The influence of important factors on ultrafiltration of oil/water emulsion using PVDF membrane modified by nano-sized TiO2/Al2O3

Polyvinylidene fluoride (PVDF) membranes modified by the nano-sized TiO2/Al2O3 were applied to the separation of oil/water emulsion. Experiments were carried out in a constant flux dead-end Ultrafiltration cell, and the influence of operating parameters such as: trans-membrane pressure (TMP), and feed properties e.g. pH, initial oil concentration, and total dissolved solid (TDS) of the feed solution on membrane performance were investigated. The results show that all the parameters except TDS played an important role in Relative Flux (RF) of this UF process, Moreover, Modified PVDF membrane (MPM) showed a better antifouling character than PVDF membrane (PM) under the same conditions. A satisfying flux recovery was observed for fouled membranes when being washed with pure water, and even better when washing with NaClO solution. However, reversed cleaning by water and mechanical scrubbing led to the RF decreased sharply. It was concluded that MPM may be considered feasible in treating oily wastewater. Due to the enhanced hydrophilicity, all the modified PVDF membranes exhibited higher RF and better antifouling property compared with the control PVDF membrane under the same operational conditions.

► TMP, pH, initial concentration, and TDS on ultrafiltration of oil/water emulsion was investigated.
► 0.1 MPa has been considered as the most preferable TMP.
► Higher the oil concentration and pH, more serious fouling of UF membranes, but TDS not.
► NaClO solution washing was a good method for cleaning the fouled membranes by oil.