(415d) Preparation and Characterization of Fouling-Resistant, Temperature-Responsive Membranes for Treatment of Produced Water

Produced water is oily wastewater that is co-produced during oil and gas exploration. Developing a technique that is economically viable and environmentally friendly to treat the large volumes of produced water is a grand challenge for oil and gas companies. Membrane based treatment processes for oily waters often fail due to membrane fouling. We hypothesize that grafting block copolymer nanolayers from commercial membranes will change the surface properties in ways that limit foulant accumulation on these membranes and provide an easy, chemical-free way to remove any attached foulants.

Poly(N-isopropylacrylamide)-block-poly(oligoethylene glycol methacrylate) was grafted by surface-initiated atom transfer radical polymerization (ATRP) from tight ultrafiltration membranes. The dual functionality provided by this block copolymer system yields fouling resistant and temperature responsive membranes for the treatment of produced water. The temperature responsive block (PNIPAAm) makes it possible for the membranes to self-clean during the filtration of produced water. Fourier-transform infrared spectroscopy spectra confirmed the successful grafting of both polymers from the membrane surfaces. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) were used to characterize changes in the surface topography, and pore morphology of the membranes after modification. The performance of the modified membranes was tested by carrying out water flux measurements using filtration experiments and examining the levels of pure water flux recovery after a temperature controlled water rinse.

In a parallel study, we studied nanolayer growth kinetics and temperature responsiveness using ellipsometry with a model surface. Data from this part of the study are used to guide membrane modification work.