Cellulose acetate membranes durability

This presentation will discuss the membrane performance and its physical and chemical changes under unfavourable conditions. This kind of studies will give us information on trouble-shooting counter-measures for unexpected membrane deteriorations, and on the durability of a cellulose acetate membrane under adverse conditions. 

Our Investigation on durability and membrane characteristics changes under adverse conditions have much contributed to development of RO applications. Among these applications are those for ultra-pure water in electronic and pharmaceutical industries. Even under the circumstance of pH 7 and with 2 to 4 times per year of sterilization by H2O2 of as high as 1 %, the cellulose acetate membrane proved to show membrane life of more than 3 years. 

The membrane must not be attacked by the solvent and must permit the solvent to permeate fast enough to achieve osmotic equilibrium in a reasonable time. If the membrane is too permeable, however, large leakage errors will result. Cellulose and cellulose acetate membranes are (he most widely used types with synthetic polymer solutions. Measurements at the relatively elevated temperatures needed to dissolve semicrystalline polymers are hampered by a general lack of membranes that are durable under these conditions. 

Durability Study of Cellulose Acetate Reverse-Osmosis Membrane Under Adverse Circumstances for Desalting... 

In 1968 we started investigations of RO applications for desalting brackish water. In the course of the investigations, we have found the spirally wound module of asymmetric cellulose acetate RO membrane shows excellent durabilities against fouling materials and free chlorine. 

The chemical sensitivity or life expectancy of reverse osmosis membranes is very important for manufacturing application. Thus chlorine is the most well known reagent for water disinfection. Glaster et al. 61 inspected the influence of halogens on the performance and durability of reverse osmosis membranes. Cellulose acetate was unresponsive to halogen agents but polyamide-type membranes deteriorated rapidly when exposed to halogens. 

PETP, cellulose acetate and Teflon. Durable and reproducible immobilization procedures have been elaborated. The membranes prepared have been used over months and no significant leaching out of the reagent was observed. Quite promising materials are microfiltration membranes (e.g. cellulose acetate), which are commercially available. They have large active surface for reagent immobilization and the response time of the sensor is short due to the easy access of the analyte to the reagent molecules. 

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