In-situ aeration-assisted polydopamine/polyethyleneimine copolymerization and deposition for rapid and uniform membrane modification

The key to membrane separation technology is to enhance membrane selectivity while ensuring high permeability. The modification of polydopamine (PDA) deposition based on mussel bionics is an important method to prepare hydrophilic membranes, in which the slow PDA deposition rate and nonuniformity are the keys to the strategy. In this work, a novel in-situ aeration-assisted PDA/PEI copolymerization and deposition method was designed. The influence of the in-situ aeration-assisted method on the structure and properties of the modified membranes was explored. The results indicated that the dissolved oxygen content and uniformity of the solution were improved, and the copolymerization and deposition rate of PDA/PEI were obviously accelerated. Hydrophilic coating could be formed on the PTFE membrane surface in a shorter time. The hydrophilicity and pore size uniformity were promoted, and approximately 19.4 times flux (from 101.7 L/(m2·h) to 1969.7 L/(m2·h)), 44% rejection to BSA and 60% FRR increase were obtained simultaneously. The stability of the compound coating and the possibility of the method on different substrate membranes were testified. The work could provide more insight for PDA/PEI reaction regulation and membrane modification.