Improved reverse osmosis thin film composite biomimetic membranes by incorporation of polymersomes

Biomimetic aquaporin-based membranes offer great promise as a disruptive water treatment technology, due to their potential of improving membrane permeability without compromising solute rejection. However, fabrication upscaling is challenging and therefore the technological potential of biomimetic membranes remains unused. We propose an easily upscalable process based on bulk hydration of diblock and triblock copolymer mixture for preparation of polymersomes which can reconstitute aquaporin proteins. Such polymersomes are incorporated into biomimetic membranes via polyamide active layer synthesis based on interfacial polymerization. By incorporation of blank polymersomes, it was possible to improve water permeability of the membrane by 30%, and by incorporation of aquaporin reconstituting polymersomes by 50%, compared to the membranes without polymersomes. In both cases NaCl rejection was not affected. X-ray photoelectron spectroscopy measurements confirmed incorporation of copolymers prepared with aquaporins into the active polyamide layer without affecting the thickness of the membrane's active layer and surface zeta-potential

Role of Operating Conditions in a Pilot Scale Investigation of Hollow Fiber Forward Osmosis Membrane Modules

Although forward osmosis (FO) membranes have shown great promise for many applications, there are few studies attempting to create a systematization of the testing conditions at a pilot scale for FO membrane modules. To address this issue, hollow fiber forward osmosis (HFFO) membrane modules with different performances (water flux and solute rejection) have been investigated at different operating conditions. Various draw and feed flow rates, draw solute types and concentrations, transmembrane pressures, temperatures, and operation modes have been studied using two model feed solutions—deionized water and artificial seawater. The significance of the operational conditions in the FO process was attributed to a dominant role of concentration polarization (CP) effects, where the selected draw solute and draw concentration had the biggest impact on membrane performance due to internal CP. Additionally, the rejection of the HFFO membranes using three model solutes (caffeine, niacin, and urea) were determined under both FO and reverse osmosis (RO) conditions with the same process recovery. FO rejections had an increase of 2% for caffeine, 19% for niacin, and 740% for urea compared to the RO rejections. Overall, this is the first extensive study of commercially available inside-out HFFO membrane modules