About Us | Help Videos | Contact Us | Subscriptions
 

Abstract

 

This article in SSSAJ

  1. Vol. 40 No. 5, p. 665-672
     
    Received: Dec 30, 1975


 View
 Download
 Alerts
 Permissions
 Share

doi:10.2136/sssaj1976.03615995004000050021x

Stability Constants of Cu2+, Pb2+, and Cd2+ Complexes with Humic Acids1

  1. F. J. Stevenson2

Abstract

Abstract

Application was made of the potentiometric titration method for determining apparent stability constants for the complexes between Cu2+, Pb2+, and Cd2+ and three humic acids from diverse sources. Complexes of Cu2+ and Pb2+ were considerably more stable than those for Cd2+. Log K2 values, obtained from the relationship kj = bj/Ki (Ki = ionization constant) increased rather dramatically with decreasing salt concentration and were of the order of those reported in the literature for metal complexes with known biochemical compounds. Average log K2 values for the three humic acids (absence of neutral salts) were 8.9 for Cu2+, 8.7 for Pb2+, and 6.9 for Cd2+. Differences between humic acids in their ability to bind metal ions were slight. At least two major sites were involved in the binding of metal ions.

  Please view the pdf by using the Full Text (PDF) link under 'View' to the left.

Copyright © . Soil Science Society of America