Micro- and nanostructured thin film composite membranes for desalination

Micro- and nanostructured thin film composite membranes for desalination

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Polyamide (PA) thin-film composite (TFC) membranes are the most prevalently used materials for pressure-driven water desalination. Recently, a number of theoretical and experimental studies have introduced topographic surface patterning as an interesting alternative to yield efficacious membranes possessing enhanced fouling resistance [1]. The patterned TFC membranes were found to exhibit higher water flux and lower tendency towards scaling, however these submicron-patterned membranes suffered from modest NaCl rejection behavior, ≤ 90% [2]. Achieving high monovalent salt rejection for these patterned membranes is still considered as a challenge.

This project aims to introduce more reliable and detailed fabrication guide towards high performance micro-structured PA TFC membranes exhibiting enhanced antifouling resistance. Two different surface micropattering methods are implemented, combined process of vapor- and non-solvent induced phase separation micromolding (PSµM) as well as nanoimprinting lithography (NIL). Novel macroporous supports of isotropic pore size distribution and average barrier pore diameter of 100 nm, developed in our group [3], are employed as supports for the new micro-structured membranes. A number of parameters were investigated for PSµM, including the range of pattern, suitable pretreatment procedure for the mold, and exposure time to humid air. Suited NIL conditions were also identified. The fidelity of the micro-patterning methods was studied comprehensively, and details for different surface pattering mechanisms are proposed. Polyamide layer synthesis was then adapted to the developed micro-structured supports and the impact on membrane performance due to difference in micro-patterning resolution was explored [4]. Moreover, the surface of the novel patterned TFC membranes will be further modified using different surface modification techniques to evaluate the change in resistance of desalination membrane towards scaling and biomolecules attachment as a result of expected synergism between surface micro-pattering approach and stimuli responsive behavior.[5]

References

  1. Y.K. Lee, Y.J. Won, J.H. Yoo, K.H. Ahn, C.H. Lee, J. Membr. Sci. 2013, 427, 320
  2. S.H. Maruf, A.R. Greenberg, Y. Ding, J. Membr. Sci. 2016, 512, 50
  3. I.M.A. ElSherbiny, R. Ghannam, A.S.G. Khalil, M. Ulbricht, J. Membr. Sci. 2015, 493, 782
  4. I. M. A. El-Sherbiny, A. S. G. Khalil, M. Ulbricht, J. Membr. Sci. 2017, 529, 11-22
  5. I. M. A. El-Sherbiny, A. S. G. Khalil, M. Ulbricht, Tailoring Surface Characteristics of Polyamide Thin-Film Composite Membranes towards Pronounced Switchable Wettability, Adv. Mater. Interf. 2018, accepted
Funding: This work was part of “SURSYS” project funded by German Academic Exchange Service (DAAD) and financed by the Federal Foreign Office of Germany (2013 – 2015).

Contact:
Prof. Dr. Mathias Ulbricht