Rate Constants for the Reaction of e^- _aq with EDTA and Some Metal EDTA-Complexes

Abstract

The rate constants for the reaction e^ + EDTA were measured as a function of the pH by the pulse-radiolysis technique. Between pH = 6 and pH = 10 this rate constant can be represented by the equation k = 4.7 X 10 e X (fraction of HEDTA 3 ") + 1.0 X 10* X (fraction Hj EDTA 2 ~)M~1 s" 1 . Also the rate constants for reactions of e^j with the following metal-EDTA complexes were measured: CuEDTA 2 -, HgEDTA 2 CoEDTA 2 ", InEDTA", NiEDTA 2 GaEDTA", MnEDTA 2 ZnEDTA 2 -, CdEDTA 2 PbEDTA 2 -. Ionic strength variation indicates that the reacting ions are not hydrolized to an appreciable amount at pH = 11.5. It is found that some of the products show light absorption in the region between 300 and 400 nm.

Studies on radiation synthesis of PVA/EDTA hydrogels

“…The OH attack on EDTA is the most important reaction, whereas H and e aq À are mostly involved in radical-radical reaction . The rate constants are k OH ¼ 2 Â 10 9 dm 3 mol À1 s À1 at pH ¼ 9 (Buxton et al, 1988) and k e ¼ 4:7 Â 10 6 dm 3 mol À1 s À1 at pH ¼ 10 ( Buitenhuis et al, 1977). The main decomposition products observed under g-irradiation are CO 2 , followed by N,N 0 -methylacetylethylenediamine and N-hydroxymethliminodiacetic acid.…”

Radiation chemistry of synthetic waste

“…The reactivity of ejg toward EDTA 4 -is rather low (k = 4 x 105 M-1 s-1 at pH 11.5 and ionic strength 1.6). (53) Because there is a correlation between the rate constant for the eiq reaction and the reactivity transfer from the CO2 or the amino groups, and an H abstraction from the ethylene groups. However, it was postulated that the carboxy radical (-CO2) is produced only in negligible amounts, whereas the other two radicals are converted to the a-carboxy radical.…”

Radiation removal of lead and cadmium complexed with ethylenediamine tetraacetic ACID from aqueous solutions

“…Attacks of OH radicals on this acid proceeds with high rate constant achieving values on the order of 10 9 dm 3 mol -1 s -1 in a weak acidic environment [3,4]. On the other hand, it has been found [5] that the rate constants for reactions of solvated electrons, eaq , with some EDTA complexed metal ions may reach the same values in a strong basic environment depending on the ionic strength of the solution. In the pH range from 6 to 10, the rate constant of the eaq reaction with EDTA decreases from 5×10 7 to 3×10 6 dm 3 mol -1 s -1 .…”