title: On the role of humic acids' carboxyl groups in the binding of charged organic compounds.
abstract: Interactions of humic acids (HAs) with two cationic dyes (methylene blue and rhodamine 6G) were studied using a unique combination of diffusion and partitioning studies in HAs, containing hydrogels and batch sorption experiments. In order to investigate the involvement of carboxyl groups of HAs in these interactions, all experiments were performed for both, the original lignite HAs and HAs with selectively methylated carboxyls. The results of the diffusion experiments confirm that the interactions between the solute and humic substances have a strong impact on the rate of diffusion process. Surprisingly, the effect is almost equally approved for original and methylated HAs. On the other hand, the results of batch sorption experiments show strong improvement of the sorption capacity (methylated HAs), which is explained by changed morphology of alkylated HAs. The comparison of the results of diffusion and adsorption experiments shows that the diffusion experiments simulate the transport of solutes in natural humics containing environment more reasonably.
authors.affiliation: Brno University of Technology, Faculty of Chemistry, Materials Research Centre CZ.1.05/2.1.00/01.0012, Purkyňova 464/118, 612 00 Brno, Czech Republic. Electronic address: xcsmilek@fch.vutbr.cz.
authors.forename: Jiří
authors.initials: J
authors.lastname: Smilek
authors.affiliation: Brno University of Technology, Faculty of Chemistry, Materials Research Centre CZ.1.05/2.1.00/01.0012, Purkyňova 464/118, 612 00 Brno, Czech Republic.
authors.forename: Petr
authors.initials: P
authors.lastname: Sedláček
authors.affiliation: Brno University of Technology, Faculty of Chemistry, Materials Research Centre CZ.1.05/2.1.00/01.0012, Purkyňova 464/118, 612 00 Brno, Czech Republic.
authors.forename: Michal
authors.initials: M
authors.lastname: Kalina
authors.affiliation: Brno University of Technology, Faculty of Chemistry, Materials Research Centre CZ.1.05/2.1.00/01.0012, Purkyňova 464/118, 612 00 Brno, Czech Republic.
authors.forename: Martina
authors.initials: M
authors.lastname: Klučáková
mesh_terms: D000327:Adsorption; D004058:Diffusion; D006812:Humic Substances; D008751:Methylene Blue / Q000737:chemistry*; D012235:Rhodamines / Q000737:chemistry*
chemical_list: D006812:Humic Substances; D012235:Rhodamines; C026188:rhodamine 6G; D008751:Methylene Blue
keywords: Diffusion; Humic acids; Hydrogel; Polyelectrolytes; Reactivity