Synthesis of Novel Hybrid NF/FO Nanocomposite Membrane by Incorporating Black TiO2 Nanoparticles for Highly Efficient Heavy Metals Removal

In this study, a hybrid of nanofiltration (NF) and forward osmosis (FO) has been used with the aim of improving the efficiency of heavy metal removal. Here, black TiO2 nanoparticles (BNPs) were synthesized first and embedded in the polyamide (PA) active layer of TFC NF membrane to rectify the performance of membranes. The resulting TFN NF membranes were then tested in hybrid NF/FO system properly. The presence of BNPs was confirmed with XPS and FTIR, while the morphological alterations in the synthetized membranes were characterized using FESEM and AFM. Nanofiltration membrane performance was examined using multivalent ions such as of MgSO4, Na2SO4, CaCl2, and NaCl monovalent ion. We demonstrated that the addition of BNPs led to a significant decrease in surface roughness and hydrophilicity, showing a further reduction with increased concentrations of BNPs. In addition, TFC membrane showed a water flux of 25 L/m2h compared to 39, 41, and 66 L/m2h for TFN0.01, TFN0.05, and TFN0.1 membranes, respectively. We also showed that under the FO process, TFN membrane demonstrated the best performance with regards to heavy metal rejection and the highest Cr (III) and Pb (II) rejection was shown in TFN0.05 under the FO process. The ideal heavy metal rejections and acceptable water flux indicate the potential of these developed membranes under FO process for the removal of heavy metals from wastewater.