IR-initiated preparation method of high performance nanofiltration membranes using graft polymerization of acrylic acid onto polyacrylonitrile surface

A new facile, cost-effective and safe approach is introduced for the modification of polyacrylonitrile (PAN) membrane surface by a polymerization process in order to improve hydrophilicity and antifouling. For this purpose, membrane activated by IR-initiated, and acrylic acid (AA) as a monomer was successfully grafted on the membrane surface. The surface properties of membranes were characterized by means of various techniques: infrared spectroscopy, zeta potential, water contact angle, atomic force microscopy (AFM), and scanning electron microscopy (SEM). The experimental results indicate that the membrane surface becomes more hydrophilic by reducing the contact angle from 67.1° to 52.5°. The existence of hydrophilic chains on the membrane surface facilitates the creation of a negative charge on the membrane surface unto −2.99 mV (from 3.51 mV in based-membrane). The separation performance of the modified membrane showed a desirable yield. For a membrane photografted for 25 min with acrylic acid solution (2 wt%), the retention of Na 2 SO 4 , MgSO 4 , NaCl, and CaCl 2 was in the order of 81%, 67%, 34%, and 28%, respectively. The membrane retention is expressed the values of 90.37%, 87.17%, and 79.5% for Acid Blue 92, Acid Red 114, and Ibuprofen. The optimized NF membrane showed a permeability factor (Lp) of 6.48 L·m −2 ·h −1 ·bar −1 . Furthermore, the surface modification of the PAN membrane via the IR-induced graft polymerization exhibits an enhancement of the membrane antifouling property.