A fast and remote screening method for sub-micro-structuration in pressurized mixtures containing water and carbon dioxide

We present a fast optical screening method for the detection of sub-micro-structures nanostructuration in water-containing fluids. The optical method is based on Raman spectroscopy of the water stretching vibration. The shape of this Raman band reveals information about the development of hydrogen bonds, from which it can be extracted whether the water molecules are homogeneously distributed in the mixture, or they are heterogeneously distributed (sub-micro-structuration). The fast screening is enabled by analyzing the potentially structured ternary system CO2/acetonitrile/water between 10 and 22 MPa and at 308 K, 318 K and 328 K in continuously spilled microcapillary system (MCS). Compared to batch systems we specify the advantages of the MCS in which the operational conditions with respect to pressure, temperature and composition can be changed fast, reproducibly and across a wide range. (C) 2019 The Authors. Published by Elsevier B.V.