Novel Thin Film Nano-Composite Forward Osmosis Membranes Prepared on a Support with In Situ Embedded Titanium Dioxide to Reduce Internal Concentration Polarization

Abstract

This paper aims at thin-film nano-composite (TFN) FO membrane synthesis by optimizing nano-TiO₂ particles in-situ incorporation concentration. 0.01 wt%, 0.03 wt%, 0.1 wt% and 0.3 wt% concentration of hydrophilic anatase nano-TiO₂were added into the phase inversion water bath, respectively. The results showed that with the increase of the concentration of nano-TiO₂ particles, the amount of nanoparticles attached to the surface and inner pores of the polysulfone support substrate increased, the dispersion of nanoparticles on the surface of the membrane improved. Moreover, the modified membrane crosslinking degree decreased compare to the control-membrane. Besides, with the increase of the concentration of nano-TiO₂ particles, the water flux of the membrane increased first but then decreased, and the reverse solute flux showed an upward trend. When 0.1wt% TiO₂ was added in the water bath, the water flux of membrane was highest of all the modified membrane (8.25 L m^-2 h^-1) indicating that internal concentration polarization of the membrane was lowest. In conclusion,the optimal concentration of nano-TiO₂ particles for in-situ incorporation was 0.1 wt% due to its high membrane permeability and low internal concentration polarization.