Search

Polyamide membranes with a controlled surface morphology were prepared by the interfacial polymerization of 1,3-phenylenediamine (MPD) with 1,3,5-benzenetricarbonyl trichloride (TMC) on polysulfone ultrafiltration supports. In a novel polymerization method, co-solvents, which included acetone, ethyl acetate, diethyl ether, toluene, isopropyl alcohol (IPA) and N,N ′-dimethyl formamide (DMF), were added into the organic phase which made it possible to control the surface morphology and polyamide network structures. As-prepared, the membranes showed multi-layered ridge-and-valley structures, and the types of co-solvent successfully controlled permeate flux and rejection. Polyamide membranes prepared by the addition of 2 wt% ethyl acetate, showed the best performance with NaCl rejection of 99% and permeate flux of more than 1 m 3 /(m 2 d) at 1.5 MPa, which was about twice that of a membrane prepared without a co-solvent.

Polyamide membranes with controlled surface morphology were prepared by the interfacial polymerization of 1,3-phenylenediamine (MPD) with 1,3,5-benzenetricarbonyl trichloride (TMC) on polysulfone ultrafiltration supports. The addition of co-solvents (acetone, ethyl acetate, and diethyl ether) into the organic phase was used to control both the surface morphology and the polyamide network structures. The as-prepared membranes had multi-layered polyamide structures, which consisted of large (1 μm) and ordinal (100–300 nm) ridge-and-valley formations. Permeate flux and rejection reactions were successfully controlled by the types and amounts of co-solvents that were added. The optimal membrane conditions included the addition of 3 wt% ethyl acetate, with a NaCl rejection of more than 99% and a permeate flux of more than 1.8 m3/(m2 d) at 1.5 MPa, which was more than three times higher than the membranes prepared without a co-solvent.

A spray-assisted, 2-step interfacial polymerization (IP) of trimesoyl chloride (TMC)/ m -phenylenediamine (MPD) was proposed for the preparation of polyamide (PA) membranes. In the first step, TMC/hexane solutions were sprayed onto MPD-impregnated polysulfone (PSf) supports for 10–60 s, followed by a second step where the first-step membranes made contact with the TMC/hexane solutions. It is noteworthy that water permeability was increased with spray time in the first step of the 2-step IP, showing approximately doubled values at the spray time of 20–30 s, compared with 1-step PA/PSf composite membranes, while NaCl rejections were practically unchanged. With longer spray time (30–60 s), water permeability decreased while NaCl rejection remained at the same level. A characterization of 1- and 2-step PA membranes, including FE-SEM and ATR-FTIR, revealed the formation of multilayered ridge-and-valley structures of polyamide from the spray-assisted IP steps, and it is suggested that the increased water permeability have been caused by the increased interfacial surface area of the 2-step PA membranes.

This study introduces a promising strategy, called co-solvent assisted interfacial polymerization (CAIP), for the synthesis of thin polyamide membranes by interfacial polymerization of 1,3-phenylenediamine (MPD) with 1,3,5-benzenetricarbonyl trichloride (TMC) on polysulfone ultrafiltration supports. A synergistic co-solvent added in the hexane phase was used to control the polymerization reaction zone and modify the membrane network structure. The resultant membrane exhibited selective molecular sieving of small molecules from larger ones. The addition of larger amounts of acetone as a co-solvent to the hexane solution increased both pore size and water flux, which was determined by analysis of the membrane permeation properties. In the permselectivity test of a 500 ppm glucose aqueous solution, the best-performing membrane was prepared by 2 wt% acetone addition. It showed a rejection of more than 99.4% and a high water transport at a rate of more than 1 × 10 −11 m 3 /(m 2 Pa s), which was more than 4-fold higher than the membrane prepared without acetone. The effects of reaction conditions, including co-solvent content and interfacial polymerization time, were studied.

A promising strategy is reported for the synthesis of inorganic-polyamide nanocomposite membranes on an ultrafiltration polysulfone support via metal-alkoxide-assisted interfacial polymerization. Three types of nanocomposite membranes were prepared using three different metal alkoxides. The metal alkoxides used here were titanium tetraisopropoxide, bis(triethoxysilyl)ethane and phenyltriethoxysilane. The as-prepared nanocomposite membranes exhibited performance superior to that of the pure polyamide membrane. Water flux and salt rejection were observed for each of the nanocomposite membranes. Addition of greater amounts of metal alkoxide to the hexane solution increased both pore size and water flux, which were determined by analysis of the membrane permeation data using aqueous solutions of sodium chloride and organic solutes at a pressure of 1.5 MPa and a temperature of 25 °C. The best nanocomposite membrane that was prepared with phenyltriethoxysilane showed water flux that was increased approximately 2-fold compared with the pure polyamide membrane with negligible rejection loss.