ZnO/PDA/Mesoporous Cellular Foam Functionalized Thin-Film Nanocomposite Membrane towards Enhanced Nanofiltration Performance

Abstract

Thin-film nanocomposite (TFN) membranes are the third-generation membranes being explored for nanofiltration applications. Incorporating nanofillers in the dense selective polyamide (PA) layer improves the permeability–selectivity trade-off. The mesoporous cellular foam composite Zn-PDA-MCF-5 was used as a hydrophilic filler in this study to prepare TFN membranes. Incorporating the nanomaterial onto the TFN-2 membrane resulted in a decrease in the water contact angle and suppression of the membrane surface roughness. The pure water permeability of 6.40 LMH bar−1 at the optimal loading ratio of 0.25 wt.% obtained was higher than the TFN-0 (4.20 LMH bar−1). The optimal TFN-2 demonstrated a high rejection of small-sized organics (>95% rejection for 2,4-dichlorophenol over five cycles) and salts—Na2SO4 (≈95%) > MgCl2 (≈88%) > NaCl (86%) through size sieving and Donnan exclusion mechanisms. Furthermore, the flux recovery ratio for TFN-2 increased from 78.9 to 94.2% when challenged with a model protein foulant (bovine serum albumin), indicating improved anti-fouling abilities. Overall, these findings provided a concrete step forward in fabricating TFN membranes that are highly suitable for wastewater treatment and desalination applications.

Nanofiltration Membranes for the Removal of Heavy Metals from Aqueous Solutions: Preparations and Applications

“…Heavy metals exhibit fouling in two ways: (1) precipitates of heavy metals directly impact the fouling of the sludge, which is a biological precipitate in lakes and ponds, and (2) heavy metals affect the metabolism of organisms and interrupt the membrane causing fouling, which consists of sludge flocs, colloids, biopolymer aggregations, extracellular polymeric substances, dissolved organic matters, soluble microbial products, and inorganic substrates [ 125 , 126 ]. Nanocomposites act as antifouling agents to reduce the fouling effect of membranes [ 127 ]. Sulfonation of graphene oxide (GO) by polyethersulfone (PES) to a sulfonated graphene oxide (sGO) nanoembedded membrane through elimination of Ni, Cr, Cu, and Cd.…”

“…By measuring the pure water flux recovery ratio (FRR) after the addition of nanoparticles, the water flux increased to 94.2%, and the flux decline ratio (DRt) was reduced to 16.14%, as shown in Figure 12 c. The increment of water flux is referred to as the smoother and less rough, as illustrated in Figure 12 (d4) membrane after the integration of Zn-PDA-MCF-5 on the reverse side in Figure 12 (d3). The formation of a leaf-like structure in Figure 12 (d2) on the nanofiltration membrane surface ensures a substantial idea of the effectiveness of membrane antifouling on the membrane performance after the addition of nanoparticles compared to the membrane in Figure 12 (d1) [ 127 ]. Siddique et al [ 20 ] incorporated graphene oxide/zinc oxide (GO/ZnO) and GO/ZnO/iron oxide nanoparticles into pristine polysulfone by electrospinning to eliminate Arsenic via nanofiltration.…”

“…( f ) Relation between the total flux and pressure, which discussed the intensive increase in water flux when added Fe/Al 2 O 3 compared to bare PS. Adapted and redrawn from [ 20 , 76 , 127 , 129 ].…”