Quaternary ammonium compounds, C18-22 (even numbered) alkyltrimethyl, chlorides; Docosyltrimethylammonium chloride; C18-22 TMAC

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Study period:

From July 16, 2008 to October 24, 2008

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

KL2 due to RA

Justification for type of information:

Refer to the Quaternary ammonium salts (QAS) category or section 13 of IUCLID for details on the category justification. The study with the read across substance is considered sufficient to fulfil the information requirements as further explained in the provided endpoint summary.

Qualifier:

according to guideline

Guideline:

OECD Guideline 106 (Adsorption - Desorption Using a Batch Equilibrium Method)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Type of method:

batch equilibrium method

Media:

other: soil, sediment and sewage sludge

Radiolabelling:

yes

Test temperature:

20 ± 2°C

Analytical monitoring:

yes

Details on sampling:

Determination of adsorption equilibrium (kinetics experiment):
- Concentration: 1 mg/L
- Sampling interval: 3, 6, 24 and 48 h (adsorption), 3, 6, 24 and 48 h (desorption)

Determination of isotherms:
- Concentrations: 0.01 - 0.05 - 0.2 - 0.5 - 1 mg/L
- Sampling interval: 24 h (adsorption) and 24 h (desorption) for soils; 42 h (adsorption) and 6 h (desorption) for sediment and sludge

Details on matrix:

CRANFIELD 164 SOIL

COLLECTION AND STORAGE
- Geographic location: Farditch Farm, Chelmorton, Buxton, United Kingdom (OS map reference SK 1050269133)
- Storage conditions: refrigerated after receipt; ambient temperature after sieving/air drying
- Storage length: maximum 9 months
- Soil preparation: sieved (2 mm) and air dried

PROPERTIES
- Soil texture
- % sand: 20
- % silt: 52
- % clay: 28
- Horizon: 10-20 cm
- Soil classification system: silty clay loam (USDA)
- pH: 6.0
- Organic carbon (%): 3.7
- CEC (meq/100 g): 22.8
- Water holding capacity (%): 65.7


CRANFIELD 277 SOIL

COLLECTION AND STORAGE
- Geographic location: Posher Farm, Upton, Leamington Spa, Warwickshire, United Kingdom (OS map reference SP 3706562304)
- Storage conditions: Ambient temperature after receipt
- Storage length: maximum 9 months
- Soil preparation: sieved (2 mm) and air dried

PROPERTIES
- Soil texture
- % sand: 19
- % silt: 24
- % clay: 57
- Horizon: 0-20 cm
- Soil classification system: clay (USDA)
- pH: 7.4
- Organic carbon (%): 2.7
- CEC (meq/100 g): 22.4
- Water holding capacity (%): 66.6


CRANFIELD 299 SOIL

COLLECTION AND STORAGE
- Geographic location: Stoke Hill Farm, Erlestoke, Wiltshire, United Kingdom (OS map reference ST 9518952867)
- Storage conditions: Ambient temperature after receipt
- Storage length: maximum 9 months
- Soil preparation: sieved (2 mm) and air dried

PROPERTIES
- Soil texture
- % sand: 28
- % silt: 46
- % clay: 28
- Horizon: 3-20 cm
- Soil classification system: loam (USDA)
- pH: 7.6
- Organic carbon (%): 2.9
- CEC (meq/100 g): 14.9
- Water holding capacity (%): 62.1


SW SEDIMENT

- Location: Schoonrewoerdse Wiel, Leerdam, The Netherlands
- Details on collection: sediment was sampled from the upper layer (0-10 cm) from the middle of the pond (depth 8 m)
- Storage conditions: refrigerated after receipt; ambient temperature after sieving/air drying
- Textural classification (i.e. %sand/silt/clay): 44/31/25
- pH: 7.6
- Organic carbon (%): 6.2
- CEC (meq/100 g): 21.7


TILBURG SLUDGE

- Type of sludge: Mix of domestic and industrial waste water
- Source of sludge: Sewage treatment plant RWZI Tilburg-Noord, Tilburg, The Netherlands
- Oxygen status: aerobic
- Details on preparation: The sludge was allowed to settle at ambient temperature. The water layer was separated as much as possible from the precipitated sludge and discarded. The sludge was centrifuged (700 g, 5 min) and the supernatant was decanted. The sludge was frozen at -80°C and subjected to freeze-drying. After freeze-drying, the sludge was sieved over a 2 mm sieve and dried overnight in an oven at 103°C.
- Storage conditions: ambient temperature
- Textural classification (i.e. %sand/silt/clay): 2/39/59
- pH: 6.6
- Organic carbon (%): 37.5
- CEC (meq/100 g): 96.2

Details on test conditions:

- Type, size and further details on reaction vessel: 100 mL Erlenmeyer flasks
- Solution: 0.01 M CaCl2 solution (1.47 g calcium chloride dehydrate/L Milli-Q water)
- Amount of soil/sediment/sludge and water per treatment: 0.45 g soil/sediment/sludge and 45 mL and 0.01 M CaCl2 solution
- Soil/sediment/sludge-water ratio: 1:100
- Number of reaction vessels/concentration: 2
- Measuring equipment: LSC
- Are the residues from the adsorption phase used for desorption: yes

Computational methods:

The Freundlich adsorption and desorption isotherm parameters were calculated by fitting the Freundlich isotherm to the data. Optimisations were performed using the program ModelMaker (AP Benson, Wallingford, Oxfordshire, UK).

Key result

Sample No.:

#1

Type:

Koc

Value:

> 950 - < 516 000 L/kg

Key result

Sample No.:

#1

Type:

log Koc

Value:

> 3 - < 5.7 dimensionless

Adsorption and desorption constants:

See tables below

Recovery of test material:

At the end of the adsorption phase more than 97% of the applied activity was recovered; at the end of the desorption phase more than 94% of the applied activity was recovered .

Concentration of test substance at end of adsorption equilibration period:

Adsorption equilibrium was reached within 6 hours for soil and after 48 hours for sediment and sludge. The amount of C22-Trimethylammonium Chloride adsorbed to sediment and sludge was ca. 80% whereas >95% was adsorbed to soil.

Concentration of test substance at end of desorption equilibration period:

Desorption equilibrium was reached within 6 h for each test system. Less than 15% desorbed.

Test substance adsorption and desorption isotherms could be described by the Freundlich equation. Freundlich isotherm parameters are summarised in the tables below.

 

Freundlich adsorption isotherm parameters for test substance

Test system	KF^ads(L/kg)	KF,oc^ads(L/kg)	1/n	r^2	data points
Cranfield 164 soil	0.73 x 10^3	19.8 x 10^3	0.79	0.929	10
Cranfield 277 soil	13.9 x 10^3	516 x 10^3	1.09	0.956	10
Cranfield 299 soil	1.53 x 10^3	52.8 x 10^3	0.82	0.976	10
SW sediment	1.08 x 10^3	17.4 x 10^3	0.95	0.991	10
Tilburg sludge	0.36 x 10^3	0.95 x 10^3	1.03	0.938	9

 

Freundlich desorption isotherm parameters forC22-Trimethylammonium Chloride

Test system	KF^des(L/kg)	KF,oc^des(L/kg)	1/n	r^2	data points
Cranfield 164 soil	6.61 x 10^3	179 x 10^3	1.04	0.858	10
Cranfield 277 soil	2.41 x 10^3	89.3 x 10^3	0.85	0.971	10
Cranfield 299 soil	13.8 x 10^3	476 x 10^3	1.04	0.874	10
SW sediment	3.10 x 10^3	50.0 x 10^3	1.08	0.886	10
Tilburg sludge	4.04 x 10^3	10.8 x 10^3	1.05	0.951	10

 

Validity criteria fulfilled:

yes

Conclusions:

based on the results of the read across study, the soil adsorption coefficient (i.e., the Koc) values of the test substance is considered to range from >950 to <516 000 L/kg (or log Koc: > 3 - < 5.7); indicating moderate to very strong sorption potential.

Executive summary:

A study was conducted to determine the adsorption / desorption of the read across substance, C22 TMAC (active: 99.9%), using the batch equilibrium method, according to OECD Guideline 106, in compliance with GLP. The adsorption behaviour of read across substance was studied in three soils, one sediment and one sludge. The soils included a silty clay loam (i.e., Cranfield 164 soil), a clay (i.e., Cranfield 277 soil) and loam soil (i.e., Cranfield 299 soil). The sediment was taken from the Schoonrewoerdse wiel (SW sediment) and the sludge was from a wastewater treatment plant treating predominantly domestic wastewater (i.e., Tilburg sludge). Adsorption and desorption kinetics were determined at a nominal initial concentration of approximately 1 mg/L, followed by sampling at 3, 6, 24 and 48 h (adsorption), 3, 6, 24 and 48 h (desorption). The adsorption and desorption isotherms were determined over a concentration range from approximately 0.01 to 1 mg/L at 20±2°C in the dark on shaker at a 1:1000 test system: 0.01 M CaCl2 solution ratio. Sampling was done at 24 h (adsorption/desorption) for soils; 42 h (adsorption) and 6 h (desorption) for sediment and sludge. The adsorption equilibrium was reached within 6 h for soil and after 48 h for sediment and sludge. The amount of read across substance which adsorbed to sediment and sludge was ca. 80% whereas >95% was adsorbed to soil. The desorption equilibrium was reached within 6 h for each test system, and only less than 15% desorbed. More than 97 and 94% of the applied activity were receovered at the end of the adsorption and desorption phases respectively. The read across substance isotherms were described by the Freundlich equations. The KFocads values were determined to be 19800 L/kg (soil 1), 516000 L/kg (soil 2), 52800 L/kg (soil 3), 17400 L/kg (sediment) and 950 L/kg (sludge) (Brands, 2009). Under the study conditions, the soil adsorption coefficient (i.e., the Koc) values of the read across substance was determined to range from >950 to <516 000 L/kg (or log Koc: > 3 - < 5.7); indicating moderate to very strong sorption potential. Based on the results of the read across study, similar adsorption coefficient values can be expected to test substance, C18-22 TMAC.

Description of key information

Based on the results of the read across study, the soil adsorption coefficient (i.e., the Koc) values of the read across substance was determined to range from >950 to <516 000 L/kg (or log Koc: > 3 - < 5.7); indicating moderate to very strong sorption potential.

Key value for chemical safety assessment

Koc at 20 °C:

51 600

Additional information

A study was conducted to determine the adsorption / desorption of the read across substance, C22 TMAC (active: 99.9%), using the batch equilibrium method, according to OECD Guideline 106, in compliance with GLP. The adsorption behaviour of read across substance was studied in three soils, one sediment and one sludge. The soils included a silty clay loam (i.e., Cranfield 164 soil), a clay (i.e., Cranfield 277 soil) and loam soil (i.e., Cranfield 299 soil). The sediment was taken from the Schoonrewoerdse wiel (SW sediment) and the sludge was from a wastewater treatment plant treating predominantly domestic wastewater (i.e., Tilburg sludge). Adsorption and desorption kinetics were determined at a nominal initial concentration of approximately 1 mg/L, followed by sampling at 3, 6, 24 and 48 h (adsorption), 3, 6, 24 and 48 h (desorption). The adsorption and desorption isotherms were determined over a concentration range from approximately 0.01 to 1 mg/L at 20±2°C in the dark on shaker at a 1:1000 test system: 0.01 M CaCl2 solution ratio. Sampling was done at 24 h (adsorption/desorption) for soils; 42 h (adsorption) and 6 h (desorption) for sediment and sludge. The adsorption equilibrium was reached within 6 h for soil and after 48 h for sediment and sludge. The amount of read across substance which adsorbed to sediment and sludge was ca. 80% whereas >95% was adsorbed to soil. The desorption equilibrium was reached within 6 h for each test system, and only less than 15% desorbed. More than 97 and 94% of the applied activity were receovered at the end of the adsorption and desorption phases respectively. The read across substance isotherms were described by the Freundlich equations. The KFocads values were determined to be 19800 L/kg (soil 1), 516000 L/kg (soil 2), 52800 L/kg (soil 3), 17400 L/kg (sediment) and 950 L/kg (sludge) (Brands, 2009). Under the study conditions, the soil adsorption coefficient (i.e., the Koc) values of the read across substance was determined to range from >950 to <516 000 L/kg (or log Koc: > 3 - < 5.7); indicating moderate to very strong sorption potential. Based on the results of the read across study, similar adsorption coefficient values can be expected to test substance, C18-22 TMAC.

[LogKoc: 4.71]