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Environmental fate & pathways

Phototransformation in water

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phototransformation in water
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study meets generally accepted scientific principles
Cross-referenceopen allclose all
Reason / purpose for cross-reference:
reference to same study
Reason / purpose for cross-reference:
reference to other study

Data source

Reference Type:
Report date:

Materials and methods

Study type:
other: ozonolysis
Test guideline
no guideline followed
Principles of method if other than guideline:
Kinetic studies on ozonolysis and the photoinduced ozonolysis of aqueous solutions
GLP compliance:
not specified

Test material

Constituent 1
Chemical structure
Reference substance name:
Adipic acid
EC Number:
EC Name:
Adipic acid
Cas Number:
Molecular formula:
Hexanedioic acid
Test material form:
not specified
Details on test material:
Purity: 99%
Specific details on test material used for the study:
Details on properties of test surrogate or analogue material (migrated information):

Study design

not specified
Analytical method:
other: flow-cell coupled with FT-IR spectrometer... (see attached file)
Details on sampling:
The decay of ozone in excess dicarboxylic acid solutions was followed using UV spectrophotometry. Decay of ozone concentration was registrated immediately after the interruption of O3/O2 flow through the reaction solution. The dicarboxylic acid concentration decay was monitored using a flow-cell coupled with FT-IR spectrometer at constant ozone concentration.
Light source:
other: 100 W Hg arc lamp
Details on light source:
Details on test conditions:
Reference substance:
not specified
Dark controls:
not specified
Computational methods:

Results and discussion

Preliminary study:
Test performance:
Predicted environmental photolytic half-life:
Transformation products:
not measured
Details on results:
Results with reference substance:

Any other information on results incl. tables

The results of both methods (ozone decay versus carboxylic acid decay) agreed within +/- 5%. The measured ozonolysis rate constant for adipic acid in 0.1 mol/l aqueous solution is: 1.7 +/- 0.1 E-3 l/mol/sec The photoassisted ozonolysis rate constant is: 2.8 +/- 0.2 E-3 l/mol/sec (The rate constants had been corrected for the ozone-self-decomposition reactions) The results obtained indicate that ozonolysis and photoinduced photolysis are not significant removal pathways for adipic acid. The authors estimated the dicarboxylic acid aerosols "lifetime" in air, assuming an ozone mixing ratio of 100 ppbv, which is an upper limit for its summertime mid-latitude continental Northern Hemisphere values. For adipic acid ozonolysis a half-life of about 13,000 years is estimated.

Applicant's summary and conclusion

Validity criteria fulfilled:
not specified
Executive summary:

A liquid phase kinetic study on the ozonolysis and on the UV-induced ozonolysis of selected dicarboxylic acids, including adipic acid was performed.For adipic acid ozonolysis a half-life of about 13,000 years is estimated, indicating thatozonolysis and photoinduced ozonolysis are not significant removal pathways for adipic acid.

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