Abstract
The complexation of heavy metals by humic acids has been studied by voltammetry for a number of different cases, including (a) different metal ions; (b) various concentrations of the supporting salt; (c) different total metal concentrations and (d) different charge densities of the humic acid. The voltammetric speciation data are compared with predictions of a theoretical model which, besides polyelectrolytic interactions, takes into account: (i) chemical binding of metal ions; (ii) ionic strength effects; (iii) entropic effects; and (iv) competitive interactions between counterions of different valences. All experimentally obtained speciation data agree well with theoretical predictions by considering a single value of the intrinsic free energy of binding, which appeared to be the same for the Cd and Zn metal ions. This means that under the presently applied experimental conditions the interactions between the humate ion and the metal ions is similar. It is furthermore shown that with the present experimental-theoretical procedure a very consistent and precise behavior of the stability constant of the complex is reached in the wide range of the physico-chemical solution variables reported in this work.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Colloids and Surfaces A: Physicochemical and Engineering Aspects
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
