MODELING OF ACIDIC AND COMPLEXATION PROPERTIES OF HUMIC ACIDS USING THE IRWING-ROSSOTTI METHOD

Demircivi P., Karadirek S., Anilanmert B., Tutar A., Hizal J., Apak R.

FRESENIUS ENVIRONMENTAL BULLETIN, vol.24, pp.4743-4750, 2015 (SCI-Expanded, Scopus) identifier identifier

  • Publication Type: Article / Article
  • Volume: 24
  • Publication Date: 2015
  • Journal Name: FRESENIUS ENVIRONMENTAL BULLETIN
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.4743-4750
  • Keywords: humic substances, acid-base properties, thermodynamic properties, proton binding, metal complexation, PROTON-BINDING, FULVIC-ACIDS, COPPER(II)
  • Istanbul University-Cerrahpasa Affiliated: No

Abstract

In this study, acidic and metal complexation properties of five humic acid samples, obtained from different source, were investigated. Humic acid samples were extracted with 1 M NaOH solution and then precipitated using concentrated HCl. Thus, purified humic acid samples were used in neutralization and Cu(II) complexation experiments. Purity of the humic acid samples varies between 75-85 %. Structural analysis of purified humic acid samples were performed by using FTIR, SEM and LC-MS methods. Molecular weights of them were determined by the aid of LC-MS method. Distribution coefficients (K-D) of humic acid samples in convenient solvent were also investigated and calculated. The data gained as a result of potentiometric titration were evaluated in Irwing-Rossotti method. Thus, acidity constants of -COOH and -OH groups, that can release proton, and formation constants of Cu(II) - humate complexes were determined. All experiments were performed at 2 degrees C and 25 degrees C.