Regular ArticleA facile method to modify polypropylene membrane by polydopamine coating via inkjet printing technique for superior performance
Graphical abstract
Introduction
Membrane fouling, which causes a decline in the membrane life and economic performance, has been considered as the major drawback restricting the wide application of membrane separation technology [1], [2], [3], [4]. Polypropylene (PP) has been regarded as one of the most popular microfiltration (MF)/ultrafiltration (UF) membrane materials due to its advantages of excellent mechanical strength, film forming ability, chemical resistance, thermal stability and especially low cost [5], [6]. However, this material is prone to membrane fouling due to its intrinsic hydrophobicity [7], [8]. Hydrophilicity/hydrophobicity has been regarded as one of the most important properties related with fouling propensity [9], [10], [11]. For the hydrophobic membranes, hydrophilic modifications including coating [12], [13], [14], grafting [15], [16] and blending [17], [18] have been regarded as effective approaches to mitigate membrane fouling.
Recently, mussel-inspired surface chemistry has been widely applied in surface modification due to its superior adhesive and cohesive properties [19], [20], [21]. Membrane surface functionalization based on mussel-inspired polydopamine (PDA) deposition for enhancing antifouling ability has attracted considerable attention [20], [21], [22], [23]. Functional groups (catechol, amine and imine) of PDA have high affinities with diverse functional molecules, endowing PDA modified membranes extra superior features [24], [25]. Immobilization of inorganic nanoparticles [26], [27] and polymers [28], [29] onto the membrane surface via PDA-based co-deposition has been extensively studied. These surface-modified membranes showed superior surface properties including high hydrophilicity, antifouling and properly sized pores. Despite the advantages in PDA-assisted modification, high cost of dopamine (DA) and longtime of reaction during typical self-polymerization of DA in aqueous solution [30], [31] still exists as problems impeding its practical application, calling for efficient modification methods to remedy these shortfalls.
Inkjet printing has emerged as an attractive technique for design of functional-substrates and for surface modification. Taking advantage of low production costs, precise deposition control and easy access to graphical painting, inkjet printing technique can tunably print functional layers directly on various substrates [32], [33]. For this reason, inkjet printing has attracted extensive interests in various engineering fields, including electronics [34], sensor [33], particle dispersion [35], tissue engineering [36] and others. Incorporation of this novel film-forming technique has opened up existing possibilities in membrane preparation and modification. Inkjet printing of graphene oxide (GO) has been reported to be capable of fabricating membranes for effective water purification [37]. Based on inkjet printing of silver-nanoparticle (AgNPs), AgNPs modified polyurethane fibrous membrane with superior antibacterial performance has been prepared [38]. Badalov et al. [39] performed a fluorine contained diamine monomer inkjet printing on m-phenylenediamine-based polyamide as a printable substrate, which yielded improved salt rejection. These studies suggested that inkjet printing was a rapid and low-cost way to modify membranes. It is therefore envisaged that inkjet printing can efficiently deposit PDA on PP membrane surface. In the literature, several approaches based on oxidant promotion have been developed to facilitate self-polymerization of DA. The polymerization and deposition rate of PDA can be improved to some extent by using various triggers, such as CuSO4/H2O2 [40], FeCl3/H2O2 [20], ammonium persulfate (APS) [41], sodium periodate (SP) [42], [43] and so forth. It is hypothesized that, inkjet printing of DA integrated with oxidant-induced strategy would well overcome the shortfalls of the conventional PDA-assisted modification method, and provide a facile, low cost and efficient alternative for membrane modification. Nonetheless, to our knowledge, no research regarding the use of DA inkjet printing for PDA deposition on separation membrane has been reported up to date.
In this paper, PP membrane was surface modified with PDA deposition via DA inkjet printing, followed by SP inkjet printing. The properties including chemical properties, hydrophilicity, morphology, water flux, filtration resistance and antifouling performance of the modified membranes were measured.
Section snippets
Materials
PP membrane (0.2 μm normalized pore size) was produced Haining Taoyuan membrane separation equipment factory. Chemicals including n-propyl alcohol (C3H7OH, purity of ≥99.5%), glycerine (C3H8O3, purity of ≥99.0%), acetic acid (CH3COOH3, purity of ≥99.5%), sodium acetate (CH3COONa, purity of ≥99.0%) and sodium periodate (NaIO4, purity of ≥99.5%) were purchased from Sinopharm Chemical Reagent Co., Ltd. Dopamine hydrochloride (C8H11NO2·HCl, purity of ≥98%) was purchased from Aladdin Chemistry Co.,
Analysis of membrane surface chemical structure
It had been proved that the SP-triggered method possessed high deposition rate of PDA thin layers. As shown in Fig. 2a, the color of printed PP membrane (DA/SP = 1) changes from white to brown with the increase of reaction time. The color of membrane surface rapidly darkens within 2 h after which it becomes stable. The ATR-FTIR measurement was used to analyze the chemical structure of membranes and to further verify the fast deposition. The spectrum of the PP-PDA-SP-0.5 h (Fig. 2a) is
Conclusions
Membrane surface functionalization based on mussel-inspired polydopamine (PDA) deposition for enhancing antifouling ability has attracted considerable attention [20], [21], [22], [23]. Despite the advantages in PDA-assisted modification, high cost of dopamine (DA) and longtime of reaction during typical self-polymerization of DA in aqueous solution [30], [31] still exists as problems impeding its practical application, calling for efficient modification methods to remedy these shortfalls. In
Acknowledgements
This study was financially supported by National College Students Innovation and Entrepreneurship Training Program (201710345025), Zhejiang Provincial Natural Science Foundation of China (Q17E080011) and National Natural Science Foundation of China (51578509).
References (70)
- et al.
Quantitative assessment of interfacial forces between two rough surfaces and its implications for anti-adhesion membrane fabrication
Sep. Purif. Technol.
(2017) - et al.
Fabrication of hydrophilic and antibacterial poly(vinylidene fluoride) based separation membranes by a novel strategy combining radiation grafting of poly(acrylic acid) (PAA) and electroless nickel plating
J. Colloid Interf. Sci.
(2019) - et al.
Quantification of interfacial interactions between a rough sludge floc and membrane surface in a membrane bioreactor
J. Colloid Interf. Sci.
(2017) - et al.
Impact of resuscitation promoting factor (Rpf) in membrane bioreactor treating high-saline phenolic wastewater: performance robustness and Rpf-responsive bacterial populations
Chem. Eng. J.
(2019) - et al.
Fabrication of composite membrane with adsorption property and its application to the removal of endocrine disrupting compounds during filtration process
Chem. Eng. J.
(2018) - et al.
Polypropylene microfiltration membranes modified with TiO2 nanoparticles for surface wettability and antifouling property
J. Membr. Sci.
(2016) - et al.
Ultrafiltration membranes with ultrafast water transport tuned via different substrates
Chem. Eng. J.
(2016) - et al.
Preparation, characterization and anti-fouling properties of nanoclays embedded polypropylene mixed matrix membranes
Chem. Eng. Res. Des.
(2017) - et al.
Novel indicators for thermodynamic prediction of interfacial interactions related with adhesive fouling in a membrane bioreactor
J. Colloid Interf. Sci.
(2017) - et al.
Effects of hydrophilicity/hydrophobicity of membrane on membrane fouling in a submerged membrane bioreactor
Bioresour. Technol.
(2015)