Removal of Iodine and Methyl Iodide in Gas by Wetted-Wall Reactor Based on Selective Electron Attachment.

Abstract

An electron attachment reaction, which produces a negative ion by the collision between an electron and a gas molecule, can be applied to gas purification because this reaction has a very high selectivity depending on the electron energy, the structure of the gas molecules and its electron affinity. In this study, a wetted-wall reactor using corona discharge was proposed and experiments involving removal of dilute iodine and methyl iodide from nitrogen were conducted. A deposition-type reactor using the discharge, which had been previously proposed by the authors, showed removal limitations of iodine and methyl iodide. On the other hand, in the removal of iodine by the wetted-wall reactor, negative ions produced by electron attachment were absorbed into the liquid film on the anode resulting in the change of chemical species in the liquid so that gas absorption increased to raise the removal efficiency. Since iodine produced by the dissociative electron attachment of methyl iodide inhibited the removal of methyl iodide, it was effective to prevent the formation of iodine in the reactor for pursuing high removal efficiency of methyl iodide. In the removal of methyl iodide by the wetted-wall reactor, the reaction byproduct, iodine, was not produced in the reactor, and the removal efficiency became high compared with the deposition-type reactor.