Oxidation of Ammonium Sulfite in Aqueous Solutions with Streamer Plasmas

A streamer corona plasma induced oxidation technique, which used the so called AC/DC power supply to convert high concentration ammonium sulfite to sulfate, was reported. The results showed that the sulfite oxidation rate was significantly higher than that in the forced air oxidation process. Research on how to use streamer discharge plasmas to oxidize high concentration ammonium sulfite in the liquid phase has obtained remarkable progress. On the basis of the experiment results, the following conclusions could be arrived: (1) In contrast to the plasma-induced oxidation, the spontaneous oxidations made negligible contributions to convert sulfite to sulfate. (2) When the initial sulfite concentration was within 1-3 mol·L^-1, plasma induced one-cycle oxidation efficiency was in the range of 20%-60%. The oxidation rate was faster than that at concentration less than 1 mol·L^-1. To make the technique industrially applicable, the plasma induced oxidation process should be performed under the initial concentration more than 1 mol·L^-1. (3) With the increase of the power density, the molar energy consumption of ammonium sulfite oxidation increased faster than the oxidation efficiency did, which indicated that radical-radical termination reactions dominated the process.