Kinetics and mechanism of the reduction of monochloramine by hydroxylamine and hydroxylammonium ion

Abstract

The kinetics and mechanism by which monochloramine is reduced by hydroxylamine in aqueous solution over the pH range of 5-8 are reported. The reaction proceeds via two different mechanisms depending upon whether the hydroxylamine is protonated or unprotonated. When the hydroxylamine is protonated, the reaction stoichiometry is 1:1. The reaction stoichiometry becomes 3:1 (hydroxylamine:monochloramine) when the hydroxylamine is unprotonated. The principle products under both conditions are Cl -, NH + 4 , and N 2 O. The rate law is given byAt an ionic strength of 1.2 M, at 25 • C, and under pseudo-first-order conditions, k + = (1.03 ± 0.06) ×10 3 L · mol −1 · s −1 and k 0 = 91 ± 15 L · mol −1 · s −1 . Isotopic studies demonstrate that both nitrogen atoms in the N 2 O come from the NH 2 OH/NH 3 OH + . Activation parameters for the reaction determined at pH 5.1 and 8.0 at an ionic strength of 1.2 M were found to be H ‡ = 36 ± 3 kJ · mol -1 and S ‡ = −66 ± 9 J · K −1 · mol −1 , and H ‡ = 12 ± 2 kJ · mol −1 and S ‡ = −168 ± 6 J · K −1 · mol −1 , respectively, and confirm that the transition states are significantly different for the two reaction pathways. C 2005 Wiley Periodicals, Inc. Int J Chem Kinet 38: [124][125][126][127][128][129][130][131][132][133][134][135] 2006

Reducing Graphene Oxide via Hydroxylamine: A Simple and Efficient Route to Graphene

“…Hydroxylamine (NH 2 OH) and its chloride and sulfate salts are commonly used for reducing metal ions, such as Ag + , Au 3+ , Pd 2+ , and Cu 2+ et al, removing monochloramine, a harmful species in the chlorine-treated water, − and even in removing oxygen . Hydroxylamine has high reduction capability but weak reactivity with water and other solvents that make it an appropriate reductant for the GO reduction in aqueous suspension.…”

Hydroxylamine addition impact to Nitrosomonas europaea activity in the presence of monochloramine

“…1): (Pathway A) reaction with various cellular components, leading to N. europaea inactivation (Holder et al, 2013;Jacangelo and Olivier, 1985;Jacangelo et al, 1991Jacangelo et al, , 1987aJacangelo et al, , 1987bWahman et al, 2009); (Pathway B) biological transformation by N. europaea (Maestre et al, 2013) through cometabolism (the fortuitous biodegradation of a target chemical [i.e., monochloramine] through reactions catalyzed by nonspecific microbial enzymes [i.e., AMO]); (Pathway C) abiotic reaction with nitrite (Johnson and Margerum, 1991;Margerum et al, 1994;Wahman and Speitel, 2012); and (Pathway D) abiotic reaction with hydroxylamine (Aoki et al, 1989;Ferriol et al, 1986;Giles, 1999;Robinson et al, 2005;Wahman et al, 2014). The four monochloramine loss pathways provide N. europaea with both possible benefits and detriments.…”