Description
Trace concentrations of metal ion impurities, such as Fe<sup>2+</sup>, Fe<sup>3+</sup> and Mg<sup>2+</sup>, which are commonlyencountered in water, can retard significantly the precipitation of CaCO<sub>3</sub>. In view of the paucity of viabletechniques for overcoming scale deposition difficulties, it is important to examine optionsfor CaCO<sub>3</sub> scale control by trace amounts of inhibiting metal ions. The literature cites Zn <sup>2+</sup> ions as beingparticularly effective in suppressing CaCO<sub>3</sub> scale deposition.This paper reviews phenomena induced by the presence of ion impurities. Literature data relating to theretardation of CaCO<sub>3</sub> nucleation and crystal growth processes by adsorption of impurities on crystalgrowth sites are analyzed and correlated. The effect of the presence of Zn<sup>2+</sup> ions on CaCO<sub>3</sub> scaledeposition from hard waters having a Langelier saturation index of 1.0 to 1.5 was measured in twoexperimental heating systems. A marked scale suppression effect was obtained with as little as 1 to 1.5PPM Zn<sup>2+</sup> ion, added to the water either by dosing a Zn<sup>2+</sup> solution or by the release of Zn<sup>2+</sup> ions throughcontact with a redox Zn-Cu alloy medium such as a granular bed of KDF-55®. Includes references, tables, figures.
Product Details
- Edition:
- Vol. – No.
- Published:
- 11/15/2004
- Number of Pages:
- 20
- File Size:
- 1 file
- Note:
- This product is unavailable in Ukraine, Russia, Belarus
