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Thermal decomposition of potassium persulfate in aqueous solution at 50°C in an inert atmosphere of nitrogen in the presence of acrylonitrile monomer
Author(s) -
Sarkar Swati,
Adhikari Mukti Sadhan,
Banerjee Monoranjan,
Konar Ranajit Singha
Publication year - 1988
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1988.070350604
Subject(s) - potassium persulfate , persulfate , aqueous solution , chemistry , acrylonitrile , monomer , ammonium persulfate , inorganic chemistry , polymerization , nuclear chemistry , polymer chemistry , organic chemistry , polymer , copolymer , catalysis
The rate of thermal decomposition of persulfate in aqueous solution in the presence of acrylonitrile (AN) monomer (M) and of nitrogen, may be written as:\documentclass{article}\pagestyle{empty}\begin{document}$$ {{ - d\left( {{\rm S}_2 {\rm O}_8^{2 - } } \right)} \mathord{\left/ {\vphantom {{ - d\left( {{\rm S}_2 {\rm O}_8^{2 - } } \right)} {dt{\rm }\alpha }}} \right. \kern-\nulldelimiterspace} {dt{\rm }\alpha }}\left( {{\rm S}_2 {\rm O}_8^{2 - } } \right)^{1.35 \pm 0.05} \times \left( M \right)^{1.26 \pm 0.069} $$\end{document} in the concentration range of persulfate (1.8 to 18.0) ×10 ‐3 , and of monomer (M), 0.30 to 1.20, mol dm ‐3 . It was observed that the pH of the solution containing persulfate and monomer did not alter during polymerization if the monomer concentrations were close to its solubility under the experimental conditions. Conductance of the aqueous solutions of persulfate and monomer was found to decrease during the reactions. In an unbuffered aqueous solution containing only persulfate, however, the pH was found to decrease continuously at 50°C with time, while the conductance of the solution was found to increase. The monomer (AN) had no effect on the glass electrodes of the pH meter in aqueous solutions, and also on the electrodes of the conductivity cell. It has been suggested that the secondary or induced decompositions of persulfate were due to the following elementary reactions:\documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {\left( {\rm X} \right)} \hfill {\rm } {\rm S}_2 {\rm O}_8^{2 - } + M \to \cdot M \hbox{---} {\rm O} \hbox{---} {\rm SO}_3^ - + {\rm SO}_4^{ \cdot ^ - }, \hfill\\ \\ {\left( {\rm Y} \right)} \hfill {\rm } {\rm S}_2 {\rm O}_8^{2 - } + M_j^ \cdot \to M_j \hbox{---} {\rm O} \hbox{---} {\rm SO}_3^ - + {\rm SO}_4^{ \cdot ^ - }, \hfill \\ \\ \end{array} $$\end{document} where ( M j · radicals ( j = 1 to 10) are water‐soluble oligomeric or polymeric free radicals. k x and k y at 50°C have been estimated as 1.70 X 10 ‐5 and 5.08 × 10 3 dm 3 mol ‐1 s ‐1 , respectively. By measuring pH of freshly prepared persulfate solutions at 25°C, it is suggested that 0.05–0.30% of persulfate reacts molecularly with water (i.e., hydrolysis), as soon as it (10 ‐3 to 10 ‐2 mol dm ‐3 ) is added to distilled water (pH 7.0). This hydrolysis was found to be stopped in dilute sulfuric acid solution (pH 3–4).