The Effect of Cu2+ and Pb2+ in the Feed Solution on the Water and Reverse Solute Fluxes in the Forward Osmosis (FO) Process Using Nanofiltration (NF) Membranes

Abstract

The application of nanofiltration (NF) membranes in the forward osmosis (FO) process to remove heavy metal ions from wastewater is an emerging concept. Unlike NF, FO does not require an external driving force. Although the product, a dilute draw solution, must further be processed by NF to produce pure water and reconcentrate a draw solution, the feed to that NF process is “clean”, which minimizes membrane fouling. This paper examines the role of Cu2+ and Pb2+ in the feed solution on the water and the reverse solute fluxes in FO process using novel thin film nanocomposite (TFN) NF membranes. The TFN membranes were fabricated by in situ interfacial polymerization of piperazine (PIP) and 1,3,5-benzenetricarbonyl trichloride (TMC) containing different amounts of dispersed halloysite nanotubes (HNTs) nanoparticles functionalized with the first generation of poly(amidoamine) (PAMAM) dendrimers. The presence of Cu2+ and Pb2+ in the feed solution decreased the reverse flux of MgCl2 by at least 2.5 times compared to the experiments with pure water as a feed. Simultaneously, the water flux also increased. The corresponding rejections of Cu2+ and Pb2+ in the FO process ranged from 94.5% to 98.1%.