Detailed analysis of single drop coalescence-Influence of ions on film drainage and coalescence time

Coalescence in liquid-liquid systems is determined by multiple factors, including droplet size ratios and the concentration and type of any continuous phase ions present. When using the standardized EFCE (European Federation of Chemical Engineering) toluene/water standard test system, these factors were systematically investigated based on a high statistical relevant database. The influence on the film drainage time was captured with a high speed imaging system. Shorter coalescence times were found to correlate with higher coalescence probabilities and an observed increase in,the coalescence time with increasing droplet diameter agrees well with simple drainage modeling. Coalescence inhibition was also observed with the addition of continuous phase electrolyte. An empirical correlation was developed to account for the influence of equivalent droplet diameter and ion concentration on the coalescence time. (C) 2016 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.