Physicochemical aspects of interaction of indolyl-3-acetic acid with superabsorbent «Solid Water»
Abstract
Indolyl-3-acetic acid (IAA) belongs to the phytohormones of a number of auxins that regulate plant growth and development. The activation of auxin metabolism in plant cells (and, consequently, an increase in crop yields) is closely related to the problems of moisture retention in the soil. To successfully solve this problem, it is very promising to use a rare-crosslinked polymer hydrophilic material with superabsorbent properties (called "Solid Water"). The purpose of this study was to establish the mechanism of interaction of indolyl-3-acetic acid with the superabsorbent "Solid water".
The study of the adsorption interaction of the superabsorbent "Solid water" with indo-lilyl-3-acetic acid was carried out. It has been shown that indolyl-3-acetic acid (IAA) protonates in aqueous and water-alcohol solutions to form cations, bipolar ions, and anions. The electronic spectra of the above-mentioned ionic forms of IAA are presented. An analytical wavelength of λmax=279 nm was chosen to determine the concentration of IAA in working solutions.
The conditions for the synthesis of a superabsorbent capable of absorbing water in the ratio of 500 dm3 per 1 kg of polymer are given; as well as data on the presence of functional groups in the sorbent that are capable of entering into ion exchange reactions in the form of cations, zwitter ions and anions. The sorption of indolyl-3-acetic acid was studied using a limited volume method at pH=5.2 (T=298 K). The variants of sorption absorption of the zwitterion IAC± by fragments of the superabsorbent matrix having "amide + COOH" groups and "amine + COOH" groupings in the structure are considered. It has been established that the absorption of IAA± by these polymer fragments is cumulative and may correspond to the distribution law. Possible mechanisms of interaction of IAA± with the functional groups of the superabsorbent with the formation of associates of
COO-...H2O, H2O...H-N+H2, COO-...H2O...H-N+H2, H-OH...O=C-NH are proposed. These mechanisms have been confirmed in the results obtained by IR spectroscopy. The thermodynamic characteristics of hydrogen bonds in the above-mentioned "IUK±–water – sorbent" associates are presented.
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References
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