Removal of heavy metal ions by modified PAN/PANI-nylon core-shell nanofibers membrane: Filtration performance, antifouling and regeneration behavior

Abstract

In this paper, the polyacrylonitrile (PAN)/polyaniline (PANI)-nylon core-shell nanofiber membrane was prepared as a filtration-adsorption membrane and its surface was modified by diethylenetriamine (DETA) for separating Pb2+ and Cd2+ ions from aqueous solutions. The modification process increased the hydrophilicity of membrane resulted to better antifouling property and higher permeability. The anti-fouling of membrane was tested by bovine serum albumin (BSA) filtration. The results showed the rejection efficiency of 89.11% for BSA and flux recovery ratio (FRR) of 91.85% because of hydrophilic nature of nanofibers. Moreover, the prepared membrane showed an adsorption capacity of 960 and 911.72 mg/g for Pb and Cd ions, respectively due to incorporation of large amounts of nitrogen atoms (32.40%, obtained by elemental analysis) on the nanofiber surface. To better investigate the adsorption mechanism, isotherm models were tested and the result indicated on conformity of equilibrium data to Langmuir model. The use of nylon as the core improved significantly mechanical properties of membrane. The results of the rejection of heavy metal ion indicated on the rejection of 96.77 and 95.11% for Pb2+ and Cd2+, respectively for 12 h without any significant change in the water flux. The modified membrane showed good regeneration property and the rejection of Pb and Cd ions was 87.57 and 86% even after 10 filtration cycles, respectively.