Cho, Kangwoo Hoffmann, Michael R. 2024-01-20T08:34:11Z 2024-01-20T08:34:11Z 2021-09-02 2014-10-07 0013-936X https://pubs.kist.re.kr/handle/201004/126251 This study investigated the transformation of urea by electrochemically generated reactive chlorine species (RCS). Solutions of urea with chloride ions were electrolyzed using a bismuth doped TiO2 (BiOx/TiO2) anode coupled with a stainless steel cathode at applied anodic potentials (E-a) of either +2.2 V or +3.0 V versus the normal hydrogen electrode. In NaCl solution, the current efficiency of RCS generation was near 30% at both potentials. In divided cell experiments, the pseudo-first-order rate of total nitrogen decay was an order of magnitude higher at E-a of +3.0 V than at +2.2 V, presumably because dichlorine radical (Cl-2(-)) ions facilitate the urea transformation primary driven by free chlorine. Quadrupole mass spectrometer analysis of the reactor headspace revealed that N-2 and CO2 are the primary gaseous products of the oxidation of urea, whose urea-N was completely transformed into N-2 (91%) and NO- (9%). The higher reaction selectivity with respect to N-2 production can be ascribed to a low operational ratio of free available chlorine to N. The mass-balance analysis recovered urea-C as CO2 at 77%, while CO generation most likely accounts for the residual carbon. In light of these results, we propose a reaction mechanism involving chloramines and chloramides as reaction intermediates, where the initial chlorination is the rate-determining step in the overall sequence of reactions. English American Chemical Society SOURCE-SEPARATED URINE ACTIVE CHLORINE SWIMMING POOLS WATER OXIDATION AMMONIA ELECTRODES MECHANISM NITROGEN DECOMPOSITION Urea Degradation by Electrochemically Generated Reactive Chlorine Species: Products and Reaction Pathways Article 10.1021/es5025405 1 Environmental Science & Technology, v.48, no.19, pp.11504 - 11511 Environmental Science & Technology 48 19 11504 11511 scie scopus 000343016600061 2-s2.0-84907938289 Engineering, Environmental Environmental Sciences Engineering Environmental Sciences & Ecology Article SOURCE-SEPARATED URINE ACTIVE CHLORINE SWIMMING POOLS WATER OXIDATION AMMONIA ELECTRODES MECHANISM NITROGEN DECOMPOSITION