I will begin by discussing practical and engineering constraints in the design of water treatment systems on the industrial or municipal scale. Using a fundamental thermodynamics and kinetics framework, I will analyze why certain commercial treatment methods outperform others and why micropollutant removal requires the development of novel methods. Highlighting how transport limitations at low concentrations hinder micropollutant removal and increase process costs, I will present two studies leveraging interfacial design through the use of colloids towards more efficient separations.
First, I will showcase how commercially available surfactants can be engineered into absorbents in the form of micelles for water treatment by using zwitterionic hydrogels. Using rational design principles that combine simulations and experiments, we synthesize hydrogels bearing multiple functionalities that can be tuned to either selectively or simultaneously remove chemically diverse micropollutants, including both organics and heavy metals, at least 10 times faster than commercial adsorbents and 100 times faster than other multifunctional materials. In a prototype packed bed filter, hydrogel microparticles reduced micropollutant concentrations below regulatory limits for two weeks under continuous flow.
Next, combining ideas from photocatalysis and redox-mediated electrosorption, we show how classical electrochemical water treatment methods being explored in the literature can also be deployed in the form of colloids to enable rapid micropollutant elimination. Semiconducting colloidal particles are Janus-functionalized with metals and redox-active polymers, allowing each particle to act as an autonomous, motile electrochemical separator.