342 / 2024-02-29 17:27:04

Support-free interfacial polymerized thin film nanocomposite (TFN) membranes with dopamine-modified multi-walled carbon nanotubes constructed interlayer for nanofiltration applications

Support-free, Dopamine modification interlayer, Thin film nanocomposite membranes, Nanofiltration applications

The uncontrollable interfacial polymerized polyamide structure and weak interlamellar interaction of polyamide (PA) with substrate inhibit the construction of highly efficient sieving membranes owing to the inferior contaminant selectivity induced by defects in PA layers and stability issues. Here, a novel organic solvent resistant nanofiltration (OSN) membrane was developed via support-free interfacial polymerization on the dopamine-modified multi-walled carbon nanotubes constructed interlayer with cross-linked polyimide (cPI) ultrafiltration (UF) substrate. An ultrathin and dense PA film was successfully synthesized and transferred onto a preloaded DMCNs cPI substrate surface. Dopamine-modified interlayer offers a positively charged hydrophilic scaffold-like structure for the microporous UF substrate, which is able to strongly attract and stably support the PA film to deduct the peel-off and collapse of the PA layer. The optimal thin film nanocomposite (TFN) membrane has a high sodium sulfate rejection of 98.8% with a water permeance of 1.4 L·m⁻²·h⁻¹·bar⁻¹ and a high Rose bengal rejection of 99.3% with an ethanol permeance of 0.72 L·m⁻²·h⁻¹·bar⁻¹. The newly developed OSN membranes also demonstrate good stability in harsh solvents, after dimethylformamide (DMF) immersion at 80℃ for 5 consecutive days, the tested membrane still retains over 90% rejection rate of Congo red (Molar weight ≈ 600 g/mol) in ethanol. To our best knowledge, this is the first endeavor of coupling dopamine-modified multi-walled carbon nanotubes constructed interlayer and support-free interfacial polymerized PA film to fabricate TFN membrane for nanofiltration applications directly. The work aims to provide valuable insights into designing environmentally friendly and highly controllable TFN membranes by support-free interfacial polymerization.