1-ethyl-1-methylpyrrolidinium bromide

Adsorption / desorption

Link to relevant study record(s)

Reference

Endpoint:

adsorption / desorption: screening

Type of information:

experimental study

Adequacy of study:

key study

Study period:

October 2016-February 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

under GLP

Qualifier:

according to guideline

Guideline:

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

GLP compliance:

yes (incl. QA statement)

Type of method:

batch equilibrium method

Specific details on test material used for the study:

Test substance name MEP
Chemical Name N-ethyl-N-methylpyrrolidinium bromide
CAS No. 69227-51-6
Molecular formula C7H16NBr
Formula weight 194.11
Physicochemical property
Appearance Colorless liquid
Solubility in water Soluble in water
Supplied by Bromine compounds Ltd.
Batch No. W5-03
Content 65.3%
Effective date 2019-08

Radiolabelling:

no

Test temperature:

During the test, the temperature of the incubator was setted as 25°C, and the actual range is 24.6~24.8°C

Analytical monitoring:

yes

Details on sampling:

Tier 1:
Analysis was done after 2,6,10 and 24h. According to the test trail at teh beginning, the test sample was stable during the test period. For the control group only 24 h sample taken. For the blank group only highest presentage of soil and water of each kind of soil was set which was 1:2.5 the sample was taken at 24h.
Tier 2:
the sampling time point per soil was kept along the preliminary study which was setted as 1, 2, 8 20 and 24h. the soil suspensions were centrifuged and the aqueous solution was analysied after tretment.
Tier 3:
The aqueous phase was analysed only once at the time to reach equilibrium of 24h in the desorption phase.

Matrix no.:

#1

Matrix type:

sandy clay loam

% Clay:

21

% Org. carbon:

7.3

pH:

4.71

CEC:

10 other: cmol(+)/kg)

Matrix no.:

#2

Matrix type:

clay loam

% Clay:

17

% Org. carbon:

34.5

pH:

6.14

CEC:

31 other: cmol(+)/kg

Matrix no.:

#3

Matrix type:

loamy sand

% Clay:

13

% Org. carbon:

10

pH:

6.8

CEC:

21.6 other: cmol(+)/kg

Matrix no.:

#4

Matrix type:

silt loam

% Clay:

13

% Org. carbon:

13

pH:

8.15

CEC:

12.8 other: cmol(+)/kg

Matrix no.:

#5

Matrix type:

silty clay loam

% Clay:

17

% Org. carbon:

12.7

pH:

8.61

CEC:

13.8 other: cmol(+)/kg

Details on matrix:

#1 Jiangxi red soil
#2 Heilongjiang black soil
#3 Liaoning brown soil
#4 Henan yellow fluvo-aquic soil
#5 Xinjiang ash soil


COLLECTION AND STORAGE
- Geographic location: The selected five representative soils were from different places of South and North China
- Collection procedures:
- Sampling depth (cm):
- Storage conditions:
- Storage length:
- Soil preparation (e.g.: 2 mm sieved; air dried etc.):

Details on test conditions:

TEST SYSTEM
- Type, size and further details on reaction vessel:Glass flasks 150 mL
- Water filtered (i.e. yes/no; type of size of filter used, if any):The water for preparing medium and solution was made by the Water Purifier (Elix70/Advantage A10).
- Soil/sediment/sludge-water ratio (if simulation test): 1:5
- Number of reaction vessels/concentration:Five test substance concentrations were used as 0.5, 1, 5, 10 and 50 mg/L and, two replicants per concentration,
- Measuring equipment:
Name Model Manufacturer
Electronic balance PL403 Mettler
Electronic balance AL204 Mettler
Analytical balance XS105DU Mettler
Moisture analyzer HG63-P Mettler

Refrigeration air bath
constant
temperature oscillator HZQ-QA Jintan Ruihua

High speed
refrigerated centrifuge Allegra X-22R BECKMAN

Ultrasonic cleaning
instrument SB 25-T2DT Ningbo Xinzhi

Ultrasonic cleaning
instrument SK8200H Shanghai Kedao

Multi-parameter meter HQ40d HACH

Liquid chromatography /
mass spectrometry TQ MS Waters

- Test performed in open system: yes
- Method of preparation of test solution:The test substance stock solutions were prepared three times during the test.
The first time, certain quantity of 0.7663 g test substance was weighed and dissolved into the 0.01mol/L CaCl2 to 1000 mL to make the concentration 500 mg/L of the stock solution;
The second time, certain quantity of 0.7661 g test substance was weighed and dissolved into the 0.01mol/L CaCl2 to 1000 mL to make the concentration 500 mg/L of the stock solution;
The third time, certain quantity of 0.7663 g test substance was weighed and dissolved into the 0.01mol/L CaCl2 to 1000 mL to make the concentration 500 mg/L of the stock solution; then, other test solutions were prepared by diluting the stock solution with 0.01 mol/L CaCl2 respectively
- Are the residues from the adsorption phase used for desorption: yes, When the mixtures of the soil with the solution were agitating to reach adsorption equilibrium for 24h in the adsorption isotherms, the phases were separated by centrifugation and the aqueous phases were removed as much as possible. The volume of solution removed was replaced by an equal volume of 0.01 mol/L CaCl2 without test substance and the new mixtures were agitated again.
- other:The soil suspensions were separated by centrifugation with the speed 4000rpm, and the duration was 3 min.

Sample No.:

#1

Duration:

24 h

Initial conc. measured:

>= 23.5 - <= 23.8 other: mg/L

pH:

3.88

Temp.:

>= 24.6 - <= 24.8 °C

Sample No.:

#2

Duration:

24 h

Initial conc. measured:

24.6 other: mg/L

pH:

5.69

Temp.:

>= 24.6 - <= 24.8 °C

Sample No.:

#3

Duration:

24 h

Initial conc. measured:

>= 15.2 - <= 15.4 other: mg/L

pH:

6.52

Temp.:

>= 24.6 - <= 24.8 °C

Sample No.:

#4

Duration:

24 h

Initial conc. measured:

>= 25.5 - <= 25.7 other: mg/L

pH:

7.96

Temp.:

>= 24.6 - <= 24.8 °C

Sample No.:

#5

Duration:

24 h

Initial conc. measured:

>= 18.4 - <= 19 other: mg/L

pH:

8.55

Temp.:

>= 24.6 - <= 24.8 °C

Sample no.:

#1

Duration:

24 h

Conc. of adsorbed test mat.:

20.4 other: mg/L

pH:

3.86

Temp.:

24.7 °C

Sample no.:

#2

Duration:

24 h

Conc. of adsorbed test mat.:

21.7 other: mg/L

pH:

5.76

Temp.:

24.7 °C

Sample no.:

#3

Duration:

24 h

Conc. of adsorbed test mat.:

14.1 other: mg/L

pH:

6.55

Temp.:

24.7 °C

Sample no.:

#4

Duration:

24 h

Conc. of adsorbed test mat.:

23.1 other: mg/L

pH:

7.95

Temp.:

24.7 °C

Sample no.:

#5

Duration:

24 h

Conc. of adsorbed test mat.:

17.3 other: mg/L

pH:

8.56

Temp.:

24.7 °C

Key result

Sample No.:

#1

Type:

Koc

Value:

1 326.4 other: mL/g

pH:

3.88

Temp.:

24.7 °C

Matrix:

Jiangxi red soil

% Org. carbon:

0.42

Key result

Sample No.:

#2

Type:

Koc

Value:

258.11 other: mL/g

pH:

5.69

Temp.:

24.7 °C

Matrix:

Heiiongjiang black soil

% Org. carbon:

2

Key result

Sample No.:

#3

Type:

Koc

Value:

1 955.1 other: mL/g

pH:

6.52

Temp.:

24.7 °C

Matrix:

Liaoning brown soil

% Org. carbon:

0.58

Key result

Sample No.:

#4

Type:

Koc

Value:

618.9 other: mL/g

pH:

7.96

Temp.:

24.7 °C

Matrix:

Henan yellow fluvo-aquatic soil

% Org. carbon:

0.77

Key result

Sample No.:

#5

Type:

Koc

Value:

1 130.9 other: mL/g

pH:

8.55

Temp.:

24.7 °C

Matrix:

Xinjiang ash soil

% Org. carbon:

0.74

Recovery of test material:

The range of the three high recovery was 90.20%~94.99% of nominal concentration, and RSD was 2.59%; the range of the three low recovery all were 89.82% of nominal concentration, and RSD was 0.00%. The recovery was between 80%~110% of nominal concentration, and RSD was less than 15% which could meet the requirement

Concentration of test substance at end of adsorption equilibration period:

#1 20.4 mg/L
#2 21.7 mg/L
#3 14.1 mg/L
#4 23.1 mg/L
#5 17.3 mg/L

Concentration of test substance at end of desorption equilibration period:

#1 10.7 mg/L
#2 14.2 mg/L
#3 11.7 mg/L
#4 12.8 mg/L
#5 11.5 mg/L

Sample no.:

#1

Duration:

24 h

% Adsorption:

91.5

Sample no.:

#2

Duration:

24 h

% Adsorption:

90.8

Transformation products:

not measured

Details on results (Batch equilibrium method):

Preliminary study
From the adsorption rate at different time points, the adsorption equilibrium had been reached after 24 hours. The adsorption rate of Jiangxi red soil and Heilongjiang black soil were 53.3% and 55.8% under the soil/solution ratio of 1:5 respectively. So the ratio of soil/solutions 1:5 was selected in Jiangxi red soil and Heilongjiang black soil. As the same, Henan yellow fluvo-aquic soil, Liaoning brown soil and Xinjiang ash soil. In the preliminary study, only the control group without sample was set up to test the stability of the test sample in the 0.01mol/L calcium chloride solution and the adsorption of the tube wall. The test sample was stable within 24 hours and the adsorption of the container wall to the test article was negligible.
Mass balance
The results of mass balance showed that the mass balance rate (MB) in Jiangxi red soil and Heilongjiang black soil were 91.5% and 90.8% seperately, which were all higher than 90% of the initial solution, which all satisfied the requirement of mass balance. Therefore, the centrifugal separation of the aqueous phase of the test concentration was only to analysis in the follow-up kinetic and isothermal tests, without the soil phase analysis (indirect method).
Adsorption kinetics at one concentration of the test substance
It can be seen from the figure that the adsorption equilibrium process of MEP in five soils were divided into two processes: fast adsorption and slow adsorption. The adsorption increased mainly in the fast adsorption process in the first 1 hour, then tended to be gentle after 2 hours. After 24 hours, the adsorption equilibrium was reached with the adsorption rates higher than 20% in five soils.
The average partition coefficient of MEP in five soils was calculated to be greater than 0.3, and the value obtained by indirect analysis was considered to be valid.
The calculated organic carbon normalized adsorption coefficient KOC values of MEP in five soils were 258.1~1955.1.
Desorption kinetics
It can be seen from the figure that the process of desorption equilibrium of MEP in five soils were divided into two stages: fast desorption and slow desorption. The increase of desorption was mainly concentrated in the fast desorption process in the first 1 hour. The desorption tended to be gentle after 2 hours, then, as the same with the adsorption kinetic, the desorption reached equilibrium after 24 hours. The desorption rates of MEP were all less than 75% in five soils.
The calculated apparent desorption coefficient kdes of MEP in five soils were 6.41 ~ 12.21.
Adsorption isotherms
According to Freundlich adsorption equation, the correlation coefficient r2, desorption exponent 1/n and freundlich adsorption constant. The desorption exponent 1/n of MEP in five soils were in the range of 0.7 to 1.0, which could meet the requirements. The freundlich adsorption constant was ranging from 9.376 to 19.770.
Desorption isotherms
According to Freundlich desorption equation, the correlation coefficient r2, desorption exponent 1/n and freundlich desorption constant. The desorption exponent 1/n of MEP in five soils were in the range of 0.7 to 1.0, which could meet the requirements. The freundlich desorption constant was ranging from 7.838 to 17.956.

Validity criteria fulfilled:

yes

Remarks:

The recovery of the test substance in the aqueous phases and the soil were 98.04%~109.56% and 89.82%~94.99%, respectively, and the limit of detection (aqueous phase: 0.0102 mg/L; soil phase: 0.0501 μg/g) could also meet the requirement of the study.

Conclusions:

The equilibration time for adsorption and desorption were both 24 hours. The range of the adsorption and desorption rates of MEP were 48.8%~69.4% and 29.1%~43.8% in five soils seperately.
The range of the distribution coefficient Kd was 4.8 ~11.3 mL/g, the range of the organic carbon normalized adsorption coefficient Koc was 258.1~1955.1 mL/g, the range of the apparent desorption coefficient Kdes was 6.41~12.21 mL/g.
The range of the freundlich adsorption constant and the freundlich desorption constant were 9.376~19.770 and 7.838~17.956 seperately, and the freundlich adsorption or desorption exponent l/n were both between 0.7 and 1.0.

Executive summary:

Objective
To estimate adsorption/desorption behaviour of MEP on five soils using a batch equilibrium method.
Methods
Known volumes of solutions of the test substance, at known concentrations in 0.01 mol/L CaCl2are added to soil samples of known dry weight which have been preequilibrated in 0.01 mol/L CaCl2. The mixture is agitated for an appropriate time. The soil suspensions are then separated by centrifugation and, if so wished, filtration and the aqueous phase is analysed. The amount of test substance adsorbed on the soil sample is calculated as the difference between the amount of test substance initially present in solution and the amount remaining at the end of the experiment (indirect method). Tier 1- Preliminary study The equilibration time for adsorptionin the two soils asJiangxi red soil and Heilongjiang black soil were both24 h.The soil/solution ratio for the five soils tested in tier 2 was set to 1:5. Mass balance: At the end of the preliminary study, the adsorption equilibrium point of 24 h was selected to study the mass balance of Jiangxi red soil and Heilongjiang black soil, the results was as follows: Soil types Soil/solution ratio The rate of mass balance（%） Jiangxi red soil 1:5 91.5 Heilongjiang black soil 1:5 90.8 Tier 2-Adsorption kinetics at one concentration of the test substance Soil types Adsorption rate Ati （%） The distribution coefficientKd（mL/g） The organic carbon normalized adsorption coefficientKoc（mL/g） Jiangxi red soil 52.7 5.6 1326.4 Henan yellow fluvo-aquic soil 48.8 4.8 618.9 Liaoning brown soil 69.4 11.3 1955.1 Xinjiang ash soil 62.6 8.4 1130.9 Heilongjiang black soil 50.8 5.2 258.1 Tier 3-Desorption kinetics,Adsorption isothermsandDesorption isotherms Soil types Desorption kinetics Adsorption isotherms Desorption isotherms Desorption rate Dti（%） The apparent desorption coefficientKdes（mL/g） Freundlich adsorption constant KF^ads 1/n Freundlich desorption constant KF^des 1/n Jiangxi red soil 29.1 12.21 13.375 0.7595 12.835 0.7480 Henan yellow fluvo-aquic soil 40.7 7.28 10.285 0.8034 8.604 0.7609 Liaoning brown soil 29.4 12.00 19.770 0.8239 17.956 0.8458 Xinjiang ash soil 30.8 11.24 16.611 0.8211 14.842 0.8096 Heilongjiang black soil 43.8 6.41 9.376 0.8407 7.838 0.7849

Description of key information

The equilibration time for adsorption and desorption were both 24 hours. The range of the adsorption and desorption rates of MEP were 48.8%~69.4% and 29.1%~43.8% in five soils seperately.

The range of the distribution coefficient Kd was 4.8 ~11.3 mL/g, the range of the organic carbon normalized adsorption coefficient Koc was 258.1~1955.1 mL/g, the range of the apparent desorption coefficient Kdes was 6.41~12.21 mL/g.

The range of the freundlich adsorption constant  and the freundlich desorption constant  were 9.376~19.770 and 7.838~17.956 seperately, and the freundlich adsorption or desorption exponent l/n were both between 0.7 and 1.0.

The key value KOC presented below is an avarage value of the five samples

Key value for chemical safety assessment

Koc at 20 °C:

1 106.6

Additional information

[LogKoc: 3.04]