Fabrication of polyamide thin film nanocomposite membranes with enhanced desalination performance modified by silica nanoparticles formed in-situ polymerization of tetramethoxysilane

The high separation performance polyamide (PA) thin film nanocomposite (TFN) reverse osmosis (RO) mem-brane for desalination was fabricated by incorporating the silica nanoparticles formed by in-situ polymerization of TMOS in the polyamide layer. The different contents and mixing methods of TMOS were investigated. The in -situ synthesized silica was uniformly embedded in the PA layer because TMOS could be fully dissolved in the organic phase solution. The agglomeration and uneven dispersion of traditional nanofillers in the polyamide layer were avoided. The best performance TFN membrane was prepared by mixing 0.8 wt% TMOS in organic phase solution and interfacial polymerization for 2 min. For brackish water desalination and high-pressure seawater desalination, the water flux of best performance membrane reached 58.4 L m- 2 h-1 and 72.77 L m- 2 h- 1 respectively, which was 3 times and 2.6 times of that of pure polyamide thin film composite (TFC) membrane, while maintaining a satisfactory salt rejection (NaCl, 98.5%). The anti-fouling and long-term stability performance of prepared TFN membrane were also superior. This work demonstrated the potential of TMOS in -situ synthesis of nanofillers embedded in PA layer to prepare TFN membrane with high separation performance, and provided a new idea for simple preparation of TFN membrane.

Automated summary

In this study, a high separation performance polyamide thin film nanocomposite reverse osmosis membrane was successfully fabricated by incorporating silica nanoparticles formed by in-situ polymerization of TMOS in the polyamide layer. The best performance membrane was prepared by mixing 0.8 wt% TMOS in the organic phase solution and interfacial polymerization for 2 minutes. The prepared TFN membrane showed significantly improved water flux and salt rejection compared to pure polyamide thin film composite membrane, while also demonstrating excellent anti-fouling and long-term stability performance.