe.ac.cn (S. Zhang)

Carboxylic acids are important raw material for food,
chemical and pharmaceutical industries [1].
The recovery of carboxylic acids from dilute aqueous solutions (< 10 wt%) is
commonly encountered in petrochemical process and fermentation processes [2, 3]. For the liquid-liquid extraction, which
is the commonly method used to separate carboxylic acid from aqueous solutions,
the core task is to attain a green and highly
efficient extractant. In this work, methacrylic acid (MAA) was employed as a model
carboxylic acid. MAA in dilute aqueous solution (1 wt%) was recovered by
quaternary ammonium salt ionic liquids (ILs) with strong hydrogen bond basicity
(HBB). The partition coefficients of MAA were used to evaluate the extraction
ability of ILs (Fig. 1). The extraction parameters such as extraction time,
extraction temperature, concentrations of MAA in feed solution, concentration
of IL were studied (Fig. 2). An internal mechanism of the extraction of MAA by
ILs was revealed by combining solvatochromic study and quantum chemical
calculations (Fig. 3). The results show that the ILs with strong hydrogen bond
basicity has the high partition coefficient of MAA, which provides guidance for
ILs molecular design to attain the high efficient extractive separation of
carboxylic acids from dilute aqueous solution.

Figure 1. The partition
coefficients of MAA between IL phase and water phase (Columns); the hydrogen
bond basicity of [A336]TFA, [A336]Oxa, [A336]Suc and [A336]TCA (Line).

Figure 2. the partition
coefficients of MAA for [A336]TCA at different concentration of MAA feed
solution.

Figure 3. optimized structure of Suc-MAA
complex at B3LYP/6-31++G(d,p) level.

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Waghmare, K.L. Wasewar, S.S. Sonawane, et al, Separation and Purification
Technology, 120 (2013) 296-303.

[2] H.
Uslu, D. Datta, H.S. Bamufleh, Industrial & Engineering Chemistry Research,
55 (2016) 3659-3667.

[3] A.
Bekatorou, A. Dima, P. Tsafrakidou, et al, Bioresource technology, 220 (2016)
34-37.