Viscosity

PERVAP™ membranes are suitable for operation with fluid viscosities up to 5 cP.

Suspended solids

Suspended solids can have a detrimental effect on membrane performance and should be avoided. DeltaMem recommends pre-filtration with a 3-4 micron filter.

Dissolved solids

Dissolved solids (e.g. sugars, salts) can have a detrimental effect on membrane performance and should be avoided. DeltaMem recommends a dry residue analysis at 110-130°C (depending upon the feed composition) and ideally <10 ppm (wt) total solids.

Melting point

Compounds which solidify on the permeate side can result in reduced membrane flux over time. It is important that the compounds that are present in the feed material do not solidify under permeate side operating conditions. Typically, this means that the permeate must have a melting point below 0°C.

Vapour pressure and boiling point

High boiling point impurities (with a boiling point above ~140°C) and also with a low vapour pressure can cross the membrane and condense on the permeate side of the membrane and result in reduced flux over time.

pH

For solvent rich mixtures, pH is an indicative value only since the pH value is defined for aqueous solutions. Nevertheless, for guidance, the typical operating range is pH 5-8 and operation outside these pH values is acceptable in some cases.