PH and electrical conductivity measurements of aqueous solutions of amino acid-based ionic

Nur Khairunnisa Talib,Omar Nashed,Ouahid Ben Ghanem,Bhajan Lal,A Nzihou,D.C.W Tsang,B Abdullah,M Nasef,R Boopathy,S Yusup,N.A Amran

doi:10.1051/e3sconf/202128702018

Abstract

Ionic liquids are promising materials for several applications. Amino acid based ionic liquids (AAILs) as a sort of a new generation of ionic liquids are recently proposed taking advantage of hydrogen bonding group and low toxicity. Three types of AAILs are examined in this work; namely 1-Octyl-3-Methylimidazolium Glycine [OMIM][Gly], 1-Octyl-3-Methylimidazolium Alanine [OMIM][Ala] and 1-Octyl-3-Methylimidazolium Proline [OMIM][Pro]. The pH and molar conductivity are measured at ambient conditions for AAILs aqueous solutions at different concentrations; specifically 1, 10, 20, and 30 wt.%. The experimental results show that all AAILs solutions are alkaline (pH>7) where [OMIM][Pro] has the highest pH compared to its counterparts. The trend is reversed for molar conductivity as [OMIM][Gly] showed the highest molar conductivity. These results are attributed to the smaller size of [Gly] compared to [Pro] and [Ala]. However, adding AAILs increases the molar conductivity of the water.

Highlights

Over the past decade, ionic liquids (ILs) have attracted immense attention as green solvent due to their low vapor pressure, high thermal-chemical stability, nonflammability, and cation and anion are tunable, that gives less impact on the health, safety, and environment [1,2,3]
The experimental results show that all acid based ionic liquids (AAILs) solutions are alkaline where [OMIM][Pro] has the highest pH compared to its counterparts
The researchers are focusing on producing a new generation of ILs that can overcome the disadvantages of conventional ILs such as toxicity [11,12,13] Amino acid based ionic liquids (AAILs) are derived from naturally occurring amino acids and consist of amino acid as anions or cations combined with other conventional cation and anions

Summary

Introduction

Ionic liquids (ILs) have attracted immense attention as green solvent due to their low vapor pressure, high thermal-chemical stability, nonflammability, and cation and anion are tunable, that gives less impact on the health, safety, and environment [1,2,3]. The first preparation of AAILs was in 2005 by Fukumoto et al, where the 1-ethyl-3-methylimidazolium cation ([C2mim]) was combined with 20 different types of amino acids [18]. They reported that these AAILs were prepared with amino acids as cations and nitrate as anions [15]. The measurements were conducted at ambient conditions where atmospheric pressure and room temperature

Materials and Solution Preparation

Equipments and procedure

Conductivity Measurement

Results and discussion

Electrical and molar conductivity of AAILs solutions

CONCLUSIONS