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Membrane Water Treatment
  Volume 11, Number 4, July 2020 , pages 237-245
DOI: https://doi.org/10.12989/mwt.2020.11.4.237
 


Morphology control in PVDF membranes using PEG/PVP additives and mixed solvents
Shima Rajabi, Foroogh Khodadadi, Toraj Mohammadi, Maryam Tavakolmoghadam and Fatemeh Rekabdar

 
Abstract
    The effects of the mixed two solvents, Dimethylacetamide (DMAc) and Dimethylformamide (DMF), and Polyethylene glycol (PEG) and Polyvinylpyrrolidone (PVP) as additives on performance of Polyvinylidene fluoride (PVDF) membranes were studied. Initially, PEG200 was used as a primary additive at fixed percentage of 5% wt. PVP was then blended with PEG200 in different concentrations. PVDF and DMAc were used as polymer and solvent in the casting solutions, respectively. To control the diffusion rate of PVP in the presence of PEG200 and PVP blend, mixtures of DMAc and DMF were used as the mixed solvent in the casting solutions. Asymmetric PVDF membranes were prepared via phase inversion process in a water bath and the effects of two additives and two solvents on the membrane morphology, pure water flux (PWF), hydrophilicity and rejection (R) were investigated. Attenuated Total Reflection Fourier Transform Infrared Spectra (ATR-FTIR) analysis was used to show the residual PVP on the surface of the membranes. Atomic Force Microscopy (AFM) was utilized to determine roughness of membrane surface. The use of mixed solvents in the casting solution resulted in reduction of PVP diffusion rate and increment of PEG diffusion rate. Eventually, PWF and R values reduced, while porosity and hydrophilicity increased.
 
Key Words
    PVDF membranes; blending; PEG/PVP; mixed solvents; DMAc/DMF
 
Address
Shima Rajabi, Foroogh Khodadadi, Toraj Mohammadi: Chemical Engineering Department, Iran University of Science and Technology, Narmak, Tehran, Iran
Maryam Tavakolmoghadam and Fatemeh Rekabdar: Research Institute of Petroleum Industry, Tehran, Iran
 

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