Preparation of Thin Film Composite Nanofiltration Membrane by Interfacial Polymerization with 3,5-Diaminobenzoylpiperazine and Trimesoyl Chloride

A new aromatic diamine, 3,5-diaminobenzoylpiperazine (3,5-DABP), was synthesized from 3,5-diaminobenzoic acid and 1-formyl piperazine. The structure of 3,5-DABP was identified by FT-IR spectra and (1)H NMR spectra. With 3,5-DABP as aqueous monomer and trimesoyl chloride (TMC) as organic monomer, thin film composite (TFC) nanofiltration membranes were prepared by interfacial polymerization technology. The salt rejection order of these TFC membranes is Na(2)SO(4)>MgSO(4)>MgCl(2)>NaCl. This sequence indicates that the membranes are negatively charged.