Aluminum complexes citric acid

Complexes of tetravalent zirconium with organic acids, such as citric, tartaric, malic, and lactic acids, and a complex of aluminum and citric acid have been claimed to be active as dispersants. The dispersant is especially useful in dispersing bentonite suspensions [288]. Polymers with amine sulfide terminal moieties are synthesized by using aminethiols as chain transfer agents in aqueous addition polymerizations. The polymers are useful as mineral dispersants [1182]. 

The small Al3+ cation with a high charge does not exist in the free form under physiological conditions. In mildly acid intracellular conditions, aluminum is bound to phosphate. Aluminum forms soluble salts with some acids, for example, with citric acid [82], or complexes with some compounds, for... 

Lopez-Quintela, M. A., Knoche, W., and Veith. J. (1984). Kinetics and thermodynamics of complex formation between aluminum(ni) and citric acid in aqueous solution. J. Chem. Soc. Faraday Trans. 80, 2313—2321. 

Wiese, G., and Veith, J. A. (1975). Formation of complexes with citric acid, I Formation of complexes between citric acid and aluminum. Z. Naturforsch. 30b, 446-453. 

Definition Complex salt of aluminum hydroxide and citric acid Empirical CsHsOy Al... 

It is well known that organic complex-formers, such as simple organic acids (citric, oxalic, tartaric, salicyclic) formed by microorganisms in soils and humic or fulvic acids, solubilize mineral iron(III) and aluminum. These complex-formers not only increase the solubility of these minerals but also are able to form chelates on hydrous oxide surfaces and thus, in turn, catalyze the dissolution of oxides and aluminum silicates (Kummert and Stumm, 1980 Sigg and Stumm, 1980). The downward vertical displacement of A1 and Fe, as it is observed in the podsolization of soils, can be accounted for by considering the effect of pH and of complex formers on both solubility equilibria and dissolution rates (Schnoor and Stumm, 1985 Schnoor and Stumm, 1986). 

Binary systems synthesized consisted of Cu/Fe, Ni/Fe, Cu/Al and Ni/Al and Cu/Cr for 4-10 wt percent Cu or Ni in the calcined mixed oxide. Anionic complexing agents acetic, citric and oxalic acids and EDTA were used in molar ratios of 1 1 with the initial copper or nickel. Two stage precipitations were used starting with an initial formation of aluminum, chromium or ferric hydroxide by addition of NaOH to an aqueous solution of A1 nitrate, Cr nitrate or Fe chloride. In the second stage aqueous solutions of Cu sulfate or Ni nitrate were mixed with the initial precipitate with or without the presence of a 1 1 mole ratio of selected anionic complexing agents to complete the precipitation. A second mode of coprecipitation used was to preadsorb oxalic acid on the initially precipitated AI, Cr or Fe hydroxide. 

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