Thermophysical properties and acute toxicity towards green algae and Vibrio fischeri of amino acid-based ionic liquids

Four new ionic liquids (ILs) based on 1-(2-hydroxyethyl-3-methylimidazolium) cation with glycinate, serinate, alaninate, and prolinate amino acid anions have been synthesized, and their thermo-physical properties (density, viscosity, surface tension, and heat capacity) were measured. Data were described using empirical expressions to determine other physical-chemical properties, such as molecular volume, standard molar entropy, and lattice energy. Moreover, acute toxicity tests toward Scenedesmus quadricauda (green algae) and Vibrio fischeri have been conducted. The high values obtained for the 50% effective concentration (EC50) indicated that these new ionic liquids can be considered eco-friendly. (C) 2015 Elsevier B.V. All rights reserved.