Exploiting interfacial polymerization to fabricate hyper-cross-linked nanofiltration membrane with a constituent linear aliphatic amine for freshwater production

• Published in: npj clean water Vol. 5; no. 1; pp. 1 - 13
• Main Authors: Baig, Umair, Waheed, Abdul
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 21-09-2022; Nature Publishing Group; Nature Portfolio
• Subjects: 639/638/169/896; 704/172/169/896; Aliphatic amines; Aquatic Pollution; Calcium chloride; Contact angle; Cross flow; Crosslinking; Curing; Drinking water; Earth and Environmental Science; Environment; Fabrication; Filtration; Hydrofluoric acid; Magnesium chloride; Membranes; Nanofiltration; Nanotechnology; NMR; Nuclear magnetic resonance; Polyamide resins; Polyamides; Polymerization; Rejection; Salt rejection; Salts; Sodium chloride; Sodium sulfate; Thin films; Waste Water Technology; Water Industry/Water Technologies; Water Management; Water pollution; Water Pollution Control; Water Quality/Water Pollution; Water resources; X ray photoelectron spectroscopy
• ISSN: 2059-7037; 2059-7037
• DOI: 10.1038/s41545-022-00186-x

Humanity is facing a global challenge of dwindling water resources and the situation is intensifying due to growing population leading to excessive water pollution. Nanofiltration is an important membrane-based technology for the production of clean and potable water for domestic and industrial setups. Hyper-cross-linked polyamide thin film composite nanofiltration (HCPA-TFC-NF) membranes have been fabricated by using multifunctional amine
1
(possessing two primary -NH
2
and two secondary -NH groups) and bifunctional terephthaloyl chloride
2
(TPC) through interfacial polymerization. The structure of the hyper-cross-linked polyamide network has been successfully confirmed by solid (CP-MAS)
13
C NMR, XPS, AFM, FT-IR, elemental mapping, and EDX analysis. The membrane features such as surface morphology and hydrophilicity have been established by FE-SEM and water contact angle measurements. The FE-SEM analysis revealed the formation of uniform polyamide active layer on the surface of PS/PET support, and the pore structure of the membranes was tuned by studying the effect of curing temperature and curing time. The nanofiltration membranes efficiently rejected a series of divalent salts including MgCl
2
, CaCl
2
, Na
2
SO
4
, MgSO
4,
and NaCl using cross-flow filtration setup. Based on the cross-flow filtration performance, the best conditions for the membrane fabrication were found to be curing temperature of 80 °C with a curing time of 1 h. The highest salt rejection was observed in case of MgCl
2
reaching to a value of 98.11% in case of HCPA-TFC-NF@M3 and it was found to be 97.45% in case of HCPA-TFC-NF@M2 while the rejection of MgCl
2
was reduced to 94.59% in case HCPA-TFC-NF@M1. HCPA-TFC-NF@M2 showed NaCl rejection of 87.36%. The hydrofluoric acid treatment of HCPA-TFC-NF-M2 increased the water flux while keeping the rejection high. The HCPA-TFC-NF@M2 showed a rejection of >99% for EBT with a permeate flux of 75 LMH.