Decomposition of Ethylenediaminetetraacetic Acid by Supercritical Water Oxidation

Ethylenediaminetetraacetic acid (EDTA) was decomposed by supercritical water oxidation (SCWO) in a tubular plug-flow reactor. The effect of the oxidant amount on the decomposition rate and efficiency was more significant at lower temperature. Also, excess oxidant played a key role in decreasing the activation energy for EDTA decomposition as COD<INF>Cr</INF>. The nitrogen from EDTA was found to transform into NO<INF>3</INF>^-−N by thermal decomposition, while a portion of the nitrogen of EDTA and NO<INF>3</INF>^-−N was transformed into NH<INF>4</INF>⁺−N and finally converted to N<INF>2</INF> gas in the SCWO process. The decomposition kinetics of EDTA as COD<INF>Cr</INF> in the SCWO process was described by a global rate expression.