Chemical behavior of iodine in aqueous solutions up to 150/sup 0/C. I. An experimental study of nonredox conditions
The chemical behavior of iodine, I/sub 2/, in (pH = 6 to 10) aqueous solutions containing 2500 ppM boron as H/sub 3/BO/sub 3/ (0.231 M) was studied at temperatures up to 150/sup 0/C. Absorption spectrophotometry was used to identify and monitor the iodine species present. The I/sub 2/ hydrolysis chemistry was found to be consistent with the two-stage mechanism: I/sub 2/ + H/sub 2/O reversible HOI + H/sup +/ + I/sup -/, 3 HOI reversible IO/sub 3//sup -/ + 2I/sup -/ + 3H/sup +/, where the intermediate species is designated as HOI to emphasize that its exact structure and composition are not defined. Three objectives were considered: (1) species identification, with special attention given to HOI; (2) the kinetics of reaction between iodine and water to produce iodide and iodate ions; and (3) partition coefficients between liquid and vapor phases for individual iodine species. Kinetic rate constants for the disproportionation of the HOI intermediate were measured. A typical activation energy for this reaction was found to be 28.4 kJ/mol (6.8 kcal/mol). Although some initial results had suggested an ionic strength dependency, a more detailed examination of the ionic strength effect on this disproportionation reaction suggests that the intermediate in solution throughout the pH 7 to 10 range is primarily an uncharged species such as the triatomic HOI. No absorption bands can be assigned to the HOI intermediate even though it has been shown, in some cases, to be present at concentrations of greater than or equal to 1 x 10/sup -3/ M. A very low molar absorptivity (< 10 M/sup -1/ cm/sup -1/) is probably responsible for its undetectability. A partition coefficient of > 1 x 10/sup 4/ has been estimated for HOI.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 7119586
- Report Number(s):
- NUREG/CR-3514; ORNL/TM-8664; ON: DE84010344
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400201* -- Chemical & Physicochemical Properties
AQUEOUS SOLUTIONS
BORIC ACID
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
DECOMPOSITION
DISPERSIONS
ELEMENTS
HALOGENS
HIGH TEMPERATURE
HYDROGEN COMPOUNDS
HYDROLYSIS
INORGANIC ACIDS
IODINE
KINETICS
LYSIS
MIXTURES
NONMETALS
PH VALUE
REACTION KINETICS
SOLUTIONS
SOLVOLYSIS
TEMPERATURE DEPENDENCE