(767d) Colloidal Foulant Behavior on Membrane Surfaces with Controlled Chemistry and Ordered Roughness

Reduction in water transport (flux) due to fouling is one of the largest costs associated with membrane processes in water treatment. A key to minimizing the energy intensity of membrane-based water treatment systems is designing membranes with high water transport and low fouling propensity. The fouling propensity of a membrane depends greatly on foulant type, operating conditions, and membrane surface properties. Thus, surface modification provides one pathway to improving membrane fouling resistance. Modification can be done by changing surface chemistry or physical properties (e.g., roughness), and these represent orthogonal membrane surface design parameters.

The objective of this project is to develop the basic science needed to design new membranes that are resistant to fouling. In this contribution, we present findings on the relationship between membrane surface properties and fouling that were derived from tests on the hypothesis that combinations of geometric patterns (i.e., ordered roughness) and controlled chemical coatings will reduce membrane fouling compared to the control.

To attain the project objective, we carried out a systematic study to understand the roles of colloidal foulant chemistry and membrane surface properties on membrane performance using crossflow filtration. Nano-patterns were applied by embossing commercial polyamide thin-film composite nanofiltration membranes such as the GE HL series. Silica nanoparticles were functionalized by silane chemistry and applied as a model foulant to study the role of colloidal foulant chemistry. In parallel, interactions between foulants and membrane surfaces were studied by computational and experimental methods to better understand the role of chemistry in membrane fouling. Results of this study support the hypothesis and suggest that combining physical patterning with chemical modification on a membrane surface is an effective strategy for designing new membranes with a low propensity for fouling by colloidal nanoparticles.