Home
INTRODUCTION RESEARCH MEMBER PUBLICATION BOARD
닫기

Create wq

Lab. on Chemical Redox Acceleration Technologies for Water Quality

home    Publication    Journal

Journal

Urea Degradation by Electrochemically Generated Reactive Chlorine Species: Products and Reaction Pathways
Year of publication 2014
Title of paper Urea Degradation by Electrochemically Generated Reactive Chlorine Species: Products and Reaction Pathways
Author Kangwoo Cho, Michael R. Hoffmann*
Publication in journal Environmental Science & Technology
Status of publication accepted
Vol 48
Link https://pubs.acs.org/doi/abs/10.1021/es5025405 2410회 연결
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 (Ea) 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 Ea of +3.0 V than at +2.2 V, presumably because dichlorine radical (Cl2–·) ions facilitate the urea transformation primary driven by free chlorine. Quadrupole mass spectrometer analysis of the reactor headspace revealed that N2 and CO2 are the primary gaseous products of the oxidation of urea, whose urea-N was completely transformed into N2 (91%) and NO3– (9%). The higher reaction selectivity with respect to N2 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.