Phytic acid, in its deprotonated form, carries a relatively high density of negative charge on a comparatively small molecule, enabling it to form coordination compounds with numerous metals. The purpose of the research work was to investigate the formation of coordination compounds between phytic acid and chromium(III) ions, and to examine how complexation affects its acid-base properties. The work was carried out through a detailed analysis of the position of equivalence points obtained by alkalimetric potentiometric titration. As part of the research, a titration method for phytic acid and its complexes with chromium(III) ions was developed and optimized. Optimization of the conditions in the titration cell was also carried out, including optimization of the amount of phytate and the concentration of the electrolyte in the titration cell, as well as evaluation of phytate source (i.e. Na- vs. K-salt). Optimization of the work and calculation method was also carried out. The results of the titrations of phytic acid in the presence of chromium(III) ions showed that chromium(III) ions form strong interactions with phytic acid, reflected in changes in the overall titration curve. The presence of chromium(III) ions caused a shift of all three equivalence points toward higher titrant consumption or a higher molar ratio between the titrant and phytate, and decreased pH at the first and third equivalence points of the phytic acid titration curve. Based on the results, the interactions of chromium(III) ions with phytic acid are comparable to those of iron(III) ions, which are known to form some of the most stable binding interactions with phytates. This study contributes to a better understanding of the interactions between phytate and chromium(III) ions and provides a basis for further research in this area. The observed interactions between phytic acid and chromium(III) ions confirm the potential use of phytic acid for the remediation of environments contaminated with heavy metals, particularly chromium.
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