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Phillip, William A.

Publications and source records attributed to Phillip, William A..

7 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

A critical review and commentary on recent progress of additive manufacturing and its impact on membrane technology

Membrane separations has been increasingly recognized as a key technology platform for improving the energy efficiency of many separations processes. Likewise, additive manufacturing (AM), or 3-dimensional (3D) printing as it is often called, is a rapidly emergent technology platform for manufacturing in many industrial sectors. It has become increasingly common to marry these two platforms to take advantage of the additive nature of 3D printing with the increasing need for membrane technology that is adaptable to separations needs. Conventional membrane manufacturing approaches, such as casting, typically result in thick membranes that limit productivity and potentially waste material in a non-performing support layer. Interfacial polymerization (IP) offered a new vision for thin-film composite desalination membranes, yet it was limited to certain chemistries while exhibiting other drawbacks. Additive manufacturing offers certain benefits over these techniques to membranes, including the ability to expand the library of materials that can be processed while also offering a degree of customization that is impossible in conventional manufacturing. This review article evaluates an increasing body of literature on using printing to make membranes and considers the limitations and opportunities for printing to enhance existing membrane technology and expand the reach of membranes into other industries. Furthermore, we also provide a perspective from leading experts in membrane technology to see where there are opportunities to use printing in different membrane science disciplines.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Water and salt transport properties of pentiptycene-containing sulfonated polysulfones for desalination membrane applications

A series of pentiptycene-containing disulfonated polysulfone copolymers (PENT-BP) were synthesized via condensation polymerization. Water and salt transport properties (solubility, diffusivity and permeability) were characterized for acid-form membranes (PENT-BP(H)) and compared with triptycene-based sulfonated polysulfones (TRP-BP(H)) and a non-iptycene-containing 4,4'-biphenol-based series (BPS(H)) of polysulfones to investigate the effect of pentiptycene on membrane performance. At comparable water content, the PENT-BP(H) exhibited increased water and salt permeability due to the additional free volume introduced by the pentiptycene units. Enhanced water/salt permeability selectivity of PENT-BP(H) series was also observed due to a significantly higher diffusivity selectivity. At comparable water permeance (P w D ~ 8 X 10 -6 cm 2 /s), the salt rejection of PENT-BP (H) copolymers obtained from dead-end filtration reached 91–93% at 400 psi, higher than that of a corresponding BPS(H) series. This study suggests that incorporation of iptycene moieties into polymer backbone is an effective strategy to enhance desalination membrane performance.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Maximizing selectivity: An analysis of isoporous membranes

Membranes are compelling candidates for many separation-based industrial processes. However, all synthetic membranes are subject to well-recognized permeability-selectivity trade-offs that hinder their use in advanced applications. Having uniform nanoscale pore size, isoporous nanofiltration and ultrafiltration membranes have attracted wide research interest. However, quantitative analysis of isoporous membrane performance is lacking - particularly at module and system-level scales. In this study, an analytical model is built to investigate how membrane pore-size distribution affects the solute separation efficiency (i.e., rejection and selectivity). The model accounts for convective hindrance as well as concentration polarization and explores effects on separation from the solute-to-pore-size ratio and percent recovery (i.e., fraction of feed flow that passes through the membrane). At the module level, our analysis suggests that a notably sharper rejection vs. solute size curve can be obtained as the pore-size distribution becomes narrower. Additionally, as the recovery increases, the rejection of a solute is maintained at a high level using isoporous membranes while the rejection drops rapidly for membranes that possess a disperse pore-size distribution. Furthermore, in the separation of mixed solutes, isoporous membranes achieve a large selectivity with a modest loss of permeability. Overall, this study elaborates the unique role that isoporous membranes play within the permeability-selectivity trade-off relations and identifies the most exciting opportunities for their future applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗