Rejection spectra of reverse osmosis membranes degraded by hydrolysis or chlorine attack

• Published in: Desalination Vol. 60; no. 2; pp. 93 - 110
• Main Authors: Watters, James C., Klein, Elias, Fleischman, Marvin, Roberts, Jane S., Hall, Barbara
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 1986; Elsevier
• Subjects: Applied sciences; chlorine attack; degradation; Drinking water and swimming-pool water. Desalination; Exact sciences and technology; hydrolysis; Pollution; rejection spectra (effect on); RO membranes; Water treatment and pollution; degradation; RO membranes; rejection spectra (effect on); hydrolysis; chlorine attack; Degradation; Hydrolysis; Rejection; Temperature; Nylon; Chlorine; Desalination; Membrane; Reverse osmosis; Cellulose acetate
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/0011-9164(86)90001-9

Cellulose acetate (CA) and polyamide (PA) membranes were subjected to accelerated degradation for up to 24 h to determine the effects of curing temperature and degradation time on transmembrane flux and on the rejection by the membranes of salts (NaCl and CaCl 2), hexose sugars and polysaccharides. Commercial PA membranes, and one set of CA membranes made in our laboratory lost all salt rejection ability after 24 h of degradation but maintained 100% rejection of polysaccharides, and thus still functioned as ultrafilters. A second set of CA membranes was cured at different temperatures. CA membranes annealed at 45°C and 55°C degraded faster than those annealed at 75°C, based on their faster loss of salt rejection ability. This rapid degradation of the membranes annealed at lower temperatures, coupled with their inherent poor initial salt rejection enforces the conclusion that membranes to be used in reverse osmosis application should not be cured below about 55°C. Based on the study, a simple test procedure is proposed to distinguish between chemical degradation and gross failure in malfunctioning reverse osmosis units.