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Reaction Kinetics of Carbon Dioxide (CO 2 ) Absorption in Sodium Salts of Taurine and Proline Using a Stopped‐Flow Technique
Author(s) -
Sodiq Ahmed,
Rayer Aravind V.,
Olanrewaju Akinola A.,
Abu Zahra Mohammad R. M.
Publication year - 2014
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.20882
Subject(s) - zwitterion , chemistry , deprotonation , aqueous solution , reaction rate constant , reaction rate , sodium , inorganic chemistry , order of reaction , reactivity (psychology) , protonation , kinetics , organic chemistry , catalysis , molecule , medicine , ion , physics , alternative medicine , pathology , quantum mechanics
The pseudo–first‐order reaction rate constants ( k 0 , s −1 ) for the reaction of carbon dioxide in aqueous solutions of sodium taurate (NaTau) and sodium prolinate (NaPr) were measured using a stopped‐flow technique at a temperature range of 298–313 K. The solutions concentration varied from 5 to 50 mol m −3 and from 4 to 12 mol m −3 for NaTau and NaPr, respectively. Comparing the k 0 values, aqueous NaPr was found to react very fast with CO 2 as compared with the industrial standard aqueous monoethanolamine (MEA) and aqueous sodium taurate (NaTau) was found to react slower than aqueous MEA at the concentration range considered in this work. For the studied amino acid salts, the order of the reactions was found to be unity with respect to the amino acid salt concentration. Proposed reaction mechanisms such as termolecular and zwitterion reaction mechanisms for the reaction of CO 2 with aqueous solutions were used for calculating the second‐order reaction rate constants ( k 2 , m 3 mol −1 s −1 ). The formation of zwitterion during the reaction with CO 2 was found to be the rate‐determining step, and the deprotonation of zwitterion was instantaneous compared to the reverse reaction of zwitterion to form an amino acid salt. The contribution of water was established to be significant for the deprotonation of zwitterion. Comparing the pseudo–first‐order reaction rate constants ( k 0 , s −1 ) of various amino acid salts with CO 2 , NaPr was found to be the faster reacting amino acid salt. The activation energy for NaTau was found to be 48.1 kJ mol −1 and that of the NaPr was found to be 12 kJ mol −1 . The Arrhenius expressions for the reaction between CO 2 and the studied amino acid salts areForNaTau :k 2 Z 3(m 3mol− 1s − 1) = 5.44 × 10 8 * exp− 5779.6 TForNaPr :k 2 Z 3(m 3mol− 1s − 1) = 5.28 × 10 2 * exp− 1440.1 T