Kinetics of nitrogen tribromide decomposition in aqueous solution

Abstract

AIC600473Tribromamine decomposes to give nitrogen gas and hypobromous acid accordng to the overall reaction 2NBr3 + 3 0 H --N2 + 3Br-+ 3HOBr. Decomposition rates were measured over the p H range 6.00 f 0.05 to 8.00 i 0.05 for initial bromine to ammonia molar ratios between 4.00 and 12.0. The experimental rate law was found to be -d[NBr3]/dt = k,[NBr3]2[OH-]/[HOBr] + kb[NBr?]*, where k, = 1.07 X lo4 and kb = 0.34 I./(mol s) a t 20 "C. The first term in the rate equation is consistent with a mechanism in which the rate-determining step is preceded by equilibria among NBr3, NHBrz, HOBr, NBr2-, and OH-. Hydroxide may attack either NBr3 or NHBrz to produce NBr2-which subsequently reacts with NBr3. The second term is a simple second-order alternate pathway, occurring in acid solutions.

Equilibria and Speciation of Chloramines, Bromamines, and Bromochloramines in Water

“…The presence of naturally occurring bromide in fresh waters can potentially lead to the production of hypobromous acid, bromamines, and bromochloramines, during chlorination, chloramination, or ozonation of natural waters. ,,,,,,,− During oxidative treatment of natural water, bromide can react with hypochlorous acid to produce HOBr, , which can subsequently brominate ammonia and substituted amines, thereby producing bromamines (eqs –). These species can then further react rapidly to form dibromamine, tribromamine, and bromochloramines (eqs –). ,,,,, Bromamines and bromochloramines can lead to the production of potentially toxic DBPs in water as well. − For example, NHBr 2 and NHBrCl are thought to be involved in the production of NDMA , and of CNBr , during water disinfection.…”

“…Aqueous chloramines, bromamines, and bromochloramines, collectively termed halamines in the present work, typically arise from the N -substitution reactions of hypohalous acids with ammonia: − where X is either Cl or Br. Dichloramine, ,,, dibromamine, ,, and bromochloramine can also form by disproportionation reactions.…”

Kinetic model for predicting the concentrations of active halogens species in chlorinated saline cooling waters. Final report

“…• EQ. 1) GO TO 600 IRIT'P (6,71). XB,Y(IJ) ,1(1ll) ,Y(15},I(16) ,Y(1) ,Y(2) ,1(3) ,Y(18) ,1(12), 1 y(7) , y ( 8) , y ( 17) , y(5) "y (23) 71 PORIUT(P7.1,1P14E9.2) RB (1) =Y (6) JU: (1 ) :: y (9) Rf.I ( 1) ::y (13) RB2 (CONVERT TO PPR, WRITB INITIAL CORCEITRlTIOIS, ARD STORE RBIUIRIRG VALU!S.…”

Benchmark thermochemistry of chloramines, bromamines, and bromochloramines: halogen oxidants stabilized by electron correlation

“…[3][4][5]12 Operationally, these reactions are largely controlled by the ratio of chlorine to ammonia nitrogen, pH, temperature, and the presence of natural acid catalysts as phosphate, sulfate, and carbonate. [14][15][16][17][18][19][20][21][22] During disinfection treatment, bromide can become oxidized to hypobromous acid/hypobromite, contributing to the formation of bromamines and bromochloramines in water. [14][15][16][17][18][19][20][21][22] During disinfection treatment, bromide can become oxidized to hypobromous acid/hypobromite, contributing to the formation of bromamines and bromochloramines in water.…”

“…11,13 Bromamines and bromochloramines may arise as well, in bromine-containing waters. [14][15][16][17][18][19][20][21][22] During disinfection treatment, bromide can become oxidized to hypobromous acid/hypobromite, contributing to the formation of bromamines and bromochloramines in water. 23 The role of bromide in monochloramine decay was considered in the kinetic model provided by Vikesland et al 13 Lei et al reported on the formation kinetics of bromamines, 24 and Luh and Marin ˜as recently investigated the formation kinetics of bromochloramines, providing more information on their aqueous chemistry.…”