Registration Dossier

Diss Factsheets

Environmental fate & pathways

Adsorption / desorption

Currently viewing:

Administrative data

Endpoint:
adsorption / desorption
Remarks:
adsorption
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: data from peer reviewed journals

Data source

Reference
Reference Type:
publication
Title:
Kinetic and Equilibrium Modeling of the Adsorption of Amaranth from aqueous solution onto Smectite Clay
Author:
Nanganoa L.T, Ketcha J.M. and Ndi J.N.
Year:
2014
Bibliographic source:
Research Journal of Chemical Sciences, Vol. 4(2), 7-14, February (2014)

Materials and methods

Principles of method if other than guideline:
The capability of smectite clay (Sa01) was investigated as a low cost adsorbent for the adsorption of a hazardous water soluble dye amaranth from aqueous solutions
GLP compliance:
not specified
Type of method:
batch equilibrium method
Media:
soil

Test material

Constituent 1
Chemical structure
Reference substance name:
Trisodium 3-hydroxy-4-(4'-sulphonatonaphthylazo)naphthalene-2,7-disulphonate
EC Number:
213-022-2
EC Name:
Trisodium 3-hydroxy-4-(4'-sulphonatonaphthylazo)naphthalene-2,7-disulphonate
Cas Number:
915-67-3
Molecular formula:
C20H14N2O10S3.3Na
IUPAC Name:
trisodium 3-hydroxy-4-(4'-sulphonatonaphthylazo)naphthalene-2,7-disulphonate
Constituent 2
Reference substance name:
trisodium (4E)-3-oxo-4-[(4- sulfonato-1- naphthyl)hydrazono]naphthalene- 2,7-disulfonate
IUPAC Name:
trisodium (4E)-3-oxo-4-[(4- sulfonato-1- naphthyl)hydrazono]naphthalene- 2,7-disulfonate
Constituent 3
Reference substance name:
Amaranth dye
IUPAC Name:
Amaranth dye
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
Name of test material (as cited in study report): Amaranth dye
Molecular formula (if other than submission substance): C20H11N2Na3O10S3
Molecular weight (if other than submission substance): 604.47
Smiles notation (if other than submission substance): c1ccc2c(c1)c(ccc2S(=O)(=O)[O])N=Nc3c4ccc(cc4cc(c3O)S(=O)(=O)[O-])S(=O)(=O)[O-].[Na+].[Na+].[Na+]
InChl (if other than submission substance): 1S/C20H14N2O10S3.3Na/c23-20-18(35(30,31)32)10-11-9-12(33(24,25)26)5-6-13(11)19(20)22-21-16-7-8-17(34(27,28)29)15-4-2-1-3-14(15)16;;;/h1-10,23H,(H,24,25,26)(H,27,28,29)(H,30,31,32);;;/q;3*+1/p-3
Substance type: Organic
Physical state: Solid
Radiolabelling:
not specified

Study design

Test temperature:
Study design
Test temp: 25°C

HPLC method

Details on study design: HPLC method:
not applicable

Batch equilibrium or other method

Analytical monitoring:
not specified
Details on sampling:
Details on sampling
Concentrations: Solutions containing known concentrations of adsorbate and accurately weighed amounts of adsorbent were introduced in 250 ml capacity flasks, sealed and agitated with a magnetic stirrer at given time intervals
Sampling interval:
Sample storage before analysis: Filter paper was used to separate the adsorbates from the adsorbent and the concentrations of dye in the filtrate determined by the UV-visible spectrophotometer.
Details on matrix:
Soil:
COLLECTION AND STORAGE
Geographic location: The clay material obtained from Sabga in the North West region of Cameroon (Sa01)
Collection procedures:
Sampling depth (cm):
Storage conditions: The sieved powder was kept in an oven at 110°C for 24 hours,
Storage length: 24 hours
Soil preparation (e.g.: 2 mm sieved; air dried etc.): Sa01 was air dried, ground into fine powder using a mortar and was then passed through an 80 μm mesh opening size sieve. The sieved powder was kept in an oven at 110°C for 24 hours, removed and cooled in a dessicator before use.

PROPERTIES
Soil texture: color – dirty white
% sand: No data
% silt: No data
% clay: No data
Horizon: No data
Soil taxonomic classification: No data
Soil classification system: Smectite
Soil series: No data
Soil order: No data
pH: No data
Organic carbon (%): No data
CEC (meq/100 g): 0.78 meq/g
Carbonate as CaCO3: No data
Insoluble carbonates (%):No data
Extractable Cations (Ca, Mg, Na, K, H) (MEQ/100 g): No data
Special chemical/mineralogical features: Montmorillonite (79.2%); quartz (10%); fedspar (5%); hematite (2.35%); limonite (0.1%)
Clay fraction mineralogy: No data
Moisture at 1/3 atm (%):No data
Bulk density (g/cm3): No data
Biomass (e.g. in mg microbial C/100 mg, CFU or other): No data
Details on test conditions:
TEST CONDITIONS
Buffer: No data
pH: The pH of the solutions was adjusted with either 0.1 M HCl or 0.1 M NaOH.
Suspended solids concentration: No data
Other: The experiments were conducted with artificial wastewater solution prepared by dissolving amaranth dye in distilled water. A 1000 mg/L stock solution of amaranth was prepared. By dilution with distilled water, standard solutions were also prepared. The concentrations of these solutions were measured with a UV spectrophotometer at a wavelength of maximum absorption of 520 nm. A calibration curve of absorbance versus concentration of the dye was plotted. The pH of the solutions was adjusted with either 0.1 M HCl or 0.1 M NaOH.

TEST SYSTEM
Type, size and further details on reaction vessel: 250 ml flasks
Water filtered (i.e. yes/no; type of size of filter used, if any): no
Amount of soil/sediment/sludge and water per treatment (if simulation test): No data
Soil/sediment/sludge-water ratio (if simulation test): No data
Number of reaction vessels/concentration: No data
Measuring equipment: UV-visible spectrophotometer.
Test performed in closed vessels due to significant volatility of test substance: No data
Test performed in open system: No data
Method of preparation of test solution: Solutions containing known concentrations of adsorbate and accurately weighed amounts of adsorbent were introduced in 250 ml capacity flasks, sealed and agitated with a magnetic stirrer at given time intervals.
Are the residues from the adsorption phase used for desorption:
Other: Batch mode adsorption studies were performed at ambient temperature of 25°C.
Duration of adsorption equilibration
Sample No.:
#1
Duration:
40 min
Initial conc. measured:
30 - 70 mg/kg soil d.w.
pH:
2
Temp.:
25
Computational methods:
Computational methods
Adsorption and desorption coefficients (Kd):no data
Freundlich adsorption and desorption coefficients: kf =0.281, kl = 0.0822
Slope of Freundlich adsorption/desorption isotherms: 1/n = 0.46

Results and discussion

Adsorption coefficient
Type:
other: Freundlich adsorption isotherm
Value:
0.281
Temp.:
25 °C
Remarks on result:
other: % org carbon not measured
Partition coefficients
Phase system:
other: Langmuir adsorption isotherm
Type:
other: Langmuir adsorption isotherm
Value:
0.082
Remarks on result:
other: Langmuir adsorption isotherm kl = 0.0822

Results: HPLC method

Details on results (HPLC method):
no data

Results: Batch equilibrium or other method

Adsorption and desorption constants:
kf =0.281, kl = 0.0822
kf = freundlich adsorption isotherm constant
kl = Langmuir adsorption isotherm constant
Recovery of test material:
no data
Concentration of test substance at end of adsorption equilibration period:
no data
Transformation products:
not specified
Details on results (Batch equilibrium method):
no data

Any other information on results incl. tables

Table 1: Physical Characteristics of Smectite (Sa01)

 

Color

Dirty white

BET surface area

86 m2/g

Total pore volume

0.15 cm3/g

Micro pore volume

0.01m3/g

Average particle size

8 µm

Mineral composition (%)

Montmorillonite (79.2); quartz (10); feldspar (5);haematite (2.5); Limonite (0.1)

Cation exchange capacity

0.78 meq/g

 

Table 2: Chemical composition of the Sa01

 

SiO2

Al2O3

MnO

MgO

CaO

Na2O

K2O

TiO2

P2O5

Fe203

LOI

63.36

14.58

<0.03

0.23

0.7

0.39

2.34

0.2

<0.05

4.24

13.79

 

Table 3: Langmuir and Freundlich Adsorption isotherm constants using Sa01 as adsorbent (Sa01 <80µm)

 

Isotherm

Parameter

Langmuir

Qm

1.845

KL

0.0822

R2

0.966

Freundlich

Kf

0.281

1/n

0.46

R2

0.989

Applicant's summary and conclusion

Validity criteria fulfilled:
not specified
Conclusions:
The removal of amaranth from aqueous solutions using Sa01 as low cost adsorbent was studied using batch adsorption mode under different conditions. Two types of isotherm models were investigated; the Langmuir and Freundlich Isotherms.
83.6% of dye was adsorbed at pH 2, adsorbent mass of 1.0 g and initial dye concentration of 30 mg/L.
The Freundlich adsorption isotherm was found to correlate better the experimental data with R2 = 0.9894.
Executive summary:

The capability of smectite clay (Sa01) was investigated as a low cost adsorbent for the adsorption of a hazardous water soluble dye amaranth from aqueous solutions.

The clay material obtained from Sabga in the North West region of Cameroon (Sa01).Sa01 was air dried, ground into fine powder using a mortar and was then passed through an 80 μm mesh opening size sieve. The sieved powder was kept in an oven at 110°C for 24 hours, removed and cooled in a dessicator before use.

The experiments were conducted with artificial wastewater solution prepared by dissolving amaranth dye in distilled water. A 1000 mg/L stock solution of amaranth was prepared. By dilution with distilled water, standard solutions were also prepared. The concentrations of these solutions were measured with a UV spectrophotometer at a wavelength of maximum absorption of 520 nm. A calibration curve of absorbance versus concentration of the dye was plotted. The pH of the solutions was adjusted with either 0.1 M HCl or 0.1 M NaOH.

Batch mode adsorption studies were performed at ambient temperature of 25°C. Solutions containing known concentrations of adsorbate and accurately weighed amounts of adsorbent were introduced in 250 ml capacity flasks, sealed and agitated with a magnetic stirrer at given time intervals.

Calculations of adsorption capacities Qt and Qe at time t and equilibrium respectively were calculated based on the following equations:

(1) QT=

(2) Qe =

The percentages of amaranth dye adsorbed (%R) were also

determined by the equation:

(3) %R =

where Co is the initial concentration (mg/ L), Ct and Ce are the residual concentrations (mg/ L) of amaranth at time t (minutes) and equilibrium respectively. V is the volume of aqueous solution (in litres) and m, the mass (g) of Sa01 used in the experiment.

Two types of isotherm models were investigated; the Langmuir and Freundlich Isotherms.

83.6% of dye was adsorbed at pH 2, adsorbent mass of 1.0 g and initial dye concentration of 30 mg/L.

kf =0.281, kl = 0.0822

kf = freundlich adsorption isotherm constant

kl = Langmuir adsorption isotherm constant

The Freundlich adsorption isotherm was found to correlate better the experimental data with R2 = 0.9894.