2.4. Characterization
Water contact angle values of the oil waste water on the PVDF
and PVDF–PVP membrane surface were measured in a DSA 100
Micromeritics Contact Anglometer (KRUSS Corporation, Germany)
at 25 C. Since the contact angle was not stable, it was measured
every 5 s.
The chemical composition of the pristine PVDF and PVDF–PVP
membranes was characterized using FTIR spectrophotometry
(NICOLET iS10, Thermo Electron Corporation, USA). Each spectrum
was captured by averaging 32 scans at a resolution of 2 cm1.
Raman spectra were gained by LabRam II Laser Raman spectrometer
(HORIBA Jobin Yvon Corporation, France).
BET analysis using ASAP2020 Surface Area and Porosity
Analyzer (Micromeritics Instrument Corporation) was conducted
to measure the pore size distribution and pore structure of the
PVDF and PVDF–PVP membranes.
Elemental analysis was used to indicate the elementary composition
of the PVDF and PVDF–PVP membranes. The weight percent
of carbon, hydrogen, oxygen, nitrogen and fluorine in each
membrane sample were determined from an elemental analyzer
(EA1110, Carco Erba Co., Italy).