Kinetics and Mechanism of Peroxymonocarbonate Formation

Abstract

The kinetics and mechanism of peroxymonocarbonate (HCO(4)(-)) formation in the reaction of hydrogen peroxide with bicarbonate have been investigated for the pH 6-9 range. A double pH jump method was used in which (13)C-labeled bicarbonate solutions are first acidified to produce (13)CO(2) and then brought to higher pH values by addition of base in the presence of hydrogen peroxide. The time evolution of the (13)C NMR spectrum was used to establish the competitive formation and subsequent equilibration of bicarbonate and peroxymonocarbonate following the second pH jump. Kinetic simulations are consistent with a mechanism for the bicarbonate reaction with peroxide in which the initial formation of CO(2) via dehydration of bicarbonate is followed by reaction of CO(2) with H(2)O(2) (perhydration) and its conjugate base HOO(-) (base-catalyzed perhydration). The rate of peroxymonocarbonate formation from bicarbonate increases with decreasing pH because of the increased availability of CO(2) as an intermediate. The selectivity for formation of HCO(4)(-) relative to the hydration product HCO(3)(-) increases with increasing pH as a consequence of the HOO(-) pathway and the slower overall equilibration rate, and this pH dependence allows estimation of rate constants for the reaction of CO(2) with H(2)O(2) and HOO(-) at 25 °C (2 × 10(-2) M(-1) s(-1) and 280 M(-1) s(-1), respectively). The contributions of the HOO(-) and H(2)O(2) pathways are comparable at pH 8. In contrast to the perhydration of many other common inorganic and organic acids, the facile nature of the CO(2)/HCO(3)(-) equilibrium and relatively high equilibrium availability of the acid anhydride (CO(2)) at neutral pH allows for rapid formation of the peroxymonocarbonate ion without strong acid catalysis. Formation of peroxymonocarbonate by the reaction of HCO(3)(-) with H(2)O(2) is significantly accelerated by carbonic anhydrase and the model complex [Zn(II)L(H(2)O)](2+) (L = 1,4,7,10-tetraazacyclododecane).

Controlled leaching with prolonged activity for Co–LDH supported catalyst during treatment of organic dyes using bicarbonate activation of hydrogen peroxide

“…Sodium bicarbonate predominantly exists in aquatic environment as well as in biological fluid in the range of 14.7-25 mM regulating pH and enzymatic activity [8,9]. In addition, bicarbonate has also been reported to activate H 2 O 2 and its activation mechanism has been studied for different compounds [10][11][12][13]. Recently bicarbonate activation of hydrogen peroxide (BAP) is reported for various organic pollutants and dyes directly with redox metals [14][15][16], even these practices clearly caused heavy metal pollution.…”

The Biological Buffer Bicarbonate/CO2 Potentiates H2O2-Mediated Inactivation of Protein Tyrosine Phosphatases

“…H 2 O 2 reacts with bicarbonate/CO 2 to generate the highly reactive oxidant, peroxymonocarbonate (Figure 1a). 15-17 This process may be catalyzed by thiols and sulfides. 15-17 Peroxymonocarbonate is an acyl peroxide 18 and based upon our recent studies of organic acyl peroxides 13 we anticipated that this species might be a potent PTP inactivator.…”

Heterogeneous Catalytic Oxidation of Methyl Orange Dye by Copper(II)–Benzoic Acid Complex/NaHCO₃/H₂O₂ System

“…(7)), which speeds up the MO dye degradation (Eqs. (3)- (6)) (Bakhmutova-Albert et al, 2010). On the other hand, when the NaHCO 3 concentration was more than 10 mM, the degradation rate of MO was found to be decreased.…”

“…It has been verified that MO could be rapidly degraded by the CuBA/ NaHCO 3 /H 2 O 2 system in a heterogeneous process under neutral and alkalic conditions. The possible mechanism of activating H 2 O 2 with NaHCO 3 has been described Yao and Richardson, 2000;Regino and Richardson, 2007;Balagam and Richardson, 2008;Bakhmutova-Albert et al, 2010), as shown in Eqs. (1) (1)- (5)), and subsequently oxidizes MO to degradation product (Eq.…”