(3-Aminopropyl)trimethoxysilane-Functionalized Titanium Dioxide Thin-Film Nanocomposite Membrane: Enhanced Rejection Performance for Unary and Binary High-Salt Wastewater

Titanium dioxide (TiO 2 ) nanoparticles act as very good nanofillers to prepare the polymeric nanocomposite membranes to tackle the problem of heavy metal pollution in the water body. A key challenge to be solved is to improve their compatibility with organic matrices and dispersion in the material. Herein, (3-aminopropyl)trimethoxysilane-modified TiO 2 (APTMS-TiO 2 ) was prepared using coupling agent modification, and APTMS-TiO 2 thin-film nanocomposite (TFN) membrane was successfully applied in the forward osmosis (FO) process. Moreover, the effects of different pretreated TiO 2, TiO 2 dosages, draw solution types, and concentrations on FO membranes were systematically studied. Results showed that APTMS-TiO 2 TFN with a TiO 2 dosage of 0.05 wt % has the maximal water permeate flux ( J w ) (18.14 LMH, 225.09% higher than the control TFC of 5.58 LMH) and the minimum specific reverse solute flux of 0.40 g/L with 1 M NaCl as the draw. Unary (Cu 2+ and Ni 2+ ) and binary (Cu 2+ + CR and Cu 2+ + RhB) high-salt wastewater were applied as the feed to investigate the reusability and dye rejection of the APTMS-TiO 2 TFN. The rejection rate of Cu 2+ and Ni 2+ by APTMS-TiO 2 TFN was above 98.00 and 97.00%, respectively, while the rejection rate of Cu 2+ + CR and Cu 2+ + RhB was 96.87 and 95.83%, respectively, indicating excellent reusability and rejection. The present research finding concludes that the incorporation of APTMS-TiO 2 nanosheets in the TFN layer enhances the flux and rejection of targeted mineral salts. Additionally, the APTMS-TiO 2 TFN revealed outstanding rejection performance of unary and binary wastewaters, signifying that contact with heavy metals and colored solutes will not affect the performance.