HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Manunza, B. Articles by Seeber, R. Search for Related Content PubMed Articles by Manunza, B. Articles by Seeber, R. Agricola Articles by Manunza, B. Articles by Seeber, R.

Stability Constants of Metal-Humate Complexes: Titration Data Analyzed by Bimodal Gaussian Distribution

Dipartimento di Scienze Ambientali Agrarie e Biotecnologie Agroalimentari, Via De Nicola, 07100 Sassari, Italy

Carlo Gessa

Istituto di Chimica Agraria, Università degli Studi di Bologna, Viale Berti Pichat 10, 40127 Bologna, Italy

Renato Seeber

Dipartimento di Chimica Industriale e dei Materiali, Università degli Studi di Bologna, Viale del Risorgimento 4, 40136 Bologna, Italy

*Corresponding author (gx6bot81{at}cray.cineca.it).

ABSTRACT

A continuous multiligand model was applied to the study of the systems Cu(II)-, Pb(II)-, Mn(II)-, and Cd(II)-humate. The model is essentially based on a bimodal Gaussian distribution of the binding sites. It allows the calculation of pH-independent metal-binding thermodynamic constants which are more representative than simple empirical curve-fitting parameters. This model was applied to the study of the potentiometric titration data of an humic acid extracted from an Andosol of Macomer (Sardinia, Italy) in order to calculate the formation constants of the complexes of humic acids with four metal ions. Its application to the potentiometric titration experiments showed that different classes of sites are involved in the binding of the metal ions considered. The affinity to the humic matrix followed the order: Cu(II) > Pb(II) > Mn(II) >> Cd(II); phenolic groups play a relevant role in Cu binding while Cd appears to bind exclusively to carboxylic groups.

Received for publication November 21, 1994.

This article has been cited by other articles:

				A. Kaschl, V. Romheld, and Y. Chen Cadmium Binding by Fractions of Dissolved Organic Matter and Humic Substances from Municipal Solid Waste Compost J. Environ. Qual., November 1, 2002; 31(6): 1885 - 1892. [Abstract] [Full Text] [PDF]

				F. J. Ochoa-Loza, J. F. Artiola, and R. M. Maier Stability Constants for the Complexation of Various Metals with a Rhamnolipid Biosurfactant J. Environ. Qual., March 1, 2001; 30(2): 479 - 485. [Abstract] [Full Text] [PDF]