Proposal Title: SGER Development of bacterial-sensing ultrafiltration membranes with improved permeability, selectivity, and fouling control. Proposal Number: CTS-0610624 Principal Investigator: Isabel C. Escobar, Institution: University of Toledo
Membranes are capable of separating species as a function of their physical and chemical properties when a driving force is applied, and they enable filtration to the removal of colloids, cells and molecules. Membrane filtration can be used both in small systems made for point-of-use as well as in large municipal systems, which makes membrane filtration a process capable of saving lives during emergency situations, as well as consistently providing high quality safe drinking water. However, there are two major concerns associated with the use of membranes: one is the efficiency of the membrane (water flux and removal rate of impurities), and the other is membrane fouling. The first concern is closely related to the microstructure of the membrane, while the latter, membrane fouling is affected by different factors, such as surface charge, hydrophobicity, and surface roughness. Fouling adversely affects membrane performance and cost through loss in flux, increase in pressure, and cleaning frequency. The PIs propose to attach a stimuli-responsive polymer brush (such as n-isopropyl acrylamide or hydroxypropyl cellulose) on the surface, which offers the potential to collapse or expand the polymer brush. The phase change arises from the existence of a lower critical solution temperature (LCST) such that the polymer precipitates from solution as the temperature is increased. This capability can be exploited to control adsorption/desorption. A temperature decrease can cause the brush to expand into a hydrophilic state while a temperature increase causes a collapse into a hydrophobic state. Protein adsorption is reduced in the expanded, hydrophilic state relative to the collapsed, hydrophobic state. Although equilibrium adsorption is reduced, significant adsorption still occurs. The proposed membrane modification/sensing technique will develop stronger membranes capable of withstanding harsh raw water quality conditions without losing their reliability in producing a high quality safe product.
