Reducing active layer thickness of polyamide composite membranes using a covalent organic framework interlayer in interfacial polymerization

Journal Pre-proof Reducing active layer thickness of polyamide composite membranes using a covalent organic framework interlayer in interfacial polymerization

Meidi Wang, Weixiong Guo, Zhongyi Jiang, Fusheng Pan PII:

S1004-9541(19)30925-5

DOI:

https://doi.org/10.1016/j.cjche.2019.11.007

Reference:

CJCHE 1587

To appear in:

Chinese Journal of Chemical Engineering

Received date:

27 September 2019

Revised date:

15 November 2019

Accepted date:

21 November 2019

Please cite this article as: M. Wang, W. Guo, Z. Jiang, et al., Reducing active layer thickness of polyamide composite membranes using a covalent organic framework interlayer in interfacial polymerization, Chinese Journal of Chemical Engineering(2019), https://doi.org/10.1016/j.cjche.2019.11.007

This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

© 2019 Published by Elsevier.

Journal Pre-proof

Reducing active layer thickness of Polyamide composite membranes using a covalent organic framework interlayer in interfacial polymerization

Meidi Wanga,b,#, Weixiong Guoa,b,#, Zhongyi Jiangb, Fusheng Pana,b,* a

State Key Laboratory of Petroleum Pollution Control, CNPC Research Institute of Safety and

oo

b

f

Environmental Technology, Beijing 102206, China.

Key Laboratory for Green Chemical Technology of Ministry of Education School of Chemical

These authors contributed equally to this work.

Jo u

rn

al

Pr

e-

#

pr

Engineering and Technology, Tianjin University, Tianjin 300072, China



Corresponding author. School of Chemical Engineering and Technology, Tianjin University, No.

135, Yaguan Road, Jinnan District, Tianjin 300350, China. Tel: +8 6-22-23500086. Fax: +86-22-23500086. E-mail address: [email protected],

Journal Pre-proof Abstract Polyamide (PA)-based thin-film composite membranes exhibit enormous potential in water purification, owing to their facile fabrication, decent performance and desirable stability. However, the thick PA active layer with high transport resistance from the conventional interfacial polymerization hampers their applications. The controllable fabrication of a thin PA active layer is essential for high separation efficiency but still challenging. Herein, a covalent organic framework TpPa-1 interlayer was firstly

oo

f

deposited on a polyethersulfone (PES) substrate to reduce the thickness of PA active layer in interfacial polymerization. The abundant pores of TpPa-1 increase the local

pr

concentration of amine monomers by adsorbing piperazine molecules, while hydrogen

e-

bonds between hydrophilic groups of TpPa-1 and piperazine molecules slow down

Pr

their diffusion rate. Arising from those synergetic effects, the PA active layer is effectively reduced from 200nm to 120nm. By optimizing TpPa-1 interlayer and PA

al

active layer, the flux of resultant membranes can reach 171.35 L m-2 h-1 MPa-1, which

rn

increased by 125.4% compared with PA/PES membranes, while the rejection rates of

Jo u

sodium sulfate and dyes solution remained more than 90% and 99%, respectively. Our strategy may stimulate rational design of ultrathin PA-based nanofiltration membranes with high performances.

Graphical abstract The PA/TpPa-1/PES nanofiltration membranes with a thin PA layer and an improved flux were prepared and manipulated by a TpPa-1 COFs interlayer.

Keywords: Thin film composite membranes; Interfacial polymerization; Covalent organic frameworks interlayer; Nanofiltration

Journal Pre-proof

1. Introduction Nanofiltration, a pressure-driven membrane separation technology, which possesses high rejection rates for small organic molecules and inorganic salts, has advantages of low consumption and environmental friendliness compared to conventional technologies in water purification[1, 2]. The interfacial polymerization of two monomers including diamines and trimesoyl chloride (TMC) at an aqueous-organic

oo

f

interface is considered as a promising way for preparing nanofiltration membranes. The consequent thin-film composite (TFC) membranes, which contain a polyamide

pr

(PA) active layer obtained by interfacial polymerization and a beneath porous

Pr

and wastewater reutilization[3, 4].

e-

substrate, have been widely used for water decontamination, seawater desalination

The permeability of the TFC membranes, that determines the efficiency of the

al

separation process, is inversely proportional to the thickness of active layer[5].

rn

However, TFC nanofiltration membranes are generally suffered from an inferior

Jo u

permeability due to the relatively thick active layer created from interfacial polymerization. The thickness of active layer in the interfacial polymerization is mainly determined by the reaction activity of two monomers and the diffusion rate of monomers to the phase interface[6]. Freger et al. summarized the kinetic model of PA active layer formed by interfacial polymerization, and demonstrated that the thickness of PA active layer is governed by the local concentration of diamine monomers and the diffusion rate of diamine monomers in organic phase[7, 8]. The thinner PA active layer can be acquired by the higher local concentration of diamines monomer, as well as their slower diffusion rate. Various modifiers or interlayers were incorporated to manipulate the interfacial polymerization process of PA-based membranes based on

Journal Pre-proof abovementioned theory[9, 10]. The hydrophilic materials such as polyvinyl alcohol (PVA)[11] and amino acids[12], as well as porous materials such as zeolites[13] and metal-organic frameworks[14] have been widely utilized. Hydrophilic materials can effectively regulate the diffusion of diamine monomers in aqueous phase through the hydrophilic interaction, while porous materials can adsorb diamine monomers in their anfractuous channels and regulate the diffusion of diamine monomers[15]. Nevertheless, integrating these two parts and synergizing multiple functions in an

oo

f

interlayer remain a grand challenge.

Covalent organic frameworks (COFs) represent a new type of porous crystalline

pr

materials, which are ingeniously linked by robust covalent bonds between light

e-

elements (C, O, N, B) to generate periodic frameworks[16]. The intriguing properties

Pr

demonstrate COFs promising materials in the field of catalysis, sensoring and energy storage[17]. Besides, the intrinsic porous and crystalline properties with the tunable

al

organic linkers make COFs attract increasing interests in separation applications[18].

rn

The highly ordered channels favor an efficient molecular sieving effect and a reduced

Jo u

mass transfer resistance. Recently, various COF membranes and COF-based mixed matrix membranes have been used in gas separation[19, 20], pervaporation[21, 22] and water treatment[23, 24], and expectedly exhibited desirable separation performance and operational stability. In comparison with the existing inorganic materials or organic-inorganic composite materials, COFs are completely connected by organic building blocks, which not only possess advantages of low density and large surface area, but also have better affinity to polymers due to their organic nature. Such desirable compatibility is benefit for eliminating non-selective interface defects and agglomeration of oligomers during interfacial polymerization. Moreover, the long-range ordered channels with abundant hydrophilic groups on COF skeleton is

Journal Pre-proof conducive to manipulate the diffusion of diamine monomers, which may contribute to a thin PA active layer in the interfacial polymerization process. In this study, a COF interlayer was deposited on a PES porous substrate to reduce the thickness of PA active layer in the fabrication of TFC membranes. The TpPa-1 COF interlayer was synthesized by polymerization of 1, 3, 5-triuronic phloroglucinol (Tp) and p-phenylenediamine (Pa-1). Then PA active layer was fabricated by interfacial polymerization between Piperazine (PIP) and trimesoyl chloride (TMC)

oo

f

under the manipulation of TpPa-1 COF interlayer. The structures and properties of the fabricated membranes were explored, such as surface and cross-section morphologies,

pr

hydrophilicity, roughness. Effects of TpPa-1 interlayer structures and interfacial

Pr

dye solutions were also investigated.

e-

polymerization time on the water flux and rejection rate of sodium sulfate as well as

al

2. Experimental

rn

2.1 Materials

Jo u

Piperazine (PIP), trimesoyl chloride (TMC), Methyl blue (MB), Congo red (CR) and Eriochome black T were obtained from Shanghai Aladdin Reagent Co. p-Phenylenediamine (Pa-1) was purchased from Adamas Chemical Reagent Co. 1, 3, 5-triuronic

phloroglucinol

(Tp)

was

purchased

from Changchun Sanbang

Pharmaceutical Co., Ltd. sodium chloride (NaCl), magnesium chloride (MgCl2), sodium sulfate (Na2SO4) and magnesium sulfate (MgSO4) were purchased from Tianjin Guangfu Fine Chemical Research Institute. N-heptane and ethanol were obtained from Tianjin Kemiou Chemical Reagent Co. Polyethersulfone (PES) porous substrate with aperture of 0.1 um was supplied by Nengda filter equipment Co., Ltd. All the reagents were used without further purification.

Journal Pre-proof

2.2 Preparation of the membranes The preparation process of the membranes was illustrated in Fig. 1. A TpPa-1 interlayer was firstly deposited on a PES substrate. A commercial PES substrate (50 mm in diameter, 0.1 um in aperture) was fixed in a fixture, and a 0.05 wt.% Pa-1 aqueous solution (containing 1.0 wt.% 3M acetic acid) was poured onto the PES membrane surface with standing for 30 s. After the membrane was dried until no

oo

f

obvious water was observed on the surface, the n-heptane solution with Tp concentration of 0.04 wt.% was poured onto the surface and reacted for x s

pr

(x=25~100). Subsequently, the resultant membrane was taken out from the fixture and

Pr

with deionized water for several times.

e-

heat-treated in oven at 60 oC for 5 min. The TpPa-1x/PES was obtained after washed

The interfacial polymerization was performed to create a thin PA active layer with

al

the TpPa-1x/PES as substrate. The substrate was placed in a 0.05 wt.% PIP aqueous

rn

solution for 2 min. Next, the membrane was removed and wiped with a filter paper to

Jo u

absorb the remaining water on the surface. After that, the membrane was sequently immersed in a n-heptane solution with 0.05 wt.% TMC for the interfacial polymerization of 90 s. The resultant membrane was removed and placed in an oven at 60 ℃ for 15 min. The final PA/TpPa-1x/PES nanofiltration membrane was obtained and soaked in deionized water for later use. The controlled PA/PES membrane was fabricated for comparison.

oo

f

Journal Pre-proof

e-

pr

Fig. 1 Scheme of the preparation method of the PA/TpPa-1x/PES membrane

Pr

2.3 Characterization

The membrane morphology was characterized by a S-4800 scanning electron

al

microscope (Hitachi, Japan). The membranes were freeze-dried for 12 h in the freeze

rn

dryer and then quenched in liquid nitrogen. After treated with ion sputtering apparatus,

Jo u

the sectional and surface morphologies were observed by scanning electron microscopy (SEM). The chemical structures of membranes were characterized using Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR, Bruker Vertex 70 FTIR). The membrane samples were freeze dried and cut into 1 cm x 1 cm slices. The contact angle measuring instrument (JC-2000D2M Contact Angle Meter) was applied to characterize the hydrophilicity of the membranes. The freeze-dried membrane samples were placed face to face on the glass slide, and a drop of deionized water was dropped on the membrane surface. At least 5 points of each sample were recorded for testing. The membrane surface zeta potential was measured by a SurPASS Electrokinetic Analyzer (Anton Paar KG, Graz) with the pH value of

Journal Pre-proof 7.5 and the temperature of 25 °C. An atomic force microscope (AFM) was applied to detect the roughness and the surface morphology of the membranes.

2.4 Nanofiltration performance evaluation A Model 8010 filtration cell with a diameter of 25 mm and working area of 4.1 cm-2 was applied to conduct a dead-end nanofiltration at room temperature. Specifically, the membrane was first fixed in the filter, and compacted under 0.25 MPa for 30min

oo

f

to obtain a constant water flux. Next, the pressure was adjusted to 0.20 MPa to record the mass change of permeated water in a certain time. The pure water flux was

pr

calculated by equation (1):

e-

𝑉

𝐽 = 𝐴∆𝑡

(1)

Pr

Where J (L m-2 h-1) was the pure water flux, V (L) was the the volume of the permeated water, A (m2) was the effective filtration area (4.1 cm2), and Δt was the

al

operation time (h).

rn

The deionized water was replaced by an inorganic salt solution (1.0 g/L) or a dye

Jo u

solution (0.1 g/L) to test the salt or dye retention performances of the membranes. And the rejection rate (R) was calculated by equation (2): 𝐶

𝑅 = (1 − 𝐶𝑓 ) × 100% 𝑜

(2)

Where Cf and Co were the concentration of permeated solution and feed solution (g/L). Salt concentrations were tested by electrical conductivity (DDS-11A), while dye concentrations were measured by a UV-vis spectrophotometer (Hitachi UV-2800).

3. Results and discussion 3.1 Characterization of the PA/TpPa-1/PES membrane The chemical composition of PA/TpPa-150/PES nanofiltration membranes was

Journal Pre-proof analyzed by FTIR spectra as shown in Fig. 2. PA/PES and PA/TpPa-150/PES membranes showed characteristic stretching vibration peaks of carbonyl groups at 1632 cm-1, evidencing the formation of PA active layer, which was due to the conversion of acyl chloride groups to carbonyl groups after reaction with PIP in the interface polymerization[2]. The vibration peak of secondary amine groups was also detected in the spectral diagram of PA/TpPa-150/PES membranes at 1560 cm-1, which was attributed to the secondary amine groups on the TpPa-1 skeleton[25],

oo

f

demonstrating the successful introduction of TpPa-1 interlayer in the membranes. PA/TpPa-1/PES

pr

1560cm-1(N-H)

PA/PES

e-

1632cm-1(C=O)

2000

1600

al

2400

Pr

PES

1200

800

400

-1

rn

Wavenumber(cm )

Jo u

Fig. 2 FTIR spectra of PES, PA/PES and PA/TpPa-150/PES membranes

The surface hydrophilicity was analyzed by the static water contact angle as shown in Fig. 3. After introducing TpPa-1 interlayer, the water contact angles decreased slightly from 62.6o of PA/PES membrane to 50-55o of PA/TpPa-1x/PES membranes. The water contact angle was determined by the chemical composition and physical roughness of the membrane surface. Since the chemical composition of PA/TpPa-1x/PES membrane surface was almost the same (PA active layer), the physical roughness played a dominant role and were characterized by AFM. As shown in Fig. 4, the surface roughness of PA/PES membrane was Ra=33.9 nm and Rq=43.5

Journal Pre-proof nm, while that of PA/TpPa-150/PES membrane increased to Ra=52.1 nm and Rq=76.0 nm after the introduction of TpPa-1 interlayer. The increase of surface roughness was mainly caused by two aspects. Firstly, the introduction of TpPa-1 interlayer increased the roughness directly. Secondly, the adsorption of PIP molecules by TpPa-1 interlayer increased the concentration of PIP on the membrane surface, producing more nozzle-like structures on PA active layer[26]. Notably, TpPa-1 interlayer with a shorter synthesis time tended to form a rougher surface, since discrete TpPa-1 crystal

pr

oo

f

nucleus would generate which are unable to achieve sufficient intergrowth[27].

e-

60 50

Pr

40 30

10 0

al

20

rn

Water contact angle(degree)

70

S /PE PA

/T PA

Jo u

S

S S S /PE /PE /PE 0 1 1 75 0 1 50 1 Pa Pa Pa/Tp /Tp /Tp PA PA PA

/PE a-1 25 pP

Fig. 3 Water contact angles of PA/PES and PA/TpPa-1x/PES membranes

Fig. 4 AFM images of (a) PA/PES and (b) PA/TpPa-150/PES membranes

Journal Pre-proof

The surface charge property of the membrane has a vital influence on its retention performance especially for ions. As revealed in Fig. 5, the zeta potential tests indicated that PA/PES membrane was negatively charged with zeta potential of -109.3 mV. The slight decrease of zeta potential was observed after introducing TpPa-1 interlayer. And the decrease became more pronounced with the increase of TpPa-1 interlayer synthesis time. Finally, when reaction time was 100 s, zeta potential

oo

f

decreased to -95.2 mV. It can be ascribed that secondary amines on TpPa-1 skeleton can react with acyl chloride groups in TMC[28]. More TpPa-1 would deposit with

pr

longer reaction time, whose secondary amines would consume more acyl chloride

Pr

e-

groups.

0

al

-40

rn

-60 -80

Jo u

Zeta potential(mV)

-20

-100 -120

PA

S S S S /PE /PE /PE /PE 1 00 75 -1 25 1 50 1 1 a a P P Pa Pa /Tp /Tp /Tp /Tp PA PA PA PA

S /PE

Fig. 5 Zeta potential of PA/PES and PA/TpPa-1x/PES membranes

The surface and cross-sectional morphologies of the membranes were characterized by SEM, and the results were shown in Fig. 6 and Fig. 7, respectively. The pristine PES substrate in Fig. 6a showed a typical macroporous structure with the aperture size of ~100 nm. After depositing TpPa-1 interlayer as shown in Fig. 6c, the pores of PES

Journal Pre-proof substrate were filled by TpPa-1 and the TpPa-1/PES substrate showed a rougher surface. PA/PES and PA/TpPa-150/PES membranes in Fig. 6b and 6d indicated that the substrates were covered by a smooth PA active layer with nodal convex structures. Such structures were derived from the rapid reaction between PIP and TMC. And the surface of PA/TpPa-150/PES manifested relatively rougher than that of PA/PES, which was consistent with the results of AFM. As illustrated in Fig. 7, the PA active layer of PA/PES membrane was ~200 nm, and the thickness decreased with the introduction of

oo

f

TpPa-1 interlayer. When TpPa-1 interlayer synthesized within 50s, the thickness of PA active layer decreased to ~120 nm. According to the Freger’s theory, the thickness of

pr

PA active layer decreased with the increase of local concentration of amine monomer

e-

and the decrease of diffusion rate of amine monomer in organic phase. TpPa-1

Pr

interlayer could adsorb more amine monomers taking advantage of its pore structures, which increased the concentration of local amine monomers. Moreover, the

al

hydrophilic groups in TpPa-1, such as carbonyl group and secondary amine group,

rn

could form hydrogen bonds with PIP molecules to slow down their diffusion[29]. The

layer.

Jo u

synergistic effects of TpPa-1 interlayer effectively reduced the thickness of PA active

Journal Pre-proof Fig. 6 SEM images of surfaces for (a) pure PES substrate, (b) PA/PES membrane

e-

pr

oo

f

(c) TpPa-150/PES membrane and (d) PA/TpPa-150/PES membrane.

Pr

Fig. 7 Cross-sectional images of (a) pure PES substrate, (b) PA/PES membrane,

al

(c) TpPa-150/PES membrane and (d) PA/TpPa-150/PES membrane.

rn

3.2 Separation performance of the membranes

Jo u

3.2.1 Effect of TpPa-1 interlayer on the nanofiltraton performance The influence of TpPa-1 synthesis time on the separation performance of the membrane was shown in Fig. 8 (a). The water flux of PA/PES membrane is 76.15 L m-2 h-1 MPa-1. After introducing the TpPa-1 interlayer, the water fluxes of PA/TpPa-1x/PES membranes were highly enhanced. With the increase of reaction time in the synthesis of TpPa-1 interlayer, flux of the prepared PA/TpPa-1x/PES membranes firstly increased to 171.35 L m-2 h-1 MPa-1, and then decreases to 125.20 L m-2 h-1 MPa-1. The enhanced water flux was attributed to the synergistic effects of porous structures and hydrophilic nature of TpPa-1, which manipulated the thickness of PA active layer. With the longer reaction time of TpPa-1 interlayer up to 50s, a more complete TpPa-1 interlayer deposited on the PES substrate, which reduced the

Journal Pre-proof thickness of the PA active more effectively. However, with the further increase of reaction time, the intergrowth and self-correction processes of TpPa-1 would result in a dense interlayer, which may increase the mass transfer resistance. The rejection of Na2SO4 mainly depends on the surface charge property based on the Donnan effect. As demonstrated in Fig. 5, the zeta potential changed slightly with different synthesis time, the rejection ability towards salts kept constant. Both the PA/PES membrane and the PA/TpPa-1x/PES membranes showed a high Na2SO4 rejection (higher than 95%),

oo

f

indicating the synthesis of a complete PA active layer in the thin-film composite

pr

100

160

e-

60

40

20

140 120 100 80

Water flux Rejecation of Na2SO4

al

0

180

Pr

Rejeaction (%)

80

0

20

40

200

60 60

80

100

Water flux (L m-2 h-1 MPa-1)

membranes.

40

rn

Reaction time (s)

Fig. 8 Effects of TpPa-1 interlayer reaction time on the separation performance

Jo u

of PA/TpPa-1x/PES membrane

3.2.2 Effects of PA active layer on the nanofiltraton performance Effects of reaction time in the interfacial polymerization using TpPa-150/PES substrate on the membrane performance were investigated as shown in Fig. 9. With the extension of interfacial polymerization time, more PIP molecules would react with TMC molecules in organic phase to form highly crosslinking structures, which increased the thickness and compactness of PA active layer. Therefore, the resultant membranes display a significantly decreased flux with a slightly improved rejection rate towards Na2SO4. A 90-second interfacial polymerization was considered as

Journal Pre-proof optimal reaction times considering separation performance and preparation efficiency. Under the 90-second interfacial polymerization, the optimum performance is achieved with a flux of 171.35 L m-2 h-1 MPa-1 and a Na2SO4 rejection rate higher than 90%. 100

280

220 80

200 180

70

160 60

140

50

40

60

f

Water flux Rejecation of Na2SO4

120

80

100

120

100

pr

Reaction time (s)

oo

Rejeaction (%)

240

Water flux (L m-2 h-1 MPa-1)

260 90

Fig. 9 Effects of reaction time in the interfacial polymerization on the separation

Pr

e-

performance of PA/TpPa-150/PES membrane

3.2.3 Dye rejection and desalination performance of the membranes

al

The dye rejection performance of the PA/TpPa-150/PES membrane was evaluated

rn

by methyl blue, congo red and alcian blue solution. The membrane can reject all of

Jo u

these dyes higher than 99% as shown in Fig. 10 (a). The prepared nanofiltration membranes are constructed by three layers including a PA active layer, a TpPa-1 interlayer and a PES substrate. PA is a typical dense polymer. TpPa-1 is a porous crystalline material with an intrinsic aperture of 1.8nm. And the PES substrate possesses macroporous structures, which featured with negligible mass transfer resistance. A solution-diffusion mechanism is usually used to describe the mass transfer of water molecules in the PA layer. Afterwards, water molecules rapidly transfer across the TpPa-1 interlayer and the PES substrate taking the advantage of the porous structures. Dye molecules hardly solute in the PA layer due to their large size, which leads to the high rejection of dye molecules. Moreover, the TpPa-1 interlayer

Journal Pre-proof also weakly contributes to the rejection of dye molecules owing to the microporous nature. The results demonstrated the structural integrity of the membranes and the potential in practical application. The desalination performance of the PA/TpPa-150/PES membrane was also evaluated as shown in Fig. 10 (b). The rejection rates of the membrane followed a sequence of Na2SO4 (93%) > MgSO4 (65%) > NaCl (25%) > MgCl2 (22%). The rejection of the membrane was determined by the size sieving and Donnan exclusion.

oo

f

The negatively charged groups on the membrane surface as shown by the zeta potential tests could generate repel electrostatic interaction towards anion ions, which

pr

give rise to the rejection rate.

e-

The judiciously introduction of a TpPa-1 interlayer effectively reduced thickness

Pr

of the PA active layer without sacrificing its structural integrity. Therefore, the resultant nanofiltration membranes with a reduced PA active layer keep constant

120

PA/PES PA/TpPa-1/PES

80 60 40

Jo u

Rejection(%)

100

(b)

80

PA/PES PA/TpPa-1/PES

60

Rejection(%)

(a)

rn

al

rejections towards dye molecules and salts while bearing an improved water flux.

40

20

20 0

0 Methyl blue

Congo red

MgSO4

Chrome black T

NaCl

MgCl2

Fig. 10 Rejections of PA /PES and PA/TpPa-150/PES membranes for (a) dyes and (b) salts

4. Conclusion Composite membranes with thin PA active layer were prepared by interfacial

Journal Pre-proof polymerization utilizing TpPa-1 COFs as the interlayer on the surface of PES porous substrate. The introduction of TpPa-1 interlayer was demonstrated by FTIR. The TpPa-1 interlayer increased the surface roughness and enhanced the surface hydrophilicity. The TpPa-1 interlayer also decreased the thickness of PA active interlayer from 200 nm of PA/PES membrane to 120nm of PA/TpPa-150/PES membrane by increasing the local concentration of amine monomers and slowing down the diffusion rate of PIP molecules in the interfacial polymerization. The

oo

f

optimum PA/TpPa-150/PES membrane exhibited a permeation flux of 171.35 L m-2 h-1 MPa-1, which increased by 125.4% compared with PA/PES membranes, and a

pr

rejection rate of sodium sulfate higher than 90% as well as dye rejection rates higher

e-

than 99%. This study provides a strategy for preparing nanofiltration membranes with

Acknowledgements

al

Pr

a thin active layer by interfacial polymerization.

rn

This research was supported by the Open Project Program of State Key Laboratory

Jo u

of Petroleum Pollution Control (Grant No. PPC2017014), CNPC Research Institute of Safety and Environmental Technology.

Declaration of Interest Statement The authors declare no conflicts of interests.

Reference [1] P. Marchetti, M.F. Jimenez Solomon, G. Szekely, A.G. Livingston, Molecular separation with organic solvent nanofiltration: a critical review, Chem. Rev., 114

Journal Pre-proof

(2014) 10735-10806. [2] R. Bi, R. Zhang, J. Shen, Y.-n. Liu, M. He, X. You, Y. Su, Z. Jiang, Graphene quantum dots engineered nanofiltration membrane for ultrafast molecular separation, J. Membr. Sci., 572 (2019) 504-511. [3] J.R. Werber, C.O. Osuji, M. Elimelech, Materials for next-generation desalination

f

and water purification membranes, Nat. Rev. Mater., 1 (2016).

oo

[4] Y.L. Ji, W.J. Qian, Y.W. Yu, Q.F. An, L.F. Liu, Y. Zhou, C.J. Gao, Recent

pr

developments in nanofiltration membranes based on nanomaterials, Chin. J. Chem.

e-

Eng., 25 (2017) 1639-1652.

Pr

[5] Z. Zhang, X. Shi, R. Wang, A. Xiao, Y. Wang, Ultra-permeable polyamide membranes harvested by covalent organic framework nanofiber scaffolds: a

al

two-in-one strategy, Chem. Sci., (2019).

rn

[6] Z.A. Yi, F.D. Wu, Y. Zhou, C.J. Gao, Novel nanofiltration membranes with tunable

Jo u

permselectivity by polymer mediated phase separation in polyamide selective layer, Chin. J. Chem. Eng., 24 (2016) 1533-1540. [7] V. Freger, Nanoscale Heterogeneity of Polyamide Membranes Formed by Interfacial Polymerization, Langmuir, 19 (2003) 4791-4797. [8] V. Freger, S. Srebnik, Mathematical model of charge and density distributions in interfacial polymerization of thin films, J. Appl. Polym. Sci., 88 (2010) 1162-1169. [9] H. Wu, H. Sun, W. Hong, L. Mao, Y. Liu, Improvement of Polyamide Thin Film Nanocomposite Membrane Assisted by Tannic Acid-Fe(III) Functionalized Multiwall Carbon Nanotubes, ACS Appl. Mater. interf., 9 (2017) 32255-32263.

Journal Pre-proof

[10] Y.-S. Guo, Y.-F. Mi, F.-Y. Zhao, Y.-L. Ji, Q.-F. An, C.-J. Gao, Zwitterions functionalized multi-walled carbon nanotubes/polyamide hybrid nanofiltration membranes for monovalent/divalent salts separation, Sep. Purif. Technol., 206 (2018) 59-68. [11] Z. Tan, S. Chen, X. Peng, L. Zhang, C. Gao, Polyamide membranes with

f

nanoscale Turing structures for water purification, Science, 360 (2018) 518-521.

oo

[12] L. Fan, Q. Zhang, Z. Yang, R. Zhang, Y.N. Liu, M. He, Z. Jiang, Y. Su,

pr

Improving Permeation and Antifouling Performance of Polyamide Nanofiltration

e-

Membranes through the Incorporation of Arginine, ACS Appl. Mater. interf., 9 (2017)

Pr

13577-13586.

[13] Q. Wang, G.-s. Zhang, Z.-s. Li, S. Deng, H. Chen, P. Wang, Preparation and

al

properties of polyamide/titania composite nanofiltration membrane by interfacial

rn

polymerization, Desalination, 352 (2014) 38-44.

Controlled

Jo u

[14] C. Van Goethem, R. Verbeke, S. Hermans, R. Bernstein, I.F.J. Vankelecom, positioning

of

MOFs

in

interfacially

polymerized

thin-film

nanocomposites, J. Mater. Chem. A, 4 (2016) 16368-16376. [15] K. Santanu, J. Zhiwei, A.G. Livingston, MEMBRANE FILTRATION. Sub-10 nm polyamide nanofilms with ultrafast solvent transport for molecular separation, Science, 348 (2015) 1347. [16] R.P. Bisbey, W.R. Dichtel, Covalent Organic Frameworks as a Platform for Multidimensional Polymerization, ACS Cent. Sci., 3 (2017) 533-543. [17] S.Y. Ding, W. Wang, Covalent organic frameworks (COFs): from design to

Journal Pre-proof

applications, Chem. Soc. Rev., 42 (2013) 548-568. [18] H. Wang, Z. Zeng, P. Xu, L. Li, G. Zeng, R. Xiao, Z. Tang, D. Huang, L. Tang, C. Lai, D. Jiang, Y. Liu, H. Yi, L. Qin, S. Ye, X. Ren, W. Tang, Recent progress in covalent organic framework thin films: fabrications, applications and perspectives, Chem. Soc. Rev., 48 (2019) 488-516.

f

[19] H. Fan, A. Mundstock, A. Feldhoff, A. Knebel, J. Gu, H. Meng, J. Caro, Covalent

oo

Organic Framework-Covalent Organic Framework Bilayer Membranes for Highly

pr

Selective Gas Separation, J. Am. Chem. Soc., 140 (2018) 10094-10098.

e-

[20] Y. Ying, D. Liu, J. Ma, M. Tong, W. Zhang, H. Huang, Q. Yang, C. Zhong, A

Pr

GO-assisted method for the preparation of ultrathin covalent organic framework membranes for gas separation, J. Mater. Chem. A, 4 (2016) 13444-13449.

Constructing

covalent

organic

facilitated

framework

transport nanosheets

membranes with

by

tunable

Jo u

incorporating

channel-mediated

rn

Jiang,

al

[21] M. Wang, F. Pan, H. Yang, Y. Cao, H. Wang, Y. Song, Z. Lu, M. Sun, H. Wu, Z.

microenvironments, J. Mater. Chem. A, 7 (2019) 9912-9923. [22] H. Yang, H. Wu, Z. Yao, B. Shi, Z. Xu, X. Cheng, F. Pan, G. Liu, Z. Jiang, X. Cao, Functionally graded membranes from nanoporous covalent organic frameworks for highly selective water permeation, J. Mater. Chem. A, 6 (2018) 583-591. [23] H. Fan, J. Gu, H. Meng, A. Knebel, J. Caro, High-Flux Membranes Based on the Covalent Organic Framework COF-LZU1 for Selective Dye Separation by Nanofiltration, Angew. Chem. Int. Ed. Engl., 57 (2018) 4083-4087. [24] J. Yuan, M. Wu, H. Wu, Y. Liu, X. You, R. Zhang, Y. Su, H. Yang, J. Shen, Z.

Journal Pre-proof

Jiang, Covalent organic framework-modulated interfacial polymerization for ultrathin desalination membranes, J. Mater. Chem. A, 7 (2019) 25641-25649. [25] S. Kandambeth, A. Mallick, B. Lukose, M.V. Mane, T. Heine, R. Banerjee, Construction of crystalline 2D covalent organic frameworks with remarkable chemical (acid/base) stability via a combined reversible and irreversible route, J. Am.

f

Chem. Soc., 134 (2012) 19524-19527.

oo

[26] J.-J. Wang, H.-C. Yang, M.-B. Wu, X. Zhang, Z.-K. Xu, Nanofiltration

pr

membranes with cellulose nanocrystals as an interlayer for unprecedented

e-

performance, J. Mater. Chem. A, 5 (2017) 16289-16295.

Pr

[27] F. Pan, W. Guo, Y. Su, N.A. Khan, H. Yang, Z. Jiang, Direct growth of covalent organic framework nanofiltration membranes on modified porous substrates for dyes

al

separation, Sep. Purif. Technol., 215 (2019) 582-589.

rn

[28] C. Wang, Z. Li, J. Chen, Z. Li, Y. Yin, L. Cao, Y. Zhong, H. Wu, Covalent

Jo u

organic framework modified polyamide nanofiltration membrane with enhanced performance for desalination, J. Membr. Sci., 523 (2017) 273-281. [29] H. Yang, H. Wu, Z. Xu, B. Mu, Z. Lin, X. Cheng, G. Liu, F. Pan, X. Cao, Z. Jiang, Hierarchical pore architectures from 2D covalent organic nanosheets for efficient water/alcohol separation, J. Membr. Sci., 561 (2018) 79-88.