Preparation and characterization of poly (vinylidene fluoride) ultrafiltration membrane with organic and inorganic porogens

• Effect of different additives on PVDF membrane properties was studied.
• Contact angle decreased as PEO-PPO-PEO was added in the casting solution.
• Membrane with PEO-PPO-PEO/oxalic acid combined addition showed the best properties.

In this paper, the effects of high molecular weight additive (PEO-PPO-PEO), low molecular weight additive (oxalic acid) and inorganic additive (nano-TiO2) on PVDF membranes were studied by phase inversion method. The experimental results showed that the contact angle decreased as PEO-PPO-PEO was added in the casting solution. With the increasing concentration of PEO-PPO-PEO from 0.5 to 3.0 wt.%, the water flux increased from 0 to 1136 L/m2h and the rejection decreased from 99.0% to 64.0%, meanwhile, the static contact angle stabilized basically around 66°. When the oxalic acid concentration increased from 0 to 3.0 wt.% and the concentration of PEO-PPO-PEO maintained at 0.5 wt.%, the water flux increased from 0 to 192 L/m2h, while the rejection firstly decreased and then stabilized around 88.0%. Compared with PEO-PPO-PEO, PEO-PPO-PEO/nano-TiO2 and PEO-PPO-PEO/oxalic acid/nano-TiO2, the PVDF membrane with PEO-PPO-PEO/oxalic acid combined addition showed the best properties. As the concentrations of PEO-PPO-PEO and oxalic acid were 2.0 and 3.0 wt.% respectively, the water flux of PVDF membrane reached 2271 L/m2h.