Where is the best site for loading nanoparticles in a membrane? To achieve a high flux and cephalexin separation simultaneously

Abstract

In this research, with the aim of achieving a high flux and rejection of cephalexin antibiotic simultaneously, separate modifications were performed on the membrane top layer (selective layer) and substrate layer (support layer). Fe3O4 (Fe) and ZrO2 (Zr) nanoparticles were synthesized for modifying the PAN support layer, while Fe3O4/ZrO2 (FZ) nanoparticles were synthesized for modifying the PA top layer. In this regard, five types of nanocomposite membranes were synthesized: In order to regulate the porosity of the support layer, PAFe2@PAN and PAZr2@PAN membranes were synthesized which showed more pores number compared to PAPAN membrane. In order to enhance the surface hydrophilicity, FZ2@PAPAN membrane was synthesized, which showed around 16% lower contact angle and 58% greater roughness compared to PAPAN membrane. In order to compensate for the roughness developed on the membrane surface, concurrent modifications were performed on the top and support layers; the FZ2@PAFe2@PAN and FZ2@PAZr2@PAN membranes were synthesized, which separated cephalexin by 91% and 95.8%. Comparison of the performance of the synthesized membrane with that of commercial FILMTEC (NF270-2450) membrane showed that the cephalexin rejection (95 ± 1) and flux recovery (99 ± 1) of FZ2@PAZr2@PAN are almost the same as cephalexin rejection (98 ± 1) and flux recovery (96 ± 1) of commercial membrane. From permeation point of view, FZ2@PAZr2@PAN membrane at transmembrane pressure of 4 bar and cross flow velocity of 0.5 m/s had a water flux of 49 L/m2.h and cephalexin flux of 38 L/m2.h, while NF270-2450 at the same condition had a water flux of 42 L/m2.h and cephalexin flux of 25 L/m2.h.