Bioinspired synthesis of Janus nanocomposite-incorporated

Subscriber access provided by University of Winnipeg Library

Article

Bioinspired synthesis of Janus nanocomposite-incorporated molecularly imprinted membranes for selective adsorption and separation applications Yilin Wu, Jian Lu, Xinyu Lin, Jia Gao, Li Chen, Jiuyun Cui, Peng Lv, Xinlin Liu, Minjia Meng, and Yongsheng Yan ACS Sustainable Chem. Eng., Just Accepted Manuscript • DOI: 10.1021/ acssuschemeng.8b01442 • Publication Date (Web): 29 May 2018 Downloaded from http://pubs.acs.org on May 29, 2018

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 29 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ACS Sustainable Chemistry & Engineering

Bioinspired

synthesis

of

Janus

nanocomposite-incorporated

molecularly

imprinted membranes for selective adsorption and separation applications

Yilin Wu,1,* Jian Lu,1 Xinyu Lin,1 Jia Gao,1 Li Chen,1 Jiuyun Cui,2 Peng Lv,2 Xinlin Liu,3 Minjia Meng,1 Yongsheng Yan1,*

1

Institute of Green Chemistry and Chemical Technology, School of Chemistry and Chemical

Engineering, Jiangsu University, Zhenjiang 212013, China 2

School of Material Science and Engineering, Jiangsu University, Zhenjiang 212013, China

3

School of Energy and Power Engineering, Jiangsu University, Zhenjiang 212013, China

Corresponding Author* E-mail: [email protected]；；[email protected] Address: Xuefu Road NO. 301, Zhenjiang, China Telephone Number: +86 0511-88790683 Fax: +86 0511-88791800

1

ACS Paragon Plus Environment

ACS Sustainable Chemistry & Engineering 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Abstract Inspired from the biomimetic polydopamine (pDA)-based self-polymerization technique and Janus nanocomposite structure, an efficient yet simple method of pDA@Au-based Janus-incorporated molecularly imprinted nanocomposite membranes (MINCMs) has been developed. The Janus nanocomposite was obtained by using pDA nanospheres as the supports, and the catechol-reduced Au nanoparticles from Au ions were then grown on the surfaces of pDA nanospheres. Highly regenerative performance and selective separability toward tetracycline (TC) were finally obtained. Because of the formation of this membrane-based Janus nanocomposite surfaces, largely enhanced TC-rebinding capacities (67.43 mg/g), permselectivity (separation factors were all more than 10.5) and rebinding stability (93% of the saturated adsorption capacity after 11 cycling adsorption/desorption cycles) were finally obtained. These results strongly illustrated that incorporation of the Janus nanocomposite into molecularly imprinted membranes would achieve both the high rebinding capacity and the excellent permselectivity. All the synthesis processes were carried out at low temperature and ordinary pressure, which were energy-efficient and environmentally friendly for large-scale applications.

Keywords: Janus nanocomposite; pDA-inspired modification; TC-imprinted membrane; selective adsorption and separation

2


Page 2 of 29

Page 3 of 29 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Introduction Membrane separation technique (MST) has been widely developed and used in many fields such as wastewater treatment, environmental engineering, food industry, desalination and so on. Meanwhile, membrane material plays the vital roles in membrane separation science.[1-4] Recently, polyvinylidenefluoride (PVDF) ultrafiltration membrane has been regarded as a promising membrane material due to its advantages such as the excellent chemical durability, thermal stability mechanical strength.[5-7] However, there exists various problems in traditional membrane materials (such as poor stability, easy pollution, high cost, and low selectivity), which had seriously restricted the applications of MST in selective separation fields. As a result, various nanocomposite membrane materials, capable of selectively recognizing and separating target molecules, would play key role in the enhancement of the membrane separation field. As is well-known that polymer membrane materials with different integrated nanocomposite structures would provide various advantages for structural stability, anti-pollution capacity, and internal active domains.[8-10] Additionally, the internal nanocomposite structures would effectively reduce the blocking probability of macromolecular polymer.[11-12] Recently, Janus-based nanocomposite has been further studied in separation field.[13] As is well-known that employ of asymmetric nanocomposite for the synthesis of separation membrane materials would discretely adjust the multi-ply reciprocities. This is due to the different particle parts in membranes are separated, which would give expression to various functions. Therefore, the abovementioned nanocomposite blending method with Janus nanostructures would not only gather the advantages of both PVDF and nanostructures, but also promote the functionality of the ordinary membranes. Separation membranes with synthetic/artificial nanocomposite which perform high selectivity has been regarded as the critical issue in chemical separation area. Molecular imprinting technique (MIT) is a well-established and simple method for obtaining specific imprinting site which is well fitted in functionality, shape, and size toward target molecule.[14-18] Recently, molecularly imprinted polymers (MIPs) with porous membrane structures had been identified as an excellent method for preparing and evaluating specific separation membrane materials, which performed tailor-made rebinding capacities of template molecule specifically.[19-23] Thereofore, molecularly imprinted membranes (MIMs), which developed from MIT and MST, have become remarkable smart materials due to the specific recognizability and selective separation ability of 3



templates.[24-27] Hence, in this work, a high-efficiency selective separation methodology of molecularly imprinted nanocomposite membranes (MINCMs) with Janus nanostructures domains had been developed. Tetracycline (TC) molecules, a broad-spectrum antibiotic, were used as the templates, which have been widely used in human and veterinary medicines due to the high quality and low cost. However, the overusing of TC has brought on severe environment pollution.[28-29] Herein, instead of constructing MIPs layers onto membranes, the MINCMs were prepared via directly infiltrated Janus nanostructures into the casting solution during the phase inversion process. This as-obtained Janus nanocomposite membrane structure could not only largely enhance the structural stability but also increase the adsorption separation capacity of MINCMs. Therefore, the as-prepared MINCMs showed excellent rebinding capacities, good stability, and outstanding specific recognition towards TC molecules, which directed this strategy as the excellent membrane-based synthesis technique for selective separation of various target molecules.

Experimental Section Materials Dopamine, N,N-dimethylfomamide (DMF), 3-methacryloxypropyltrimethoxysilane (kh-570), ammonia solution (NH4OH), tetracycline (TC), cefalexin (CEX), sulfamethazine (SMZ), tris (hydroxymethyl) aminomethane (Tris-HCl), ascorbic acid (AC), azo-bis-isobutryronitrile (AIBN), methylene bisacrylamide (MBAA), and hydrogen tetrachloroaurate (III) hydrate (HAuCl4) were obtained from Aladdin Reagent (Shanghai, China). N-methylpyrrolidone (NMP), poly(vinylidene fluoride) (PVDF) powder, polyvinylpyrrolidone (PVP), and acrylamide (AM) were purchased from Sinopharm Chemical Reagent (Shanghai, China). Deionized water was used in the whole synthesis and cleaning processes. Characterization Micromorphologies of various membrane materials were studied by field emission scanning electron microscopy (SEM, S-4800, Japan). Transmission electron microscopy with a 200 kV accelerating voltage (TEM, Tecnai G2, FEI Co.) was used for observing microstructure of the synthesized nanoparticles. The functional groups of different synthesized membranes were obtained and confirmed by using attenuated total reflectance Fourier transform infrared 4


Page 4 of 29

Page 5 of 29 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(ATR-FTIR) spectra (FT-IR Nicolet 560), and the spectra were recorded over the wavenumber range from 4000 to 600 cm-1. X-ray photoelectron spectroscopy (XPS) was recorded using a monochromatized Al Kα X-ray source with an ESCALAB 250 spectrometer to test the surface chemical composition of membranes. The conditions of high performance liquid chromatography (HPLC) (Agilent 1200 series, U.S.A.) determination were as follows: methanol/H2O (80/20, v/v) mobile phase, 1.0 mL min-1 flow rate, 217 nm UV detection and 25 oC column temperature. Synthesis of Janus nanocomposite (Au@pDA) followed by the modification of kh-570 Firstly, in the typical polydopamine (pDA) nanoparticles synthesis, 0.5 g of dopamine was dissolved in 250 mL of 10 mM Tris-HCl (pH=8.5) aqueous solution (45 oC) to obtain the dopamine solution (2.0 mg mL-1). After that, 1.0 M NH4OH standardized solution was used for regulation of pH value (pH=8.5). The polymerization solution was then stirred vigorously for 6.0 h to start the oxidative polymerization of dopamine, the as-prepared pDA nanoparticles were collected by centrifuging at 10000 r/min, and washed with deionized water for several times (the self-polymerization mechanism of dopamine was described in Figure S1).[30] Subsequently, a Janus nanocomposite was then obtained by the reduced reaction of Au+ with catechol of dopamine to synthesize the pDA-Au Janus nanoparticles. In a typical Janus nanocomposite synthesis, the as-prepared pDA nanoparticles were dispersed in deionized water, 10 mg of HAuCl4 was then added to the pDA solution under stirring constantly for 1.0 h. After that, 15 mg of AC was added to the above mixed solution and the solution was stirred for another 5.0 h. Finally, the resultant nanoparticles were washed with deionized water for several times, and the as-obtained Janus nanocomposites (pDA@Au) were then dried in the vacuum oven at 45 oC for 24 h. Secondly, Janus nanocomposites (pDA@Au) were modified with kh-570 to introduce the polymerizable double bonds for TC-imprinted polymerization process. Briefly, 0.5 g of pDA@Au and 2.0 mL of kh-570 were dispersed in the mixture of ethanol-water (4:1, v/v) solution (60 mL). The mixture was then heated at 80 °C for 24 h under magnetic stirring (150 rpm). Finally, the kh-570 modified pDA@Au (kh570-pDA@Au) were obtained after several washing steps using deionized water, the kh570-pDA@Au were finally dried in the vacuum oven at 45 oC. Synthesis of MINCMs with Janus nanostructures domains Typically, 0.5 g of the as-prepared kh570-pDA@Au, 4.0 g of PVDF and 21 g NMP were intensive mixed, the as-obtained mixed solution was then stirred for 24 h to create the uniformly 5



Page 6 of 29

distributed mixture without any air bubbles. The as-obtained mixtures were finally cast onto the glass plates using a doctor knife. A phase inversion process was then carried by immersing the mixtures into a coagulant bath containing deionized water. After that, membranes (a diameter of 25 mm) with Janus nanostructures domains were finally obtained. For the MINCMs synthesis, TC (0.4 mmol) was dissolved in 50 mL aqueous solution containing 10 mg of AIBN, 1.2 mmol of AM and 3.2 mmol of MBAA. Two pieces of the as-prepared membranes with Janus nanostructures domains were then added the above mixture solution. The MINCMs were then synthesized by developing a two-step-temperature imprinting process, the mixture solution was initially reacted and stirred at 45 oC for 2.0 h, the solution was then kept at 60 oC for another 16 h, the imprinting procedure was conducted under nitrogen environment. After that, the synthesized membranes were rinsed by using ethanol/acetic acid (9:1, v/v) as the extractant to remove the unreacted monomers and templates. After being dried in the vacuum oven at 45 oC, the MINCMs with Janus nanostructures domains were obtained. In contrast, non-imprinted nanocomposite membranes (NINMs) were also prepared by similar procedures without the addition of TC. Batch rebinding experiments. Adsorption kinetics and isotherm experiments were carried out to study the rebinding capacities of MINCMs by batch mode operations. For adsorption isotherm experiments, the rebinding concentrations of TC were set at 50, 100, 200, 400, 600 and 800 mg L-1, respectively. A slice of MINCMs or NINMs was added to 10 mL of TC aqueous solutions with various concentrations, the as-obtained rebinding solution were shaken for 1.5 h at 25 oC. Thereafter, HPLC was used for the detection of the concentrations of rebinding solutions. The rebinding capacities of MINCMs or NINMs were calculated by the following equation: =

(1)

where Co and Ce (mg L-1) were initial and equilibrium concentrations, respectively. Qe (mg), V (L) and m (g) represented the adsorption amount, volume of solution and weight of MINCMs or NINMs, respectively. For adsorption kinetics experiments, a slice of MINCMs or NINMs was added to 10 mL of TC aqueous solutions (400 mg L-1), the membrane was taken out at predetermined time intervals

6


Page 7 of 29 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(5.0, 10, 20, 30, 60, 90 min). The adsorption amount of TC was calculated by the following equation: =

(2)

where Ct (mg L-1) was the concentration of TC solution at different time. Qt (mg), V (L) and m (g) represented the rebinding amount of TC, volume of solution and weight of MINCMs or NINMs. Additionally, the structural analogues CEX and SMZ were chosen for comparison to prove recognition specificity of the MINCMs, which have several differences in chemical structures and dimensions with TC (selective rebinding concentration was set at 400 mg L-1). Selective permeation experiments. Permselectivity results can provide critical data about the selective separation mechanism of molecularly imprinted membranes. Herein, the selective permeation experiments were carried out by developing a U-shaped permeation device (Figure S2), a feeding solution (400 mg L-1) containing TC, CEX and SMZ (400 mg L-1) was used as the feeding solution in isomer competitive and time-dependent permeation experiments. The U-shaped permeation device was composed of two tubular compartments which were made by glass or copper tubes. And they were separated by the as-synthesized membranes (inner diameters of 25 mm). Waterbath oscillator was applied to keep he solution homogeneous in both chambers. HPLC was finally used for the detection of the filtrates which contained TC, CEX, and SMZ. The permeation flux J (mg cm-2 s-1), permeability coefficient P (cm2 s-1) and permselectivity factor β were calculated by the following equations: = P=

∆

i= TC, CEX, and SMZ

∆

i= TC, CEX, and SMZ

⁄ =

i, j =TC, CEX, SMZ, MINCMs and NINMs

(3) (4) (5)

where A, d and V represented the effective membrane area (cm2), thickness of membrane (cm) and volume of feeding and receiving solution (mL), respectively. △Ci/△t were the changes of concentrations in the receiving solution. (CFi-CRi) was the concentration difference between feeding and receiving chambers. Results and discussion

7



Synthesis route of MINCMs for selective separation of TC Herein, the pDA@Au-based Janus structure was used as internal nanocomposite of MINCMs through a straightforward immersion strategy during the phase inversion process, our fabrication method for MINCMs was schematically illuminated Scheme 1, which illustrated how the ‘specific recognition sites’ can be effectively constructed on the membrane surfaces. The MINCMs were synthesized by a two-step strategy, pDA nanospheres were primarily synthesized by oxidative polymerization of dopamine molecules, the pDA@Au Janus nanocomposite was then obtained by developing the chelating reactions between Au and catechol of dopamine. Secondly, after a kh-570 modification procedure at the surfaces of pDA@Au, the as-prepared kh570-pDA@Au was then used for the synthesis of nanocomposite membranes with Janus nanostructures, the mixture of PVDF powder, NMP, and kh570-pDA@Au would be undergone a phase inversion process to obtain the nanocomposite membrane. A reformative imprinting methodology, in this work, was then triggered by AIBN with TC molecules as templates, AM as functional monomer and MBAA as the cross-linker. In addition, to obtain the best rebinding capacity of the as-prepared MINCMs, a two-step-temperature imprinting strategy was developed during the synthesis process. After the removal of TC molecules by using the mixture of ethanol/acetic acid (9:1, v/v), the specific recognition sites of TC were fabricated on the as-synthesized membranes, suggesting the MINCMs were finally obtained. In comparison, the MINCMs without 2.0 h of prepolymerization process at 45 oC (MINCMs-0) were also prepared, not surprisingly, the rebinding capacities of MINCMs were much higher than that of MINCMs-0 (Figure S3), which strongly illustrating the excellent imprinting efficiency of the as-designed two-step-temperature imprinting strategy. Characterization of pDA@Au Janus nanocomposite Figure 1 described TEM images of pDA nanoparticles and pDA@Au Janus nanocomposite under different magnifications. As shown in Figure 1a, b, the pDA nanospheres were spherical in shape with the uniform size of 300 nm. Moreover, particles with the sizes of 50 nm were attached to the bigger pDA nanoparticles could be observed, which was the typical Janus nanocomposite feature. These results explicitly demonstrated the creation of the pDA@Au-based Janus nanocomposite. In addition, the surface composition of different as-prepared nanomaterials was investigated by XPS (Figure 2a). The formation of pDA nanoparticles was further supported by the analysis of curve-fitting results for C1s peak (Figure 2b), the C-N and N-H bonds clearly 8


Page 8 of 29

Page 9 of 29 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


proved the self-polymerization of pDA nanoparticle. As shown in Figure 2a and the enlarged image, when comparing the pDA and pDA@Au, a new Au peak emerged could be observed from the XPS wide scans, demonstrating the formation of Au nanoparticles on the surface of pDA, which further demonstrated the preparation of the pDA@Au Janus nanocomposite. Characterization of different synthesized membranes Analysis of membrane surfaces with scanning electron microscope (SEM) allowed the visualization of each grafted layer-by-layer nanocomposite structures on PVDF, as could be observed when comparing the MINCMs to other synthesized membranes. As shown in Figure 3, analysis of the membranes with SEM allowed the visualization of each grafted multilevel structures on PVDF surfaces, as can be observed when comparing the MINCMs to other membranes. As shown in Figure 3a, the nanocomposite membranes with Janus nanostructures showed the typically porous structures with fairly smooth surfaces, further clarified images with higher magnitude in SEM (Figure 3a2-3a3) were also described, obvious pDA@Au-based Janus nanocomposite could be observed from nanocomposite membrane after the phase inversion process. As to the MINCMs (Figure 3b), much rougher surfaces and relatively diminished pore size were clearly observed after the imprinting process, demonstrating the complete polymerization of TC-imprinted layers on membrane surfaces. Similarly, the further clarified images with higher magnitude in SEM of MINCMs were studied, as shown in Figure 3b 2-3, the MIPs layers of TC could be obviously obtained on the Janus nanocomposite. In addition, Figure 3c showed the cross-sectional SEM structures of MINCMs, all of membranes exhibited finger-like voids, typical asymmetric cross-sectional structures were observed, and the Janus-based nanocomposite with MIPs layers were clearly discovered. Finally, the formation of this so-called Janus-based nanocomposite membrane structure was further supported by the analysis of XPS wide spectra (Figure 2a) and curve-fitting results (Figure 2c). As shown in Figure 2a, MINCMs displayed a new F1s peak, which implied the ready preparation of PVDF-based membrane structure. In addition, when comparing pDA and MINCMs, the intensity of C-O s peak enhanced and a new emerging C=O peak could be observed in the MINCMs (Figure 2c), suggesting the successful polymerization of TC-based imprinted polymers. Optimization of synthesis conditions Rebinding capacity of MIMs system is of crucial importance, therefore, the synthesis 9



conditions were studied and optimized in detail to obtain efficient rebinding capacities and specific recognizability of TC (Figure 4). Meanwhile, in the whole optimized experiments, 400 mg L-1 of TC and 25 oC of rebinding temperature were used as the constant rebinding conditions to increase measurement precision and reduce errors. The optimization of synthesis conditions (amount of pDA@Au Janus nanocomposite, amount of TC, polymerization time of imprinted process, washing time of templates) were evaluated by optimization of synthesis experiments. The selective rebinding capacities of MINCMs toward TC molecules were then investigated and the optimistic synthesis conditions were finally obtained. Firstly, the rebinding capacities of MINCMs increased with increasing the amount of pDA@Au Janus nanocomposite until 0.5 g (Figure 4a). When the amount of pDA@Au was 0.5 g, the maximum adsorption amount (62.92 mg g-1) was obtained. However, obvious reduction circumstances were then observed when the synthesis amount of pDA@Au was more than 0.5 g. These results strongly demonstrated that this pDA@Au Janus nanocomposite-incorporated structure could highly influence the rebinding capacity and imprinted polymerization process for the synthesis MINCMs. Secondly, various synthesis concentrations of TC (ranging from 0.05 to 0.4 mmol) were used for the preparation of MINCMs. As shown in Figure 4b, the adsorption results of MINCMs obviously enhanced with the concentration increase of TC, which should be ascribed to the creation of more and more imprinting cavities and recognition sites. On the contrary, when the synthesis conditions of TC molecules were more than 0.5 mmol, obvious reductions in rebinding capacities could be obtained. It should be explained that the excess use of TC molecules would largely reduce the imprinted effect and cased the decrease of imprinted sites. Thirdly, in order to create more TC-imprinted sites and achieve rapid adsorption responses, different imprinted polymerization time was investigated by adjusting polymerization time from 4.0 to 36 h. As depicted in Figure 4c, the rebinding capacities of MINCMs observably increased with the increase of polymerization time and obtained the best binding capaciry (63.51 mg g-1) at 16 h. The best polymerization time of 16 h was then obtained after the optimized rebinding experiments. Finally, elution processes are significantly important for MIMs, herein, the mixture of ethanol/acetic acid (9:1, v/v) was used for the remove of template molecules from MINCMs. As shown in Figure 4d, more and more TC would be extracted from MINCMs as the extraction processes were going on, that left lots of imprinted sites of templates. Meanwhile, the adsorption 10


Page 10 of 29

Page 11 of 29 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


results of MINCMs reached the maximum value at the washing time of 12 h.

Rebinding and selectivity analysis of MINCMs Static rebinding experiments of MINCMs and NINMs were then studied in detail, the equilibrium adsorption processes and linear regression values were also investigated and developed. As shown in Figure 5a, the adsorption concentrations of TC were ranging from 50 to 800 mg L-1, and the adsorption isotherms of MINCMs and NINMs were initially described by correlative studies of batch binding operations. When the rebinding concentration of TC molecules increased, the equilibrium rebinding capacities for both MINCMs and NINMs increased simultaneously. However, as shown in the isothermal adsorption curves, much higher adsorption capacities toward TC could be observed from MINCMs in comparison with NINMs over a wide range of TC concentrations. It should be owing to various high-affinity recognition sites of TC molecules on MINCMs, which were created during the imprinting process with the addition of TC molecules. It was obvious that the rebinding capacities of MINCMs first increased rapidly then slightly, adsorption mount of 67.43 mg g-1 from MINCMs could be obtained, which was more than three times of NINMs (22.74 mg g-1). Therefore, the isothermal adsorption results indicated that MINCMs represented the specific high adsorption ability of TC molecules compared to NINMs. Moreover, Langmuir model assumed a homogeneous adsorption sites distribution with equal energy.[31] The equilibrium adsorption data of MINCMs and NINMs were fitted by the Langmuir model equation: =

!

(6)

"#

where Qe (mg g-1) and Qm (mg g-1) were the equilibrium and maximum rebinding capacity of TC, Ce (mg L-1) was the equilibrium concentration of TC, KL (L mg-1) is the Langmuir constant. As shown in Figure 5a and Table 1, it was obvious that the linear regression values of MINCMs fitted well with Langmuir model. It was also demonstrated that the imprinting factor of MINCMs was excellent. Moreover, the imprinting layers on MINCMs with the homogenous distribution were monolayer adsorption. Adsorption kinetics studies would provide rate-controlling and rebinding mechanism of TC molecules, and they were performed by varying the adsorption time from 5.0 to 90 min. The

11



Page 12 of 29

rebinding concentration of TC and rebinding temperature were set at 400 mg L-1 and 25 oC, respectively. As shown in Figure 5b, the MINCMs took up 91% of the saturated adsorption capacity of TC molecules within 20 min, and the adsorption equilibrium was obtained within 30 min. This as-obtained fast adsorption dynamics should be duo to creation of high-proportioned recognition sites and complete removal of templates. On the contrary, the much slower rebinding dynamics of NINMs could be observed, which should be due to the inexistence of TC-imprinted sites. Moreover, the much higher rebinding capacities from MINCMs could be observed in comparison with NINMs. Furthermore, to investigate the dynamic adsorption properties of MINCMs, the adsorption data was fitted with pseudo-first-order rate and pseudo-second-order rate equations.[32-33] The adsorption data of MINCMs and NINMs were fitted by following equations: = − % &

(7)

'

' = "#

(8)

'

where Qe and Qt (mg g-1) are the rebinding amount of MINCMs and NINMs at equilibrium and at different times t. K1 (min-1) and K2 (g mg-1 min-1) are constants of Pseudo-first-order model and Pseudo-second-order model, respectively. As shown in Figure 5b and Table 2, the as-obtained results exhibited the adsorption kinetics data was fitted well with pseudo-second-order model compared to pseudo-first-order model, which indicated that chemical reactions during the adsorption procedures played an important role and specific reaction ability between TC molecules and MINCMs. Moreover, to examine the selectivity of MINCMs to TC, the rebinding characteristics of MINCMs toward comparative molecules (CEX, SMZ), which are different from the molecular structure of TC, were checked. The feeding concentrations of TC, CEX and SMZ were all ranging from 50 to 800 mg L-1 and the adsorption temperature was set at 25 oC. As shown in Figure 5c, the maximum adsorption capacity of MINCMs toward TC reached 68.31 mg g-1, which was much higher than that toward other molecules (18.25 and 17.52 mg g-1), showing an excellent selectivity of the as-prepared MINCMs toward the TC molecules. Meanwhile, selectivity factor α of TC/CEX and TC/SMZ, taken as the rebinding ratio of MINCMs, was determined as 3.74 and 3.9, respectively, which suggested that the MINCMs exhibited no selectivity toward other

12


Page 13 of 29 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


non-template molecules. To further confirm the selective adsorption capacity of the MINCMs, the selective adsorption experiments of NINMs were also studied in detail. As show in Figure S4, the NINMs possessed similar rebinding capacities for TC, CEX and SMZ, which strongly illustrating the non-selective adsorption capacity of NINMs toward TC molecules, and the rebinding capacities of NINMs toward TC molecules were much lower than that of MINCMs. In addition, when the CEX and SMZ molecules were both imprinted (denoted as CEX-imprinted membrane and SMZ-imprinted membrane), similar results were obtained which were dependent on the target molecules (Figure 5d, 5e). Finally, the regeneration performance of the MINCMs was studied, which was a significant ability for further applications in separation industries, and the results of regeneration experiments were described in Figure 5f. The adsorption/desorption cycles of TC were then performed to understand the rebinding regeneration performance and structural stability of our MINCMs. Figure 5f clearly indicated that the rebinding capacities of MINCMs were not obviously lost after 11 adsorption/desorption cycles. The same MINCMs, which had been used for 11 times, still got 93% of the saturated adsorption capacity, which strongly demonstrating the excellent adsorption stability of MINCMs. Permselectivity results and separation mechanism of MINCMs Permselectivity properties toward template molecules were finally studied and tested to better understand the specific adsorption separation properties of the as-prepared MINCMs. The selective permeation performance of MINCMs and NINMs were initially confirmed by isothermal permeability tests at 25oC, the permeation concentrations of TC molecules were ranging from 50 to 400 mg L-1. As shown in Figure 6a, the transport fluxes of NINMs were all much higher than that of MINCMs, which should be concluded that abundance of imprinted sites toward TC molecules were formed into the MINCMs during the imprinting polymerization process, thus the TC molecules were initially adsorbed onto the imprinted sites of MINCMs. Importantly, the as-calculative permeation factors (βNINMs/MINCMs) were all more than 10.5, which further illustrating the specific separation performance toward TC molecules of the as-prepared MINCMs. Selective permeation experiments of MIMs would provide crucial comprehensions about the relationship between the arrangements of template-imprinted sites and functional groups. Herein, time-dependent permselectivity performance of MINCMs and NINMs were then investigated by using CEX and SMZ as the competitive transport molecules, and the selective separation time of 13



MINCMs was ranging from 5.0 to 90 min. Figure 6b described the time-dependent permselectivity curves of MINCMs, as shown, MINCMs represented much lower permeation rates of TC molecules than that of other molecules. It should be because of the presence of sterically complementary imprinting cavities of TC that hindering the transports of TC via rebinding/desorption onto the TC-imprinted sites in MINCMs. But other molecules (CEX and SMZ) had no specific recognition capability with MINCMs, thus facilitating the transports by diffusion or convection. Furthermore, we also performed the additional "blank" control experiments with the artemisinin (Ars) and m-cresol molecule, which were not similar in structure or size to TC (the chemical structures of Ars and m-cresol are shown in the Figure S5). And this competitive permeation solution with the totally different molecules (Ars and m-cresol) could be regarded as the pseudo samples for the selective separation performance testing of MINCMs. As shown in the permeation result in Figure S6, not surprisingly, MINCMs also presented much lower transport rates of TC molecules than that of Ars and m-cresol molecules, which further demonstrating the excellent permselectivity of the as-prepared MINCMs. On the contrary, as shown in the time-dependent permselectivity curves of NINMs (Figure 6c), a contrary phenomenon could be observed, the as-prepared NINMs possessed nearly the same permeation fluxes of all the transport molecules, non-selectivity could be achieved in these results, which also suggested that no imprinted sites were built in NINMs. In other words, the random arrangement of the functional groups in NINMs resulted in no imprinting effects. Importantly, the permselectivity results and separation factors (β) in time-dependent permeation experiments were described in Table 3, the as-obtain β values of MINCMs were all more than 9.9, which clearly demonstrating the excellent selective separation performance and the construction of specific recognition sites toward TC. The as-obtained permselectivity results demonstrated the formation and presence of TC ‘recognition sites’ in MINCMs. As to selective permeation of a molecularly imprinted membrane material, it is well-known that two opposing mechanisms could be summarized: facilitated permeation and retarded permeation.[25, 34-35] Herein, according to the above obtained transport results, the retarded permeation mechanism played the dominant roles in the selective permeation and separation of TC. As schematically depicted in Figure 6d, because of the saturation behaviors, separation efficiency of TC was mainly determined by the selective rebinding sites of MINCMs. 14


Page 14 of 29

Page 15 of 29 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Therefore, the TC molecules initially approached the surfaces of MINCMs, and were then adsorbed by the rebinding cavities. That is to say, TC molecules were preferentially bound by the affinity imprinting sites and other non-specific molecules (CEX and SMZ) would transport directly through the MINCMs without any resistance.

Conclusions In summary, for the first time, by utilizing a biomimetic Janus nanocomposite-incorporated platform as the separation domains, a TC-imprinted membrane methodology was designed and developed for the preparation of MINCMs, which were innovatively used as highly efficient systems for regulating specific rebinding and separation of TC molecules reversibly and noninvasively. The pDA@Au-based Janus nanocomposite was initially proposed, which was used as the imprinting domains in the separation membrane system and facilitated the high-stability and uniform growth of imprinted sites on membrane surfaces. The rebinding capacities and regenerative stability results showed that the as-developed synthesis stratrgy could not only largely improve the specific separation performance of TC, but also remarkably enhance the structural stability of membranes. Such transformation made the interactions between TC-bound surfaces switchable, thus leading to the reversible separation of TC. Importantly, the key design of the as-designed MINCMs was to employ the MIT to introduce the specific recognition mechanism (TC-imprinted sites) into a Janus nanocomposite based separation membrane system, which could be innovatively used as a highly efficient novel system for the selective separation of TC molecules. Therefore, the as-prepared MINCMs with reversible fast-recognized properties could also possess excellent permselectivity of template molecule, and the selective permeation results illustrated that the separation factors were all more than 10.5, which strongly illustrating the permselectivity of TC molecules. We envision that this study opens a new direction to obtain intelligent MIMs with fast recognition affinity of specific compound, which showed promising potential for selective separation membranes and high-throughput devices.

ASSOCIATED CONTENT Supporting Information Figure S1. Possible reaction mechanism for dopamine polymerization. Figure S2. The H-model 15



tube installation of permeation experiment. Figure S3. The rebinding capacity comparison of the MINCMs and MINCMs-0. Figure S4. Selective adsorption results of NINMs toward different molecules. Figure S5. Chemical structures of Ars and m-cresol. Figure S6. Time-dependent permselectivity curves of various targets (TC, Ars, m-cresol) through MINCMs. This material is available free of charge via the Internet at http://pubs.acs.org/.

Acknowledgment This work was financially supported by the National Natural Science Foundation of China (Nos. U1507118, 21406085, 21676127) and Natural Science Foundation of Jiangsu Province (Nos. BK20171315, BK20151350, BK20161367). In addition, Dr. Yilin Wu wants to thank the support, care and patience from Dr. Ming Yan over the past years. Please marry me!

References [1] Yu, J. M.; Xie, L. H.; Li, J. R.; Ma, Y. G.; Seminario, J. M.; Balbuena, P. B. CO2 capture and separations using MOFs: Computational and experimental studies. Chem. Rev. 2017, 117 (14), DOI 10.1021/acs.chemrev.6b00626. [2] Yu, L.; Han, M.; He, F. A review of treating oily wastewater. Arab. J. Chem. 2017, 10 (S2), DOI 10.1016/j.arabjc.2013.07.020. [3] Xu, Y. C.; Tang, Y. P.; Liu, L. F.; Guo, Z. H.; Shao, L. Nanocomposite organic solvent nanofiltration membranes by a highly-efficient mussel-inspired co-deposition strategy. J. Membrane Sci. 2017, 526, DOI 10.1016/j.memsci.2016.12.026. [4] Du, X.; You, S. J.; Wang, X. H.; Wang, Q. R.; Lu, J. D. Switchable and simultaneous oil/water separation induced by prewetting with a superamphiphilic self-cleaning mesh. Chem. Eng. J. 2017, 313, DOI 10.1016/j.cej.2016.12.092 [5] An, A. K.; Guo, J. X.; Lee, E. J.; Jeong, S.; Zhao, Y. H.; Wang, Z. K.; Leiknes, T. PDMS/PVDF hybrid electrospun membrane with superhydrophobic property and drop impact dynamics for dyeing wastewater treatment using membrane distillation. J. Membrane Sci. 2017, 525, DOI 10.1016/j.memsci.2016.10.028. [6] Zeng, G. Y.; He, Y.; Zhan, Y. Q.; Zhang, L.; Pan, Y.; Zhang, C. L.; Yu, Z. X. Novel polyvinylidene fluoride nanofiltration membrane blended with functionalized halloysite nanotubes 16


Page 16 of 29

Page 17 of 29 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


for

dye

and

heavy

metal

ions

removal.

J.

Hazard.

Mater.

2016,

317,

DOI

10.1016/j.jhazmat.2016.05.049. [7] Shi, H.; He, Y.; Pan, Y.; Di, H. H.; Zeng, G. Y.; Zhang, L.; Zhang, C. L. A modified mussel-inspired method to fabricate TiO2 decorated superhydrophilic PVDF membrane for oil/water separation. J. Membrane Sci. 2016, 506, DOI 10.1016/j.memsci.2016.01.053. [8] Wu, Y. L.; Liu, X. L.; Cui, J. Y.; Meng, M. J.; Dai, J. D.; Li, C. X.; Yan, Y. Y. Bioinspired synthesis of high-performance nanocomposite imprinted membrane by a polydopamine-assisted metal-organic method. J. Hazard. Mater. 2017, 323, DOI 10.1016/j.jhazmat.2016.10.030. [9] Kochameshki, M. G.; Marjani, A.; Mahmoudian, M.; Farhadi, K. Grafting of diallyldimethylammonium chloride on graphene oxide by RAFT polymerization for modification of nanocomposite polysulfone membranes using in water treatment. Chem. Eng. J. 2017, 309, DOI 10.1016/j.cej.2016.10.008. [10] Zhu, J. Y.; Qin, L. J.; Uliana, A.; Hou, J. W.; Wang, J.; Zhang, Y. T.; Li, X.; Yuan, S. S.; Li, J.; Tian, M. M. Elevated performance of thin film nanocomposite membranes enabled by modified hydrophilic MOFs for nanofiltration. ACS Appl. Mater. Inter. 2017, 9 (2), DOI 10.1021/acsami.6b14412. [11] Furukawa, S.; Suda, Y.; Kobayashi, J.; Kawashima, T.; Tada, T.; Fujii, S.; Kiguchi, M.; Saito, M. Triphosphasumanene trisulfide: High out-of-plane anisotropy and Janus-type Pi-surfaces. J. Am. Chem. Soc. 2017, 139 (16), DOI 10.1021/jacs.6b12119. [12] Peng, H. J.; Wang, D. W.; Huang, J. Q.; Cheng, X. B.; Yuan, Z.; Wei, F.; Zhang, Q. Janus separator of polypropylene-supported cellular graphene framework for sulfur cathodes with high utilization in lithium-sulfur batteries. Adv. Sci. 2016, 3 (1), DOI 10.1002/advs.201500268. [13] Zhou, T. T.; Luo, L.; Hu, S.; Wang, S. F.; Zhang, R. N.; Wu, H.; Jiang, Z. Y.; Wang, B. Y.; Yang, J. Janus composite nanoparticle-incorporated mixed matrix membranes for CO2 separation. J. Membrane Sci. 2015, 489, DOI 10.1016/j.memsci.2015.03.070. [14] Zhang, Z. J.; Zhang, X. H.; Liu, B. W.; Liu, J. W. Molecular imprinting on inorganic nanozymes for hundred-fold enzyme specificity. J. Am. Chem. Soc. 2017, 139 (15), DOI 10.1021/jacs.7b00601. [15] Pan, G. Q.; Zhang, Y.; Ma, Y.; Li, C. X.; Zhang, H. Q. Efficient one-pot synthesis of water-compatible molecularly imprinted polymer microspheres by facile RAFT precipitation 17



polymerization. Angew. Chem. Int. Ed. 2011, 123 (49), DOI 10.1002/ange.201104751. [16] Guo, P. Q.; Luo, Z. M.; Xu, X. Y.; Zhou, Y. L.; Zhang, B. L.; Chang, R. M.; Du, W.; Chang, C.; Fu, Q. Development of molecular imprinted column-on line-two dimensional liquid chromatography for selective determination of clenbuterol residues in biological samples. Food Chem. 2017, 217, DOI 10.1016/j.foodchem.2016.09.021. [17] Liu, X. Y.; Ren, J.; Su, L. H.; Gao, X.; Tang, Y. W.; Ma, T.; Zhu, L. J.; Li, J. R. Novel hybrid probe based on double recognition of aptamer-molecularly imprinted polymer grafted on upconversion nanoparticles for enrofloxacin sensing. Biosens. Bioelectro. 2017, 87, DOI 10.1016/j.bios.2016.08.051. [18] Lin, Z. Z.; Zhang, H. Y.; Peng, A. H.; Lin, Y. D.; Li, L.; Huang, Z. Y. Determination of malachite green in aquatic products based on magnetic molecularly imprinted polymers. Food Chem. 2016, 200, DOI 10.1016/j.foodchem.2016.01.001. [19] Chen, L. X.; Wang, X. Y.; Lu, W. H.; Wu, X. Q.; Li, J. H. Molecular imprinting: Perspectives and spplications. Chem. Soc. Rev. 2016, 45, DOI 10.1039/C6CS00061D. [20] Wackerlig, J.; Lieberzeit, P. A. Molecularly imprinted polymer nanoparticles in chemical sensing-synthesis, characterisation and application. Sensor. Actuat. B 2015, 207, DOI 10.1016/j.snb.2014.09.094. [21] Liu, Y.; Liu, Z. C.; Gao, J.; Dai, J. D.; Han, J. A.; Wang, Y.; Xie, J. M.; Yan, Y. S. Selective adsorption behavior of Pb(II) by mesoporous silica SBA-15-supported Pb(II)-imprinted polymer based on surface molecularly imprinting technique. J. Hazard. Mater. 2011, 186 (1), DOI 10.1016/j.jhazmat.2010.10.105. [22] Pan, G. Q.; Guo, Q. P.; Ma, Y.; Yang, H. L.; Li, B. Thermo-responsive hydrogel layers imprinted with RGDS peptide: A system for harvesting cell sheets. Angew. Chem. Int. Ed. 2013, 52 (27), DOI 10.1002/anie.201300733. [23] Awino, J. K.; Zhao, Y. Protein-mimetic, molecularly imprinted nanoparticles for selective binding of bile salt derivatives in water. J. Am. Chem. Soc. 2013, 135 (34), DOI 10.1021/ja406089c. [24] Wu, Y. L.; Yan, M.; Cui, J. Y.; Yan, Y. S.; Li, C. X. A multiple-functional Ag/SiO2/organic based biomimetic nanocomposite membrane for high-stability protein recognition and cell adhesion/detachment. Adv. Funct. Mater. 2015, 25 (36), DOI 10.1002/adfm.201502465. 18


Page 18 of 29

Page 19 of 29 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


[25] Ulbricht, M. Membrane separations using molecularly imprinted polymers. J. Chromatogr. B 2004, 804 (1), DOI 10.1016/j.jchromb.2004.02.007. [26] Szekely, G.; Valtcheva, I. B.; Kim, J. F.; Livingston, A. G. Molecularly imprinted organic solvent nanofiltration membranes-revealing molecular recognition and solute rejection behavior. J. Membrane Sci. 2015, 86, DOI 10.1016/j.reactfunctpolym.2014.03.008. [27] Wu, Y. L.; Yan, M.; Liu, X. L.; Lv, P.; Cui, J. Y.; Meng, M. J.; Dai, J. D.; Yan, Y. S.; Li, C. X. Accelerating the design of multi-component nanocomposite imprinted membranes by integrating a versatile metal-organic methodology with a mussel-inspired secondary reaction platform. Green Chem. 2015, 17, DOI 10.1039/C5GC00453E. [28] Boxall, A. B. A.; Kolpin, D. W.; Halling-Sørensen, B.; Tolls, J. Are veterinary medicines causing environmental risks. Environ. Sci. Technol. 2003, 37 (15), DOI 10.1021/es032519b. [29] Cooper, A. D.; Stubbings, G. W. F.; Kelly, M.; Tarbin, J. A.; Farrington, W. H. H.; Shearer, G. Improved method for the on-line metal chelate affinity chromatography-high-performance liquid chromatographic determination of tetracycline antibiotics in animal products. J. Chromatogr. A 1998, 812 (1-2), DOI 10.1016/S0021-9673(97)01290-9. [30] Lee, H.; Dellatore, S. M.; Miller, W. M.; Messersmith, P. B. Mussel-inspired surface chemistry for multifunctional coatings. Science 2007, 318 (5849), DOI 10.1126/science.1147241. [31] Langmuir, I. The adsorption of gases on plane surfaces of glass, mica and platinum. J. Am. Chem. Soc. 1918, 40, DOI 10.1021/ja02242a004. [32] Ho, Y. S.; McKay, G. The sorption of lead (II) on peat. Water Res. 1999, 33 (2), DOI 10.1016/S0043-1354(98)00207-3. [33] Ho, Y. S., McKay, G. Pseudo second-order model for sorption processes. Process Biochem. 1999, 34 (5), DOI 10.1016/S0032-9592(98)00112-5. [34] Roper, D. K.; Lightfoot, E. N. Separation of biomolecules using adsorptive membranes. J. Chromatogr. A 1995, 702 (1-2), DOI 10.1016/0021-9673(95)00010-K. [35] Noble, R. D. Generalized microscopic mechanism of facilitated transport in fixed site carrier membranes. J. Membrane Sci. 1992 (1-2), 75, DOI 10.1016/0376-7388(92)80011-8.

19



Scheme 1. Schematic diagram for the synthesis process of MINCMs.

20


Page 20 of 29

Page 21 of 29 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


21



Figure 1. TEM images of (a, b) pDA nanoparticles and (c, d) pDA@Au-based Janus nanocomposite.

22


Page 22 of 29

Page 23 of 29 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 2. (a) XPS results of various synthesized materials in (a) wide scan and narrow scans for: (b) C 1s of pDA nanoparticles and (c) C 1s of MINCMs.

23



Figure 3. SEM top images of (a) the membranes with Janus nanostructures domains and (b) MINCMs, (c) the SEM cross-sectional structures of MINCMs.

24


Page 24 of 29

Page 25 of 29 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 4. Effects of the (a) amount of pDA@Au Janus nanocomposite, (b) amount of TC, (c) imprinted polymerization time and (d) washing time on rebinding capacities of MINCMs.

25



Figure 5. (a) Rebinding isotherms (a) and kinetics (b) isotherms for MINCMs and NINMs, respectively; (c) Selective adsorption results of MINCMs, (d) selective adsorption results of CEX-imprinted membrane and (e) selective adsorption results of SMZ-imprinted membrane; (f) Cycling operations and regeneration performance of MINCMs.

26


Page 26 of 29

Page 27 of 29 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Figure 6. (a) Isothermal transport results of MINCMs and NINMs towards TC; (b) Time-dependent permselectivity curves of various targets (TC, CEX, SMZ) through (b) MINCMs and (c) NINMs; (d) Schematic diagram of the permselectivity mechanism of MINCMs towards TC.

Table 1. Langmuir data for the adsorption of TC onto MINCMs and NINMs. Membranes

Qe,exp (mg g-1)

Qe,c (mg g-1)

KL (L mg -1)

27


R2


Page 28 of 29

MINCMs

67.43

66.23

0.0077

0.9982

NINMs

22.74

22.96

0.0056

0.9995

Table 2. Kinetics constants (30 min) for the pseudo-first-order and pseudo-second-order rate equations. Pseudo-first-order model

Pseudo-second-order model

k2 Membranes

Qe,exp (mg/g)

Qe,cal (mg/g)

k1

Qe,cal

R2

-1

(min )

(g mg-1

(mg/g)

R2

min-1)

MINCMs

60.51

34.58

0.0232

0.8164

57.76

0.0025

0.9989

NINMs

15.64

10.55

0.0166

0.9711

15.64

0.0017

0.9991

Table 3. Time-permeation results (90 min) of MINCMs and NINMs for TC, CEX, and SMZ. The data are the mean of at least three independent experiments.

Membranes

AINMs

NINMs

J

P

（mgcm-2h-1）

(cm2h-1)

TC

2.61

2.22

CEX

5.61

24.42

SMZ

5.54

22.01

TC

5.41

18.57

CEX

5.48

20.35

SMZ

5.53

21.82

Substrates

TOC graphic

28


βCEX/TC

βSMZ/TC

11.0

9.92

1.1

1.18

Page 29 of 29 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


Janus nanocomposite-incorporated molecularly imprinted membranes for selective separation of TC molecules.

29


Bioinspired synthesis of Janus nanocomposite-incorporated

Recommend Documents