4. Conclusion
In this study, oily waste water was treated by PVDF grafted with
PVP ultrafiltration membranes. The grafting process consisted of
defluorination, double bond hydration and PVP grafting. The modified
membranes were characterized by FTIR, BET, and contact
angles. Modification mechanism was discussed and it showed that
the hydroxyl and ketone group were generated during modification.
The results showed that PVP was grafted onto PVDF membrane
surface and the average pore sizes increased slightly while
pore structure was not nearly changed after modification.
When the PVDF–PVP membranes were used to treat oily waste
water, their separation performance was improved greatly compared
with that of the PVDF membranes. Besides, fouling mechanism
was studied and it could be found that external fouling was
the main cause of flux decline. Moreover, flux recovery of the
fouled PVDF–PVP membranes after cleaned using 3 wt.% NaOH
aqueous solution exceeded 90% and was much superior to that of
the fouled PVDF membranes.
Acknowledgements
This work was financially supported by the National Natural
Scientific Funds of China (No. 81274095) and Natural Scientific
Funds of Jiangsu Province of China (BK2012727).