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Methodology of the fabrication of Glycerol coated Polyvinylidene

Fluoride (PVDF) Membranes

Group Members:

1. Kelvin Ho Pau Hui

2. Gong Wee Jie

3. Mohammed Hussain

4. Yugaraj Balar

5. Muhammad Asfand Yar

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Methodology

Coating / Dip Coating

1. Immersion – Substrate is immersed in a solution containing 70 wt% glycerol, 0.2-1.5% cellulosic polymer and 1-3% cross-linking agents at a constant speed (preferably jitter-free)

2. Start-Up – Substrate has remained inside the solution for a while and is starting to be pulled up.

3. Deposition – The thin layer deposits itself on the substrate while it is pulled up. Withdrawing is carried out.

4. Drainage – Excess liquid will drain from the surface.5. Evaporation – The solvent evaporates from the liquid, forming

thin layers.

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Change in Properties

Porosity

• Increases initially with increasing glycerol concentration until a certain point where it starts to decrease.

• Volume of pores divided by total volume of porous membrane or;

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Shrinkage

• Increase in hydrophilicity decreases shrinkage ratio

• High shrinkage ratio decreases pore size

• Percentage of shrinkage can be calculated using a micrometer

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Membrane Thickness

• Flux decreases with increasing thickness

• Increase of transmembrane resistance

• Thick membrane increases mechanical strength (tensile strength and bursting pressure)

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Contact Angle

• Hydrophobic surfaces have higher contact angle than hydrophilic

• Membranes with higher concentration of glycerol have lower contact angle

• Measured using a goniometer

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References

1. Mulder, M. (1992) “Basic Principle of Membrane Technology”, Dordrecht: Kluer Academic Publishers.

2. Hilal, N., Khayet, M. and Chris J. Wright (2012) “Membrane Modification: Technology and Applications”, USA: CRC Press.