Enhancing thermal stability of nanofiltration membrane with polydopamine/ melamine co-deposition interlayer

Abstract

The increasing demand for efficient water treatment at elevated temperatures has driven significant efforts in the development of thermally resistant nanofiltration (NF) membranes. This study presents a novel thermally resistant thin-film composite (TFC) NF membrane fabricated by utilizing the adhesive properties of polydopamine and the thermal resistance of melamine to construct in-situ a co-deposition interlayer, and followed by interfacial polymerization reaction between piperazine and trimesoyl chloride to form the polyamide selective layer. The optimized NF membrane, i-TFC_1.0/1.0, has superior separation performance and thermal resistance. It achieves a Na₂SO₄ rejection of 99.4 % with a water permeance of 263 L m⁻² h⁻¹ MPa⁻¹ at 25 °C, and remains a Na₂SO₄ rejection of above 97 % and a high water permeance of 553 L m⁻² h⁻¹ MPa⁻¹ during 100 h of continuous filtration operation at an elevated temperature of 80 °C. Furthermore, the optimized membrane demonstrates excellent antifouling property, with flux recovery ratios of 99.6 %, 98.7 % and 92.7 % for sodium alginate, humic acid, and bovine serum albumin, respectively. This work provides critical insights into the design and fabrication of robust thermal resistant NF membrane, paving the way for innovations in high-temperature water treatment and desalination technologies.