Thin-film polyamide nanocomposite membranes with mesoporous silica having tailored organic surface functionalization

Thin-film polyamide nanocomposite membranes with mesoporous silica having tailored organic surface functionalization

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Thin film nanocomposite membranes (TFN) have emerged as one of the most promising candidates of next generation materials for water desalination and other separations [1]. Incorporation of porous materials such as mesoporous silica nanoparticles (MSN) into the barrier polyamide (PA) layer of reverse osmosis membranes is an attractive approach not only to improve membrane performance but also to gain deeper understanding of the selective transport in nanocomposite membrane barriers.

This project aims to improve the desalination performance and stability of TFN membranes by incorporation of MSN in combination with their controlled functionalization using various silanization reagents, e.g. octadecyltrichlorosilane (OTS). Two kinds of MSN nanofillers are produced, hydrophilic pores MSN (referred to as LMSN), and hydrophobic pores MSN (referred to as HMSN). The external surface of both nanofillers is hydrophobic in order to improve their integration inside the PA layer during the interfacial polymerization reaction. The membranes’ performance was then assessed based on water permeability and salt rejection measurements. Several parameters were found to have a strong influence on the membrane performance such as amount of grafted OTS on MSN and the loading of the PA layer with nanofiller. The results indicated that TFN membranes containing OTS-functionalized nanofillers produced higher water permeability without sacrificing the membrane selectivity. This work clearly emphasizes the direct relationship between the internal pores of MSN as functional nanofiller in the PA barrier layer and increasing or decreasing the water permeability of resulting TFN membranes [2]. Furthermore, the OTS-functionalization reduces the dissolution tendency of MSN in aqueous solutions due to the formation of a protective organic layer leading to enhanced long time stability of the respective TFN membranes.

References

  1. G. Xu, J. Wang, C. Li, Desalination 2013, 328, 83
  2. A. M. A. Abdelsamad, A. S. G. Khalil, M. Ulbricht, J. Membr. Sci. 2018, 563, 149

Funding

This project is funded by the DAAD through the GERLS program.

Contact:
Ahmed Abdelsamad