Forward osmosis thin film composite membrane incorporated with metal organic framework for arsenic (V) removal

Abstract

The importance of the substrate layer in composite membranes lies not only in providing mechanical strength to the active layer, but also in serving as a foundation for the formation of polyamide. Therefore, the objectives of this study were to investigate the physicochemical properties of water stable metal organic framework University of Oslo-66 (UiO-66) nanoparticle and thin film composite (TFC) mixed matrix membrane (TFC-MMM). The membranes were fabricated by a phase inversion process that consists of UiO-66 nanoparticles embedded in a polysulfone matrix ranging from 0, 0.05, 0.1, 0.3 and 0.5 wt%. Then, an interfacial polymerization process has taken place to form polyamide on the outer membrane surface. These nanoparticles and membranes were characterized with field emission scanning electron microscopy, x-ray diffraction, contact angle, overall porosity, atomic absorption spectroscopy, attenuated total reflectance Fourier transform infrared, atomic force microscopy, pore size distribution and zeta potential. Based on the characterizations, the membranes have the potential to be used for arsenic (V) rejection in water flux tests. The forward osmosis process was utilized to determine water flux and solute reverse flux. Pure water and 1 M NaCl solution were used as feed and draw solution, respectively. The water flux was increased up to 20 LMH at TFC-0.3 and it went down to 17 LMH at TFC-0.5 while the solute reverse flux kept elevated but at a controlled rate. Then, 100 ppm arsenic (V) was used as feed for As rejection performance. It was demonstrated that the physicochemical properties of MMM affect the interfacial polymerization of polyamide, leading to greater arsenic (V) rejection which up to 96%. Then, the pH of the feed solution was adjusted to 5, 6, 7, 8 and 9. The membrane performs optimally at a pH of 9 due to electrostatic repulsion between HAsO42- and polyamide.