Reduced Fouling Ultrafiltration Membranes via In-Situ Polymerisation Using Polydopamine Functionalised Titanium Oxide

Abstract

The trade-off phenomenon between selectivity and permeation flux is a major challenge in pressure-driven membranes, and specifically for ultrafiltration membranes. Currently, many research studies have been performed to try to increase permeability while maintaining the rejection at a high level. However, in most of these studies, the improvement of permeability was accompanied by a decrease in rejection or vice versa. To tackle this problem, TiO2 nanoparticles were attached on the surface of PES membranes using polydopamine as adhesive agent. In general, it is quite challenging to attach/bind TiO2 on the surface of membranes due to agglomeration of nanoparticles. Therefore, we developed a practical, simple and a scalable method to attach TiO2 nanoparticles (NPs) on the top surface of membrane using one-step dip coating. Experimental results revealed that the modified layer enhanced the hydrophilicity of the PES UF membranes as confirmed by the decrease of contact angle from. As a result, the modified membranes exhibited a significant improvement in anti-fouling properties, with 12 times higher water permeation flux (962 LMH for pDA-f-TiO2-PES30) as compared to the pristine PES membranes (79.9 LMH). The static adsorption of BSA on the surface of membranes was reduced from (60 µg/cm2 for pristine PES to 21 µg/cm2 for pDA-f-TiO2- PES120). Furthermore, the modified PES membranes displayed a higher flux recovery ratio (97%) and fouling reversibility (98.62%) than pristine PES membrane (37.63%). Also, the coated PES membranes bestowed a good antibacterial property relative to the pristine one. Besides, the membranes showed better physical and chemical stability as compared with unmodified PES membranes. Thus, this study provided a facile approach for enhancing the anti-fouling performance of PES ultrafiltration membranes.

Progress for Co-Incorporation of Polydopamine and Nanoparticles for Improving Membranes Performance

“…Recently, membrane enhancement employing materials inspired by the adhesive secretions of mussels such as dopamine (DA) with molecular formula C 8 H 11 NO 2 has attracted great scientific interest. Dopamine is known as a bio-adhesive or mussel inspired bio-glue that is utilized to modify the surface of various inorganic and organic substances through self-polymerization on the materials’ surface, forming thin polydopamine (PDA) layers as shown in Figure 1 [ 16 , 17 ]. Dopamine is a molecule that has a high rate of reactivity with the highest oxidation potential among catechol amines.…”

“…Dopamine is a molecule that has a high rate of reactivity with the highest oxidation potential among catechol amines. PDA possesses catechol groups, primary amines, and secondary amines that can easily oxidize to create reactive quinone, which combines with a variety of functional groups, including amines and thiols, to form covalently grafted functional layers via Michael addition or Schiff base reaction [ 16 , 18 ]. PDA is insoluble in water and organic solvents, which makes it a suitable candidate for membrane modification [ 12 ].…”

“…It is used for environmentally friendly catalyst preparation [ 42 , 43 , 44 , 45 ] and detection and degradation of pesticides [ 46 ] too. Moreover, it can be used as nano-adsorbents for water remediation [ 47 ] and as modifiers for water purification membranes [ 16 ], as will be illustrated in the following sections.…”

“…A simple, practical, and facile coating technique of a variety of membranes was proposed by a number of studies using PDA-f-NPs. A single step in situ dip coating of the hydrophilic layer of PDA-f-TiO 2 is used to modify UF-PES membranes [ 16 ]. The modified membrane with a small pore size improved the membrane selectivity with improved hydophilicity and permeate flux.…”

“…Therefore, it has been used as an interlayer for post functionalization before embedding the nanomaterials [ 13 ], co-deposited simultaneously with nanomaterials on the membrane’s surface [ 14 ], blended with nanomaterials into the membrane polymer matrix [ 15 ], and incorporated with nanomaterials into a polyamide selective layer [ 15 ]. In another way, it has been widely used to functionalize a variety of nanomaterials (ultrathin imprinted polydopamine (PDA) films on the surface of nanomaterials) before embedding them into the membrane by either simple coating and deposition or phase inversion or during interfacial polymerization methods [ 16 ]. However, no comprehensive review of the use of polydopamine and nanomaterials in improving water purification membranes has been conducted.…”