A Potentiometric Study of Ferric Ion Complexes in Synthetic Media and Seawater

Robert H. Byrne, Dana R. Kester

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Abstract

<p> An investigation of ferric ion complexing has been conducted in synthetic media and seawater at 25&deg;C. Formation constants were potentiometrically determined for the species FeCl <sup> 2+ </sup> , FeCl <sub> 2 </sub> <sup> + </sup> , FeOH <sup> 2+ </sup> , and Fe(OH) <sub> 2 </sub> <sup> + </sup> at an ionic strength of 0.68 <em> m </em> . Formation constants for the ferric chloride complexes were determined as <sub> <em> Cl </em> </sub> <em> &beta; </em> <sub> 1 </sub> = 2.76 and <sub> <em> Cl </em> </sub> <em> &beta; </em> <sub> 2 </sub> = 0.44. In a study of the reaction Fe <sup> 3+ </sup> + <em> n </em> H <sub> 2 </sub> O &rlhar; Fe(OH) <sub> n </sub> <sup> (3&minus;n)+ </sup> + nH <sup> + </sup> in NaClO <sub> 4 </sub> , NaNO <sub> 3 </sub> and NaCl the formation constants &lowast;&beta;1and&lowast;&beta;2"&gt;&lowast;&beta;1and&lowast;&beta;2 were shown to be relatively independent of medium when the effects of nitrate and chloride complexing were taken into account. The average values obtained for these constants are &lowast;&beta;1= 1.93 &middot; 10&minus;3and&lowast;&beta;2= 8.6 &middot; 10&minus;8"&gt;&lowast;&beta;1= 1.93 &middot; 10&minus;3and&lowast;&beta;2= 8.6 &middot; 10&minus;8 . Reasonable agreement with these values was obtained when these constants were determined in seawater by accounting for the effects of chloride, fluoride and sulfate complexing.</p>
Original languageAmerican English
JournalMarine Chemistry
Volume4
DOIs
StatePublished - Jan 1 1976
Externally publishedYes

Disciplines

  • Life Sciences

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