Cyanuric Chloride with the s-Triazine Ring Fabricated by Interfacial Polymerization for Acid-Resistant Nanofiltration

Area of Science:

• Materials Science
• Chemical Engineering
• Separation Science

Background:

• Conventional nanofiltration (NF) membranes face degradation issues in acidic environments, limiting their use in industrial acid treatment.
• Purification of wet-process phosphoric acid is challenging due to multivalent metal ion impurities, and NF technologies for such harsh conditions are underdeveloped.

Purpose of the Study:

• To develop novel, acid-resistant nanofiltration membranes for effective purification of acidic industrial streams.
• To investigate the performance of these membranes in removing metal impurities from phosphoric acid under simulated industrial conditions.

Main Methods:

• Fabrication of acid-resistant NF membranes via interfacial polymerization (IP) of polyethyleneimine (PEI) and cyanuric chloride (CC).
• Optimization of the IP process using orthogonal experiments to achieve desired membrane properties (positively charged, MWCO of 337 Da).
• Testing membrane performance in a simulated phosphoric acid solution (20 wt% P2O5, 2 g/L Fe3+, 2 g/L Al3+, 2 g/L Mg2+) under specific pressure and temperature conditions.

Main Results:

• The developed PEI-CC membranes demonstrated 56% rejection of Fe, Al, and Mg ions.
• Achieved over 97% permeation of phosphorus, indicating efficient separation.
• Exhibited excellent acid resistance during a 48-hour dynamic acid permeation test.

Conclusions:

• The novel PEI-CC nanofiltration membranes possess excellent acid resistance and effective impurity removal capabilities.
• The simple fabrication process and robust performance suggest significant potential for industrial applications in acidic stream treatment.