Chlorine resistance of polypiperazineamide membranes and modules.

Abstract The Chlorine resistance of Poly (trans 2,5 dimethyl) piperazinthiofurazanamide and of the resulting membrane has been studied. Kinetics and equilibrium values of the system exposed to Chlorine concentration up to 800 ppm, pH from 4 to 10, and temperatures from 15°C to 25°C have been evaluated. The polymer does not show any important variation of molecular weight up to 200 ppmCl2. The membrane is practically unattached by Chlorine at acid or alcaline pH's. At pH in the ranges 6–7 it has a minimum resistance of 3 years when exposed to 3 ppmCl2 and of 24,000 ( hr-ppmCl2) when exposed to 100 ppm Cl2. The resistance of the relative spiral wound modules is equal to the resistance of the membrane and well above any other commercially available polyamide or acetate reverse osmosis module. The results reported in this is paper lead us to believe that Separem's polypiperazineamide modules are truly Chlorine resistant.