Calcium dodecylbenzenesulphonate

Phototransformation in water

Link to relevant study record(s)

Reference

Endpoint:

phototransformation in water

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

Sodium dodecylbenzenesulfonate (CAS# 25155-30-0 , EC Number; 246-680-4 ) is a very close analogue of Calcium dodecylbenzenesulfonate (CAS No 26264-06-2, EC Number; 247-557-8) ) and read-across is valid.

Reason / purpose for cross-reference:

read-across source

Study type:

indirect photolysis

Qualifier:

no guideline followed

Principles of method if other than guideline:

A study was conducted to determine the photodegradation of LAS in aqueous TiO2 dispersions. Experiments were carried out with 25 mL solutions containing LAS surfactant with TiO2. Some experiments used open vessels (37 mL Pyrex glass reaction vessels) under aerobic conditions. Others used vessels sealed with a rubber septum, the solution purged with argon and a fixed volume of oxygen injected. Spectrophotometric analysis was performed at regular intervals.

GLP compliance:

not specified

Radiolabelling:

not specified

Light source:

Xenon lamp

Light spectrum: wavelength in nm:

> 330

Details on light source:

Xe lamp (450W)

Type of sensitiser:

other: aqueous solution with TiO2 particles

Concentration of sensitiser:

50 mg/L

Details on test conditions:

- Sensitizer : TiO2 suspension- Temperature : 25 deg C; during photolysis the solution temperature 35-40 deg C- Con. of subst : 50 ppm

Preliminary study:

Dodecylbenzene sulfonate is quickly decomposed when an aqueous solution of this compound is irradiated with light (λ> 330 nm) in the presence of TiO2 particles. The reaction proceeds in two steps: the decomposition of the aromatic ring occurs rapidly and is followed by oxidation of the alkyl chain. The adsorption of the surfactant on the surface of TiO2 makes the first step particularly effective even in the absence of catalysts such as noble metals. The application of this process in the detoxification of polluted waters is discussed

Details on results:

After 30 minutes the DBS have been decomposed and removal of the DBS absorption is complete after 2 hours of the light exposure.Rapid photodegradation (within 2 hours of light exposure) .Rapid (<1-2 hours) decomposition

Validity criteria fulfilled:

yes

Conclusions:

Rapid (<1-2 hours) decomposition. Dodecylbenzene sulfonate is rapidly photodegraded in aqueous aerated TiO2 suspensions. The reaction involves fast decomposition of the aromatic ring followed by slower oxidation of the aliphatic chain.

Executive summary:

Dodecylbenzene sulfonate is quickly decomposed when an aqueous solution of this compound is irradiated with light (λ> 330 nm) in the presence of TiO2 particles. The reaction proceeds in two steps: the decomposition of the aromatic ring occurs rapidly and is followed by oxidation of the alkyl chain. The adsorption of the surfactant on the surface of TiO2 makes the first step particularly effective even in the absence of catalysts such as noble metals. The application of this process in the detoxification of polluted waters is discussed

Description of key information

After 30 minutes the Sodium dodecylbenzenesulfonate (DBS) have been decomposed and removal of the DBS absorption is complete after 2 hours of the light exposure.Rapid photodegradation (within 2 hours of light exposure) .Sodium dodecylbenzenesulfonate (CAS# 25155-30-0 , EC Number; 246-680-4 ) is a very close analogue of Calcium dodecylbenzenesulfonate (CAS No 26264-06-2,  EC Number; 247-557-8) ) and  read-across is valid.
Dodecylbenzene sulfonate is rapidly photodegraded in aqueous aerated TiO2 suspensions. The reaction involves fast decomposition of the aromatic ring followed by slower oxidation of the aliphatic chain. 

Key value for chemical safety assessment

Half-life in water:

2 h

Additional information

Data are available on the photodegradation of Na-C12 LAS in water.

Sodium dodecylbenzenesulfonate (CAS# 25155-30-0 , EC Number; 246-680-4 ) is a very close analogue of Calcium dodecylbenzenesulfonate (CAS No 26264-06-2, EC Number; 247-557-8) ) and read-across is valid.

The results are as follows:

Table   Photodegradations of Na-C12 LAS

Light source	Light spectrum	Test material	Result	References
Xe lamp	>330 nm	Sodium dodecylbenzenesulfonate	Rapid (<1-2 hours) decomposition	Hidakaet al., 1985
Mercury vapor lamp	200-350 nm	Sodium dodecylbenzenesulfonate	>95% photolytic degradation after 20 minutes	Matsuura and Smith, 1970
Mercury lamp	400-580 nm	Sodium dodecylbenzenesulfonate	The presence of humic substances delayed the photodegradation	Hermannet al., 1997