Aqueous polymerization of acrylamide initiated by acidic potassium permanganate–ascorbic acid redox system

Abstract

Abstract The polymerization of acrylamide initiated by the acidic permanganate–ascorbic acid redox pair has been studied in aqueous media at 30 ± 0.2°C in nitrogen atmosphere. The initial rate of polymerization has been found to be proportional to nearly the first power of the catalyst KMnO 4 concentration within the range 6.0 × 10 −3 –14.0 × 10 −3 mole/l. The rate is proportional to the first power of the monomer concentration within the range 4.00 × 10 −2 –12.0 × 10 −2 mole/l. However, the rate of polymerization is independent of ascorbic acid concentration within the range 3.0 × 10 −3 –6.0 × 10 −3 mole/l., but the further increase of the concentration depresses the rate of polymerization as well as maximum conversion. The initial rate increases but the maximum conversion decreases as the temperature is increased within the range 20–35°C. The overall energy of activation has been found to be 9.8 kcal/mole. The optimum amount of sulfuric acid is essential to initiate the polymerization but its presence in excess produces no effect either on the rate of reaction or the maximum conversion. Water‐miscible organic solvents and salts, e.g., CH 3 OH, C 2 H 5 OH, (CH 3 ) 2 CHOH, KCl, and Na 2 SO 4 , depress the rate. Slight amounts of MnSO 4 · H 2 O and a complexing agent NaF increase the rate of polymerization. Cationic and anionic detergents have been found to decrease and increase the rate, respectively, while nonionic surfactants have no effect on the rate of polymerization.