Facile Monitoring of Water Hardness Levels Using Responsive Complex Emulsions

Marko Pavlovic, Heman Kumar Ramiya Ramesh Babu, Saveh Djalali, Milan Vraneš, Vasa Radonić, Lukas Zeininger

Research output: Contribution to journalArticlepeer-review

3 Scopus citations


The cationic content of water represents a major quality control parameter that needs to be followed by a rapid, on-site, and low-cost method. Herein, we report a novel method for a facile monitoring of the mineral content of drinking water by making use of responsive complex emulsions. The morphology of biphasic oil-in-water droplets solely depends on the balance of interfacial tensions, and we demonstrate that changes in the surfactant effectiveness, caused by variations in the mineral content inside the continuous phase, can be visualized by monitoring internal droplet shapes. An addition of metal cations can significantly influence the surfactant critical micelle concentrations and the surface excess values and therefore induce changes in the effectiveness of ionic surfactants, such as sodium dodecyl sulfate. The morphological response of Janus emulsions droplets was tracked via a simple microscopic setup. We observed that the extent of the droplet response was dependent on the salt concentration and valency, with divalent cations (responsive for water hardness), resulting in a more pronounced response. In this way, Ca2+and Mg2+levels could be quantitatively measured, which we showcased by determination of the mineral content of commercial water samples. The herein demonstrated device concept may provide a new alternative rapid monitoring of water hardness levels in a simple and cost-effective setup.

Original languageEnglish
Pages (from-to)9390-9396
Number of pages7
JournalAnalytical Chemistry
Issue number27
StatePublished - 13 Jul 2021
Externally publishedYes

ASJC Scopus subject areas

  • Analytical Chemistry


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