VISCOSITY OF MONO-, DI- AND TRIETHYLENE GLYCOL AQUEOUS SOLUTIONS AT 298.15 K

The aim of this study was to analyze the change in the complex structure formed in water-glycols mixture under mixture composition. The dynamic viscosity for various glycol (mono-, di- and triethylene glycol) aqueous solutions have been measured over wide range of concentration at temperature 25 °C and atmospheric pressure. The new scale of viscosity concentration dependences of various glycols for common description in range of low glycol composition was suggested. From experimental data, the excess viscosity (deviation in viscosity) was calculated. Excess viscosity was negative for monoethylene glycol – water mixture over the entire range of composition. In the case diethylene glycol –water mixture excess viscosity values were found to be negative between 0 and 20 mol %, then became positive in the diethylene glycol rich region. In the case triethylene glycol – water mixture excess viscosity values were negative between 0 and 10 mol %. The Grunberg-Nissan parameter was calculated. By comparing the monoethylene glycol – water hydrogen bonding, reported in literature and Grunberg-Nissan parameter variation versus glycol molar fraction, a correspondence between Grunberg-Nissan parameter and the complex varieties was established. It was shown, that concentration dependence of the Grunberg-Nissan parameter separates the different concentration regions. The variation of the Grunberg-Nissan parameter with glycol molar fraction deals with the interaction variation between water and glycol molecules, the Grunberg-Nissan parameter slop varies.

Excess acoustic absorption attributable to the biological modification of seawater viscosity

Rhodes, C. J. 2008. Excess acoustic absorption attributable to the biological modification of seawater viscosity. – ICES Journal of Marine Science, 65: 1747–1750. There is increasing evidence that a ubiquitous species of oceanic phytoplankton (Phaeocystis globosa) can significantly modify the rheological properties of seawater. The effect is seasonal and, during spring when the species multiplies rapidly, one can observe large increases in the viscosity of the seawater they inhabit. One of the principal determinants of acoustic absorption in a fluid is viscosity, so in addition to the well-understood modulations attributable to temperature- and salinity-dependent molecular relaxation, there may be an additional absorption component resulting from the presence of phytoplankton. Using data from recent measurements of biologically induced excess viscosity during blooms of P. globosa, the additional acoustic absorption attributable to the presence of this organism is estimated. This suggests that a novel, biologically induced acoustic-absorption mechanism may be observable in seawater for frequencies >100 kHz. The implications for a variety of at-sea acoustic-measurement activities are noted.