US EPA

3808148 

Journal Article 

Water chlorination chemistry: Nonmetal redox kinetics of chloramine and nitrite ion 

Margerum, DW; Schurter, LM; Hobson, J; Moore, EE 

1994 

1 

Environmental Science & Technology
ISSN: 0013-936X
EISSN: 1520-5851 

BIOSIS/94/09234 

28 

2 

331-337 

English 

22176180 

10.1021/es00051a021 

WOS:A1994MV34700025 

BIOSIS COPYRIGHT: BIOL ABS. The first step in NH2Cl oxidation of NO2- is the general acid-assisted formation of nitryl chloride, where kHA is 7.6for H2PO4- (25.0 ?C, mu = 0.50 M). This is the rate-limiting step at very low (NH3)kappaHA and high (NO2-) concentrations: HA + NH2Cl + NO2- - A- + NH3 + NO2Cl, where the subsequent reactions of NO2Cl are rapid. Under conditions of higher (NH3) and lower (NO2-), the overall rate of loss of NH2Cl is suppressed, and a complex rate expression is observed. This rate dependence is derived from an analogous mechanism found for the reaction between OCl- and NO2-: (-d(NH2Cl))/dt = (k1'(1 + (k2/k4)(NO2-))(NO2-)(H+))/ ((k-1'/k4)(NH3)+(1+(k2/k4)(NO2-))). In this mechanism, NO2Cl forms reversibly in the first step (k1'/k-1) and either reacts with a second NO2- (k2) to give N2O4 or loses Cl(k4) to give NO2+; both N2O4 and NO2+ hydrolyze rapidly to give NO3-. The relative reaction rate of OCl- + H+ + NO2- is estimated to be 1.8um formation constant, Kf = (NH2Cl)/(NH3)