Thin Film Composite Forward Osmosis Membrane with Single-Walled Carbon Nanotubes Interlayer for Alleviating Internal Concentration Polarization

Abstract

This study reported a series of thin film composite (TFC) membranes with single-walled nanotubes (SWCNTs) interlayers for the forward osmosis (FO) application. Pure SWCNTs with ultrahigh length-to-diameter ratio and without any functional group were applied to form an interconnect network interlayer via strong π-π interactions. Compared to the TFC membrane without SWCNTs interlayer, our TFC membrane with optimal SWCNTs interlayer exhibited more than three times the water permeability (A) of 3.3 L m−2h−1bar−1 in RO mode with 500 mg L−1 NaCl as feed solution and nearly three-fold higher FO water flux of 62.8 L m−2 h−1 in FO mode with the deionized water as feed solution and 1 M NaCl as draw solution. Meanwhile, the TFC membrane with SWCNTs interlayer exhibited significantly reduced membrane structure parameters (S) to immensely mitigate the effect of internal concentration polarization (ICP) in support layer with micro-sized pores in favor of higher water flux. It showed that the pure SWCNTs interlayer could be an effective strategy to apply in FO membranes.

Enantiomeric Separation of Racemic Mixtures Using Chiral-Selective and Organic-Solvent-Resistant Thin-Film Composite Membranes

“…Second, a set of well-defined characteristic peaks of C–C (282.7 eV), C–O (283.7 eV), and N–CO (285.7 eV) can be observed from the C 1s spectrum (Figure b1). From Figure b2, the characteristic peaks of the N–CO (528.9 eV), COO – (529.7 eV), and C–O (535.8 eV) were observed in the O 1s spectrum . The presence of N–CO can be ascribed to the reaction between the amino group and acyl chloride group during IP, while the C–O and COO – groups can be derived from the hydrolysis of the unreacted acyl chloride group originally from the TPC monomer …”

“…From Figure 4b2, the characteristic peaks of the N−CO (528.9 eV), COO − (529.7 eV), and C− O (535.8 eV) were observed in the O 1s spectrum. 48 The presence of N−CO can be ascribed to the reaction between the amino group and acyl chloride group during IP, while the C−O and COO − groups can be derived from the hydrolysis of the unreacted acyl chloride group originally from the TPC monomer. 48 Besides that, the sharp peak observed at 397.5 eV from the N 1s spectrum (Figure 4b3) can be attributed to the N−CO group and further confirms the formation of the polyamide film on the PES support.…”

Commercial Pressure Retarded Osmosis Systems for Seawater Desalination Plants

“…In the FO test with 0.5 M NaCl and DI water, a water flux of 22.6 LMH was obtained, which is equivalent to 3.3 times the permeability of commercially available membranes. Tang et al developed a thin film composite (TFC) membrane with a single-walled carbon nanotube (SWCNT) intermediate layer [ 38 ]. A membrane in which an intermediate layer is formed through a strong π-π interaction was prepared with SWCNTs with no functional group.…”

Shale Oil and Gas Produced Water Treatment: Opportunities and Barriers for Forward Osmosis

“…TFC-FO membranes are currently at the forefront of FO membrane research. The common methods in these studies are IP for the fabrication of the active layer, phase inversion for the support layer (electrospinning, vacuum filtration, immersion precipitation), membrane coating, and the integration of nanoparticles and nanofibers into the membrane [53][54][55][56][57][58][59]. Materials commonly used in the processes are N, N-dimethylformamide (DMF) within the support layer, polyamide for the active layer, and NaCl as DS.…”