Table 3.

Physico-chemical properties of MD membranes with basic requirements for prevention of membrane wetting.

Factors	Conditions	Reference
Layers	At least the top layer must be hydrophobic or superhydrophobic in nature to avoid wetting in the MD process	[48]
Pore size distribution	Selection of a narrow pore size range with a high liquid entry pressure (LEP) value	[32,49,50]
Tortuosity factor	Must be as lower as possible: This is a measure of the deviation in pore structure from normal straight cylindrical pores. Typically, the tortuosity factor is inversely proportional to MD permeability	[4]
Thermal conductivity of the membrane surface	The thermal conductivity of the membrane surface must be as low as possible	[51]
Fouling resistance	The polymeric membrane can be coated with fouling resistant materials to ensure high permeate flux	[52]
Thermal stability	The MD polymeric membrane must show high thermal stability up to 80 °C.	[53]
Chemical resistance	The MD membranes must exhibit good chemical resistance because they may come in contact with acids and bases	[54]