Calculating the Ionization Constant of Functional Groups of Carboxyl Ion Exchangers
- Autores: Meychik N.1, Stepanov S.2, Nikolaeva Y.1
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Afiliações:
- Department of Chemistry
- Mendeleev University of Chemical Technology
- Edição: Volume 92, Nº 2 (2018)
- Páginas: 265-270
- Seção: Chemical Kinetics and Catalysis
- URL: https://journals.rcsi.science/0036-0244/article/view/169889
- DOI: https://doi.org/10.1134/S0036024418010156
- ID: 169889
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Resumo
The potentiometric titration of a weakly basic carboxyl cation exchanger, obtained via alkaline hydrolysis of an acrylonitrile copolymer with divinyl benzene (degree of crosslinking, 12%) in a wide range of variation in a solution of рН (2–12) and NaCl (concentration 0.01, 0.1, 0.5, 1 М), is considered. The maximum ion-exchange capacity of the ion exchanger for Na+ is determined (10.10 ± 0.088 mmol/g of the dry mass) and found to be independent of the solution’s ionic strength. It is established that in the investigated range of NaCl concentrations and рН, the acid–base balance is adequately described by Gregor’s equation. The parameters of this equation are calculated as a function of the NaCl concentration: рKа = 8.13 ± 0.04, n = 1.50 ± 0.02 for 0.01 М; рKа = 6.56 ± 0.04, n = 2.60 ± 0.07 for 0.1 М; and рKа = 5.66 ± 0.6, n = 2.62 ± 0.06 for 0.5 and 1 М. It is shown that to describe the acid–base balance correctly within the proposed model we must estimate the adequacy of the experimental and calculated values of the ion exchanger’s capacity at each рН value according to the calculated parameters of Gregor’s equation.
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Sobre autores
N. Meychik
Department of Chemistry
Autor responsável pela correspondência
Email: meychik@mail.ru
Rússia, Moscow, 119991
S. Stepanov
Mendeleev University of Chemical Technology
Email: meychik@mail.ru
Rússia, Moscow, 125047
Yu. Nikolaeva
Department of Chemistry
Email: meychik@mail.ru
Rússia, Moscow, 119991