Ion-selective Organic Materials: Sensing, Removal & Recovery (dr. L.C.P.M. (Louis) de Smet)

In our research group we design, prepare and characterize organic materials, mostly polymers, that show specific interactions to ions. Ion-selectivity does not only play an important role in ion sensing, but it is also relevant for ion-separation processes. The need for ion-specific separations becomes clear when one embraces (waste) water as resource water. One of the main challenges is: how to catch specific ions like Li+, Na+, PO43– or NH4+ in a selective way? To study this, we functionalize the surfaces of electrodes and membranes with ion-selective materials. The resulting coatings are studied for their ion partitioning, filtering and transport properties.

Ion Sensing

Ion-selective electrodes convert the concentration of a certain ion into an electrical potential. They usually contain a polymer-based affinity layer to achieve selectivity. However, these electrodes have a limited stability and a relatively short shelve life. Using molecular surface engineering approaches we aim to improve the performance such electrodes in terms of fouling and degradation. Next to that, we aim to measure different ions simultaneously and selectively, using one sensor device.

Recent sensors publications:
Nano Lett. 2017, 17, 1-7 [doi] Front Cover Article
ACS Sensors, 2016, 1, 1188-1192 [doi]

Anal. Chem. 2015, 87, 1173–1179 [doi]

Ion Removal & Recovery

Within this research theme we combine functionalized polymer coatings with an electrical field to achieve the electro-driven removal of ions in a selective way. Examples include Na+ (greenhouse applications), Mg2+/Ca2+(water softening). Interestingly, electro-driven, ion-removal processes have also the potential to recover or harvest ions at high purity. Our main focus is on the recovery of phosphate, which is an essential nutrient needed for all forms of life and at the same time it is a limited resource, which today is wasted at a large scale (see e.g. this link). This research program is funded via an ERC Consolidator Grant. Additionally, we explore the possibility to apply our approach to harvest Li+ from brines, addressing the growing appetite for Li-ion batteries.


Schematic showing the focus of our research group: functionalizing polymers with ion-selective moieties to, e.g. recover phosphate from (waste) water.

Wetsus (European centre of excellence for sustainable water technologies, Leeuwarden), Holst Centre (R&D Centre, Eindhoven), FujiFilm (Tilburg).

Recent publication:

Soft Matter 2016, 12, 1496-1505 [doi]

Contact and more info:
Louis de Smet,, 0317– 481268 / 82361, Helix 7.034