Antiorganic Fouling and Low-Protein Adhesion on Reverse-Osmosis Membranes Made of Carbon Nanotubes and Polyamide Nanocomposite

Abstract

We demonstrate efficient antifouling and low protein adhesion of multiwalled carbon nanotubes-polyamide nanocomposite (MWCNT-PA) reverse-osmosis (RO) membranes by combining experimental and theoretical studies using molecular dynamics (MD) simulations. Fluorescein isothiocyanate (FITC)-labeled bovine serum albumin (FITC-BSA) was used for the fouling studies. The fouling was observed in real time by using a crossflow system coupled to a fluorescence microscope. Notably, it was observed that BSA anchoring on the smooth MWCNT-PA membrane was considerably weaker than that of other commercial/laboratory-made plain PA membranes. The permeate flux reduction of the MWCNT-PA nanocomposite membranes by the addition of FITC-BSA was 15% of its original value, whereas those of laboratory-made plain PA and commercial membranes were much larger at 34%-50%. Computational MD simulations indicated that the presence of MWCNT in PA results in weaker interactions between the membrane surface and BSA molecule due to the formation of (i) a stiffer PA structure resulting in lower conformity of the molecular structure against BSA, (ii) a smoother surface morphology, and (iii) an increased hydrophilicity involving the formation of an interfacial water layer. These results are important for the design and development of promising antiorganic fouling RO membranes for water treatment.

Preparation of high‐performance carbon nanotube/polyamide composite materials by elastic high‐shear kneading and improvement of properties by induction heating treatment

“…First, on a trial basis, we reported high reinforcement and improvement of the high temperature characteristics by applying it to polypropylene, 24 and also tried to improve the performance of reverse osmosis membranes by applying it to aramid. [25][26][27] It is probable that high performance was obtained by defibrating CNTs. 17,18,21 In addition, as a representative application to highperformance automobile parts, we tried to apply it to a polyamide (PA) resin with an excellent balance of characteristics.…”

“…Therefore, the authors measured the dynamic viscoelasticity in order to determine the temperature at which the resin has both kneadable viscosity and elasticity, and then applied this temperature to the high shear elastic kneading method by strictly controlling the roll in its narrow temperature range. First, on a trial basis, we reported high reinforcement and improvement of the high temperature characteristics by applying it to polypropylene, 24 and also tried to improve the performance of reverse osmosis membranes by applying it to aramid 25–27 . It is probable that high performance was obtained by defibrating CNTs 17,18,21 …”

Effective Antiscaling Performance of Reverse-Osmosis Membranes Made of Carbon Nanotubes and Polyamide Nanocomposites

“…29,30 Atomic force microscopy (AFM) observations confirmed that the roughness of the MWCNT–PA membrane was smaller. 20 The membrane with higher surface area provided by such ridge-and-valley structures 2,30,31 has a higher permeate flux and salt rejection, although it is likely that surface roughness could trigger scale deposition. 32 By increasing the MWCNT content up to 15.5 wt % (Figure 4a), the surface became much smoother than that of the plain PA membranes.…”

Frontiers of Membrane Desalination Processes for Brackish Water Treatment: A Review

“…Surface functionalization methods include nanoparticle (NP) doping, functional group grafting, and changing surface morphology to improve membrane performance [21,53]. Various materials have been studied for RO including cellulose [54], aquaporin [55], bentonite [56], carbon-based materials (graphene [57,58], carbon nanotubes (CNT) [59], and carbon quantum dot [60]), bromoacetic groups [46], zeolites [61], metal organic frameworks (MOFs) [62], and metal-based NPs (metals [63,64], metal oxides [65], and metal alkoxides [66]). Grafting hydrophilic groups, e.g., polydopamine [67], polyethylene glycol groups [68,69], and zwitterion groups [70,71], have been reported to improve membrane antifouling properties.…”