SRS -Nanofiltration Sulfate Removal

The main effect of sulfate to ionic membrane caustic soda plants has following several aspects:

(1) Sulfate ion release oxygen at the anode, reduce anode current efficiency and the purity of chlorine gas.

(2) Melamine salt format with other material impacting the life of ion-exchange membrane.

(3) Sulfate ion effect the content of sodium chloride in brine. When sulfate content get too high, crystallization will happen ,which may cause pipeline blockage or pump impeller.

Currently, the methods of sulfate removal are as follows:
(1) Chemical precipitation process: adding barium chloride, or calcium chloride, or barium carbonate;
(2) SRS-nanofiltration Membrane plus freezing process.

At present, most of the soda plants use chemical precipitation methods to remove sodium sulfate by adding barium chloride, which is a highly expensive and toxic substance and is categorized as high-risk chemicals in the factory,which should be very careful. On the other hand, such barium will cause extra harmful waste discharge. The Barium sulfate precipitation must be overdoses to prevent barium ion not exceed the safty point.

TFT SRS nanofiltration sulfate removal technology runs as physical method, the new impurities (barium) can’t be brought into brine, moreover, sulfate ion concentration can also be controlled less than 5g/L. This can obviously increase quality of brine, greatly reduce the influence of ion-exchange membrane internal channel by barium ion and sulfate ion, further improve the current efficiency of electrolytic, potentially prolong service life of ion-exchange membrane. At the same time, it creates the conditions for the preparation of purity chlorine from the source.

SRS nanofiltration sulfate removal technology only needs one-time investment in equipment, low operation cost, no toxic and harmful substances, no pollution,less waste discharge, easy for clean production, contribute to the achievement of energy conservation and emission reduction. It can also improve the utilization efficiency of the brine compared with traditional sulfate removal process.

The nanofiltration membrane is characterized by a molecular weight cut-off of 200-300Daltons for uncharged organic molecules.Divalent and multivalent anions like Mg, Ca,SO4,PO4 are preferentially rejected by the membrane, while monovalent ion like Cl, Na, NO3 rejection is dependent upon feed concentration and composition.

TFT provides  can offer a nanofiltration membrane which can be suitable for sodium sulfate removal for diluted brine in chlor-alkali industry. It has a long service life, high removal rate of sulfate >98%, stable performance, high endurance to Cl* etc.