Preparation of TMC/TMPIP nanofiltration composite membrane with ultra-thin skin layer

A nanofiltration(NF)composite membrane,with an ultra-thin skin layer,was prepared through interfacial polymerization on a polysulfone support with trimesoyl chloride(TMC)and a key aqueous monomer trimesoyl piperazine(TMPIP)hydrochloride with branched triimine structure,which was designed and synthesized based on the principle of interfacial polymerization of TMC and piperazine(PIP).Fourier transform infrared spectroscopy(FTIR)was combined with scanning electron microscope(SEM)to characterize the chemical composition and structure of the skin layer.The results showed that an ultra-thin poly(piperazineamide)skin layer,around 100 nm thick,was formed on the surface of support membrane.Compared with the performance of TMC/PIP composite membrane against PEG 200,the improved performance of TMC/TMPIP composite membrane was attributed to its high crosslinking and ultra-thin skin layer.The performance for aqueous solution of different salts was investigated,and it was found that the rejection and flux were both better than those of TMC/PIP composite membrane,with the same rejection order.