Dodecylbenzenesulphonic acid, compound with 2-amino-2-methylpropan-1-ol (1:1)

Adsorption / desorption

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Remarks:

the tested substance is the sodium salt of DDBSA one of the components of the compound

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other:

Remarks:

the substance tested is one of the dissociation products

Qualifier:

no guideline followed

Principles of method if other than guideline:

A sorption-isotherm and the kinetics of adsorption and desorption of LAS to activated sludge were determined in batch experiments. Three different biodegradation tests were also carried out (an OECD 301F ready biodegradation test; a batch activated sludge [BAS] test; and a ¿by-pass¿ test developed to mimic condition of the pilot scale activated sludge plant).

GLP compliance:

no

Type of method:

HPLC estimation method

Media:

other: pilot-scale municipal activated sludge

Radiolabelling:

no

Test temperature:

20 deg C

Details on study design: HPLC method:

The HPLC mobile phase consisted of a 16:85 (v/v) suprapur water/methanol mixture containing 12.3 g/L of sodium perchlorate. The HPLC column was operated at 20 deg C and a flow rate of 1ml/min. The column was preconditioned by rinsing with suprapur water for 45 min, followed by rinsing with mobile phase for another 45 min.

Analytical monitoring:

yes

Details on sampling:

At least every other day 24-h samples of 2.51 influent and 2.51 effluent were collected in PE bottles.

Details on test conditions:

The pilot-scale activated sludge plant consisted of a completely mixed aeration tank (490 L) and a secondary settler (280 L). The pH in the aeration tank was 7.2-7.4 which was controlled using automated NaOH and HCl. Total (sum of adsorbed and dissolved) LAS concentrations were determined using an HPLC method.

Type:

log Koc

Value:

3.21

Temp.:

20 °C

Remarks on result:

other: C12 LAS

Type:

Koc

Value:

2 360

Temp.:

20 °C

Remarks on result:

other: C12 LAS

Adsorption and desorption constants:

KP (sludge-water partition coefficient) = 3.21 g-1 VSS (correlation coefficient 0.991)

Validity criteria fulfilled:

yes

Remarks:

The log of the adsorption coefficient (KOC) of LAS-C12 was estimated to be log KOC = 3.21 which is equal to a KOC value of 2360

Conclusions:

The log of the adsorption coefficient (KOC) of LAS-C12 was estimated to be log KOC = 3.21 which is equal to a KOC value of 2360
Monitoring data showed consistently low LAS-C12 concentrations of 5–10 mg/L in the effluent of a pilotscale municipal activated sludge plant, irrespective of the influent concentration of LAS-C12 (2–12 mg/L) and of the sludge retent time(10 and 27 d). Sorption equilibrium was achieved rapidly, within 5-10 minutes. Desorption was less pronounced, but still reached rapid equilibration. The sludge-water partition coefficient Kp of 3,210 L/kg volatile suspended solids is reported.

Executive summary:

Monitoring data were collected in a pilot-scale municipal activated sludge plant to assess the fate of the C12-homologue of linear alkyl benzene sulfonate (LAS-C12). The pilot-plant was operated at influent LAS-C12 concentrations between 2 and 12 mg l(-1) and at sludge retention times of 10 and 27 days. Effluent and waste sludge concentrations varied between 5 and 10 microg l(-1) and between 37 and 69 microg g(-1) VSS, respectively. In the sludge samples only 2-8% was present as dissolved LAS-C12, whereas the remaining 92-98% was found to be adsorbed to the sludge. In spite of this high degree of sorption, more than 99% of the LAS-C12 load was removed by biodegradation, showing that not only the soluble fraction but also the adsorbed fraction of LAS-C12 is readily available for biodegradation. Sorption and biodegradation of LAS-C12 were also investigated separately. Sorption was an extremely fast and reversible process and could be described by a linear isotherm with a partition coefficient of 3.2 l g(-1) volatile suspended solids. From the results of biodegradation kinetic tests it was concluded that primary biodegradation of LAS-C12 cannot be described by a (growth) Monod model, but a secondary utilisation model should be used instead. The apparent affinity of the sludge to biodegrade LAS-C12 increased when the sludge was loaded with higher influent concentrations of LAS-C12.

Reference 2

Endpoint:

adsorption / desorption: screening

Type of information:

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

Adequacy of study:

weight of evidence

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
For detailed description see section 13

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
It is anticipated that the toxicity of the target substance is caused by its cation and anion. The compound is very well water soluble and therefore it can be expected that dissociation in aqueous solution is complete. The target substance is a UVCB. The amine is a mono-constituent substance, while DDBSA is considered a UVCB.
Thus, the source and the target substances share structural similarities with similar functional groups. Therefore, read-across from the existing environmental fate, ecotoxicity and toxicity studies on the source substances is considered an appropriate adaptation to the standard information requirements of Annex VII and VIII of the REACH Regulation for the target substance, in accordance with the provisions of Annex XI, 1.5 of the REACH Regulation.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Target: DDBSA AMP compound (Benzenesulfonic acid, dodecyl-, compd. with 1,1'-iminobis[2-propanol] (1:1), EC 614-005-6 /CAS 66989-21-7).
Source: DDBSA (4-C10-13 Alkylbenzene sulfonic acid, CAS 85536-14-7 EC 287-494-3)
AMP(2-amino-2-methylpropan-1-ol, CAS 124-68-5, EC 204-709-8)

3. ANALOGUE APPROACH JUSTIFICATION
Data on both dissociation products DDBSA and AMP are available. In a worst case approach it is assumed that the adsorption is determined by DDBSA, which leads to a logKoc of 3.2 based on a measured value.

4. DATA MATRIX
see section 13

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across: supporting information

Reason / purpose for cross-reference:

read-across: supporting information

Type:

log Koc

Value:

3.2 dimensionless

Remarks on result:

not measured/tested

Remarks:

based on read-across

Conclusions:

The logKoc of the substance is set at 3.2 based on read-across

Description of key information

Data on both dissociation products DDBSA and AMP are available. In a worst case approach it is assumed that the adsorption is determined by DDBSA, which leads to a logKoc of 3.4 based on a measured value.

Key value for chemical safety assessment

Koc at 20 °C:

2 360