Carbon dioxide pseudo-first-order

Emmert and Pigford (E2) have studied the reaction between carbon dioxide and aqueous solutions of monoethanolamine (MEA) and report that the reaction rate constant is 5400 liter/mole sec at 25°C. If it is assumed that MEA is present in excess, the reaction may be treated as pseudo first-order. This pseudo first-order reaction has been recently used by Johnson et al. (J4) to study the rate of absorption from single carbon dioxide bubbles under forced convection conditions, and the results were compared with their theoretical model. 

Pyruvic acid is an intermediate in the fermentation of grains. During fermentation the enzyme pyruvate carboxylase causes the pyruvate ion to release carbon dioxide. In one experiment a 200.-mL aqueous solution of the pyruvate in a sealed, rigid 500.-mL flask at 293 K had an initial concentration of 3.23 mmol-L -l. Because the concentration of the enzyme was kept constant, the reaction was pseudo-first order in pyruvate ion. The elimination of CU2 by the reaction was monitored by measuring the partial pressure of the C02 gas. The pressure of the gas was found to rise from zero to 100. Pa in 522 s. What is the rate constant of the pseudo-first order reaction ... 

Absorption rates of carbon dioxide were measured in organic solutions of glycidyl methacrylate at 101.3 kPa to obtain the reaction kinetics between carbon dioxide and glycidyl methacrylate using tricaprylylmethylammonium chloride(Aliquat 336) as catalysts. The reaction rate constants were estimated by the mass transfer mechanism accompanied by the pseudo-first-order fast reaction. An empirical correlation between the reaction rate constants and the solubility parameters of solvents, such as toluene, A-methyl-2-pirrolidinone, and dimethyl sulfoxide was presented. 

In this study, the absorption rates of carbon dioxide into the solution of GMA and Aliquat 336 in such organic solvents as toluene, N-methyl-2-pirrolidinone(NMP), and dimethyl sulfoxide(DMSO) was measured to determine the pseudo-first-order reaction constant, which was used to obtain the elementary reaction rate constants. 

The overall reaction between CO2 and GMA was assumed to consist of two elementary reactions such as a reversible reaction of GMA and catalyst to form an intermediate and an irreversible reaction of this intermediate and carbon dioxide to form five-membered cyclic carbonate. Absorption data for CO2 in the solution at 101.3 N/m were interpreted to obtain pseudo-first-order reaction rate constant, which was used to obtain the elementary reaction rate constants. The effects of the solubility parameter of solvent on lc2/k and IC3 were explained using the solvent polarity. 

Note first of all that the concentration of the OH ion, 0.5M assuming complete dissociation, will be very much greater than the concentration of the carbon dioxide in the solution. The reaction can therefore be treated as a pseudo first order reaction with a rate constant ... 

Dynamics of the Reaction Network. Information on the concentration changes of 4-chlorophenol and its intermediates (4-chlorocatechol, 4-chlororesorcinol, hydroquinone, and hydroxyhydroquinone) allows us to perform some dynamic analysis of the photocatalytic oxidation of 4-chlorophenol. Scheme IV shows a reaction network that can be established to describe the overall mineralization of 4-chlorophenol. According to this reaction network, 4-chlorophenol (4-CP) first decomposes to 4-chlororesorcinol (4-CRE), 4-chlorocatechol (4-CCA), or hydroquinone (HQ) 4-chlorocatechol is the major primary product. Further oxidation of the primary intermediates yields hydroxyhydroquinone (HHQ), as the secondary intermediate, which is readily mineralized to carbon dioxide. For simplicity, a pseudo-first-order expression was used to model the dynamics of the reaction network (eqs 9-14). 

Most reactions that have been investigated using PTC in supercritical fluids have been solid-SCF systems, not liquid-SCF. The first published example of PTC in an SCF is the displacement reaction of benzyl chloride 1 with potassium bromide in supercritical carbon dioxide (SCCO2) with 5 mol % acetone, in the presence of tetraheptylammonium bromide (THAB) [19-20] (Scheme 4.10-1) to yield benzyl bromide 2. The effects on reaction rate of traditional PTC parameters, such as agitation, catalyst type, temperature, pressure, and catalyst concentration were investigated. The experimental technique is described below. PTC appeared to occur between an SCF phase and a solid salt phase, and in the absence of a catalyst the reaction did not occur. With an excess of inorganic salt, the reaction was shown to follow pseudo-first order kinetics. 

The experimental results of this work were analysed using the theory of mass transfer with chemical reaction. The data presented in this work have been obtained at conditions where the mathematical treatment of the problem was simplified assuming a pseudo-first-order assumption for kinetics. In this case, the concentration of the amine across the cross section of the liqitid boundary layer was assumed to be uniform. Thus, transforming the second-order reaction expression of carbon dioxide with amine into an approximated first-order expression. Hence, For piperazine ... 

The enzyme urease catalyzes the reaction in which urea is hydrolyzed to ammonia and carbon dioxide. The half-life of urea in the pseudo-first-order reaction for a certain amount of urease doubles when the temperature is lowered from 20°C to 10°C and the equilibrium constant for binding of urea to the enzyme is largely unchanged. What is the activation energy of the reaction ... 

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