These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Effects of pH and electrolyte concentration on the binding between a humic acid and an oxazine dye.
    Author: Zanini GP, Avena MJ, Fiol S, Arce F.
    Journal: Chemosphere; 2006 Apr; 63(3):430-9. PubMed ID: 16307779.
    Abstract:
    The binding between an oxazine dye and a humic acid was studied in aqueous solutions in the pH range 4-10 and in the supporting electrolyte (KCl) range 0.001-0.1M. A rather simple spectrophotometric method was developed to construct binding isotherms under conditions were traditional centrifugation or filtration methods fail. The use of this method is possible because humic acid molecules have the ability of changing the spectrum of dye molecules, and this ability is used to quantify the isotherms. All binding isotherms have a Langmuirian shape. The amount of bound dye is strongly dependent on the ionic strength and less dependent on the pH of the solution. The binding is rather strong and mainly driven by non-electrostatic forces. Whereas the Langmuir binding constant is independent of the pH and electrolyte concentration, the number of assessable sites in humic acid for binding oxazine increases by increasing pH and decreasing electrolyte concentration. These results can be directly related to the flexibility of humic acid molecules, which can swell at high pH and low ionic strength, increasing consequently the availability of binding sites. The results also indicate that humic substances may strongly affect the mobility and fate of dyes and related pollutants in the environment.
    [Abstract] [Full Text] [Related] [New Search]