Modelling of natural and synthetic polyelectrolyte interactions in natural waters by using SIT, Pitzer and Ion Pairing approaches

Interaction of Natural Organic Matter with Layered Minerals: Recent Developments in Computational Methods at the Nanoscale

“…This is an important finding in the development of specific organic-mineral FF parameters, and it is consistent with experimental results showing that metal complexation behavior in NOM is similar to well-characterized polymers with similar functionalization [109][110][111][112][113]. The fact that different organic FF parameters yield similar structural and energetic properties for surface complexes indicates a very broad energy minimum for such complexes.…”

Sequestration of organometallic compounds by natural organic matter. binding of trimethyltin(IV) by fulvic and alginic acids

“…The values of the protonation constants of fulvic and alginic acids here used were previously determined in different ionic media at different ionic strengths. 45,46 Since the aim of this work is to define the sequestering capacity of fulvic and alginic acids towards trimethyltin(IV), i.e. the stability of the TMT-FA and TMT-AA complex species formed in the pH range of natural waters (5-8a), only the protonation constants of polyelectrolytes when α → 1 (log K H 1 ) have been considered in the calculations.…”

“…A chemical model based on the dependence of protonation constants on the dissociation degree of the polyelectrolyte under investigation allowed us to determine the proton exchange capacity of both fulvic and alginic acids in different ionic media and at different ionic strengths. The results, reported in recent papers, 45,46 are used here to determine the formation constants of complex species in the systems under investigation. Details of the chemical model for the binding capacity of poly-carboxylate ligands are reported in the section on the association chemical model.…”

Sequestering ability of phytate towards protonated BPEI and other polyammonium cations in aqueous solution

“…To simplify the thermodynamic study of some natural organic molecules, such as humic and fulvic acids [1], often high molecular weight polyelectrolytes were chosen as model molecules in order to obtain information about the behaviour (acid-base properties and complexing ability) of natural macromolecules. The literature reports several thermodynamic data for the interaction properties of some high molecular weight polyelectrolytes [2][3][4][5][6]; in particular these data regard the acidbase properties of polycarboxylates and their interactions with alkali, alkaline earth metals [2][3][4][5] and some low molecular weight polyamines [6]. Natural and biological fluids contain also amino compounds (amines, polyammonium cations, polyaminocarboxylates, etc.)…”

“…As a further contribution to the study of the acid-base properties and complexing ability of polyelectrolytes already undertaken [2][3][4][5][6], in the present paper we studied the interaction of an high molecular weight ammonium polyelectrolyte (branched polyethylenimine MW = 750 kDa) with an high charged polyphosphate, such as phytate. This high molecular weight polyamine has a monomeric unit which contains primary, secondary and tertiary amino groups in the ratio 1:2:1, as shown in Figure 1.…”