Acid stable thin-film composite membrane for nanofiltration prepared from naphthalene-1,3,6-trisulfonylchloride (NTSC) and piperazine (PIP)

Acid stable thin-film composite membrane for nanofiltration was fabricated by interfacial polymerization of naphthalene-1,3,6-trisulfonylchloride (NTSC) and piperazine (PIP) on porous polysulfone support membrane. The performance of the membrane was optimized by studying the preparation parameters including monomer content, reaction temperature and additive in organic phase. The separation performance of the resultant membrane was evaluated through permeation experiments, the membrane property was characterized by ATR-FTIR, XPS AFM, SEM and streaming potential measurements, and the acid stability was investigated through both static acid soaking tests and long-term permeation tests under acidic condition. After exposure to 20%(w/v) H2SO4 for 2 months or running with 4.9%(w/v) H2SO4 for 60 day, the PIP-NTSC composite membrane showed minor change in separation performance and no evident chemical change in the active skin layer, indicating that the developed membrane possessed good acid stability. The desired membrane exhibited a pure water permeability of about 5.8 l/m2 h bar, a MWCO of as high as 5000 Da, and an attractive solute rejection of higher than 86.5% for a feed containing 500 mg/l Na2SO4 at 0.5 MPa. Furthermore, the PIP-NTSC composite membrane could be used to treat acidic effluents from metal industries with good perm-selectivity and long-term stability.