Graphene quantum dots (GQDs)-polyethyleneimine as interlayer for the fabrication of high performance organic solvent nanofiltration (OSN) membranes

Chemical Engineering Journal 380 (2020) 122462

Contents lists available at ScienceDirect

Chemical Engineering Journal journal homepage: www.elsevier.com/locate/cej

Graphene quantum dots (GQDs)-polyethyleneimine as interlayer for the fabrication of high performance organic solvent nanofiltration (OSN) membranes ⁎

T

⁎

Yizhi Lianga,b, Can Lia,b, Shuxuan Lia,b, Baowei Sua,b, , Michael Z. Huc, , Xueli Gaoa,b, Congjie Gaoa,b a b c

Key Laboratory of Marine Chemistry Theory and Technology (Ocean University of China), Ministry of Education, 238 Songling Road, Qingdao 266100, China College of Chemistry & Chemical Engineering, Ocean University of China, 238 Songling Road, Qingdao 266100, China Energy and Transportation Science Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, United States

H I GH L IG H T

G R A P H I C A L A B S T R A C T

(Ra less than 2 nm) surface of • Smooth the GQDs-interlayered membrane was achieved.

25 nm-thick skin layers of the • The GQDs-interlayered membranes. GQDs-PEI interlayer covalent • The bonded between substrate and skin layer.

prepared membrane maintained • The stable performance in DMF for 45 days at 80 °C.

A R T I C LE I N FO

A B S T R A C T

Keywords: Organic solvent nanofiltration (OSN) Graphene quantum dots (GQDs) Interlayer Interfacial polymerization (IP)

Novel thin film nanocomposite (TFN) organic solvent nanofiltration (OSN) membranes with sandwich-like structure were developed via interfacial polymerization (IP) using both low concentration m-phenylenediamine (MPD) and trimesoyl chloride (TMC), on graphene quantum dots (GQDs)-polyethyleneimine (PEI) modified polyimide substrate surface, and followed by post-IP crosslinking and solvent activation. Such GQDs-interlayered OSN membranes have exhibited a remarkable reduced thickness (about 25 nm) and an ultra-low average surface roughness (less than 2 nm) of their IP skin layers, respectively. Both material features are rarely reported in literature. Meanwhile, our GQDs-interlayered OSN membranes have shown an increased Rhodamine B (479 Da) rejection (from 87.4% to 98.7%) and an increased ethanol permeance (from 33.5 to 40.3 L m−2 h−1 MPa−1) compared with the pristine OSN membrane. Superior solvent resistance was demonstrated after long immersion in pure N, N-dimethylformamide (DMF) at room temperature for 81 days, and at 80 °C for 45 days, and after a long-term consecutively filtration with Rose Bengal (1017 Da) DMF solution at 25 °C for 5 days, without scarifying solute rejection. Antifouling properties during the long-term filtration were also

Abbreviations: OSN, organic solvent nanofiltration; SRNF, solvent resistant nanofiltration; TFC, thin film composite; TFN, thin film nanocomposite; IP, interfacial polymerization; UF, ultrafiltration; NF, nanofiltration; MPD, m-phenylenediamine; TMC, trimesoylchloride; PI, polyimide; PA, polyamide; PEI, polyethyleneimine; GQDs, graphene quantum dots; RDB, Rhodamine B (479 Da); RB, Rose Bengal (1017 Da); IPA, isopropyl alcohol; DMF, N,N-dimethylformamide; THF, tetrahydrofuran; HDA, 1, 6-hexanediamine ⁎ Corresponding authors at: Ocean University of China, China (B. Su) and Oak Ridge National Laboratory, United States (M.Z. Hu). E-mail addresses: [email protected] (B. Su), [email protected] (M.Z. Hu). https://doi.org/10.1016/j.cej.2019.122462 Received 9 June 2019; Received in revised form 5 August 2019; Accepted 8 August 2019 Available online 09 August 2019 1385-8947/ © 2019 Elsevier B.V. All rights reserved.

Chemical Engineering Journal 380 (2020) 122462

Y. Liang, et al.

Nomenclature A Δt Δp Δm P R Cp Cf fR(r) r

Vs

the molecular volume

Greek letter

Membrane area, m2 Time, h Transmembrane pressure, MPa Permeate mass, kg Solvent permeance, L m−2 h−1 MPa−1 Solute rejection, % Concentration of solute in the permeate, mg L−1 Concentration of solute in the feed, mg L−1 Log-normal probability density function, m−1 Membrane pore radius, m

r* σ* ρ Ε δp, s ηs

Mean pore radius, m Distribution standard deviation, m Pore density, m−2 Surface porosity, – the polar Hansen solubility parameter of the solvent, MPa0.5 the dynamic viscosity, mPa·s

indicated. This paper presents a novel GQDs-interlayered strategy in developing high-performance TFN membranes for OSN application.

1. Introduction

incorporated multi-walled carbon nanotubes (MWCNTs) as an interlayer and fabricated a novel TFN-NF membrane having a water permeance of 175 L m−2 h−1 MPa−1 and a Na2SO4 rejection of 95%. Gong et al. [27] incorporated an interlayer of carbon nanotubes (CNTs) between the poly(ether sulfone) MF substrate and the PA selective layer and fabricated a triple-layered TFN-NF membrane with a salt rejection of > 98.3% for Na2SO4 and MgSO4 and a dye rejection of > 99.5% for methyl violet (408 Da), while maintaining a water permeance of 210 L m−2 h−1 MPa−1. Wu et al. [28] fabricated an ultra-thin TFN-NF membrane via IP process mediated by an interlayer of polydopamine (PDA)-covalent organic frameworks (COFs), and achieved desirable rejections (93.4% for Na2SO4), and an outstanding water permeance (207 L m−2 h−1 MPa−1). Nanoparticles incorporation within the barrier layer of TFC membrane to form a kind of thin film nanocomposite (TFN) membrane with enhanced separation performance, which originated from the pioneering research work of Hoek’s group [29], is a very good approach to solve the “trade-off” phenomenon [30]. Some researchers found that incorporating nanoparticles of smaller size could increase the solvent permeance [31], while nanoparticles of larger size could increase the surface roughness and lead to faster fouling of the membranes [32]. Vrijenhoek et al. [33] found that the extent of the contamination of the membrane surface was strongly related to its average roughness. More particulate contaminants are likely to deposit on rougher membrane surface than smoother surface under the same conditions. Recently, graphene oxide (GO) nanomaterials have gained a lot of attention in membranes preparation [34–38]. Graphene quantum dots (GQDs) are a type of zero-dimensional nanomaterials of the GO family [39]. GQDs have good thermal stability, chemical stability, excellent biocompatibility, and low toxicity [40–42]. GQDs have wide application potential in many fields (such as catalysis [43,44] and sensing [45–47]), and are found important in the membrane fabrication recently. Bi et al. [32] incorporated GQDs in the PA barrier layer and prepared a kind of TFN-NF membranes with a maximal water permeance of 510 L m−2 h−1 MPa−1, nearly 6.8 times that of the pristine PA membrane, while maintaining good antifouling performance. Fathizadeh et al. [48] fabricated a kind of PA TFN membranes incorporated with nitrogen-doped graphene oxide quantum dots (NGOQD) via IP, and achieved a water permeance of two folds that of the pristine membranes, while remaining an unchanged (93%) salt rejection. Li et al. [49] prepared a novel GQDs-incorporated polyimide (PI)based TFN membrane and achieved a nearly 50% higher of the ethanol permeance while without scarifying rejection. It was worth mentioning that all the above GQDs-incorporated membranes are not GQDs-interlayered membranes. Meanwhile, some of the above membranes have a rather large surface roughness along with

According to the recent sustainability assessment [1,2], organic solvent nanofiltration (OSN) technique, i.e. solvent-resistance nanofiltration (SRNF) technique, has great potential in organic solution separation and purifications. It can be used in many solvent-intensive processes such as solvent dewaxing in the petrochemical industry [3], catalyst recovery [4] and polymer fractionation in the chemical industry [5,6], as well as solvent recovery in the pharmaceutical industry [7,8]. OSN process allows for mild operating conditions while no additional liquid waste generates, and is considered more energy efficient than most of the traditional separation technologies such as distillation [9], adsorption [7], and crystallization [10,11]. The “heart” of OSN processes is OSN membranes with stable separation performance. Similar to aqueous polymer-based NF membranes, there are mainly two types of polymer-based OSN membranes, integral skinned asymmetric (ISA) membranes and thin film composite (TFC) ones, fabricated corresponding to phase inversion and interfacial polymerization (IP) technique, respectively [12]. Although ISA membranes are advantageous in solvent compatibility [13], they usually suffer from relatively low solvent permeance. An improvement was carried out by incorporation of nanoparticles in the ISA membranes to prepare a kind of mixed matrix membranes (MMMs) to enhance their separation performance [14]. Another approach was by using the IP method, which is a simple and rapid membrane-forming process for the preparation of TFC membranes on ultrafiltration (UF) substrate surface [15,16], during which, both the selective barrier layer and the UF substrate require optimization depending on the separation performance of the resultant membranes [17,18]. The physicochemical properties of UF substrates affect the formation of the barrier layers greatly. UF substrates prepared via the phase inversion method usually have low porosity and large pore diameter which are disadvantageous to enhance the separation performance of nanofiltration (NF) membranes [19,20]. Some researchers had made great efforts to solve these problems via regulating the pores structure of the substrates, for example, using high porosity substrates [19], or incorporating hydrophilic additives and/or hydrophilic polymers to the substrates [21,22], as well as incorporating nanomaterials to form a kind of MMMs substrates [23–25]. Recent researches indicated that depositing a hydrophilic interlayer can effectively modify the substrate surface and control the IP reaction. Karan et al. [26] introduced a hydrophilic cadmium hydroxide nanocoating as a sacrificial interlayer prior to the IP process, then removed the interlayer via a post-IP acid dissolution process, the resultant OSN membranes owned an ultra-thin polyamide (PA) skin layer of sub10 nm together with high separation performance. Wu et al. [19] 2

Chemical Engineering Journal 380 (2020) 122462

Y. Liang, et al.

OSN membranes, except that very recently we used crosslinking graphene oxide (cGO) as an interlayer and achieved excellent performances in solvent resistance, separation performance, and fouling resistance [54]. This inspired us to incorporate other nanomaterials of the graphene family to fabricate high performance OSN membranes. In this paper, we reported a novel modification of the surface pore structure and hydrophilicity of a polyimide substrate via depositing an ultra-thin hydrophilic layer of GQDs with the aid of polyethyleneimine (PEI). We then used aqueous MPD solution and TMC/n-hexane solutions, both of ultra-low concentration, to perform the IP reaction on the modified substrate surface to fabricate a barrier layer of ultra-thin and ultra-smooth for OSN. We investigated the effects of the GQDs content on the morphology of the barrier layer. We further carried out solvent resistance evaluation of the OSN membranes via both static immersion in DMF at 80 °C and continuously filtration with dye/DMF solution at 25 °C for certain time. Moreover, we showed the antifouling performance of the prepared OSN membrane.

a rather thick barrier layer [49]. The TFC membranes prepared via IP typically have a “trade-off” phenomenon between their selectivity and permeability. It is very important to decrease the thickness of the barrier layer and control its uniformity so as to maintain a high solvent permeability without compromising the solute selectivity [50,51]. Nevertheless, traditional IP process of TFC membranes fabrication is very difficult to control because the IP reaction is very quickly and usually forms above 100 nm thickness of the barrier layer within one or several seconds [52], which makes it a huge challenge to form a uniform, defect-free and ultra-thin barrier layer [19]. The thickness of the barrier layer has significant effect on the permeance of the TFC membrane. Karan et al. [26] pointed out that thinner films would achieve ultra-fast solvent permeance when their thickness was reduced below 100 nm. Zhang et al. [53] also proved that the water permeance of the TFC-NF membrane they prepared was significantly improved when the thickness of the barrier layer was less than 100 nm. The TFN membrane prepared by Wu et al. [19] with MWCNTs as interlayer also showed an ultra-fast water permeance with a thin skin thickness of only 77 nm. So far, most research works on TFN membranes with interlayer have been focusing on NF membranes orienting aqueous solutions. Often there is only relatively weak intermolecular force between the reported interlayer and the selective layer, no covalent bonding is particularly enabled within/between the multiple layers of the membranes. This might be not critical for NF membranes used in aqueous solutions, but for membranes designed to deal with organic solvent systems, an interlayer that can covalently bond with the barrier layer and/or with the substrate surface is urgently demanded to enhance their solvent resistance. Little work was pursued on covalent bonding development for

2. Experimental 2.1. Materials Polyimide polymer (Lenzing P84) was bought from Inspec Fibers GmbH, Lenzing (Austria). m-phenylenediamine (MPD, 99.5%) was purchased from Macklin Biochemical Technology Co., Ltd (China). Trimesoyl chloride (TMC, 98%) was procured from J&K Scientific Ltd. Rose Bengal (RB, 1017 Da), n-Hexane (98%), citric acid (99%), tetrahydrofuran (THF, 99%), N,N-dimethylformamide (DMF, 99.5%), isopropanol (IPA, 99.7%), ethanol (99.7%), 1,6-hexanediamine (HDA,

Fig. 1. The fabrication process of the GQDs-interlayered TFN-OSN membranes. 3

Chemical Engineering Journal 380 (2020) 122462

Y. Liang, et al.

2.3. Fabrication of the PI UF substrates

99%), Rhodamine B (RDB, 479 Da), aqueous polyethyleneimine solution (PEI, 25, 000 Da, 99%), HCl (35%), and sodium hydroxide (NaOH, 98%) were procured from Sinopharm Chemical Reagent Co. The above chemicals didn’t require any further purification. PET polyester nonwoven fabric was obtained from Teijin Co., Ltd (Japan).

The fabrication of the PI UF substrate membranes can be referred to our previous work [55]. 2.4. TFC membranes and GQDs-interlayered TFN membranes preparation

2.2. Synthetic method of GQDs

2.4.1. TFC membranes (baseline interlayer-free membranes) TFC membranes were prepared according to our previous work [55]. However, in this work we used quite low concentration, 0.1 wt% and 0.005 wt% for aqueous MPD solution and TMC/n-hexane solution, respectively, according to Karan et al. [26]. The aqueous immersion

Synthetic method of GQDs was according to our previous work [49] via thermally decomposition of citric acid.

(d) O

O

C NH

O C HN C OHN

C O NH

CH 2

NH N

N

N H

n

O C NH C HN

HO

O HO O

O

HO

O OH

O

OH

O O

OH

O

O O

OH

O

OH

HO

O

HO

O

HO O

O

OH HO

HO O

O OH O

OH

GQDs

O

H N

H N O

O

O

OH OH

HN

O OH

OH

O

O

HN

O O

N H

H N

PI

PEI

N

O

NH

HN

1- n

HN

HO

O O

HO

H N

N

NH

HO

O

N

N H NH

O

CH 2

NH

H N

N N

OH

O

O

O C HN C

N

HN O

O

O

H N

PA 1- m

m

Fig. 2. The molecular structures of the PI substrate (a), PEI (b), GQDs (c) and possible chemical bonding between PEI and the PI substrate [56], between PEI and the GQDs, and between the GQDs and the PA skin layer [49,57] (d). 4

Chemical Engineering Journal 380 (2020) 122462

Y. Liang, et al.

calculated using Eqs. (1) and (2), respectively.

time and the IP time were set at 2 min and 1 min, respectively. After the IP, the nascent membrane was heat-treated in an oven at 80 °C for 5 min, thus a pristine PA membrane was obtained and was termed as “(PA/PI)”. Then, it was crosslinked by 10.0 wt% HDA in IPA solution at 60 °C for 30 min, and was marked as “(PA/PI)X”. Afterward, it was activated by immersing in DMF at 80 °C for 30 min to improving its separation performance. The resultant membrane was marked as “(PA/ PI)XA”.

Cp ⎞ R = ⎛1 − × 100% Cf ⎠ ⎝ ⎜

⎟

(1)

where the permeate and the feed solution concentrations, Cp and Cf, respectively, were measured via UV–Vis spectrophotometer (UV-5100, China).

P = 1000· 2.4.2. GQDs-interlayered TFN membranes preparation The schematic diagram of the fabrication of GQDs-interlayered TFNOSN membranes was shown in Fig. 1. Firstly, a series of PEI aqueous solutions (50, 100, 250, 500, 1000 mg L−1) and a series of GQDs aqueous suspensions (20, 50, 100, 125, 150 mg L−1) were prepared. All the GQDs suspensions were ultrasonicated to assist a uniform dispersion. For the IP process, the PI substrate was immersed in a certain concentration of the aqueous PEI solution for 30 s to perform an initial modification, then the PEI-modified substrate was immersed in DI water for a certain time to remove the excess PEI molecules. Afterward, a certain amount of the aqueous GQDs suspension was quickly poured onto the PEI-modified substrate surface to perform a further modification for a certain time (0, 30, 60, 90, 180 s). The excess aqueous GQDs solution was quickly poured off and the GQDs-modified PEI/PI substrate was dried in the air for a certain time. Thus, a substrate modified with an ultra-thin GQDs layer was obtained. The GQDs-modified PEI/PI membrane was marked as “(GQDs-c-PEIn/PI)”, wherein “c” and “n” represent the content of GQDs in the aqueous GQDs suspension solution and the concentration of PEI in the aqueous PEI solution, respectively. The subsequent preparation steps were the same as those of the TFC membranes, in which the GQDs-interlayered PA membranes were marked as “(PA/GQDs-c-PEI-n/PI)”, “(PA/GQDs-c-PEI-n/PI)X”, and “(PA/GQDs-c-PEI-n/PI)XA”, respectively. Fig. 2 shows the molecular structures of the PI substrate, PEI, GQDs, and the possible chemical bonding interactions among the interlayer, the PI substrate and the PA skin layer. Since the GQDs interlayer can be covalently bonded not only to the PI substrate but also to the PA skin layer, the stability of the prepared TFN-OSN membranes with the GQDs-PEI interlayer were enhanced greatly.

Δm ρs ·A·Δt·Δp

(2)

where Δm represents the permeate mass, A denotes the effective filtration area, Δt refers to the interval of the test time, and Δp represents the specific operating pressure at 25 ± 1 °C. The standard deviations of the separation performances under each condition were calculated from the average of at least three membrane samples. Long-term cross-flow filtration experiment was used to evaluate the antifouling performance of the OSN membranes. Firstly, the initial flux of the membrane sheet, JV1 (L m−2 h−1), was measured at 0.6 MPa for 5 min, then the membrane sheet was continuously filtered at 0.6 MPa for 24 h, and the flux was monitored periodically, the final flux was denoted as Jp (L m−2 h−1). Then the membrane sheet was taken out from the membrane cell and was physically cleaned using DMF (wipe the membrane surface gently using DMF-soaked cotton). Afterward, the membrane sheet was installed in the membrane cell again and the initial flux of the cleaned membrane, JV2 (L m−2 h−1), was measured again for 5 min. The flux recovery ratio (FRR), the flux decline rate (DRt), the reversible fraction (DRr), and the irreversible fraction of the flux decline rate (DRir) [58,59] were calculated by Eqs. (3)–(6), respectively, to evaluate the antifouling performance.

J FRR = ⎛ V2 × 100%⎞ ⎝ JV1 ⎠

(3)

JV1 − Jp ⎞ DRt = ⎛ × 100% ⎝ JV1 ⎠

(4)

JV2 − Jp ⎞ DRr = ⎛ × 100% ⎝ JV1 ⎠

(5)

J − JV2 ⎞ DRir = ⎛ V1 × 100% ⎝ JV1 ⎠

(6)

⎜

⎜

⎜

⎜

2.5. Characterizations

⎟

⎟

⎟

⎟

A lower DRt and a higher FRR indicate a better antifouling performance. A lower DRir indicates that the foulants can be removed easily from the membrane surface by cleaning.

The characterization of the GQDs was according to our previous work [49]. For the characterization of the membranes, the chemical structure was investigated by X-ray photoelectron spectroscopy (XPS, ESCALAB 250 XI, US) and Fourier transform infrared spectrometer (FTIR, Nicolet Magna-560, USA); The membrane surface morphology and cross-sectional microstructure were characterized via scanning electron microscope (SEM, S-4800 SEM, Hitachi, Japan). The skin layer thickness and the surface roughness were investigated via transmission electron microscopy (TEM, HT-7700, Hitachi, Japan) and atomic force microscope (AFM, Agilent 5400, USA), respectively. The surface water contact angle (WCA) was measured via an automatic contact angle meter (DSA100, KRÜSS, Germany) at ambient temperature to characterize the surface hydrophilicity.

2.7. Theoretical calculation of pore size distribution A lognormal probability density function was used to describe the pore size distribution of the barrier layer according to the previous reports [60–63], as expressed in Eq. (7):

(

r ⎧ ⎪ ⎡log r ∗ + 1 fR (r ) = ·exp − ⎣ ⎨ 2b r 2πb ⎪ ⎩

b 2

2

) ⎤⎦ ⎫⎪ ⎬ ⎪ ⎭

(7)

where r* is the average pore radius of the barrier layer. It can be calculated via fitting the experimental separation performance data with the pore distribution models which were summarized in our previous work [55].

2.6. Evaluation of the separation performance and anti-fouling performance The separation performance of the prepared membranes was evaluated with 100.0 mg L−1 RDB in ethanol solution using the cross-flow filtration apparatus under 1.0 MPa. The antifouling performance was evaluated with 100.0 mg L−1 RB in DMF solution using long-term filtration under 0.6 MPa. Both experiments were performed at 25 ± 1 °C. The solute rejection (R) and the solvent permeance (P) were

3. Results and discussion 3.1. GQDs characteristics The characterizations of the prepared GQDs via ATR-FTIR, AFM, 5

Chemical Engineering Journal 380 (2020) 122462

Y. Liang, et al.

membranes was significantly increased, as can be seen in Fig. 3 (a). Therefore, the formation of the PA cortex was confirmed [66]. Fig. 3 (b, c, d) showed the O1s XPS spectra of the PI, (PEI-500/PI) and (GQDs-100-PEI-500/PI) membranes. There are two fitting peaks, 531.2 eV and 531.6 eV for the PI substrate, corresponding to the NeC] O and C]O groups, respectively [67]. The percentage of the NeC]O bond of the PI substrate increased after the PEI modification, as seen in Fig. 3 (c), confirming the successful reaction of PEI with the PI substrate and the formation of covalent bonds [54,56]. This kind of covalent bonding is very important for the further preparation of OSN membranes with super solvent resistance. After modification by PEI + GQDs, the OeC]O (530.97 eV) and CeOH (532.6 eV) bonds [68] occurred, as shown in Fig. 3 (d), which proved that the formation of the GQDs-PEI interlayer [64].

TEM and XPS can be seen in our previous papers [49,64]. The average sheet size of the GQDs is about 1.9 nm, and the average thickness is about 1.8 nm. 3.2. Effects of GQDs-PEI interlayer on the membranes 3.2.1. FTIR analysis The FTIR spectra of the membranes prepared at different stages were shown in Fig. 3 (a). On the spectrum of the (PEI-500/PI) substrate, the absorption peaks of 1779 cm−1 and 1720 cm−1 and 1365 cm−1 which belong to the characteristic peaks of the imide groups [56,65] became weakened after the PEI modification as compared to those of the PI substrate. After the IP reaction, the intensity of the above imide peaks was greatly reduced, and conversely, the intensity of the absorption peaks (1654 cm−1 and 1536 cm−1) of the amide groups on the spectra of both the (PA/PI) and the (PA/GQDs-100-PEI-500/PI)

Fig. 3. The FTIR spectra of the membranes prepared during different stages (a); XPS spectra of O1s of the PI substrate (b), (PEI-500/PI) substrate (c) and (GQDs-100PEI-500/PI) membrane (d). 6

Chemical Engineering Journal 380 (2020) 122462

Y. Liang, et al.

3.2.3. Membrane morphology analysis SEM images of the surface and cross-section of the prepared membranes were shown in Fig. 4. There are many visible pores on the PI substrate surface (Fig. 4 (a)). After modification by the GQDs-PEI interlayer, the pores on the (GQDs-100-PEI-500/PI) substrate turned to be smaller, and the number of pores became much less, as shown in Fig. 4 (e), indicating that the GQDs-PEI interlayer significantly modified the surface morphology of the PI substrate. After the IP reaction, the surface of the (PA/GQDs-100-PEI-500/ PI)XA membrane became more uniform and dense, as shown in Fig. 4 (g). There was no significant difference between the (PA/GQDs-100-PEI500/PI)XA membrane and the PI substrate from the cross-sectional SEM images, indicating that the skin layer of the OSN membrane is ultrathin.

3.2.2. Hydrophilicity of the substrate Generally, a lower WCA indicated a higher surface hydrophilicity [69]. Fig. S1 showed that the WCA of the substrate surface was reduced when PEI was added and the GQDs content was increased, because they introduced hydrophilic eCOOH, eOH, and eNH2 groups. When the GQDs content was increased to 200 mg L−1, the WCA of the substrate surface decreased from 63.1° to 43.2°, indicating that the surface of the substrate modified by GQDs became more hydrophilic with the increase of the GQDs content. It is suggested that this could accommodate more aqueous monomers during the IP process, thus help to promote the rapid formation of the PA selective layer, and conversely, the formed PA layer could hinder the further diffusion of the MPD molecules, reduce the rate of the further IP reaction [17,19,70,71], thus greatly decrease the thickness of the barrier layer and improve the smoothness of the barrier layer surface as well.

Fig. 4. The surface and cross-sectional SEM images of the PI substrate (a, b), (PEI-500/PI) substrate (c, d), (GQDs-100-PEI-500/PI) substrate (e, f), and (PA/GQDs100-PEI-500/PI)XA membrane (g, h). 7

Chemical Engineering Journal 380 (2020) 122462

Y. Liang, et al.

However, this was accompanied by a reduction of the solvent permeance to 28.9 L m−2 h−1 MPa−1, which was the effect of a typical “trade-off” phenomenon. However, after the further modification of the PEI/PI substrate by GQDs, both the ethanol permeance and the dye rejection were greatly improved, to 40.3 L m−2 h−1 MPa−1 and 98.7%, respectively. This clearly proved that the hydrophilic GQDs-PEI interlayer promoted the formation of a quite uniform, defect-free, and ultra-thin barrier layer by adjusting the IP process, which is beneficial for the solute rejection and the solvent permeation [19,70].

TEM images demonstrated the same results of the ultra-thin skin layer, as shown in Fig. 5 (a, b). The pristine (PA/PI)XA TFC membrane has a thickness of about 45 nm for the PA skin layer. In contrast, the thickness of the PA skin layer of the GQDs-interlayered TFN membrane was greatly reduced to about 25 nm, which proved that the hydrophilic GQDs-PEI interlayer effectively decreased the thickness of the PA skin layer [19]. This was great advantageous for the improvement of the solvent permeance [17]. The AFM images in Fig. 5 (c, d, e) indicated that the surfaces of the (PA/PI)XA, (PA/PEI-500/PI)XA, and (PA/GQDs-100-PEI-500/PI)XA membranes fabricated via IP using both low concentration MPD and TMC were extremely smooth, which was in accordance with the research work of Karan et al. [26]. The average surface roughness (Ra) of the three membranes was 2.4 nm, 2.0 nm and 1.6 nm, respectively (the Ra of the other membranes prepared by the conventional IP method usually can be as large as 50–80 nm [49,67,72]). The Ra value of the GQDs-interlayered TFN membrane was slightly smaller than those of the interlayer-free TFC membranes, although there is only marginally difference between them. This slightly smaller Ra value of the GQDsinterlayered TFN membrane might be attributed to the GQDs interlayer which could help to improve the wettability of the substrate surface, and ensure a uniform diffusion of the MPD molecules during the IP process. Consequently, this could help to form an even smoother surface of the prepared membrane [53], which was also beneficial for the improvement of the antifouling performance of the membranes [33].

3.3. Effects of GQDs incorporation 3.3.1. XPS analysis Figs. 6 and S2 showed the C1s, N1s and O1s XPS spectra for the GQDs-interlayered membranes prepared with different content of GQDs. The signals of the amide and the eCOOH groups were reflected on the deconvoluted spectra of C1s (Fig. 6 a-e). The calculation results of the specific percentage of the unreacted amine groups of MPD (reflected in the deconvoluted spectrum of N1s (Fig. 6 f-j)) and the eCOOH groups produced by the hydrolysis of the unreacted eCOCl groups were shown in Table S2. It can be seen that with the increase of the content of GQDs, the proportions of both the unreacted amine groups and the formed eCOOH groups inside the skin layer gradually increased. This suggested the adjustment of the IP process due to the GQDs-PEI interlayer formed on the PI substrate with the increase of GQDs content, and the rapidly formed uniform PA barrier layer thus resulted [70]. This in turn, effectively hindered the diffusion of the inner MPD molecules to the interface. Thus, the amount of MPD molecules participating the IP reaction was greatly decreased, resulting in a decreased thickness of the barrier layer, an increased amount of the unreacted amine groups inside the barrier layer, as well as an increased amount of the carboxylic acids generated from the unreacted acryl chloride groups [74], which is beneficial for the improvement of hydrophilicity.

3.2.4. Separation performance Table S1 showed the comparison of the separation performance of the (PA/PI)XA, (PA/PEI-500/PI)XA, and (PA/GQDs-100-PEI-500/PI)XA membranes. The pristine (PA/PI)XA membrane has a RDB rejection of only 87.4%, since the IP reaction at quite low MPD and TMC concentrations could not form a defect-free PA skin layer and effectively cover the large pores of the PI substrate surface thus resulting in the formation of a large number of defects in the skin layers. However, the ethanol permeance was not so high, only 33.5 L m−2 h−1 MPa−1, which indicated that the low concentration MPD and TMC by themselves could not help to increase the solvent permeance of the pristine (PA/PI)XA membrane. After the substrate were modified by PEI, the solute rejection of the OSN membranes was increased up to 92.2%. This suggested that the pore size of the formed PEI/PI substrate was reduced by the PEI branches, and hence the defects in the skin layer was greatly reduced, the degree of the densification of the skin layer was also increased [73]. Thus, the solute rejection of the OSN membranes was increased.

3.3.2. Hydrophilicity of the GQDs-interlayered OSN membranes The variation of the WCA of the prepared OSN membranes with different content of GQDs were shown in Fig. 7. As the content of GQDs increased, the WCA of the membranes gradually decreased, indicating the improved hydrophilicity of the membranes, which was in consistent with the analysis results of XPS. This improved hydrophilicity is suggested to promote the permeation of polar solvent and obtain a higher solvent permeance.

Fig. 5. TEM images of the (PA/PI)XA membrane (a) and (PA/GQDs-100-PEI-500/PI)XA membrane (b); AFM images of the (PA/PI)XA membrane (c), (PA/PEI-500/ PI)XA membrane (d) and (PA/GQDs-100-PEI-500/PI)XA membrane (e). 8

Chemical Engineering Journal 380 (2020) 122462

Y. Liang, et al.

Fig. 6. The deconvoluted XPS spectra of C1s (a, b, c, d, e) and N1s (f, g, h, i, j) for the (PA/GQDs-c-PEI-500/PI)XA OSN membranes.

9

Chemical Engineering Journal 380 (2020) 122462

Y. Liang, et al.

Fig. 9. The separation performance of the (PA/GQDs-100-PEI-500/PI)XA OSN membranes with the GQDs deposition time. Fig. 7. WCA of the GQDs-interlayered membranes with GQDs content.

Fig. 8. AFM images of the (PA/GQDs-c-PEI-500/PI)XA OSN membranes. 10

Chemical Engineering Journal 380 (2020) 122462

Y. Liang, et al.

[73,77–79]. The ethanol permeance increased with the PEI concentration increasing up to 500 mg L−1. This suggested that more GQDs can react with PEI when the PEI concentration increased, and thus the substrate surface would be covered completely with an ultra-thin layer of GQDs. This in turn, greatly helped to manipulate the IP reaction and resulted in an ultra-thin and ultra-smooth IP skin layer. Thus, the higher the PEI concentration, the more uniform and more complete GQDs-PEI interlayer as well as the smoother and thinner IP skin layer would be formed, which resulted in both higher solute rejection and solvent permeance. However, at PEI concentration even higher than 500 mg L−1, the substrate surface would covered by redundant PEI molecules, thus resulting in a much denser and thicker PEI layer [80], and subsequently a decreased solvent permeance of the GQDs-interlayered OSN membranes. From the above analysis, we chose 500 mg L−1 as the optimized concentration of PEI.

3.3.3. AFM images The surface AFM images of the GQDs-interlayered membranes with GQDs content were shown in Fig. 8. It was worth noting that the Ra of each GQDs-interlayered membranes was extremely low, less than 2 nm, regardless of the GQDs content used. This indicated that the combination effect of the GQDs-PEI interlayer and the interfacial polymerization under ultra-low concentration aqueous and organic phase monomers could produce an extremely smooth selective skin layer on the porous substrate surface [26,73]. Moreover, the Ra of the membranes marginally decreased from 1.9 nm to 1.4 nm with the content of GQDs increased from 20 to 200 mg L−1, well in accordance with the increased hydrophilicity of the GQDs-PEI interlayer and the increased wettability of the substrate surface, thus ensuring a uniform diffusion of the MPD molecules during the IP process [53,75]. 3.3.4. Effect of the GQDs deposition time and GQDs content Fig. 9 shows the variation of the separation performance of the GQDs-interlayered OSN membranes with the GQDs deposition time when the content of the GQDs was fixed at 100 mg L−1. As the GQDs deposition time increased from 0 to 30 s, i.e. as the effective deposition amount of the GQDs increased, the RDB rejection increased from 92.2% to 98.6%, accompanied by an increase of the ethanol permeance from 28 to 36 L m−2 h−1 MPa−1. However, the solvent permeance maintained basically stable while the rejection decreased slightly with the further elongation of the deposition time from 30 s to 180 s. Therefore, we selected 60 s as the preferred GQDs deposition time considering both the ethanol permeance and the RDB rejection. The effect of the GQDs content on the separation performance of the GQDs-interlayered OSN membranes is shown in Fig. 10. The GQDs deposition time was fixed at 60 s. It can be seen that the effect of the GQDs content was similar to that of the GQDs deposition time, because both of them directly caused the changes of the effective deposition amount of the GQDs on the substrate surface. The increase in solvent permeance might be attributed to the fact that the hydrophilic GQDs-PEI interlayer formed on the surface of the PI substrates could effectively reduce the thickness of the PA skin layers (Section 3.2.3), as well as the increased hydrophilicity of the GQDsinterlayered OSN membranes as the content of the GQDs increased (Section 3.3.2). Hence, the hydraulic resistance of the skin layer was greatly reduced, the transport of polar solvent (ethanol) was remarkably improved [32,76]. The rejection increased as the GQDs incorporated compared with the pristine membranes due to the formation of the defect-free and uniform PA skin layer on the surface of the GQDs-modified substrates. The probability distribution of the GQDs-interlayered membranes with different content of GQDs is shown in Fig. 11. The average pore size, porosity and pore density of the fabricated (PA/GQDs-c-PEI-500/PI)XA membranes were calculated and listed in Table S3. As the GQDs content increased from 0 to 100 mg L−1, the average pore diameter decreased from 0.89 down to 0.65 nm. With the further increase of the GQDs content up to 200 mg L−1, the average pore diameter showed an increase trend up to 0.73 nm. The opposite trends were showed for the membrane porosity and pore density. This indicated that an appropriate GQDs content was advantageous for the adjustment of the structure of the selective layers. Therefore, considering the permeability and rejection of the OSN membranes, we selected the optimum GQDs content as 100 mg L−1.

3.5. The permeances of different organic solvents The permeance of different pure solvents penetrating through the (PA/GQDs-100-PEI-500/PI)XA OSN membrane at 1.0 MPa are shown in Fig. 13 (a). Since the surface of the GQDs-interlayered membrane is highly hydrophilic, it has a higher affinity to polar solvents [81]. Therefore, polar solvents such as DMF, THF, and ethanol showed relative higher permeance, while non-polar solvents such as n-hexane showed almost no permeation. Fig. 13 (b) showed the correlation between the solvent permeance of the (PA/GQDs-100-PEI-500/PI)XA membrane and the solvent properties (expressed as δp, s−1Vs−1ηs−1, where δp, s, Vs, and ηs correspond to the Hansen solubility parameter, molecular volume and dynamic viscosity of the solvent, respectively) [82]. Table S4 showed the specific values of the solvents investigated in this study. Obviously, the permeance of the organic solvents was approximately proportional to δp, s−1Vs−1ηs−1. Similar results have been obtained by other researchers [82–84]. 3.6. Long-term stability, separation and antifouling performance The long immersion test of the (PA/GQDs-100-PEI-500/PI)XA membranes in strong polar solvent DMF at 80 °C is shown in Fig. 14 (a). After being immersed for 2 days, the ethanol permeance increased apparently from 39.0 to 55.0 L m−2 h−1 MPa−1. With the further extension of the immersion time, the ethanol permeance gradually

3.4. Effect of PEI concentration As shown in Fig. 12, the rejection of the GQDs-interlayered OSN membranes gradually increased with the PEI concentration increased from 50 to 1000 mg L−1. This suggested that more PEI molecules were deposited on the substrate surface and resulted in a decrease in the pore size of the substrate owing to the vast amount of branches of the PEI molecules and thus caused the increase in the size sieve effect

Fig. 10. Effect of GQDs content on the separation performance of the GQDsinterlayered membranes. 11

Chemical Engineering Journal 380 (2020) 122462

Y. Liang, et al.

Fig. 11. The pore size distribution curves (a), and the corresponding porosity and pore density (b) of the GQDs-interlayered membranes with content of GQDs.

Fig. 13. The solvents permeance of the (PA/GQDs-100-PEI-500/PI)XA OSN membrane (a), and their distribution with solvent properties expressed as δp, −1 −1 −1 V s ηs (b). s

at 80 °C. The GQDs-interlayered OSN membranes kept substantially constant solute rejection after a long immersion in DMF at room temperature for 81 days, as can be seen from Fig. 14 (b). These two sets of experiments demonstrated that the (PA/GQDs100-PEI-500/PI)XA membranes have remarkable solvent resistance and thermal resistance to the strong polar DMF at high temperature. Apparently, the prepared GQDs-interlayered OSN membranes showed broad application prospects in chemical and related industries. The GQDs-interlayered OSN membranes were also undergone a continuous filtration using RB/DMF solution of 100 mg L−1 at 0.6 MPa for 5 days to evaluate their separation and antifouling performance. The results are shown in Fig. 15 (a). During the 120-h filtration, the rejection of RB was always close to 100%, which confirmed the excellent solvent stability of the GQDs-interlayered OSN membranes. We could see that the initial DMF permeance reached a much high value (125 L m−2 h−1 MPa −1). However, it decreased gradually with the increased filtration time due to the conglutination of contaminants on the membrane surface, as can be seen in Fig. S3 (a). Simply physical cleaning of the membrane surface using DMF was performed once per 24 h, each physical cleaning was last for about 5 min, the fouling substance could be removed easily, as shown in Fig. S3 (b). The antifouling ability of the (PA/GQDs-100-PEI-500/PI)XA membranes during the long-term filtration is shown in Fig. 15 (b). The FRR of the GQDs-interlayered membranes were averaged at 92.6% after five

Fig. 12. Separation performance of the fabricated (PA/GQDs-100-PEI-n/PI)XA OSN membranes with the PEI concentration.

decreased, suggesting the slight degrade of the membrane due to their persistent immersion in solvent at high temperature, which is a kind of persistent annealing effect [72,85]. However, the solute rejection basically remained at about 98.5% during these 45 days, indicating the super resistance of the fabricated OSN membranes to strong polar DMF

12

Chemical Engineering Journal 380 (2020) 122462

Y. Liang, et al.

Fig. 14. The separation performance of the (PA/GQDs-100-PEI-500/PI)XA OSN membranes after being statically immersed in strong polar solvent, DMF at 80 °C (a), and ambient temperature (b).

Fig. 15. The separation performance (a) and antifouling indexes (b) of the (PA/ GQDs-100-PEI-500/PI)XA OSN membranes tested during the long-term crossflow filtration using RB/DMF solution.

cycles of cleaning. The final DRir of the membrane was only 5%, indicating that the fouling was easily removed from the membrane surface by simply physical cleaning. The above data proved that the combination effect of the GQDs-PEI interlayer and the IP reaction using much lower concentration aqueous and organic phase reactive monomers could result in a barrier layer with excellent antifouling performance.

substrate, and followed by post-IP crosslinking and DMF activation procedures. The novel GQDs-interlayered OSN membranes exhibited both ultra-thin (about 25 nm) and ultra-smooth (with an average surface roughness about 2 nm) of the IP skin layer as compared with those of the membranes prepared via the traditional IP process, which was much beneficial for the solvent permeance and antifouling performance. The GQDs-interlayered OSN membranes exhibited apparent improvement in surface hydrophilicity, which was also much beneficial for the solvent permeance. The separation performance was also greatly enhanced, with a rejection of 98.7% for RDB (479 Da) and a permeance of 40.3 L m−2 h−1 MPa−1 for ethanol under the optimal GQDs content of 100 mg L−1. In addition, the GQDs-interlayered OSN membranes showed excellent solvent resistance during static immersion in DMF at ambient temperature for 81 days and at 80 °C for 45 days, as well as during continuously cross-flow filtration with RB (1017 Da)/DMF solution for 5 days, without significant change in the dye rejection, which was due to the covalent bonding between the interlayer and the substrate, as well as the skin layer. Meanwhile, the GQDs-interlayered membranes showed good antifouling performance. All of the above performance improvement indicated the vast potential application of the GQDs-interlayered OSN membranes in organic solvent separation and purification.

3.7. Benchmark Table 1 compared the separation performance of the OSN membranes in literature and those of our newly prepared (PA/GQDs-100PEI-500/PI)XA OSN membranes. The comparison indicated that the GQDs-interlayered OSN membrane in this work had a relatively high solvent permeance and solute rejection compared with most polymer OSN membranes. Moreover, the GQDs-interlayered OSN membranes showed excellent long-term solvent-resistance performance in DMF at 80 °C for 45 days, seldom seen in literature, indicating its promising prospect for broad OSN applications. 4. Conclusions We have developed a novel class of GQDs-interlayered, sandwichlike thin film nanocomposite (TFN) membranes via interfacial polymerization (IP) using both low concentration aqueous MPD solution and TMC/n-hexane solution on GQDs-PEI-modified polyimide (PI)

Acknowledgements This work is financially supported by the Fundamental Research 13

Chemical Engineering Journal 380 (2020) 122462

Y. Liang, et al.

Table 1 Comparison of the OSN performance between the (PA/GQDs-100-PEI-500/PI)XA membrane prepared in this work and other OSN polymer membranes in literature. Membrane

Pure solvents permeance (L m−2 h−1 MPa −1)

TiO2/Ppy TPP/GO/HPEI PEI-sPPSU PEI-DBX/PBI MWCNTs-NH2/P84 MMM Kevlar PAN-Pebax/GO PDA/PI (PI-GQDs-50/PI)XA

Ethanol Ethanol Ethanol Ethanol Ethanol Ethanol Ethanol Ethanol Ethanol DMF Ethanol IPA DMF THF Ethanol IPA DMF THF Ethanol IPA DMF THF

TAPA-30–120 °C

PEG400/cPI 1:2, 50 W

(PA/GQDs-100-PEI-500/PI)XA

162 149 100 45 33 29 19 9.1 22.6 18.3 28.3 11.5 55.7 60.9 137.8 59.1 108 237.9 54.7 14.8 146.8 79.2

Funds for the Central Universities of China (No. 201822012), the National Natural Science Foundation of China (No. 21476218) and the Young Taishan Scholars Program of Shandong Province, China. This is MCTL Contribution No. 213. The authors thank Dr. Prof. W. S. Winston Ho for his kind guidance and Dr. Dongzhu Wu for his kind help when Prof. B. Su worked as a visiting scholar in The Ohio State University during Nov.2016∼Nov.2017. Dr. Michael Z. Hu’ research effort to prepare this paper is partially sponsored by the U.S. Department of Energy, Bioenergy Technologies Office, Separations Consortium program (WBS 2.5.5.507).

Dye used and its molecular weight (g mol−1)

Rejection (%)

Ref.

Rose Bengal (1017) Alcian blue (1299) Methyl Orange (327) Tetracycline (444) Eosin Y (648) Rose Bengal (1017) Brilliant blue (854) Methyl Blue (800) Rhodamine B (479) Rose Bengal (1017) Rose Bengal (1017)

> 98 95 66.8 99 98.1 95.4 > 95 99 98 99.9 99.2 (in IPA)

[86] [87] [88] [89] [90] [91] [92] [93] [49]

Rose Bengal (1017)

[82]

Rhodamine B (479)

83.6 99.6 72.9 98.5 98.7 (in ethanol)

Rose Bengal (1017)

99.3 (in DMF)

[94]

This work

[11] P. Vandezande, L.E. Gevers, I.F. Vankelecom, Solvent resistant nanofiltration: separating on a molecular level, Chem. Soc. Rev. 37 (2008) 365–405. [12] S.K. Lim, K. Goh, T.-H. Bae, R. Wang, Polymer-based membranes for solvent-resistant nanofiltration: a review, Chin. J. Chem. Eng. 25 (2017) 1653–1675. [13] Y. Zhang, M. Zhong, B. Luo, J. Li, Q. Yuan, X.J. Yang, The performance of integrally skinned polyetherimide asymmetric nanofiltration membranes with organic solvents, J. Membr. Sci. 544 (2017) 119–125. [14] H. Siddique, E. Rundquist, Y. Bhole, L.G. Peeva, A.G. Livingston, Mixed matrix membranes for organic solvent nanofiltration, J. Membr. Sci. 452 (2014) 354–366. [15] G. Szekely, M.J. Solomon, P. Marchetti, J.F. Kim, A.G. Livingston, Sustainability assessment of organic solvent nanofiltration: from fabrication to application, Green Chem. 16 (2014) 4440–4473. [16] Z. Yuan, X. Wu, Y. Jiang, Y. Li, J. Huang, L. Hao, J. Zhang, J. Wang, Carbon dotsincorporated composite membrane towards enhanced organic solvent nanofiltration performance, J. Membr. Sci. 549 (2018) 1–11. [17] C.J. Zhe Zhai, Na Zhao, Wenjing Dong, Hongling Lan, Ming Wang, Q. Jason Niu, Fabrication of advanced nanofiltration membranes with nanostrand-hybrid morphology mediated by ultrafast Noria-polyethyleneimine co-deposition, J. Mater. Chem. A 6 (2018) 21207–21215. [18] G.-R. Xu, J.-M. Xu, H.-J. Feng, H.-L. Zhao, S.-B. Wu, Tailoring structures and performance of polyamide thin film composite (PA-TFC) desalination membranes via sublayers adjustment-a review, Desalination 417 (2017) 19–35. [19] M.-B. Wu, Y. Lv, H.-C. Yang, L.-F. Liu, X. Zhang, Z.-K. Xu, Thin film composite membranes combining carbon nanotube intermediate layer and microfiltration support for high nanofiltration performances, J. Membr. Sci. 515 (2016) 238–244. [20] P.B. Kosaraju, K.K. Sirkar, Interfacially polymerized thin film composite membranes on microporous polypropylene supports for solvent-resistant nanofiltration, J. Membr. Sci. 321 (2008) 155–161. [21] N. Widjojo, T.-S. Chung, M. Weber, C. Maletzko, V. Warzelhan, Corrigendum to “The role of sulphonated polymer and macrovoid-free structure in the support layer for thin-film composite (TFC) forward osmosis (FO) membranes” [J. Membr. Sci. 383 (2011) 214–223], J. Membr. Sci. 389 (2012) (2011) 544. [22] M. Shi, Z. Wang, S. Zhao, J. Wang, P. Zhang, X. Cao, A novel pathway for high performance RO membrane: Preparing active layer with decreased thickness and enhanced compactness by incorporating tannic acid into the support, J. Membr. Sci. 555 (2018) 157–168. [23] S. Zha, P. Gusnawan, G. Zhang, N. Liu, R. Lee, J. Yu, Experimental study of PES/SiO 2 based TFC hollow fiber membrane modules for oilfield produced water desalination with low-pressure nanofiltration process, J. Ind. Eng. Chem. 44 (2016) 118–125. [24] Q. Xie, S. Zhang, Z. Hong, H. Ma, B. Zeng, X. Gong, W. Shao, Q. Wang, A novel double-modified strategy to enhance the performance of thin-film nanocomposite nanofiltration membranes: Incorporating functionalized graphenes into supporting and selective layers, Chem. Eng. J. 368 (2019) 186–201. [25] G.S. Lai, W.J. Lau, P.S. Goh, A.F. Ismail, N. Yusof, Y.H. Tan, Graphene oxide incorporated thin film nanocomposite nanofiltration membrane for enhanced salt removal performance, Desalination 387 (2016) 14–24. [26] Z.J. Santanu Karan, Andrew G. Livingston, < MEMBRANE FILTRATION. Sub-10 nm polyamide nanofilms with ultrafast solvent transport for molecular separation.pdf > , Science 348 (2015). [27] G. Gong, P. Wang, Z. Zhou, Y. Hu, New insights into the role of an interlayer for the fabrication of highly selective and permeable thin-film composite nanofiltration membrane, ACS Appl. Mater. Interfaces 11 (2019) 7349–7356.

Appendix A. Supplementary data Supplementary data to this article can be found online at https:// doi.org/10.1016/j.cej.2019.122462. References [1] M.F.J.-S. Gyorgy Szekely, Patrizia Marchetti, Jeong F. Kim, A.G. Livingston, Sustainability assessment of organic solvent nanofiltration: from fabrication to application, Green Chem. (2014). [2] L. Chen, N. Li, Z. Wen, L. Zhang, Q. Chen, L. Chen, P. Si, J. Feng, Y. Li, J. Lou, L. Ci, Graphene oxide based membrane intercalated by nanoparticles for high performance nanofiltration application, Chem. Eng. J. 347 (2018) 12–18. [3] M.H. Abdellah, L. Pérez-Manríquez, T. Puspasari, C.A. Scholes, S.E. Kentish, K.V. Peinemann, Effective interfacially polymerized polyester solvent resistant nanofiltration membrane from bioderived materials, Adv. Sustainable Syst. 2 (2018) 1800043. [4] A. Cano-Odena, P. Vandezande, D. Fournier, W. Van Camp, F.E. Du Prez, I.F. Vankelecom, Solvent-resistant nanofiltration for product purification and catalyst recovery in click chemistry reactions, Chemistry 16 (2010) 1061–1067. [5] C. Didaskalou, J. Kupai, L. Cseri, J. Barabas, E. Vass, T. Holtzl, G. Szekely, Membrane-grafted asymmetric organocatalyst for an integrated synthesis–separation platform, ACS Catal. 8 (2018) 7430–7438. [6] W.L. Peddie, Separation of homogeneous hydroformylation catalysts using organic solvent nanofiltration, Chem. Eng. Res. Des. (2016). [7] G. Szekely, Valorisation of agricultural waste with adsorption/nanofiltration hybrid process: from materials to sustainable process design, Green Chem. (2017). [8] X.Q. Cheng, K. Konstas, C.M. Doherty, C.D. Wood, X. Mulet, Z. Xie, D. Ng, M.R. Hill, L. Shao, C.H. Lau, Hyper-cross-linked additives that impede aging and enhance permeability in thin polyacetylene films for organic solvent nanofiltration, ACS Appl. Mater. Interfaces 9 (2017) 14401–14408. [9] J. Micovic, K. Werth, P. Lutze, Hybrid separations combining distillation and organic solvent nanofiltration for separation of wide boiling mixtures, Chem. Eng. Res. Des. 92 (2014) 2131–2147. [10] J.T. Scarpello, D. Nair, L.M.F.D. Santos, L.S. White, A.G. Livingston, The separation of homogeneous organometallic catalysts using solvent resistant nanofiltration, J. Membr. Sci. 203 (2002) 71–85.

14

Chemical Engineering Journal 380 (2020) 122462

Y. Liang, et al.

[55] C. Li, S. Li, L. Lv, B. Su, M.Z. Hu, High solvent-resistant and integrally crosslinked polyimide-based composite membranes for organic solvent nanofiltration, J. Membr. Sci. 564 (2018) 10–21. [56] J. Gao, S.-P. Sun, W.-P. Zhu, T.-S. Chung, Polyethyleneimine (PEI) cross-linked P84 nanofiltration (NF) hollow fiber membranes for Pb2+ removal, J. Membr. Sci. 452 (2014) 300–310. [57] L. Shen, S. Xiong, Y. Wang, Graphene oxide incorporated thin-film composite membranes for forward osmosis applications, Chem. Eng. Sci. 143 (2016) 194–205. [58] Y. Li, Y. Su, X. Zhao, X. He, R. Zhang, J. Zhao, X. Fan, Z. Jiang, Antifouling, highflux nanofiltration membranes enabled by dual functional polydopamine, ACS Appl. Mater. Interfaces 6 (2014) 5548–5557. [59] H. Guo, Y. Ma, Z. Qin, Z. Gu, S. Cui, G. Zhang, One-step transformation from hierarchical-structured superhydrophilic NF membrane into superhydrophobic OSN membrane with improved antifouling effect, ACS Appl. Mater. Interfaces 8 (2016) 23379–23388. [60] W.R. Bowen, J.S. Welfoot, Modelling the performance of membrane nanofiltration—critical assessment and model development, Chem. Eng. Sci. 57 (2002) 1121–1137. [61] A.L. Zydney, P. Aimar, M. Meireles, J.M. Pimbley, G. Belfort, Use of the log-normal probability density function to analyze membrane pore size distributions: functional forms and discrepancies, J. Membr. Sci. 91 (1994) 293–298. [62] G. Belfort, J.M. Pimbley, A. Greiner, K.Y. Chung, Diagnosis of membrane fouling using a rotating annular filter. 1. Cell culture media, J. Membr. Sci. 77 (1993) 1–22. [63] J. Campbell, J.D.S. Burgal, G. Szekely, R.P. Davies, D.C. Braddock, A. Livingston, Hybrid polymer/MOF membranes for Organic Solvent Nanofiltration (OSN): chemical modification and the quest for perfection, J. Membr. Sci. 503 (2016) 166–176. [64] S. Xu, F. Li, B. Su, M.Z. Hu, X. Gao, C. Gao, Novel graphene quantum dots (GQDs)incorporated thin film composite (TFC) membranes for forward osmosis (FO) desalination, Desalination 451 (2019) 219–230. [65] H. Toiserkani, Polyimide/nano-TiO2 hybrid films having benzoxazole pendent groups: in situ sol–gel preparation and evaluation of properties, Prog. Org. Coat. 88 (2015) 17–22. [66] I. Soroko, M. Sairam, A.G. Livingston, The effect of membrane formation parameters on performance of polyimide membranes for organic solvent nanofiltration (OSN). Part C. Effect of polyimide characteristics, J. Membr. Sci. 381 (2011) 172–182. [67] Y. Guo, S. Li, B. Su, B. Mandal, Fluorine incorporation for enhancing solvent resistance of organic solvent nanofiltration membrane, Chem. Eng. J. 369 (2019) 498–510. [68] R. Al-Gaashani, A. Najjar, Y. Zakaria, S. Mansour, M.A. Atieh, XPS and structural studies of high quality graphene oxide and reduced graphene oxide prepared by different chemical oxidation methods, Ceram. Int. (2019). [69] H. Sui, B.G. Han, J.K. Lee, P. Walian, K.J. Bing, Structural basis of water-specific transport through the AQP1 water channel, Nature 414 (2001) 872–878. [70] W. Zhao, H. Liu, Y. Liu, M. Jian, L. Gao, H. Wang, X. Zhang, Thin-film nanocomposite forward-osmosis membranes on hydrophilic microfiltration support with an intermediate layer of graphene oxide and multiwall carbon nanotube, ACS Appl. Mater. Interfaces 10 (2018) 34464–34474. [71] G. Han, S. Zhang, X. Li, N. Widjojo, T.-S. Chung, Thin film composite forward osmosis membranes based on polydopamine modified polysulfone substrates with enhancements in both water flux and salt rejection, Chem. Eng. Sci. 80 (2012) 219–231. [72] C. Li, S. Li, L. Tian, B. Su, M.Z. Hu, Covalent organic frameworks (COFs)-incorporated thin film nanocomposite (TFN) membranes for high-flux organic solvent nanofiltration (OSN), J. Membr. Sci. 572 (2019) 520–531. [73] Y. Lv, H.-C. Yang, H.-Q. Liang, L.-S. Wan, Z.-K. Xu, Nanofiltration membranes via co-deposition of polydopamine/polyethylenimine followed by cross-linking, J. Membr. Sci. 476 (2015) 50–58. [74] G. Chen, S. Li, X. Zhang, S. Zhang, Novel thin-film composite membranes with improved water flux from sulfonated cardo poly(arylene ether sulfone) bearing pendant amino groups, J. Membr. Sci. 310 (2008) 102–109. [75] B.B. Vyas, P. Ray, Preparation of nanofiltration membranes and relating surface chemistry with potential and topography: application in separation and desalting of amino acids, Desalination 362 (2015) 104–116. [76] C.V. Goethem, R. Verbeke, S. Hermans, R. Bernstein, I. Vankelecom, Controlled positioning of MOFs in interfacially polymerized thin-film nanocomposites, J. Mater. Chem. A 4 (2016) 16368–16376. [77] P. Li, Z. Wang, L. Yang, S. Zhao, P. Song, B. Khan, A novel loose-NF membrane based on the phosphorylation and cross-linking of polyethyleneimine layer on porous PAN UF membranes, J. Membr. Sci. 555 (2018) 56–68. [78] J. Song, X.M. Li, Z. Li, M. Zhang, Y. Yong, B. Zhao, D. Kong, C. Gang, H. Tao, Stabilization of composite hollow fiber nanofiltration membranes with a sulfonated poly(ether ether ketone) coating, Desalination 355 (2015) 83–90. [79] J. Xu, X. Feng, C. Gao, Surface modification of thin-film-composite polyamide membranes for improved reverse osmosis performance, J. Membr. Sci. 370 (2011) 116–123. [80] C. Ba, J. Langer, J. Economy, Chemical modification of P84 copolyimide membranes by polyethylenimine for nanofiltration, J. Membr. Sci. 327 (2009) 49–58. [81] J. Liu, D. Hua, Y. Zhang, S. Japip, T.S. Chung, Precise molecular sieving architectures with Janus pathways for both polar and nonpolar molecules, Adv. Mater. 30 (2018) 1705933. [82] Z.F. Gao, G.M. Shi, Y. Cui, T.-S. Chung, Organic solvent nanofiltration (OSN) membranes made from plasma grafting of polyethylene glycol on cross-linked polyimide ultrafiltration substrates, J. Membr. Sci. 565 (2018) 169–178. [83] J.H. Kim, S.J. Moon, S.H. Park, M. Cook, A.G. Livingston, Y.M. Lee, A robust thin

[28] M. Wu, J. Yuan, H. Wu, Y. Su, H. Yang, X. You, R. Zhang, X. He, N.A. Khan, R. Kasher, Z. Jiang, Ultrathin nanofiltration membrane with polydopamine-covalent organic framework interlayer for enhanced permeability and structural stability, J. Membr. Sci. 576 (2019) 131–141. [29] B.-H. Jeong, E.M.V. Hoek, Y. Yan, A. Subramani, X. Huang, G. Hurwitz, A.K. Ghosh, A. Jawor, Interfacial polymerization of thin film nanocomposites: a new concept for reverse osmosis membranes, J. Membr. Sci. 294 (2007) 1–7. [30] W.J. Lau, S. Gray, T. Matsuura, D. Emadzadeh, J.P. Chen, A.F. Ismail, A review on polyamide thin film nanocomposite (TFN) membranes: history, applications, challenges and approaches, Water Res. 80 (2015) 306–324. [31] M.L. Lind, A.K. Ghosh, J. Anna, H. Xiaofei, H. William, Y. Yang, E.M.V. Hoek, Influence of zeolite crystal size on zeolite-polyamide thin film nanocomposite membranes, Langmuir 25 (2009) 10139–10145. [32] R. Bi, Q. Zhang, R. Zhang, Y. Su, Z. Jiang, Thin film nanocomposite membranes incorporated with graphene quantum dots for high flux and antifouling property, J. Membr. Sci. 553 (2018) 17–24. [33] E.M. Vrijenhoek, S. Hong, M. Elimelech, Influence of membrane surface properties on initial rate of colloidal fouling of reverse osmosis and nanofiltration membranes, J. Membr. Sci. 188 (2001) 115–128. [34] D. Ji, C. Xiao, S. An, J. Zhao, J. Hao, K. Chen, Preparation of high-flux PSF/GO loose nanofiltration hollow fiber membranes with dense-loose structure for treating textile wastewater, Chem. Eng. J. 363 (2019) 33–42. [35] W. Zhao, H. Liu, N. Meng, M. Jian, H. Wang, X. Zhang, Graphene oxide incorporated thin film nanocomposite membrane at low concentration monomers, J. Membr. Sci. 565 (2018) 380–389. [36] B. Li, Y. Cui, S. Japip, Z. Thong, T.-S. Chung, Graphene oxide (GO) laminar membranes for concentrating pharmaceuticals and food additives in organic solvents, Carbon 130 (2018) 503–514. [37] J. Yin, G. Zhu, B. Deng, Graphene oxide (GO) enhanced polyamide (PA) thin-film nanocomposite (TFN) membrane for water purification, Desalination 379 (2016) 93–101. [38] L. Chen, Y. Li, L. Chen, N. Li, C. Dong, Q. Chen, B. Liu, Q. Ai, P. Si, J. Feng, L. Zhang, J. Suhr, J. Lou, L. Ci, A large-area free-standing graphene oxide multilayer membrane with high stability for nanofiltration applications, Chem. Eng. J. 345 (2018) 536–544. [39] X. Li, M. Rui, J. Song, Z. Shen, H. Zeng, Carbon and graphene quantum dots for optoelectronic and energy devices: a review, Adv. Funct. Mater. 25 (2015) 4929–4947. [40] W. Kwon, Y.H. Kim, C.L. Lee, M. Lee, H.C. Choi, T.W. Lee, S.W. Rhee, Electroluminescence from graphene quantum dots prepared by amidative cutting of tattered graphite, Nano Lett. 14 (2014) 1306–1311. [41] S.K. Tuteja, R. Chen, M. Kukkar, C.K. Song, R. Mutreja, S. Singh, A.K. Paul, H. Lee, K.H. Kim, A. Deep, C.R. Suri, A label-free electrochemical immunosensor for the detection of cardiac marker using graphene quantum dots (GQDs), Biosens. Bioelectron. 86 (2016) 548–556. [42] S. Wang, Z.-G. Chen, I. Cole, Q. Li, Structural evolution of graphene quantum dots during thermal decomposition of citric acid and the corresponding photoluminescence, Carbon 82 (2015) 304–313. [43] Z. Zeng, S. Chen, T.T.Y. Tan, F.-X. Xiao, Graphene quantum dots (GQDs) and its derivatives for multifarious photocatalysis and photoelectrocatalysis, Catal. Today 315 (2018) 171–183. [44] Y. Lei, C. Yang, J. Hou, F. Wang, S. Min, X. Ma, Z. Jin, J. Xu, G. Lu, K.-W. Huang, Strongly coupled CdS/graphene quantum dots nanohybrids for highly efficient photocatalytic hydrogen evolution: unraveling the essential roles of graphene quantum dots, Appl. Catal. B 216 (2017) 59–69. [45] A.B. Ganganboina, A. Dutta Chowdhury, R.A. Doong, N-doped graphene quantum dots-decorated V2O5 nanosheet for fluorescence turn off-on detection of cysteine, ACS Appl. Mater. Interfaces 10 (2018) 614–624. [46] P. Zheng, N. Wu, Fluorescence and sensing applications of graphene oxide and graphene quantum dots: a review, Chem-ASIAN J 12 (2017) 2343–2353. [47] H. Liu, N. Li, H. Zhang, F. Zhang, X. Su, A simple and convenient fluorescent strategy for the highly sensitive detection of dopamine and ascorbic acid based on graphene quantum dots, Talanta 189 (2018) 190–195. [48] M. Fathizadeh, H.N. Tien, K. Khivantsev, Z. Song, F. Zhou, M. Yu, Polyamide/nitrogen-doped graphene oxide quantum dots (N-GOQD) thin film nanocomposite reverse osmosis membranes for high flux desalination, Desalination 451 (2019) 125–132. [49] S. Li, C. Li, X. Song, B. Su, B. Mandal, B. Prasad, X. Gao, C. Gao, Graphene quantum dots doped thin film nano-composite polyimide membrane with enhanced solvent resistance for solvent resistant nanofiltration, ACS Appl. Mater. Interfaces (2019) 6527–6540. [50] Z. Yan, Y. Su, J. Peng, X. Zhao, J. Liu, J. Zhao, Z. Jiang, Composite nanofiltration membranes prepared by interfacial polymerization with natural material tannic acid and trimesoyl chloride, J. Membr. Sci. 429 (2013) 235–242. [51] H.B. Park, J. Kamcev, L.M. Robeson, M. Elimelech, B.D. Freeman, Maximizing the right stuff: the trade-off between membrane permeability and selectivity, Science 356 (2017) 1138–1148. [52] N. Misdan, W.J. Lau, A.F. Ismail, Seawater Reverse Osmosis (SWRO) desalination by thin-film composite membrane—Current development, challenges and future prospects, Desalination 287 (2012) 228–237. [53] X. Zhang, Y. Lv, H.C. Yang, Y. Du, Z.K. Xu, Polyphenol coating as an interlayer for thin-film composite membranes with enhanced nanofiltration performance, ACS Appl. Mater. Interfaces 8 (2016) 32512–32519. [54] Y. Li, C. Li, S. Li, B. Su, L. Han, B. Mandal, Graphene oxide (GO)-interlayered thinfilm nanocomposite (TFN) membranes with high solvent resistance for organic solvent nanofiltration (OSN), J. Mater. Chem. A (2019).

15

Chemical Engineering Journal 380 (2020) 122462

Y. Liang, et al.

[84]

[85]

[86]

[87]

[88]

[89]

film composite membrane incorporating thermally rearranged polymer support for organic solvent nanofiltration and pressure retarded osmosis, J. Membr. Sci. 550 (2018) 322–331. A. Asadi Tashvigh, T.-S. Chung, Facile fabrication of solvent resistant thin film composite membranes by interfacial crosslinking reaction between polyethylenimine and dibromo-p-xylene on polybenzimidazole substrates, J. Membr. Sci. 560 (2018) 115–124. H. Mariën, I.F.J. Vankelecom, Transformation of cross-linked polyimide UF membranes into highly permeable SRNF membranes via solvent annealing, J. Membr. Sci. 541 (2017) 205–213. X. Cheng, S. Ding, J. Guo, C. Zhang, Z. Guo, L. Shao, In-situ interfacial formation of TiO 2 /polypyrrole selective layer for improving the separation efficiency towards molecular separation, J. Membr. Sci. 536 (2017) 19–27. D. Hua, T.-S. Chung, Polyelectrolyte functionalized lamellar graphene oxide membranes on polypropylene support for organic solvent nanofiltration, Carbon 122 (2017) 604–613. Y. Feng, M. Weber, C. Maletzko, T.-S. Chung, Facile fabrication of sulfonated polyphenylenesulfone (sPPSU) membranes with high separation performance for organic solvent nanofiltration, J. Membr. Sci. 549 (2018) 550–558. A.A. Tashvigh, T.-S. Chung, Facile fabrication of solvent resistant thin film

[90]

[91]

[92]

[93]

[94]

16

composite membranes by interfacial crosslinking reaction between polyethylenimine and dibromo-p-xylene on polybenzimidazole substrates, J. Membr. Sci. (2018). M.H. Davood Abadi Farahani, D. Hua, T.-S. Chung, Cross-linked mixed matrix membranes (MMMs) consisting of amine-functionalized multi-walled carbon nanotubes and P84 polyimide for organic solvent nanofiltration (OSN) with enhanced flux, J. Membr. Sci. 548 (2018) 319–331. S. Yuan, J. Swartenbroekx, Y. Li, J. Zhu, F. Ceyssens, R. Zhang, A. Volodine, J. Li, P. Van Puyvelde, B. Van der Bruggen, Facile synthesis of Kevlar nanofibrous membranes via regeneration of hydrogen bonds for organic solvent nanofiltration, J. Membr. Sci. 573 (2019) 612–620. J. Aburabie, K.V. Peinemann, Crosslinked poly(ether block amide) composite membranes for organic solvent nanofiltration applications, J. Membr. Sci. 523 (2017) 264–272. Y. Xu, F. You, H. Sun, L. Shao, Realizing mussel-inspired polydopamine selective layer with strong solvent resistance in nanofiltration toward sustainable reclamation, ACS Sustain. Chem. Eng. 5 (2017) 5520–5528. Z.F. Gao, Y. Feng, D. Ma, T.-S. Chung, Vapor-phase crosslinked mixed matrix membranes with UiO-66-NH2 for organic solvent nanofiltration, J. Membr. Sci. 574 (2019) 124–135.