Removal of BSA and HA Contaminants from Aqueous Solution Using

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Removal of BSA and HA Contaminants from Aqueous Solution Using Amphiphilic Triblock Copolymer Modified Poly(ether imide) UF Membrane and Their Fouling Behaviors P. Kanagaraj,† S. Neelakandan,† A. Nagendran,*,† D. Rana,*,‡ T. Matsuura,‡ and M. Shalini† †

PG & Research Department of Chemistry, Polymeric Materials Research Lab, Alagappa Government Arts College, Karaikudi-630 003, India ‡ Department of Chemical and Biological Engineering, Industrial Membrane Research Institute, University of Ottawa, 161 Louis Pasteur Street, Ottawa, ON K1N 6N5, Canada ABSTRACT: Amphiphilic triblock copolymer (Pluronic F127) was used as a macromolecular additive to modify the surface of poly(ether imide) (PEI) ultrafiltration (UF) membranes with additive contents from 0 to 3 wt % in the casting solution. The surface modification of the membranes was confirmed by Fourier transform infrared spectroscopy and contact angle measurements. The membranes were also characterized by scanning electron microscopy, UF of proteins, and flux recovery. A membrane with the highest Pluronic (3 wt %) in PEI exhibited the highest pure water flux, highest water content, and lowest membrane hydraulic resistance. It exhibited high UF fluxes of 170 and 180 L m−2 h−1 at 345 kPa, for 1.0 g/L bovine serum albumin (BSA) in phosphate buffer solution and 1.0 g/L humic acid (HA) in deionized water feed solutions, with solute rejections of 84 and 82%, respectively. It also showed that the blended membranes with 3 wt % Pluronic content had a higher flux recovery ratio (92.4 and 89.4%), slightly higher reversible fouling (25.8 and 18.8%), and lower irreversible fouling (7.6 and 10.6%) after the UF of BSA and HA solute separation. This explained their low fouling behaviors compared to the neat PEI membranes.

1. INTRODUCTION Humic substances usually account for half of the total organic carbon (TOC) content in aquatic environments. Natural organic matter (NOM) reduces the water quality, i.e., properties such as color, taste, and odor problems and the major contributor of harmful disinfection byproducts (DBPs). DBPs developed negative effects in water treatment. The phosphate’s adsorption on the surfaces of soil constituents could be reduced by the presence of humic substances in the NOM and increased levels of complexed heavy metals which lead to the formation of toxic organic pollutants. NOM is accountable for the fouling of membranes and contributes to the absorption of UV radiation and decreasing effectiveness of UV disinfection. Recently, with the presence of NOM in an aqueous stream, the oxidation step applied prior to As(III) removal could lead to the formation of toxic oxidation by products.1−4 Due to water quality problems and stricter regulations for drinking water treatment, the removal and recovery of NOM is a technological challenge. NOM can be removed from drinking water by several conventional water treatment techniques of which the membrane filtration technique has been suggested as the main treatment options. On the other hand, protein separations from biorelated industrial waste streams are gaining increased visibility owing to environmental concern and to save precious substances. In various industrial sectors, such as food, water, and medical industries, it is becoming increasingly significant to separate solute constituents such as proteins, NOM, and blood proteins. There are several different methods to separate proteins and NOM from their aqueous stream including sand filtration, electrocoagulation/flotation, liquid chromatography, electro© XXXX American Chemical Society

phoretic, and membrane-based processes. Among the aforesaid processes, UF has been extensively used for product recovery and pollution control in water treatment industries.5,6 Membrane fouling is the major disadvantage for all membrane filtration processes. The foulants (i.e., inorganic particles, proteins, NOM, and some other biological substances, etc.) block the pore entrance at the membrane surface or the flow channel inside the pores due to the electrostatic and hydrophobic interactions.7−9 The lifetime of fouled membranes is shortened significantly, and the frequent replacement of a fouled membrane becomes necessary with a high cost. Therefore, the fouling mitigation is a major challenge for both industrial and academic researchers of the field. PEI is often used as a membrane material due to its good mechanical properties, chemical and thermal resistance, as well as outstanding film forming abilities.10 However, the relatively hydrophobic nature of PEI causes severe fouling when the feed contains substances such as NOM, colloidal particles, proteins, etc. In order to make PEI more hydrophilic, their surface should be modified by a method such as the addition of a surface modifying agent to the host polymer matrix. A wide range of hydrophilic additives including poly(vinyl alcohol) (PVA), poly(ethylene glycol) (PEG), poly(vinylpyrrolidone) (PVP), inorganic acids, etc., have been used as pore forming agents. When these additives are blended into the casting dope of base polymer(s), the membrane surface Received: September 4, 2015 Revised: November 5, 2015 Accepted: November 6, 2015

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DOI: 10.1021/acs.iecr.5b03290 Ind. Eng. Chem. Res. XXXX, XXX, XXX−XXX

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Industrial & Engineering Chemistry Research

available for UF is 38.5 cm2. The feed solution filled in the UF cell was stirred at 300 rpm via a magnetic stirrer. All of the UF experiments were carried out at 30 ± 2 °C. The membranes were initially pressurized with deionized water at 414 kPa for 5 h, followed by UF experiments at 345 kPa. 2.3. Membrane Fabrication. The membranes were prepared by the standard phase inversion technique. The casting solutions, PEI (17.5 wt %) and Pluronic F127 additive (1, 2, and 3 wt %) in NMP (81.5−79.5 wt %), were prepared under constant (500 rpm) mechanical stirring of the polymer/ additive/solvent mixture in a round-bottomed flask for 4 h at 40 °C. The membrane-casting chamber was maintained at a temperature of 24 ± 1 °C and a relative humidity of 50 ± 2 °C. The polymer solution was cast on a glass plate using a casting knife. After the cast film was left on the glass plate for 30 s, the cast film together with the glass plate was gently placed in the gelation bath (containing of 2.5 wt % NMP and 0.2 wt % surfactant (SLS) in 2 L deionized water) for at least 1 h to complete coagulation and membrane formation. The formed membrane was removed from the glass plate gently and washed thoroughly with deionized water to remove solvent and surfactant from the membrane. Finally, the membrane was preserved in a 0.1 wt % aqueous formaldehyde solution to prevent microbial growth on the membrane surface. The chemical structures of PEI and Pluronic F127 are shown in Figure 1.

hydrophilicity increases only marginally, and they may also leach out after a prolonged water treatment operation.11 On the other hand, amphiphilic copolymers can remain at the membrane surface for a much longer period while importing hydrophilicity to the membrane surface. PEO−PPO−PEO is a class of typical amphiphilic triblock copolymers consisting of hydrophilic poly(ethylene oxide) (PEO) and hydrophobic poly(propylene oxide) (PPO) segments which are often known as Poloxamers or Pluronics.12 Recently, the use of amphiphilic block copolymers as additives has received great interest in membrane fabrication. Unlike conventional pore forming additives, Pluronics usually serve as an antifouling surface modifier. When Pluronics are introduced as an additive in the membrane, the hydrophilic PEO segment will protrude toward water at the membrane/water interface due to the affinity between the PEO segment and water, whereas the water insoluble hydrophobic PPO segment is anchored in the membrane matrix.13 Pluronics are also reported as a pore former when used in a polymer dope solution. Thus, the dual functions of Pluronic (surface modifier and pore former) make it attractive particularly when Pluronic F127 is used.14 For example, Pluronic F127 was blended with different polymer(s) such as poly(ether sulfone),15 poly(vinylidene fluoride),16 cellulose acetate,17 and poly(vinyl butyral)18 to develop an UF membrane with improved hydrophilicity and antifouling activities. Based on the above concept, Pluronic F127 was chosen as a macromolecular additive in this study and blended into the casting dope of PEI to prepare novel PEI membranes with the amphiphilic copolymer at the membrane surface, with enhanced UF performance by means of increasing the flux and antifouling properties of the membrane. Therefore, the main objective of the present work is to examine the effects of membrane surface modification by blending Pluronic F127 in the PEI flat sheet UF membranes. To the best of our knowledge, there is no record in literature regarding the PEI membrane surface modified by Pluronic F127. The prepared membranes were subjected to different characterization studies including a pure water flux (PWF) test, water content (WC), resistance of the membrane (Rm), contact angle (CA), and SEM. Lastly, the antifouling performances of the prepared membranes in UF treatment of BSA and HA solutions were evaluated.

Figure 1. Chemical structure of Pluronic F127 and PEI.

2.4. Membranes Characterizations. Fourier transform infrared spectroscopy (FT-IR, RX1 spectrometer, PerkinElmer) with a KBr pellet was used to confirm the presence of Pluronic F127 molecules in the membrane. The top and cross-sectional images of the neat PEI and PEI/Pluronic F127 blend membranes were taken by a scanning electron microscope (Hitachi, S3000N, Japan) under vacuum conditions with a gold scattered sample. PWF (Jw1) of the membranes was calculated by the following equation19

2. EXPERIMENTAL SECTION 2.1. Materials. PEI (Ultem 1000) was generously provided by GE Plastics, India as a free sample. BSA (69 kDa) was procured from SRL Chemicals Ltd., India. N-Methyl-2pyrrolidone (NMP), Pluronic F127, HA, and sodium lauryl sulfate (SLS) of AR grades were procured from Sigma-Aldrich Inc. (St. Louis, MO). Sodium dibasic phosphate heptahydrate and anhydrous sodium monobasic phosphate were also purchased from Sigma-Aldrich Inc. (St. Louis, MO) and used for the preparation of buffer solutions in the protein study. Trypsin (20 kDa) and egg albumin (EA) (45 kDa) were purchased from HiMedia Ltd., Mumbai, India. All chemicals were utilized without further purification. Deionized water was used for the fabrication of the membranes and UF measurements. 2.2. Experimental Setup. The fabricated membranes were cut to the required size and installed in the UF cell (Amicon 8400-Model, Millipore, Bedford, MA) which was equipped with a Teflon-coated magnetic paddle. The effective membrane area

Jw = 1

Q A × Δt

(1) −2

−1

where Jw1 is the PWF (L m h ), Q the permeate volume (L), A the membrane area (m2), and Δt the permeation time (h). The percentage WC of the membrane was obtained by20 ⎛ W − Wd ⎞ WC = ⎜ w ⎟ × 100% ⎝ Ww ⎠

(2)

where Wd is the dry weight of the membrane and Ww is the wet weight of the membrane, respectively. B


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Industrial & Engineering Chemistry Research ⎡J − J ⎤ w2 p1 ⎥ × 100% R rf = ⎢ ⎢⎣ Jw ⎥⎦ 1

The PWF was obtained at trans-membrane pressure (TMP) differences of 69, 138, 207, 276, and 345 kPa, where the resistance of the membrane (Rm, kPa/L m−2 h−1) was evaluated from the slope of Jw1 versus TMPs based on the following equation.21

Jw = 1

ΔP Rm

⎡ Jp ⎤ R t = ⎢1 − 1 ⎥ × 100% ⎢⎣ Jw ⎥⎦ 1

(3)

(4)

where γw is the water surface tension (7.2 × 10−2 N/m) and θ is the CA. The molecular weight cutoff and average pore size of the membranes were calculated from the %SR data of different molecular weights of protein solutions such as trypsin (20 kDa), EA (45 kDa), and BSA (69 kDa). The %SR and pore size of the membranes were determined from eqs 5 and 6. ⎡ ⎛ Cp ⎞⎤ %SR = ⎢1 − ⎜ ⎟⎥ × 100 ⎢⎣ ⎝ Cf ⎠⎥⎦

(5)

⎛ α ⎞ ⎟ R̅ = 100⎜ ⎝ %SR ⎠

(6)

3. RESULTS AND DISCUSSION 3.1. FT-IR Analysis. The FT-IR spectra of the PEI/Pluronic F127 blended membranes are shown in Figure 2. The peaks at

where Cp and Cf are the concentrations of permeate and feed solutions, respectively. R̅ the average pore size of the membrane (Å), and α the Stokes radius (Å) of the particular solute. The Stoke radii of the solutes were measured through the plot of solute molecular weight against solute radius.23 2.5. Anti-Fouling Studies. The fouling resistance of the UF membrane was evaluated by the UF of BSA (1.0 g/L BSA in phosphate buffer solution, pH ≈ 7.2) and HA (1.0 g/L HA in deionized water, pH ≈ 6.9) solutions as the model biosolutions.24,25At first, the steady state PWF (Jw1) of the membranes was measured. Then, the BSA solution was introduced into the permeation cell, and the permeate flux Jp1was measured at 345 kPa and at ambient temperature after the steady state was reached. Subsequently, the membrane was washed with deionized water under stirring for 2 h, and then the PWF (Jw2) of the cleaned membrane was evaluated. These PWFs after the cleaning of the fouled membrane were designated as Jw2. In order to judge the fouling resistance of the membranes, the FRR was calculated by26 ⎡J ⎤ w FRR = ⎢ 2 ⎥ × 100% ⎢⎣ Jw ⎥⎦ 1

Figure 2. FT-IR measurement of neat PEI, 1 wt % Pluronic F127, and 3 wt % Pluronic F127 with PEI membranes.

1776 and 1721 cm−1 (asymmetric and symmetric CO in the imide ring), 1390 cm−1 (C−N), 1229 cm−1 (C−O), and 1271 cm−1 (aromatic ether group) are the characteristic peaks of the pristine PEI membrane. The peaks at around 1105 and 1109 cm−1 were observed for membranes prepared with the addition of Pluronic F127. This absorbance peak represents the characteristic band for C−O−C stretching corresponding to the ether group of PEO and PPO blocks, which confirms the uniform distribution of Pluronic F127 additive in the PEI membrane matrix. 3.2. Surface Morphology of Membranes. Figure 3 shows the SEM top (T) surface and cross-sectional (C) images of the prepared membranes. In T1, the top surface of the

(7)

In order to examine the antifouling propensity of the membranes in more detail, the Rirf, Rrf, and total (Rt) fouling ratios27 were calculated by the following eqs 8−10): ⎡J − J ⎤ w w2 ⎥ R irf = ⎢ 1 × 100% ⎢⎣ Jw ⎥⎦ 1

(10)

The experiment was repeated for the HA solution. Initially, the steady state PWF (Jw1) of the membranes was measured. Afterward, the HA solution was introduced into the permeation cell, and the permeate flux Jp2 was measured at 345 kPa and at ambient temperature after the steady state was reached. Eventually, the membrane was washed with deionized water under stirring for 2 h, and then the PWF (Jw3) of the cleaned membrane was evaluated. Subsequently, the irreversible Rirf, Rrf, and Rt fouling ratios were calculated by the following eqs 8−10 using Jw3 and Jp2 values instead of Jw2 and Jp1 values, respectively.

The CA (θ) of water on the membrane surface was measured by a goniometer (VCA Optima surface analyzing system, AST Products, Inc.). From the CA values, the adhesion work (ωA), the work necessary to pull liquid water away from a square meter of membrane surface, was calculated by22 ωA = γW(1 + cos θ )

(9)

(8) C


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Figure 3. SEM top (T) surface and cross-sectional images (C) of the neat PEI and PEI/Pluronic F127 blended membranes. Top surfaces images: Neat PEI (T-0), 1 wt % Pluronic F127 (T-1), 2 wt % Pluronic F127 (T-2), and 3 wt % Pluronic F127 (T-3) with PEI membranes. Cross-sectional images: Neat PEI (C-0), 1 wt % Pluronic F127 (C-1), 2 wt % Pluronic F127 (C-2), and 3 wt % Pluronic F127 (C-3) with PEI membranes.

pristine PEI membrane seems very dense with few pores. When Pluronic F127 is added, the surface becomes porous and the pore size becomes larger with an increase in the amount of Pluronic F127 from T-1 to T-3. This is due to the higher hydrophilic nature of Pluronic F127, which can intake more water to the membrane surface. Figure 3c shows the crosssectional images. In the figure the fabricated membranes had an asymmetric structure with a dense skin layer, followed by a layer of fingerlike pores that further merges into macrovoids at the bottom. The more Pluronic F127 is added to the PEI casting dope, the thinner the fingerlike sublayer becomes and the larger the size of the macrovoid at the membrane bottom becomes. 3.3. Membrane Surface Hydrophilicity Measurements. The membrane surface hydrophilicity can be evaluated by measuring the CA. The static CA values of the resultant membranes are shown in Figure 4 and Table 1. The pristine PEI membrane CA (93.5°) is significantly higher than PEI/ Pluronic F127 blended membranes with 1 wt % Pluronic F127 (78.2°), 2 wt % Pluronic F127 (60.1°), and 3 wt % Pluronic F127 (45.0°), indicating the presence of hydrophilic PEO segment (in Pluronic F127) at the surface of the PEI membrane. From the table, it can be seen that the CA of the top surface is significantly lower than the bottom surface, confirming the hydrophilic PEO segment on the membrane surface. Table 1 also shows the adhesion work, ωA, calculated by eq 4. It increases gradually with the increase in the Pluronic F127 content, i.e., 67.6, 86.7, 108, and 123 mN/m for 0, 1, 2, and 3 wt % Pluronic F127, respectively. In general, the increase in the work of adhesion means the higher wettability of the surface. A similar trend was reported in PEI/NPHCs blend UF systems.28 Additionally, the CA is coupled with WC. The WC increases with a decrease in CA. Considering that WC is a bulk property while CA is a surface property, it discloses that the surface and bulk properties are closely related to each other.29 3.4. Membrane Hydraulic Resistance and Water Permeation. Rm is the resistance of the membrane for water permeation.30 Jw1 and Rm values are shown in Figure 5. From the figure Jw1 is 30, 76.4, 202.5, and 255 L m−2 h−1 while Rm is 10.5, 4.5, 3, and 1.6 kPa/L m−2 h−1, respectively, for Pluronic

Figure 4. Contact angle images: top (T-0) and bottom (B-0) surfaces of the neat PEI membranes, and top (T-3) and bottom (B-3) surfaces of the 3 wt % Pluronic F127 with PEI membranes.

F127 content of 0, 1, 2, and 3 wt %. It can be seen that the Jw1 increased whereas Rm decreased as the Pluronic F127 content increased due to the increase in hydrophilicity (see the CA data given in Table 1), pore size, and porosity of the membranes (SEM images given in Figure 3).14 3.5. Ultrafiltration with BSA and HA Filtration. UF experiments were conducted with the BSA and HA solution, individually, and the results are shown in Table 2. The rejection and permeate flux of the pristine PEI membrane were 96% and 15 L m−2 h−1, respectively, for the BSA solution. As the Pluronic F127 content was increased from 1 to 3 wt % in the PEI casting dope, the percentage rejection decreased from 90 to 84%, while permeate flux increased from 42 to 170 L m−2 h−1. A similar tendency was also observed for the HA, with varying magnitudes. The decrease of rejection and increase of permeation with an increase in the Pluronic F127 content in D


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Table 1. Membrane Composition, Water Content, Contact Angle, Adhesion Work, Pore Size, and MWCO of the Control PEI and PEI/Pluronic F127 Blended Membranes blend composition, wt %

contact angle (CA) (θ°)

PEI

pluronic F127

NMP

17.5 17.5 17.5 17.5

0 1 2 3

82.5 81.5 80.5 79.5

water content (WC) (%) 62.0 76.5 81.0 83.0

± ± ± ±

0.5 1.2 0.4 0.2

top 93.5 78.2 60.1 45.0

± ± ± ±

1.5 2.0 2.5 1.8

adhesion work (ωA) (mN/m)

bottom

top

bottom

pore size, R (Å)

MWCO (kDa)

± ± ± ±

67.6 86.7 108.0 123.0

63.2 80.1 94.7 109.5

36.7 47.5 63.9 69.6

20 45 69 69

97.0 83.5 71.6 58.6

0.6 1.2 2.7 3.0

Figure 5. Pure water flux and membrane hydraulic resistance of the neat PEI and PEI/Pluronic F127 blended membranes.

the PEI casting dope are ascribed to the increased pore size and increased surface hydrophilicity of the membranes as observed by SEM images and confirmed by the average pore size (Table 1), MWCO (Table 1), and CA data. As well, even though the solute rejection decreased by the addition of Pluronic F127, they were above 80% for both BSA and HA indicating that the surface covered by hydrophilic PEO segment of Pluronic F127 prevented BSA and HA molecules from coming near the surface. 3.6. MWCO and Average Pore Size. The MWCO values are given in Table 1. From the table MWCO increases progressively from 20 to 69 kDa as the Pluronic F127 content increased from 0 to 3 wt %. These results are in good accord with those obtained in the former study.31,32 3.7. Fouling Analysis. FRR values were introduced to evaluate the fouling properties of the membranes. The higher FRR indicates that there is better permeation and fouling resistant properties of the membrane.33 Figure 6 exemplified the FRR values for the membranes in the BSA solution. The PEI neat membrane exhibited both low water permeation and poor FRR: flux was 30 L m−2 h−1 and FRR as low as 73.3%, respectively. In comparison, the water permeation and FRR of the PEI membrane blending with Pluronic F127 improved remarkably. For example, with a PEI membrane with 3 wt % Pluronic F127, the water permeation increases to 255 L m−2

Figure 6. Flux recovery ratio of the neat PEI and PEI/Pluronic F127 blended membranes.

h−1 and the FRR reached up to 92.4%. A similar tendency has been obtained in the HA solution. The addition of hydrophilic PEO segment could reduce the deposition of foulant or formation of a cake layer on the surface or inside the membrane walls.34 Therefore, foulants can be simply washed out as a result of higher reprocessing property of blended membranes. The fouling analysis is studied more in detail by calculating the Rt, Rrf, and Rirf ratio of the membranes. These values are summarized in Figure 7. The Rt and Rirf values for the PEI/ Pluronic F127 membranes were low compared to the pristine PEI membrane. The lower Rt indicates that the lower total flux loss is less prone to fouling on the membranes and lower Rif which indicates that the introduction of hydrophilic PEO layer to the PEI casting dope reduces the total fouling, in particular internal fouling. The reversible fouling data obtained from protein solution of BSA and HA increases as the Pluronic F127 content increases because this kind of fouling was reversible and accumulated in close proximity to the boundary layer of the membranes which can be effortlessly recovered by water cleaning.27

Table 2. Ultrafiltration Performance of BSA and HA Solutions membrane composition, wt % PEI

pluronic F127

NMP

17.5 17.5 17.5 17.5

0 1 2 3

82.5 81.5 80.5 79.5

BSA solution Jp1 (L m−2 h−1) 15 42 130.4 170

± ± ± ±

0.3 0.5 1.0 0.8

HA solution

Jw2 (L m−2 h−1) 22 60.5 180.2 235.7

± ± ± ±

0.3 1.0 1.1 1.6 E

%SR 96 90 86 84

± ± ± ±

2.1 1.6 0.4 2.5

Jp2 (L m−2 h−1) 16 51 142 180

± ± ± ±

2.0 1.5 0.1 0.7

Jw3 (L m−2 h−1) 20 62.1 174 228

± ± ± ±

0.2 0.7 0.5 1.0

%SR 92 87.5 85 82

± ± ± ±

1.3 1.0 0.5 0.4


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Research Council of Canada for the partial support of this work.

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(1) Matilainen, A.; Vepsalainen, M.; Sillanpaa, M. Natural organic matter removal by coagulation during drinking water treatment: A review. Adv. Colloid Interface Sci. 2010, 159, 189−197. (2) Redman, A. D.; Macalady, D.; Ahmann, D. Natural organic matter affects arsenic speciation and sorption onto hematite. Environ. Sci. Technol. 2002, 36, 2889−2896. (3) Dubrawski, K. L.; Fauvel, M.; Mohseni, M. Metal type and natural organic matter source for direct filtration electrocoagulation of drinking water. J. Hazard. Mater. 2013, 244−245, 135−141. (4) Mohora, E.; Roncevic, S.; Dalmacija, B.; Agbaba, J.; Watson, M.; Karlovci, E.; Dalmacija, M. Removal of natural organic matter and arsenic from water by electrocoagulation/flotation continuous flow reactor. J. Hazard. Mater. 2012, 235−236, 257−264. (5) Susanto, H.; Roihatin, A.; Aryanti, N.; Anggoro, D. D.; Ulbricht, M. Effect of membrane hydrophilization on ultrafiltration performance for biomolecules separation. Mater. Sci. Eng., C 2012, 32, 1759−1766. (6) Baker, R. W.; Strathmann, H. Ultrafiltration of macromolecular solution with high-flux membranes. J. Appl. Polym. Sci. 1970, 14, 1197−1214. (7) Nagendran, A.; Arockiasamy, D. L.; Mohan, D. Cellulose acetate and polyetherimide blend ultrafiltration membranes, I. Preparation, characterization, and application. Mater. Manuf. Processes 2008, 23, 311−319. (8) Kim, Y.; Rana, D.; Matsuura, T.; Chung, W. J. Towards antibiofouling ultrafiltration membranes by blending silver containing surface modifying macromolecules. Chem. Commun. 2012, 48, 693− 695. (9) Tang, S.; Wang, Z.; Wu, Z.; Zhou, Q. Role of dissolved organic matters (DOM) in membrane fouling of membrane bioreactors for municipal wastewater treatment. J. Hazard. Mater. 2010, 178, 377− 384. (10) Celik, E.; Liu, L.; Choi, H. Protein fouling behavior of carbon nanotube/polyethersulfone composite membranes during water filtration. Water Res. 2011, 45, 5287−5294. (11) Lafrenière, L. Y.; Talbot, F. D. F.; Matsuura, T.; Sourirajan, S. Effect of poly(vinylpyrrolidone) additive on the performance of poly(ether sulfone) ultrafiltration membranes. Ind. Eng. Chem. Res. 1987, 26, 2385−2389. (12) Zhao, W.; Su, Y.; Li, C.; Shi, Q.; Ning, X.; Jiang, Z. Fabrication of antifouling polyethersulfone ultrafiltration membranes using Pluronic F127 as both surface modifier and pore-forming agent. J. Membr. Sci. 2008, 318, 405−412. (13) Asatekin, A.; Kang, S.; Elimelech, M.; Mayes, A. M. Anti-fouling ultrafiltration membranes containing polyacrylonitrile-graft-poly(ethylene oxide) comb copolymer additives. J. Membr. Sci. 2007, 298, 136−146. (14) Loh, C. H.; Wang, R.; Shi, L.; Fane, A. G. Fabrication of high performance polyethersulfone UF hollow fiber membranes using amphiphilic Pluronic block copolymers as pore-forming additives. J. Membr. Sci. 2011, 380, 114−123. (15) Zhang, Y.; Sua, Y.; Chen, W.; Peng, J.; Dong, Y.; Jiang, Z.; Liu, H. Appearance of poly(ethylene oxide) segments in the polyamide layer for antifouling nano-filtration membranes. J. Membr. Sci. 2011, 382, 300−307. (16) Loh, H.; Wang, R. Effects of additives and coagulant temperature on fabrication of high performance PVDF/Pluronic F127 blend hollow fiber membranes via non solvent induced phase separation. Chin. J. Chem. Eng. 2012, 20, 71−79. (17) Lv, C.; Su, Y.; Wang, Y.; Ma, X.; Sun, Q.; Jiang, Z. Enhanced permeation performance of cellulose acetate ultrafiltration membrane by incorporation of Pluronic F127. J. Membr. Sci. 2007, 294, 68−74. (18) Qiu, Y.-R.; Matsuyama, H.; Gao, G. − Y; Ou, Y.-W.; Miao, C. Effects of diluent molecular weight on the performance of hydrophilic poly(vinyl butyral)/Pluronic F127 blend hollow fiber membrane via

Figure 7. Antifouling studies of the neat and PEI/Pluronic F127 blended membranes with UF of BSA and HA solution as model foulants.

4. CONCLUSIONS Novel surface-modified PEI membranes were fabricated by blending Pluronic F127. FTIR confirmed the presence of Pluronic F127 in the PEI membrane matrix. SEM crosssectional images showed that the thicknesses of the top dense layer and the fingerlike porous sublayer became less with increasing Pluronic F127 content. The membrane surface hydrophilicity increased significantly with the increase in the additive content as evidenced by the decrease in CA. As a result, the PWF at 345 kPa increased from 30 L m−2 h−1 of neat PEI membrane to 255 L m−2 h−1 of the highest Pluronic F127 content (3 wt % in the casting dope). From the UF filtration experiments of BSA and HA feed solutions, it was found that the permeate flux increased while solute rejection slightly decreased by the addition of Pluronic F127; however, more than 80% of the solute rejection could be maintained for both BSA and HA. As well, the FRR increased significantly by adding Pluronic F127. It was concluded that the addition of Pluronic F127 leads to decreased Rrf and Rt fouling ratios of BSA and HA filtration which explains the lower fouling behaviors on the neat PEI membrane. As a result, PEI with 3 wt % Pluronic F127 achieved higher FRR of 92.4 and 89.4% after UF of BSA and HA solute separation, respectively.

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REFERENCES

AUTHOR INFORMATION

Corresponding Authors

*E-mail: [email protected]. Tel.: 91-4565-224283. Fax: 91-4565-227497. *E-mail: [email protected]. Tel.: 1-613-562 5800, ext. 6085. Fax: 1-613-562 5172. Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was supported by the Science and Engineering Research Board (SERB), Department of Science and Technology (DST), Government of India, under project number SR/FT/CS-22-2011. This support is gratefully acknowledged. The authors also gratefully acknowledge the financial support from Natural Sciences and Engineering F


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Industrial & Engineering Chemistry Research thermally induced phase separation. J. Membr. Sci. 2009, 338, 128− 134. (19) Kanagaraj, P.; Neelakandan, S.; Nagendran, A.; Rana, D.; Matsuura, T.; Muthumeenal, A. Performance studies of PEI/SPEI blend ultrafiltration membranes via surface modification using cSMM additives. RSC Adv. 2015, 5, 27594−27602. (20) Tamura, M.; Uragami, T.; Sugihara, M. Studies on syntheses and permeabilities of special polymer membranes: 30. Ultra-filtration and dialysis characteristics of cellulose nitrate-poly (vinyl pyrrolidone) polymer blend membranes. Polymer 1981, 22, 829−835. (21) Nagendran, A.; Lawrence Arockiasamy, D.; Mohan, D. Effect of poly(ethylene glycol) on separations by cellulose acetate/poly(ether imide) blend membranes. Int. J. Polym. Mater. 2007, 57, 138−153. (22) Nunes, S. P.; Peinemann, K. V. Ultrafiltration membranes from PVDF/PMMA blends. J. Membr. Sci. 1992, 73, 25−35. (23) Sarbolouki, M. N. A general diagram for estimating pore size of ultrafiltration and reverse osmosis membranes. Sep. Sci. Technol. 1982, 17, 381−386. (24) Kanagaraj, P.; Nagendran, A.; Rana, D.; Matsuura, T.; Neelakandan, S.; Malarvizhi, K. Effects of polyvinylpyrrolidone on the permeation and fouling-resistance properties of polyetherimide ultrafiltration membranes. Ind. Eng. Chem. Res. 2015, 54, 4832−4838. (25) Mehrparvar, A.; Rahimpour, A. Surface modification of novel polyether sulfone amide (PESA) ultrafiltration membranes by grafting hydrophilic monomers. J. Ind. Eng. Chem. 2015, 28, 359−368. (26) Kanagaraj, P.; Neelakandan, S.; Nagendran, A. Preparation, characterization and performance of cellulose acetate ultrafiltration membranes modified by charged surface modifying macromolecule. Korean J. Chem. Eng. 2014, 31, 1057−1064. (27) Baker, R. W. Membrane Technology and Applications, 2nd ed.; John Wiley & Sons Ltd.: West Sussex, England, 2004. (28) Kanagaraj, P.; Nagendran, A.; Rana, D.; Matsuura, T.; Neelakandan, S.; Karthikkumar, T.; Muthumeenal, A. Influence of N-phthaloyl chitosan on poly (ether imide) ultrafiltration membranes and its application in bio molecules and toxic heavy metal ion separation and their antifouling properties. Appl. Surf. Sci. 2015, 329, 165−173. (29) Dang, H. T.; Amelot, C.; Rana, D.; Narbaitz, R. M.; Matsuura, T. Performance of a newly developed hydrophilic additive blended with different ultrafiltration base polymers. J. Appl. Polym. Sci. 2010, 116, 2205−2215. (30) Nagendran, A.; Vidya, S.; Mohan, D. Preparation and characterization of cellulose acetate/sulfonated poly(ether imide) blend ultrafiltration membranes and their applications. Soft Mater. 2008, 6, 45−64. (31) Kanagaraj, P.; Nagendran, A.; Rana, D.; Matsuura, T.; Neelakandan, S. Separation of macromolecular proteins and rejection of toxic heavy metal ions by PEI/cSMM blend UF membranes. Int. J. Biol. Macromol. 2015, 72, 223−229. (32) Vidya, S.; Vijayalakshmi, A.; Nagendran, A.; Mohan, D. Effect of additive concentration on cellulose acetate blend membranes − preparation, characterization and application studies. Sep. Sci. Technol. 2008, 43, 1933−1954. (33) Kanagaraj, P.; Neelakandan, S.; Nagendran, A. Poly(ether imide) membranes modified with charged surface-modifying macromolecule-Its performance characteristics as ultrafiltration membranes. J. Appl. Polym. Sci. 2014, 131, 40320. (34) Zhang, Y.; Sua, Y.; Chen, W.; Peng, J.; Dong, Y.; Jiang, Z.; Liu, H. Appearance of poly(ethylene oxide) segments in the polyamide layer for antifouling nano-filtration membranes. J. Membr. Sci. 2011, 382, 300−307.

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