Chemical and Structural Transformation of Aggregated Al₁₃ Polycations, Promoted by Salicylate Ligand

Abstract

The chemical and structural consequences of the interaction between aggregates made of Al13 polycations and salicylate ligand were examined using adsorption isotherms, electrophoresis, infrared spectroscopy, Fraunhofer light diffraction, and static light scattering spectroscopy. Drastic changes were observed for a pseudo equilibrium ligand concentration equimolar to Al13. Below this concentration, salicylate forms monodentate complexes with the charged aluminum sites, decreasing the electrostatic repulsion between Al13 particles. A densification of the aggregates is evident by an increase of the apparent fractal dimension from 1.8 to 2.9. No dissolution was observed in this concentration range. Above this ligand concentration, excess adsorption of salicylate causes charge reversal, and dissolution of the aggregates, in the form of soluble complexes and small clusters was observed. The consequences were a size reduction and loosening of the aggregates. In aquatic media, such radical in situ changes are able to strongly influence the transport of colloids and associated species.

Fate of coagulant species and conformational effects during the aggregation of a model of a humic substance with Al13 polycations

“…Therefore, Al 13 polymers and aluminum polycations with a Al VI /Al IV < 12, are the dominating species within dialyzed coagulated MHS. Previous reports indicated that low molecular weight organic acids hinder aluminum hydrolysis (Masion et al, 2000) and depolymerize preformed Al 13 polycations (Molis et al, 1996;Amirbahman et al, 2000). Our results suggest that, in the OCC range and in the timescale of the experiment, the Al 13 coagulant species seem to be stable in presence of MHS, which is consistent with previous evidence of Al 13 polycations found in organic soil horizons (Hunter and Ross, 1991).…”

Aluminum speciation of coagulants with low concentration: Analysis by electrospray ionization mass spectrometry

“…In this study, salicylic acid and Al 13 species in the PACl 2 immediately formed Al 13 -salicylate complexes. Similar results obtained by Molis et al [37] indicated the presence of salicylate-Al 13 surface complex by infrared spectroscopy.…”

Effect of Al13 Polycation Grafting on Apple Wastes Activated Carbon That Have A Porous Structure

“…Using this standard method, the resulting solution will contain 90-95 % of the polycation Al 13 . In fact, many studies using the nuclear magnetic resonance spectroscopy (NMR), provided the proof of its existence and allowed the aluminum speciation [40][41][42][43][44][45][46] .…”