Woongjin Chemical reported the development of the CRM (Chlorine Resistant) RO Membrane). This product shows a higher resistance to chlorine than other RO membranes currenlty on the market.
Free chlorine or chloramine is the typical choice for pretreatment to control microorganisms in the feed water. However, since these kinds of oxidants may cause damage to the RO membrane, they must be neutralized prior to entering the RO system. If insufficient SBS (sodium bisulfite) is used to neutralize the oxidizing agent, the unoxidized agent may pass through the RO membrane elements and fouling the membrane surface.
It was known experimentally that polyamide membranes having tertiary amide links showed more chlorine resistance than standard RO membranes. Woongjin Chemical used this finding to make a chlorine resistant membrane. The newly developed membrane displayed at least four times chlorine tolerance compared to the regular RO membrane.
Several experiments with CSM CRM for verification of its chlorine resistance have been carried out by Dr. S. K. Hong at the Korea University. The results will be presented at upcoming conferences around the world. According to Dr. Hong, pilot tests demonstrated that CSM CRM has 4 to 5 times more chlorine tolerance than regular PA membranes. Also, XPS analysis exhibited the chlorine uptake by CSM CRM was much less than the regular PA membranes.
Chlorine tolerance of CSM CRM is about 4000 ppm•hr compared to 1000 ppm•hr of the regular membrane. However, this does not permit users to continuously inject chlorine into the RO system but it means that the CRM RO element may be safe to accidental or infrequent exposure to chlorine. |
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