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Environmental fate & pathways

Phototransformation in air

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Reference
Endpoint:
phototransformation in air
Type of information:
(Q)SAR
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification
Justification for type of information:
QSAR prediction: Model considered valid by OECD
Qualifier:
no guideline required
Principles of method if other than guideline:
QSAR model, EPI Suite v 4.1/Aopwin v1.92
GLP compliance:
no
Remarks:
not applicable
Estimation method (if used):
PHOTOCHEMICAL REACTION WITH OH RADICALS - assumed reaction conditions used in model:
- Concentration of OH radicals:1.5E6 per cm3
- Temperature for which rate constant was calculated: 25C
- Computer programme: AOPWIN v1.92
Light source:
sunlight
Preliminary study:
Using the AOPWIN QSAR model, the photochemical degradation rate of Calcium dodecylbenzenesulphonate in the atmosphere is 32.4364 E-12 cm3/molecule-sec, with a resultant predicted half live of 3.957 Hrs ( 0.330 Days (12-hr day; 1.5E6 OH/cm3))
OVERALL OH Rate Constant = 32.4364 E-12 cm3/molecule-sec
HALF-LIFE = 0.330 Days (12-hr day; 1.5E6 OH/cm3)
HALF-LIFE = 3.957 Hrs

Reaction with:
OH radicals
Rate constant:
0 cm³ molecule-1 s-1
Transformation products:
no
Results with reference substance:
OVERALL OH Rate Constant = 32.4364 E-12 cm3/molecule-sec
HALF-LIFE = 0.330 Days (12-hr day; 1.5E6 OH/cm3)
HALF-LIFE = 3.957 Hrs




Hydrogen Abstraction      = 30.3647 E-12 cm3/molecule-sec

Reaction with N, S and -OH =  0.0000 E-12 cm3/molecule-sec

Addition to Triple Bonds  =  0.0000 E-12 cm3/molecule-sec

Addition to Olefinic Bonds =  0.0000 E-12 cm3/molecule-sec

**Addition to Aromatic Rings =  2.0717 E-12 cm3/molecule-sec

Addition to Fused Rings   =  0.0000 E-12 cm3/molecule-sec

 

  OVERALL OH Rate Constant = 32.4364 E-12 cm3/molecule-sec

  HALF-LIFE =    0.330 Days (12-hr day; 1.5E6 OH/cm3)

  HALF-LIFE =    3.957 Hrs

Validity criteria fulfilled:
yes
Remarks:
The photochemical degradation rate of Calcium dodecylbenzenesulphonate in the atmosphere is 32.4364 E-12 cm3/molecule-sec, with a resultant predicted half live of 3.957 Hrs ( 0.330 Days (12-hr day; 1.5E6 OH/cm3))
Conclusions:
Using the AOPWIN QSAR model, the photochemical degradation rate of Calcium dodecylbenzenesulphonate in the atmosphere is 32.4364 E-12 cm3/molecule-sec, with a resultant predicted half live of 3.957 Hrs ( 0.330 Days (12-hr day; 1.5E6 OH/cm3))
Executive summary:

Using the AOPWIN QSAR model, the photochemical degradation rate of Calcium dodecylbenzenesulphonate in the atmosphere is 32.4364 E-12 cm3/molecule-sec, with a resultant predicted half live of 3.957 Hrs ( 0.330 Days (12-hr day; 1.5E6 OH/cm3))

Description of key information

Using the AOPWIN QSAR model, the photochemical degradation rate of Calcium dodecylbenzenesulphonate in the atmosphere is 32.4364 E-12 cm3/molecule-sec, with a resultant predicted half live of 3.957 Hrs ( 0.330 Days (12-hr day; 1.5E6 OH/cm3))
If released to air, a vapor pressure of 4.18E-021 mm Hg at 25 deg C (4.18E-021 mm Hg   is equivalent to vapour pressure of 5.57E-019 Pa) indicates significant amounts of Calcium dodecylbenzenesulphonate are unlikely to be present in the atmosphere for photodegradation and therefore Calcium dodecylbenzenesulphonate is not expected to be susceptible to direct photolysis by sunlight.

Key value for chemical safety assessment

Half-life in air:
0.33 d
Degradation rate constant with OH radicals:
0 cm³ molecule-1 s-1

Additional information

Using the AOPWIN QSAR model, the photochemical degradation rate of Calcium dodecylbenzenesulphonate in the atmosphere is 32.4364 E-12 cm3/molecule-sec, with a resultant predicted half live of 3.957 Hrs ( 0.330 Days (12-hr day; 1.5E6 OH/cm3))

  OVERALL OH Rate Constant = 32.4364 E-12 cm3/molecule-sec

  HALF-LIFE =    0.330 Days (12-hr day; 1.5E6 OH/cm3)

  HALF-LIFE =    3.957 Hrs

   

Calcium dodecylbenzenesulphonate has low vapor pressure (5.57E-019at 25C) indicating significant amounts of Calcium dodecylbenzenesulphonate are unlikely to be present in the atmosphere for photodegradation.

The estimated half-life is about 3.957 hours (32.4364 E-12 cm3/molecule-sec) with the AOPWIN (US EPA, 2011).

If released to air, a vapor pressure of 4.18E-021 mm Hg at 25 deg C (4.18E-021 mm Hg   is equivalent to vapour pressure of 5.57E-019 Pa) indicates significant amounts of Calcium dodecylbenzenesulphonate are unlikely to be present in the atmosphere for photodegradation and therefore Calcium dodecylbenzenesulphonate is not expected to be susceptible to direct photolysis by sunlight.

 

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