Development and Performance Characterization of a Polyimine Covalent Organic Framework Thin-Film Composite Nanofiltration Membrane

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1 Development and Performance Characterization of a Polyimine Covalent rganic Framework Thin-Film Composite anofiltration Membrane Lauren Valentino, Michio Matsumoto, William R. Dichtel, Benito J. Mariñas* Safe Global Water Institute, Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL Department of Chemistry, orthwestern University, Evanston, IL *Corresponding author [phone: ; marinas@illinois.edu] SUPPRTIG IFRMATI Summary of Contents: 11 pages Figure S1. Schematic of the interfacial polymerization reaction and synthesis of iminelinked 2D CF. Figure S2. SEM images for cross sections of pristine PES, PES+polyimine CF, and PES control membranes. Figure S3. RBS characterization of pristine PES and PES+polyimine CF membranes. Figure S4. FTIR spectra of TAPB and PDA monomers, the imine CF in powder form synthesized via solvothermal synthesis, and PES+polyimine film, and pristine PES support. Figure S5. Wide angle x-ray scattering (WAXS) diffractograms for pristine PES and CF membranes. Figure S6. Water permeability for R-WT experiments. Figure S7. Water permeability for acl experiments. Text S1. Water and solute permeation analysis. Figure S8. R-WT rejection for CF membranes prepared with 1 and 2 layers. References 1

2 a) 4:1 dioxane/ mesitylene H 2 H 2 H 2 PES support water F F F S - 3 Sc 3+ silicone -ring membrane holder b) H 2 + Sc(Tf) 3 H 2 H 2 tris(4-aminophenyl)benzene (TAPB) terephthalaldehyde (PDA) Figure S1. a) Schematic of the interfacial polymerization reaction to form a TAPB-PDA CF film on top of a PES support and b) chemical structures of TAPB and PDA and reaction scheme of TAPB-PDA CF synthesis catalyzed by Sc(Tf)3. 2

3 pristine PES PES + polyimine CF PES control 2,500 10,000 40,000 Figure S2. SEM images for cross sections of a pristine PES membrane (left column), PES+polyimine CF membrane (center column), and control membrane (right column) at magnifications of 2,500 (top row), 10,000 (middle row), and 40,000 (bottom row). The control PES membrane was subject to the IP reaction conditions in the absence of PDA, TAPB, and Sc(Tf)3; therefore, there was no CF film formation. 3

4 C pristine PES PES + polyimine CF a) Counts b) Counts S Energy (MeV) 700 c) Counts Energy (MeV) Energy (MeV) 400 S d) 300 Counts Energy (MeV) Figure S3. Full spectrum RBS characterization of pristine PES (red triangles) and PES+polyimine CF (blue circles) membranes. C,,, and S denote carbon, nitrogen, oxygen, and sulfur, respectively. The shift in oxygen (c) and sulfur (d) indicated a film thickness of 10.4 ± 2.6 nm. pen points represent raw data points, and solid lines indicate simulations obtained using SIMRA. The nitrogen peak (b) at ~0.66 MeV resulted from modeling the RBS spectra of the PES+polyimine CF membrane, but it was not resolved from the background variability of the RBS data. 4

5 TAPB Absorbance PDA polyimine CF powder PES + polyimine CF (1 layer) pristine PES Wavenumber (cm -1 ) Figure S4. FTIR spectra of TAPB (purple) and PDA (pink) monomers, the polyimine CF in powder form synthesized via solvothermal synthesis (blue), PES+polyimine CF membrane (green), and pristine PES membrane (black). The peaks in the region of cm -1, which are indicative of primary amine groups in TAPB and the peak at 1685 cm -1 representative of aldehyde functional groups are absent in spectra for the CF membrane supporting the occurrence of a reaction between the monomers. Each data set was normalized using the greatest peak intensity in that spectrum. 5

6 pristine PES PES + polyimine CF Intensity ( ) Figure S5. Wide angle x-ray scattering (WAXS) diffractograms for pristine PES (black) and CF membranes (red) prepared by performing the IP reaction consecutively to form 3 CF layers on the PES support. The patterns obtained for the CF membranes (1, 3, and 6 CF layers on the PES) are comparable and undistinguishable from the PES membrane itself. 6

7 J v (m/d) pristine PES #1 pristine PES #2 pristine PES #3 PES + polyimine CF #1 PES + polyimine CF #2 PES + polyimine CF #3 PES control F-270 PES + polyimine CF - 2 layers Pressure (MPa) Figure S6. Water permeability for R-WT experiments. Control PES membrane was exposed to the organic solvents and water under the same conditions used for film formation but in the absence of PDA, TAPB, and Sc(Tf) J v (m/d) pristine PES PES + polyimine CF PES control F Pressure (MPa) Figure S7. Water permeability for acl experiments. Control PES membrane was exposed to the organic solvents and water under the same conditions used for film formation but in the absence of PDA, TAPB, and Sc(Tf)3. 7

8 Text S1. Water and Solute Permeation Analysis Measurements of water flux and the solute rejection of R-WT by the pristine PES and F- 270 membranes and acl for pristine PES, CF membrane, and F-270 were fit according to Equations S1 and S2: 1 Jv = A (pf-πw) (S1) Rejection (%) = 100 (1- C p ) = C f 100 B 1+[ (1-α)Jv + α 1-α ]exp(j v k ) (S2) where Jv (m/d) is the permeate flux, A (m/(d MPa)) is the water permeation coefficient, pf (MPa) is the feed hydraulic pressure, and πw (MPa) is the feed osmotic pressure adjacent to the membrane wall. The permeate flux is the volumetric flow rate (m 3 /d) normalized by the effective membrane area (m 2 ), which simplifies to m/d (m 3 /m 2 /d). Cp and Cf, are the solute concentrations in the permeate and bulk feed solution, respectively, B (m/d) is the solute diffusive permeation coefficient, α is the fraction of the total water flux that corresponds to advection through the membrane due to imperfections, and k (m/d) is the mass transfer coefficient of the solute in the concentration polarization film. The mass transfer coefficient k for R-WT was determined using a regression analysis (constraining α, B, and k > 0) to obtain the best-fit value for the commercial F-270 membrane because this is the most selective out of membranes tested in this study. R-WT is the larger of the two solutes; therefore, it experiences greater concentration polarization and provides the most accurate determination of its mass transfer coefficient in the concentration-polarization layer. The mass transfer coefficient for acl (measured with Cl - ion) was calculated from that of R-WT with Equation S3: 1 k acl k R-WT = ( D 2 acl 3 ) D R-WT (S3) 8

9 where the molecular diffusion coefficients for acl and R-WT are DaCl = 1.6x10-9 m 2 /s and DR- WT = 3.3x10-10 m 2 /s. The molecular diffusion coefficient for acl was calculated using the selfdiffusion coefficients 2 for each of the respective ions and assuming dilute solution conditions. For R-WT, the diffusion coefficient in water was estimated using the Wilke-Chang correlation. 3 The initial fitting of the F-270 rejection data according to the aforementioned procedure resulted in B = 0 m/d. As a result, the data set was fit with varying B values, and each of these model outputs was compared with the B = 0 m/d case using Akaike s Information Criteria (AIC) to obtain the largest non-zero B value that accurately represented the data. In order to determine the intrinsic transport parameters for the CF active layer, the following steady-state two-film model equations were combined and used to find BCF and CF using a regression analysis. JvCp = BCF(Cw-Ci) + CFJvCw JvCp = BPES(Ci-Cp) + PESJvCi (S4) (S5) C w C f C i C p CF PES where Cw and Ci are the solute concentrations at the membrane surface and at the interface between the CF active layer and PES support, respectively, BCF (m/d) is the intrinsic solute diffusive 9

10 permeation coefficient of the CF active layer, and αcf is the fraction of the total water flux that corresponds to advection through the CF active layer due to imperfections. BPES (m/d) is the solute diffusive permeation coefficient of the PES support, and αpes is the fraction of the total water flux that corresponds to advection through the PES support due to imperfections. These transport parameters for PES were determined by fitting the PES rejection data using Equation S2. Jv and Cp were defined in the previous section. Equations S4 and S5 may be combined to obtain the rejection for the two-film PES+polyimine CF membranes. Rejection = 100 (1- C p C f ) = 100 [ (J v - B CF - α CF J v) + B CF (Jv + B PES )/(B PES + α PES Jv) (B CF + α CF Jv) exp( J v k ) ] (S6) 100 R-WT Rejection (%) PES + polyimine CF - 1 layer #1 PES + polyimine CF - 1 layer #2 PES + polyimine CF - 1 layer #3 PES + polyimine CF - 2 layers J v (m/d) Figure S8. R-WT rejection by CF membranes prepared by IP of the imine film on the PES support membrane. 10

11 REFERECES 1. Urama, R. I.; Mariñas, B. J., Mechanistic Interpretation of Solute Permeation through a Fully Aromatic Polyamide Reverse smosis Membrane. J. Membr. Sci. 1997, 123, (2), Haynes, W. M.; Lide, D. R., Crc Handbook of Chemistry and Physics : A Ready-Reference Book of Chemical and Physical Data. 92nd ed. ed.; CRC Press: Boca Raton, Fla.: Logan, B. E., Diffusive Transport. In Environmental Transport Processes, John Wiley & Sons, Inc.: 2012; pp