Preparation And Performances Of Anti-fouling And Chlorine Resistant Aromatic Polyamide Composite Reverse Osmosis Membranes

Reverse osmosis (RO) membrane technology is still faced with the problem ofmembrane fouling and membrane oxidation, which increses the operating cost of ROprojects and restricts further development and application of RO technology. In orderto develop antifouling and chlorine resistant RO membranes, a series of researches arecarried out in this work.Imidazolidinyl urea (IU) was grafted onto aroamtic polyamide composite ROmembrane surface by carbodiimide-induced method. The effective structure ofmembrane was not effected by the IU grafting process. After the IU grafting, themembrane was endowed with excellent anti-biofouling property. Conbined with freechlorine pretreament, the anti-biofouling property of IU-modified membrane wassignificantly improved. Meanwhile, the IU-modified membrane was endowed withexcellent chlorine resistent property. More importantly, the anti-biofouling propertyand chlorine resistent property were regenerable.Polyethyleneimine (PEI) was used as the regulator of commericial aromaticpolyamide RO membrane surface charge. PEI with different molecular weights weregrafted onto membrane surface by chemical bond. The PEI-modified membranesurface shows positive charge during the normal pH range of RO system. ThePEI-modified membrane show good anti-fouling property to positive chargedpollutants (Lysozyme and cation surfactants).Based on the modification of the commercial aromatic polyamide RO membranegrafted with PEI, glycidyltrimethylammonium chloride (GTA) was introduced intothe PEI chain on the membrane surface by reacting with the end amine groups of PEI.The anti-biofouling structure with PEI polymer chains as the frame and the moveableend quaternary ammonium salt as the functional groups was built on membranesurface to enow the membrane with excellent anti-biofouling property.Based on the research of IU modification of commercial RO membranes, thefeasibility of another IU modification process was evaluated. That is the feasibility ofthe grafting of IU on self-made nacent composite aromatic polyamide RO membranesurface. The results shown that IU was successfully grafted on membrane surface byreacting with the acyl chloride groups on nacent membrane surface. Simmilar with the effect of the IU modification on commercial aroamtic polyamide composite ROmembrane, the effective structure of self-made aromatic polyamide RO membranewas not damaged by the modification process. After the modification, theIU-modified self-made membranes show good anti-microbial property andanti-biofouling property.