Single-side hydrolysis of hollow fiber polyacrylonitrile membrane by an interfacial hydrolysis of a solvent-impregnated membrane

In this paper, a new method was proposed to improve the mechanical strength and flux of polyacrylonitrile (PAN)-based membrane by a single-side hydrolysis of hollow fiber PAN substrate membrane. A non-water miscible solvent of cyclohexane was firstly incorporated into membrane pores to form cyclohexane-impregnated hollow fiber PAN membrane by stepwise solvent replacement method. Alkaline aqueous solution was then fed into lumen side to introduce interfacial hydrolysis reaction on the inner surface of hollow fiber by using the cyclohexane/water phase interface. After the reaction, the cyclohexane incorporated was displaced by water to remain the pore pathway. The ATR-FTIR and EDX analyses confirmed that the alkaline hydrolysis did not occur in the membrane pores. SEM and AFM were also conducted to further understand the microtopographical changes on membrane surfaces. During the assembly of PAN-based polyelectrolyte pervaporation composite membranes, both flux and mechanical strength was highly improved by using single-side hydrolysis of PAN substrate membrane while the selectivity was still kept at a relatively high level.