Investigation of surface tension and surface properties of alkanolamine–alcohol mixtures at T = 313.15 K and P = 90.6 kPa

Abstract

Alkanolamine compounds are especially useful in the adsorption of acid–gases from gas streams. In this work, surface tension for nine binary systems containing an alkanolamine (monoethanolamine (MEA), diethanolamine (DEA) and triethanolamine (TEA)) and a short chain alcohol (methanol, ethanol and isopropanol) were measured over the entire concentration range at 313.15 K and 90.6 kPa by means of the ring detachment method. From these data, the surface tension deviations were computed. The maximum deviation in nine systems was <1%. Then these surface tension data were correlated using Myers–Scott (MS) and Fu et al. (FLW) polynomial expansions. Also, the surface tension data have been predicted based on the Sprow–Prausnitz (SP) equation. The results show that good agreement is obtained between experimental and predicted data of surface tension, a fact which confirms the applicability of the SP equation in the binary mixtures with polar components. The modified UNIFAC group contribution method is used for calculation of activity coefficients of components in mentioned systems. Finally, surface mole fraction of alcohol at the (air + liquid) interface were calculated from (SP) equations. The results show that the surface concentration of alcohol in binary mixtures increase with increasing the alkyl chain length of alcohol.