Thermochimica Acta 541 (2012) 70–75 Contents lists available at SciVerse ScienceDirect Thermochimica Acta jou rnal h omepage: www.elsevier.com/locate/tca Fruit sugar-based deep eutectic solvents and their physical properties Adeeb Hayyan a,b , Farouq S. Mjalli a,∗ , Inas M. AlNashef c , Talal Al-Wahaibi a , Yahya M. Al-Wahaibi a , Mohd Ali Hashim b a Petroleum and Chemical Engineering Department, Sultan Qaboos University, Muscat 123, Oman b Department of Chemical Engineering, Centre for Ionic Liquids (UMCiL), University of Malaya, Kuala Lumpur 50603, Malaysia c Chemical Engineering Department, King Saud University, Riyadh 11421, Saudi Arabia a r t i c l e i n f o Article history: Received 18 February 2012 Received in revised form 23 April 2012 Accepted 25 April 2012 Available online 4 May 2012 Keywords: Fructose Monosaccharides Deep eutectic solvents Ionic liquids a b s t r a c t In this study, a novel fructose-based DES of choline chloride (2-hydroxyethyl-trimethylammonium) has been synthesized at different molar ratios. The physical properties such as density, viscosity, surface ten- sion, refractive index and pH were measured and analyzed as function of various temperatures (25–85 ◦ C). The analysis of these physical properties revealed that these new DESs have the potential to be utilized for possible industrial applications involving processing and separation of food constituents. The suggested DESs have many desirable characteristics, e.g. they have low vapor pressure, inflammable, biodegradable, and made from renewable resources. The use of these DESs will positively affect the environment and make use of available renewable resources. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Industrial products based on abundant agricultural bio- resources such as sugars are addressed as one of the essential products for the sustainability of human life. Sugars industry research and development is gaining increasing concern due to the impact of increased consumption of refined sugar on human health [1]. Numerous types of sugar and syrups are available to domestic and industrial users [2,3]. As a consequence of pressure from con- servationists and local communities, sugar industry is continuously refining its production methodologies and technologies to cope with environmental considerations. The most important factors to improve the sugar industry are finding new and available sources associated with economical extraction and purification processes to produce high quality sugars. Al-Eid et al. [4] considered the nutritional value of date syrups and sugars as well as their chemical composition. The study reported that there is higher percentage of fructose than glucose in date syrup. Consequently, by separating fructose, more profitable value-added products could be achieved. Palm date is a rich raw material for producing fructose in high abundance of supply and perennial availability [5]. Fructose is a highly important product in the food industry as well as the pharmaceutical industries. These industries require a continuous and cheap sustainable supply of sugars. On a dry weight basis, palm dates contain 65–80% equal ∗ Corresponding author. Tel.: +968 24142558; fax: +968 24141354. E-mail address: farouqsm@yahoo.com (F.S. Mjalli). amounts of glucose and fructose. Currently, only about 30% of the usable produced dates are utilized for human consumption and the remaining quantity contributes as an ingredient serving the food industry. Recently, AlNashef et al. [6] patented the use of ionic liquids ([dimethylimidazolium dimethylphosphate] and [1-ethyl- 3-methylimidazolium ethylsulfate]) for the separation of monosac- charides from their aqueous and solid mixtures. The patent claimed that ionic liquids work as selective agent that can separate glucose and fructose under ambient conditions. There are many advantages and favorable merits for using ILs in many industrial applications. Examples include, the undetectable vapor pressure, liquidity at a wide temperature range, the high sol- ubility for a wide range of chemical compounds, as well as their less toxicity [7,8,9]. In recent years, deep eutectic solvents (DES) were introduced as a promising class of room temperature ionic liquids that lend themselves as efficient alternatives for conventional ionic liquids with better cost effectiveness. Their simple synthesis and the flexi- bility in choosing their constituent components facilitate their use over complex and expensive ILs. This encourages their utilization in food processing applications. DESs are relatively new class of ionic liquids that are simply synthesized via mixing of salt with a hydrogen bond donor compound [9,10]. They have many of ILs mer- its such as their biodegradable components, non-flammability due to their low or none measurable vapor pressure and low toxicity [8,10,11]. DESs were introduced in many industrial applications as attractive alternatives to ILs such as the synthesis of zeolite analog [12], solvent extraction of aromatics from naphtha [13], removal 0040-6031/$ – see front matter © 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.tca.2012.04.030