Supporting information

Nanofibrous Hydrogel Composite Membrane with Ultrafast

Transport Performance for Molecular Separation in Organic

Solvents

Yi Li,a Eric Wong,b Alexander Volodine,c Chris Van Haesendonck,c Kaisong

Zhang,*d Bart Van der Bruggen,*a,e

a Department of Chemical Engineering, KU Leuven, Celestijnenlaan 200F, B-3001, Leuven, Belgium. b Department of Management and Technology, UC Leuven-Limburg, Herestraat 49, 3000, Leuven, Belgiumc Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200 D, 3001 Leuven, Belgiumd Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, 361021, Xiamen, PR Chinae Faculty of Engineering and the Built Environment, Tshwane University of Technology, Private Bag X680, Pretoria 0001, South Africa

* Corresponding authors.E-mail address: bart.vanderbruggen@kuleuven.be (Bart Van der Bruggen); kszhang@iue.ac.cn (Kaisong Zhang).

Electronic Supplementary Material (ESI) for Journal of Materials Chemistry A.This journal is © The Royal Society of Chemistry 2019

Fig. S1 (a- c) The assumed exfoliation process of Kevlar fiber in DMSO/KOH solution.

Fig. S2 The ANF hydrogel preparation process. (a) ANF dope solution (2.0 wt%). (b) The non-solvent induced phase separation process of ANFs dispersions in water. (c) The as-prepared hydrogels with different shapes. (d) The cut hydrogel cubic from a bulk hydrogel. (e) The hydrogel under compressing with fingers. (f) The interactions between water and ANFs. (g) The nanofibrous structure of ANF hydrogel.

Fig. S3 The solvent resistance investigation of the ANF TFC membrane by immersing the membrane in different organic solvents. The membrane surface was examined after two weeks.

0 30 60 90 120 150 180 2105

1015202530354045

Cont

act a

ngle

(deg

rees

)

Time (s)

Contact angle

5 s

60 s

120 s

180 s210 s

Fig. S4 Variations of water contact angle with time on ANF hydrogel substrate membrane surface.

12 μm

C

O

C

O

H

N

H

N

n

Fig. S5 SEM image of Kevlar fiber.

5.0 μm 2.0 μm

1.0 μm 500 nm

Fig. S6 The SEM images of the surface of the ANF TFC membrane in different magnifications.

Fig. S7 SEM image of the polyolefin (PO) non-woven fabric surface (left) and the ANF TFC membrane with the support of PO fabric.

Fig. S8 (a) SEM image of the cross-section of the ANF hydrogel membrane without non-woven support. (b) TEM observation of the TFC membrane without DMF treatment.

Fig. S9 SEM image of the ANF hydrogel surface on PP/PE non-woven fabric surface (left) and the surface with higher magnification (20,000×) (right).

Fig. S10 (a, b) Cross sectional SEM images of the ANF TFC composite membrane without DMF treatment (The red dashed line showing the interface between polyamide layer and ANF hydrogel). (c, d) Cross-sectional SEM images of ANF TFC membrane with DMF treatment of 16 hours. (Membrane was dried with supercritical CO2)

Fig. S11 Comparison of the interfacial polymerization on conventional polymeric substrate (Left) and nanofibrous hydrogel substrate (Right).

0 5 10 15 20 25 30 350

10

20

30

40

50

60

Tensile stress: 46.5 MPaYoung's modulus: 139.0 MPa

Stre

ss (M

Pa)

Strain (%)

ANF TFC membrane (without non-woven fabric)

Fig. S12 Strain-stress curve of the dried ANF TFC membrane without the non-woven support.

8 12 16 20 24 28 320

20406080

100120140

Hydrogel /PP substrate membrane

Perm

eanc

e

Visc

osity

(1

0-8 L

m-2)

Total Hansen solubility parameter (MPa1/2)

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.50

200

400

600

800

1000

1200

R2=0.999y=146.662x

1 IPA 2 Ethanol 3 Methanol 4 Acetone

5 DMSO 6 NMP 7 DMF 8 DMAc

9 Water 10 THF

Perm

eabi

lity (L

m-2 h

-1 b

ar-1)

Viscosity-1 (mPa s-1)

1

2 9

10

3

4

7 85 6

y=339.712xR2=0.999

a

b

Fig. S13 (a) The transportation behavior of ANF hydrogel membrane against various solvents. (b) Product of permeance and viscosity of solvent as a function of the total Hansen solubility parameter for an ANF hydrogel membrane.

0 10 20 30 40 50 6020

24

28

32

36

40

Perm

eanc

e (L

m-2 h

-1 b

ar-1)

Reaction time (s)

Permeance

0

20

40

60

80

100

Rejection

Reje

ctio

n (%

)

0 4 8 12 16 20 2405

10152025303540

Perm

eanc

e (L

m-2 h

-1 b

ar-1)

Treatment time (h)

Permeance

0

20

40

60

80

100

Rejection

Reje

ctio

n (%

)

a b

Fig. S14 Effect of DMF treatment time (a) and interfacial polymerization reaction time (b) on the separation performance of ANF TFC membrane. (Feed with the methanol/RB solution with dye concentration of 20 mg L-1, tested at 4 bar, 500 rpm)

0 1 2 3 4 5 6 7 8 9 100.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

RB re

ject

ion

(%)

Met

hano

l per

mea

nce

(L m

-2 h

-1 b

ar-1)

Operation time (h)

Methanol permeance

0102030405060708090100110

RB rejection

1.5 LMHbar-1

99.7%

0 1 2 3 4 5 6 7 8 9 100.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

RB re

ject

ion

(%)

Acet

one

perm

eanc

e(L

m-2 h

-1 b

ar-1)

Operation time (h)

Acetone permeance

0102030405060708090100110

RB rejection

1.7 LMHbar-1

99.9%

0 1 2 3 4 5 6 7 8 9 101.01.52.02.53.03.54.04.55.05.56.0

RB re

ject

ion

(%)

DMF

perm

eanc

e (L

m-2 h

-1 b

ar-1)

Operation time (h)

DMF permeance

0102030405060708090100110

RB rejection

2.4 LMHbar-1

99.8%

0 1 2 3 4 5 6 7 8 9 103.5

4.0

4.5

5.0

5.5

6.0

6.5

7.0

RB re

ject

ion

(%)

DMAc

per

mea

nce

(L m

-2 h

-1 b

ar-1)

Operation time (h)

DMAc permeance

0102030405060708090100110

RB rejection

4.7 LMHbar-1

99.7%

0 1 2 3 4 5 6 7 8 9 101.0

1.5

2.0

2.5

3.0

3.5

4.0

RB re

ject

ion

(%)

NMP

perm

eanc

e (L

m-2 h

-1 b

ar-1)

Operation time (h)

NMP permeance

0102030405060708090100110

RB rejection

2.3 LMHbar-1

99.6%

0 5 10 15 20 25 30 35 40 45 50

0

5

10

15

20

25

30

35

40

1

1 NMP2 IPA

3 DMSO 4 DMAc

5 Ethanol 6 DMF7 THF

8 Acetone 9 Methanol

97 8

6

5

34

2

R2=0.932y=0.061x

Solvent permeance

Perm

eanc

e (L

m-2 h

-1 b

ar-1)

Vmcm3 mol-1 cP-1

a b

c d

ef

Fig. S15 (a) Pure solvent permeances against the combined solvent properties (solubility parameter, viscosity and mole volume) for ANF TFC membrane without DMF treatment. (b- f) Separation performance of ANF TFC membrane under solvent of (b) methanol, (c) acetone, (d) DMF, (e) DMAc and (f) NMP, respectively, with rose Bengal (1017 g mol-1) concentration of 40 mg L-1 as the solute at 6 bar with stirring of 500 rpm.

200 250 300 350 400 450 500 550 600 650 700

0.00.51.01.52.02.53.03.54.0

Abso

rban

ce (a

.u.)

Wavelength (nm)

Feed Permeate

RB (MW=1017)

P F

R= 100%

200 250 300 350 400 450 500 550 600 650 700

0.00.51.01.52.02.53.03.54.0

Abso

rban

ce (a

.u.)

Wavelength (nm)

Feed Permeate

EB (MW=836)

P F

200 250 300 350 400 450 500 550 600 650 700

0.00.51.01.52.02.53.03.54.0

Abso

rban

ce (a

.u.)

Wavelength (nm)

Feed Permeate

EY (MW=691.9)

P F

200 250 300 350 400 450 500 550 600 650 700

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Abso

rban

ce (a

.u.)

Wavelength (nm)

Feed Permeate

RO16 (MW=618)

P F

200 250 300 350 400 450 500 550 600 650 700

0.0

0.4

0.8

1.2

1.6

2.0

2.4

2.8

Abso

rban

ce (a

.u.)

Wavelength (nm)

Feed Permeate

JGB (MW=511)

P F

200 250 300 350 400 450 500 550 600 650 700

-0.2

0.0

0.2

0.4

0.6

0.8

1.0

Abso

rban

ce (a

.u.)

Wavelength (nm)

Retentate Permeate

SBB (MW=457)

P F

200 250 300 350 400 450 500 550 600 650 700

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

Abso

rban

ce (a

.u.)

Wavelength (nm)

Feed Permeate

MO (MW=327)

P F

200 250 300 350 400 450 500 550 600 650 700-0.20.00.20.40.60.81.01.21.41.61.8

Abso

rban

ce (a

.u.)

Wavelength (nm)

Feed Permeate

DO3 (MW=242)

P F

R= 100%

R= 100%R= 100%

R= 99.9%R= 99.9%

R= 98.6%R= 54.8%

Fig. S16 Rejection of dyes with different molecular weight (MW) for ANF TFC membrane. Inset photographs of the feed and permeate of dye/ethanol solution.

200 400 600 800 10000

20

40

60

80

100

Molecular weight cut-off (MWCO): 339 Da

PEG

reje

ctio

n (%

)

Molecular weight (Da)

ANF TFC membrane

a b

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.00.0

0.5

1.0

1.5

2.0

2.5

Geometric standarddeviation (p):1.51

Mean effective pore diameter (p): 0.545 nm

Prob

abilit

y de

nsity

func

tion

(nm

-1)

Pore diameter (nm)

ANF TFC membrane

Fig. S17 (a) The rejection of PEGs with different molecular weights through ANF TFC membrane. (b) Probability density function curve of the ANF TFC membrane.

0 5 10 15 20 25 30

1400

1600

1800

2000

2200

2400

2600

2800

4 bar 6 bar 10 bar

Flux

(L m

-2 h

-1)

Time (min)

Fig. S18 Compaction of ANF hydrogel substrate tested with pure water at different pressures in the first half an hour.

2.0 cm

Without post-treatment

Withpost-treatment

Fig. S19 Comparison of the ANF hydrogel TFC membrane without (Left) and with post-treatment (Right) after 180 d stored in a sealed bag. The membrane was treated with a mixture solution of isopropanol (IPA) and glycerol in a ratio of 7:3 (v/v) for one day.

80 84 88 92 96 1000

5

10

15

20

25

30

Upper bound This work

ISA membrane TFC membrane via IP TFC membrane via coating Mixed matrix membrane Commercial membrane ANF TFC membrane

Perm

eanc

e (L

m-2 h

-1 b

ar-1)

Rejection of molecule (%)

Fig. S20 Plot of permeance versus rejection of molecules, showing “trade-off” between permeance and selectivity. Typical OSN data of integral asymmetric (ISA) membrane, TFC membrane, mixed matrix membrane and commercial membrane were summarized from reported literature.

Table S1

Information of dyes used in this study.

Dyes StructureChar

ge

Molecular

weight (g

mol-1)

Topological

polar surface

area (Å2)

UV-vis absorption

(nm)

Disperse

Orange 3 (DO3)0 242 96.6 λEtOH = 445;

Methyl Orange

(MO)- 327 93.5

λEtOH =418;

λDMF, λDMAc =424;

λNMP = 430;

λwater = 464;

Sudan Black B

(SBB)0 457 73.5 λEtOH = 606;

Janus Green B

(JGB)+ 511 48 λEtOH = 651

Reactive

Orange 16

(RO16)

- 614 -

λEtOH = 525;

λDMF, λNMP =508;

λDMAc = 506;

Eosin Y (EY) 0 648 76 λEtOH =528;

Erythrosin B

(EB)0 836 76

λEtOH = 530;

λDMF =544;

λDMAc =549;

λNMP = 541;

Rose Bengal

(RB)- 1017 89.5

λEtOH, λMeOH, λAceonte

=559; λDMF, λDMAc

=564; λNMP = 560;

Table S2Water content and swelling degree of the ANF hydrogel. (Size: 4 × 3 cm)

Swelling degree Water content (%)(Wwet- Wdry) * Wdry-1 (g g-1) (Wwet- Wdry) * Wwet-1 *100%

ANF hydrogel 2.5± 0.3 60.0± 3.8

Table S3

Solvent swelling degrees of ANF hydrogel membrane with PP/PE fabric in various organic solvents for two weeks.

Solvent (Wwet- Wdry) · Wdry-1 (Wwet- Wdry) · Wdry

-1· density-1 (cm3 g-1)

Methanol 1.10 1.39

Ethanol 1.37 1.73

IPA 1.12 1.42

Acetone 0.19 0.24

Ethyl acetate 0.42 0.47

THF 1.26 1.42

DMF 1.68 1.78

DMAc 1.79 1.92

NMP 1.92 1.87

DMSO 2.08 1.89

Table S4

Physical properties of solvent used in this work.

a Data were obtained from the book “Hansen Solubility Parameters: A User’s Handbook (second edition)”. Hansen Solubility Parameters, HSP, δd for Dispersion (van der Waals), δp for Polarity (related to dipole moment) and δh for hydrogen bonding.b Data were calculated from the Hansen solubility parameters.

Hansen solubility parameter

Solvent

Molec

ular

weight

(Mw, g

mol-1)

Dens

ity (g

cm-3)

Surface

tension

(γ, mN

m-1, 20

℃)

Visco

sity

(η, cP,

20 ℃)

Relati

ve

permit

tivity

(g)

Mole

volum

e (Vm,

cm3

mol-1) a

δd

(MPa

1/2) a

δp

(MPa

1/2) a

δh

(MPa

1/2) a

δsp

(MPa

1/2) b

Methanol 32.0 0.79 22.7 0.59 32.7 40.7 15.1 12.3 22.3 29.6

Ethanol 46.1 0.79 22.1 1.2 24.5 58.5 15.8 8.8 19.4 26.5

IPA 60.1 0.79 23.0 2.4 19.9 76.8 15.8 6.1 16.4 23.6

Acetone 58.1 0.79 25.2 0.32 20.7 74.0 15.5 10.4 7.0 20.0

NMP 99.1 1.03 40.8 1.67 32.2 96.5 18.0 12.3 7.2 23.0

DMAc 87.1 0.94 36.7 2.14 37.8 92.5 16.8 11.5 10.2 22.8

DMF 73.1 0.94 37.1 0.92 36.7 77.0 17.4 13.7 11.3 24.8

DMSO 78.1 1.10 43.5 2.24 46.7 71.3 18.4 16.4 10.2 26.7

EtOAc 88.1 0.90 24.0 0.46 6.0 98.5 15.8 5.3 7.2 18.2

THF 72.1 0.89 26.4 0.55 7.6 81.7 16.8 5.7 8.0 19.5

Hexane 86.2 0.66 18.4 0.31 1.9 131.6 14.9 0 0 14.9

Water 18.0 1.00 72.8 1.0 78.5 18.0 15.5 16.0 42.3 47.8

Table S5

Comparison of OSN performance in harsh organic solvent for nanofibrous hydrogel TFC membrane in this work with other polymer substrate based TFC membrane via interfacial polymerization.

Materials SolventPermeance(L m-2 h-1

bar-1)Solute (g mol-1) Rejection (%) Ref.

PA/PI Acetone 2.4Styrene oligomers(236- 1200 g mol-

1)

95.0 (236 g mol-1)

[1]

DMF 1.5 91.0 (236 g mol-1)

PA/PI DMF 3.9 Tetracycline (444 g mol-1) 95.0 [2]

(PA-COF)/PI DMF 5.5 Rose Bengal (1017 g mol-1) 99.5 [3]

(DA/TMC)/PI DMF 1.15 Rose Bengal (1017 g mol-1) 99.9 [4]

(PAR-BHPF)/PI Acetone 8.4

Styrene oligomers(236- 1200 g mol-

1)

97.0 (236 g mol-1)

[5]

PA/PAN Acetone 6.0 Oleic acid (282 g mol-1) 92.0 [6]

(Morin-TPC)/PAN NMP 0.3 Brilliant Blue

(826 g mol-1) 96.0 [7]

PA/PBOI DMF 7.7Styrene oligomers(236- 1200 g mol-

1)

>90.0 (600 g mol-1)

[8]

(Tannic acid-TPC)/PAN NMP 0.08 Brilliant Blue

(826 g mol-1) 95.0 [9]

PA/Cellulose DMF 1.4 Amido-Black(617 g mol-1) 92.0 [10]

PA/ANF hydrogel (without solvent

treatment)

DMF 20.3 Methyl orange (327 g mol-1) 64.0 This

work

10.6Reactive orange

16 (618 g mol-1)

92.3

8.1 Erythrosin B (836g mol-1) 99.3

3.5 Rose Bengal (1017 g mol-1) 99.4

DMAc 8.4 Methyl orange (327 g mol-1) 91.4 This

work

7.6Reactive orange

16 (618 g mol-1)

93.0

7.3 Erythrosin B (836g mol-1) 97.1

5.3 Rose Bengal (1017 g mol-1) 99.7

NMP 4.9 Methyl orange (327 g mol-1) 94.4 This

work

8.8Reactive orange

16 (618 g mol-1)

93.1

1.8 Erythrosin B (836g mol-1) 99.9

2.3 Rose Bengal (1017 g mol-1) 99.6

PA/ANF hydrogel (with

solvent treatment)

Acetone 19.0 Rose Bengal (1017 g mol-1) 100.0 This

work

DMF 6.0 99.5 This work

DMAc 10.0 97.0 This work

NMP 5.0 100.0 This work

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