Tannic Acid/Fe³⁺ Nanoscaffold for Interfacial Polymerization: Toward Enhanced Nanofiltration Performance

Area of Science:

• Materials Science
• Chemical Engineering
• Environmental Science

Background:

• Conventional thin-film composite (TFC) membranes face a permeability-selectivity trade-off, limiting their performance.
• This limitation, known as the "upper bound", hinders advancements in separation technologies.

Purpose of the Study:

• To develop a high-performance TFC membrane that overcomes the permeability-selectivity upper bound.
• To investigate the role of a tannic acid-Fe nanoscaffold in enhancing membrane properties.

Main Methods:

• Fabrication of a TFC membrane (TFCn) using a tannic acid (TA)-Fe nanoscaffold on a polysulfone substrate.
• Interfacial polymerization of trimesoyl chloride (TMC) and piperazine (PIP) on the nanoscaffold.
• Characterization of membrane permeability and selectivity for various salts.

Main Results:

• The TFCn membrane exhibited a water permeability of 19.6 L m⁻² h⁻¹ bar⁻¹, an order of magnitude higher than control TFC membranes (2.2 L m⁻² h⁻¹ bar⁻¹).
• Significantly enhanced salt rejection for NaCl, MgCl₂, Na₂SO₄, and MgSO₄ was observed.
• Improved divalent to monovalent ion selectivity (e.g., NaCl/MgSO₄) was achieved.

Conclusions:

• The TA-Fe nanoscaffold effectively enhances monomer uptake and controls release, leading to a more ordered polyamide layer.
• The novel TFCn membrane successfully surpasses the permeability-selectivity trade-off, offering a new pathway for high-performance membrane fabrication.
• This work presents a promising approach for advanced nanofiltration and desalination applications.