Reverse osmosis testing using monochloramine (NH<sub>2</sub>Cl) and free chlorine (HOCl) in
the presence of ferrous iron [Fe(II)] resulted in accelerated chlorination of polyamide
membranes. Similar effects were not observed when using ferric iron. Membrane
damage was detected through irreversible increases in salt passage and the presence
of chloride on the membrane surface using energy-dispersive spectroscopy. A
mechanistic study suggested that the formation of an amidogen radical (·NH<sub>2</sub>) during
NH<sub>2</sub>Cl decomposition with Fe(II) led to the reduction of the activation energy for the
chlorination reaction to proceed using NH<sub>2</sub>Cl. Enhanced oxidation using HOCl and
Fe(II) may have resulted from the formation of ·OH radicals, which also lowered the
chlorination-activation energy. Both pH suppression (from 8.0 to 6.0) and dechlorination
(7.0 mg/L sodium sulfite) successfully halted the chlorination reaction. Includes 33 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 660 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 12 |
| Published : | 03/01/2005 |
