New Insights into the Role of an Interlayer for the Fabrication of Highly Selective and Permeable Thin-Film Composite Nanofiltration Membrane

Abstract

A triple-layered TFC nanofiltration (NF) membrane consisting of a polyamide (PA) top layer covered on a poly(ether sulfone) microfiltration membrane with a carbon nanotube (CNT) interlayer was fabricated via interfacial polymerization. The structure and properties of the PA active layer could be finely tailored by tuning the interfacial properties and pore structure of the CNT interlayer, including its surface pore size and thickness, thus improving its NF performance. This TFC NF membrane exhibited a high divalent salt rejection (the rejection of Na 2 SO 4 and MgSO 4 solution >98.3%) and dye rejection (the rejection of methyl violet (MV) >99.5%) with a high pure water flux of around 21 L m −2 h −1 bar −1 . Excitingly, this membrane also showed excellent selectivity to both mono/divalent salt ion (the selectivity of Cl − /SO 4 2− is as high as 85.5) and NaCl/dye solution (the selectivity of NaCl/MV is more than 123.5), which are much higher than most of other commercial and reported NF membranes. Moreover, this membrane also showed a good separation performance and long-term stability during a continuous NF process for a salt/dye mixture solution. This triple-layered TFC NF membrane showed a great promise for applications in both wastewater treatment and dyes recycling.

Asymmetric polyamide nanofilms with highly ordered nanovoids for water purification

“…Upper-bound line represents the level of permeability and selectivity achieved by the currently prepared membranes. In order to illustrate the superiority of the asymmetric polyamide nanofilm between permeability and selectivity, we calculated related permeability/selectivity data of different types of polyamide membranes as currently reported in the literature, such as commercial polyamide membrane (Commercial membrane) 44 , crumpled polyamide membrane (IP with crumpled structure) 16,28,32 , polyamide membrane prepared by interlayer (Interlayer-IP) 20,21,26,[45][46][47][48] , traditional IP membrane (IP) 12,28,[49][50][51][52] , and mixed matrix polyamide membranes (MMMs) 14,[53][54][55][56][57][58][59][60] , as shown in Fig. 6a, b.…”

Fouling is the beginning: upcycling biopolymer-fouled substrates for fabricating high-permeance thin-film composite polyamide membranes

“…The as-formed TFC PA membrane showed a solvent permeability of 112 L m -2 h -1 bar -1 . Other alternative coatings (e.g., tannic acid-Fe 3+ complexes (32), polydopamine (33), carbon nanotubes (34,35), and graphene oxide (36,37)) as substrate surface modifiers have also been proven effective for improving the quality of the PA layer and the separation performance of the TFC membranes. Inspired by the critical roles of the sublayer or interlayer on the IP process and the membrane transport properties, we postulate that a biopolymer fouled MF/UF membrane can be a possible substrate for fabricating high-permeance NF/RO membranes.…”

Polyethyleneimine‐Mediated Polyamide Composite Membrane with High Perm‐Selectivity for Forward Osmosis

“…Numerous research works have focused on designing a proper substrate for the IP reaction by improving its hydrophilicity. [ 16–20 ] For example, the hydrophilicity of polyethylene substrate was significantly increased after polydopamine modification or plasma treatment. [ 21 ] Consequently, a PA layer with uniformly distributed nodular and ridge features was fabricated, and a higher water permeation flux was obtained.…”