Studies on the Oxidation of Corn Starch Granules by Sodium Hypochlorite Behavior III

Behavior of Dissolved Oxygen in the Reaction Mixture and Its Application to Process Control

Abstract

Dissolved oxygen in the reaction mixture during the oxidation of corn starch granules by sodium hypochlorite was measured with a Beckman oxygen analyzer. The dissolved oxygen decreased to almost zero ppm immidiately after the start of oxidation and did not increase again until the latter half of the oxidation reaction. Increase in the amount of dissolved oxygen in the latter half of the reaction was delayed when pH was raised or temperature was lowered or the amount of available chlorine added was increased. This phenomenon was' closely related to the reaction rate. The amount of dissolved oxygen was reciprocally related to the amount, of hypochlorite remaining in the reaction mixture. The curves of concentrations of dissolved oxygen plotted against duration of reaction showed good reproducibility when the experiments were done under the similar condition. This was also the case with the experiment using a larger scale reactor. Not only the amounts of dissolved oxygen but also times of reagents added were recorded on the curves. This measuring method of dissolved oxygen can be applied to control the process for the production of oxidized starch.