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  • 1 Department of Chemistry and Bio-chemistry, The Florida State University Tallahassee, FL-32306, USA
  • | 2 Department of Chemistry and Bio-chemistry, The Florida State University Tallahassee, FL-32306, USA
  • | 3 Department of Chemistry and Bio-chemistry, The Florida State University Tallahassee, FL-32306, USA
  • | 4 Department of Chemistry and Bio-chemistry, The Florida State University Tallahassee, FL-32306, USA
  • | 5 Department of Chemistry and Bio-chemistry, The Florida State University Tallahassee, FL-32306, USA
  • | 6 Department of Chemistry and Bio-chemistry, The Florida State University Tallahassee, FL-32306, USA
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Summary  

The complexation behavior of Ni2+with ortho-silicic acid (o-SA) has been studied as a function of ionic strength (I) from 0.20 to 1.00M (NaClO4) at pcH 4.55±0.05 and 25 °C by a solvent extraction technique with bis(2-ethylhexyl) phosphoric acid (HDEHP) as the extractant. The stoichiometry of the extracted species was determined to be Ni(DEHP)2(HDEHP)2. Ni2+forms a 1:1 complex, Ni(OSi(OH)3)+, as the predominant species withconcentrations of 1.00. 10-3to 1.00. 10-2M o-SA. The stability constant (logb1) values for Ni(OSi(OH)3)+complex formation decrease with increased ionic strength. These values have been fitted with the extended Debye-Huckel expression to obtain the value of logb1=6.34±0.03 at I=0.00M. The data allowed the calculation of speciation of the Ni2+- silicate system as a function of ionic strength.