Competition effects in cation binding to humic acid: Conditional affinity spectra for fixed total metal concentration conditions

Abstract

Abstractcan be used as a direct measure of the heterogeneity, also shows a significant dependence on the total metal concentration. A discussion of the factors that influence ACCEPTED MANUSCRIPT 2 the heterogeneity of the HA under the conditions of each experiment is provided, so that the smoothed pattern exhibited by the titration curves can be justified.

Acid-base properties of dissolved organic matter extracted from the marine environment

“…Potentiometric titrations using glass/selective electrodes are routinely applied for the physicochemical analysis of e.g. biomass (Lodeiro et al, 2019) and fulvic and humic substances of terrestrial or freshwater origin (David et al, 2010;Koopal et al, 2005). In coastal waters like the Baltic Sea, a significant part of the DOM pool is of terrestrial origin and supplied by rivers (Deutsch et al, 2012;Hoikkala et al, 2015;Seidel et al, 2017), although overall a very small fraction of terrestrial DOM (b0.03%) is exported to the ocean (Cai et al, 1998;Carlson and Hansell, 2015;Dittmar and Stubbins, 2014).…”

Speciation of uranyl ions in fulvic acid and humic acid: a DFT exploration

“…10 Although the conclusive structural data of HAs and FAs are debatable, the binding affinities of various cations are investigated using various spectroscopic measurements. [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40] Binding of different metal ions (alkali and alkaline earth metal ions, 31,33 transition [27][28][29][30]39 and inner transition metal ions 32 ) with varying ionic radii and oxidation states to HAs and FAs has been investigated. It has been thought that carboxylate and phenolate groups were the major binding sites, although other binding motifs cannot be ruled out.…”

“…30 Similarly, tri-valent cations (Al 3+ ) have been reported to bind stronger as compared to mono-valent cations (K + ). 9 Based on the titration experiments, binding of uranyls [34][35][36][37][38]40 and other cations [27][28][29][30][31]33,39 to HA has been reported and tentatively assigned to the carboxylate binding site. Similarly, the complex formations of soil FA for different 3d-transition metal ions have been measured by dialysis titration.…”

Especiação termodinâmica de metais traço com substâncias húmicas: o modelo Nica-Donnan

“…Esta metodologia permitiu verificar que as constantes de acidez são influenciadas pelos íons metálicos. 58 Em outro trabalho interessante sobre a aplicação da equação NICA, Orsetti et al 59 utilizaram um procedimento padronizado para extrair a distribuição de afinidade condicional a partir das curvas de titulação para o hidrogênio e para Cd(II), Pb(II) e Cu(II). Neste trabalho constataram que para o hidrogênio as distribuições são, na maioria dos casos, bimodais (carboxílicos e fenólicos), como assumido na literatura.…”