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Environmental fate and pathways

 

Environmental exposure

 

Sodium dodecylbenzenesulfonate is manufactured from linear alkylbenzene (LAB) in self-contained, enclosed systems. LAB is produced by reacting paraffins with benzene and a catalyst and isolating the LAB by distillation. The LAB is then sulfonated, which in turn is then neutralized to sodium salts of LAS.

In the Sodium dodecylbenzenesulfonate reaction process, the measured concentrations of SO2, NaOH were 0.0026 and 0.0356 mg/m3, which were below the occupational exposure limit of 0.2 mg/m3 and 2 mg/m3, respectively. And the dust are emitted to atmosphere but the concentration of the substances were below 10% level of environmental emission standard (10 mg/m3).

All occurred waste organic solvents are burned by waste consignment treatment. Wastewater is treated chemically and biologically, and then it is discharged to wastewater treatment plant. Most of the substance that is used in industrial and consumer products as surfactant and ingredient in detergents will be disposed of by the sewerage system. Exposure of the environment may occur mainly via effluents of STP’s and application of sewage sludge in agriculture.

 

Environmental fate

 

The environmental fate assessment for Sodium dodecylbenzene sulfonate (SDBS) is based on US EPA’s Estimation Programs Interface (EPI) Suite. EPI Suite provides estimations of physical/chemical properties and environmental fate properties.

Based on the output of the model, Sodium dodecylbenzene sulfonate (SDBS) is highly unlikely to bioaccumulate in the environment or aquatic organisms (i.e. fish) because the low value for the log Kow (1.96).

 This also supports that the chemical is soluble in water such that it will exhibit mobility through the soil. In addition, the low log Koc (2.0092) further supports the expected soil mobility. The model-calculated linear and non-linear biodegradation probabilities suggest that the linear carbon chain will biodegrade rapidly, whereas the benzene ring is not expected to biodegrade as rapidly. The extremely low vapor pressure along with the short half life of approximately 7.9 hours indicates that if this chemical is present in the soil, it is not likely to be volatile and is expected to degrade rapidly.

The output parameters from the EPI Suite model support that any potential impacts of this chemical is expected to be very short-lived. This is because it is not likely to persist in water or microbial soils and sediments. As a result, the environmental fate of Sodium dodecylbenzene sulfonate (SDBS) is not likely to be of concern.

 

Hydrolysis will be not a significant factor in determining the environmental fate of Sodium dodecylbenzene sulfonate (SDBS).

Based on the results, dodecylbenzenesulfonic acid as a read across for Sodium dodecylbenzene sulfonate (SDBS) was hydrolytically stable (half life > 1 year) specified by the OECD Guidelines. Since the chemical is degradable less than 10% after 5 days in this test condition, it is presumably stable in water. (Hydrolytically stable).

 

 

Stability

 

Phototransformation in air

  

Using the AOPWIN QSAR model, the photochemical degradation rate of Sodium dodecylbenzenesulfonate in the atmosphere is 16.2182 E-12 cm3/molecule-sec, with a resultant predicted half live of  7.914 Hrs ( 0.660 Days (12-hr day; 1.5E6 OH/cm3))

   

  OVERALL OH Rate Constant = 16.2182 E-12 cm3/molecule-sec

  HALF-LIFE =    0.660 Days (12-hr day; 1.5E6 OH/cm3)

  HALF-LIFE =    7.914 Hrs

 

   

Sodium dodecylbenzenesulfonate has low vapor pressure (3.05E-013Pa) indicating significant amounts of Sodium dodecylbenzenesulfonate are unlikely to be present in the atmosphere for photodegradation. The estimated half-life is about 7.9.14 hours (OH rate = 16.2182 E-12 cm3/ molecule-sec) with the AOPWIN (US EPA, 2011).

  

If released to air, a vapor pressure of 2.29E-015 mm Hg at 25 deg C ( 2.29E-015 mm Hg is equivalent to vapour pressure of 3.05E-013Pa) indicates significant amounts of Sodium dodecylbenzenesulfonate are unlikely to be present in the atmosphere for photodegradation and therefore Sodium dodecylbenzenesulfonate is not expected to be susceptible to direct photolysis by sunlight.

 

   

Phototransformation in water

 

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) .

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.

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

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

 

 

Phototransformation in soil

If released to soil, Sodium dodecylbenzenesulfonate is expected to have very high mobility based upon an estimated Koc of 102.1. Volatilization from moist soil surfaces is not expected to be an important fate process.

Therefore testing for Phototransformation in soils does not need to be performed.

 

Hydrolysis

 

Hydrolysis is a chemical reaction during which molecules of water (H2O) are split into hydrogen cations (H+, conventionally referred to as protons) and hydroxide anions (OH−) in the process of a chemical mechanism).

The study of MOE 2008 was performed following “OECD Guidelines for Testing of Chemicals No. 111: Hydrolysis as function of pH. The preliminary test was performed at 50 ±5°C and pH 4, 7 and pH 9. The hydrolysis of the substance was less than 10% over the 5 days, so a definitive test was not performed. Based on these results, dodecylbenzenesulfonic acid was hydrolytically stable (half life > 1 year) specified by the OECD Guidelines .Dodecylbenzene sulfonic acids (CAS# 27176-87-0 , EC Number; 248-289-4) ) is a very close analogue of Sodium dodecylbenzenesulfonate (CAS No. 25155-30-0, EC Number; 246-680-4) ) and the dissociated acid it readily dissociates in water and release the dodecylbenzene sulfonic anion in solution .

Since the chemical is degradable less than 10% after 5 days in this test condition, it is presumably stable in water. (Hydrolytically stable)

 

 Biodegradation

 

Data of following studies are demonstrating rapid biodegradation of C12-LAS (including sodium dodecylbenzene sulfonate (DBS)) under aerobic and anaerobic conditions. Temmink and Klapwijk (2004) conducted OECD 301F test and the result is that more than 60% of mineralisation was achie

Biodegradation of sodium dodecylbenzene sulfonate (DBS), at 10 ppm was measured 75% after 11 days and test temperature was maintained at 20 deg C for 17 days. The sodium dodecylbenzene sulfonate (DBS) could be conclued as readily degradable.ved within 28 days.

For dodecylbenzene sulfonic acid (Dodecylbenzene sulfonic acids (CAS# 27176-87-0 , EC Number; 248-289-4) ) is a very close analogue of Sodium dodecylbenzenesulfonate (CAS No. 25155-30-0, EC Number; 246-680-4) ) and the dissociated acid it readily dissociates in water and release the dodecylbenzene sulfonic anion in solution.), the available study indicates 69% of the material mineralized after 28 days ,OECD 301B test (USEPA 1992).

 

Ward and Larson (1989) conducted a laboratory study and observed the biodegradation rate constant and half-life for C12-LAS in sludge-amended soil. The biodegradation rate constant for C12-LAS is 0.030 day-1and half-life for C12-LAS is 23.1 days. Scheunertet al., (1987) measured the biomineralization rate of dodecylbenzenesulfonate in soil/water suspension under anaerobic and aerobic conditions for 42 days. The results (40.6%14CO2: aerobic, 51.9%14CO2: anaerobic) showed that the substance was readily biodegradable by the micro-organisms present in soil.

 

Summary of Biodegradation

 

Type/ Method

Test material

Degradation

Duration

References

Aerobic/

OECD 301F

C12-LAS

> 60 % of mineralisation

28 days

Temmink and Klapwijk, 2004

Aerobic/

Other

Sodium dodecylbenzenesulfonate

75 %

11 days

Cook and Glodman, 1974

Aerobic/

OECD 301B

Dodecylbenzenesulfonic acid

69 % of mineralisation

28 days

USEPA 1992

Aerobic/

Other

C12-LAS

50%

23.1 days

Ward and Larson, 1989

Aerobic and Anaerobic/

Other

Dodecylbenzenesulfonate

40.6%14CO2of mineralization

(aerobic),

51.9%14CO2of mineralization (anaerobic)

42 days

Scheunertet al., 1987

 

    

 

Biodegradation in water:screening tests

Data of following studies are demonstrating rapid biodegradation of C12-LAS (including Na-LAS) under aerobic conditions. Temmink and Klapwijk (2004) conducted OECD 301F test and the result is that more than 60% of mineralisation was achieved within 28 days.

Cook and Glodman, 1974 conducted Biodegradation of sodium dodecylbenzene sulfonate (DBS), at 10 ppm was measured 75% after 11 days and test temperature was maintained at 20 deg C for 17 days. The sodium dodecylbenzene sulfonate (DBS) could be conclued as readily degradable.

For dodecylbenzene sulfonic acid, the available study indicates 69% of the material mineralized after 28 days ,OECD 301B test (USEPA 1992).

  

Table     Summary of Biodegradation in water:screening tests

 

Type/ Method

Test material

Degradation

Duration

References

Aerobic/

OECD 301F

C12-LAS

> 60 % of mineralisation

28 days

Temmink and Klapwijk, 2004

Aerobic/

Other

 Sodium dodecylbenzenesulfonate

75 %

11 days

Cook and Glodman, 1974

Aerobic/

OECD 301B

Dodecylbenzenesulfonic acid

69 % of mineralisation

28 days

USEPA 1992

 

  

Biodegradation in water and sediment: simulation tests

 

In the study of Federle TW and Itrich NR 1997, Linear alkylbenzene sulfonate (14C-ring C12LAS) was tested as model compounds in two sludges.

-        Within 8 h, 41−44% was evolved as 14CO2,

-        1−2% remained as parent,

-        24−33% was incorporated into biomass,

-        and 10−15% was present as intermediates, primarily sulfophenylcarboxylates.

 Primary and complete biodegradation were best described by a first-order model. First-order rate constants for LAS were 0.96−1.10 h-1 for primary loss and 0.50−0.53 h-1 for complete degradation. This approach provides an accurate and comprehensive kinetic picture of biodegradation under realistic conditions as well as information on the mechanism of biodegradation.

Biodegradation of Linear alkylbenzene sulfonate (14C-ring C12LAS), at 1mg/lwas measured>96% after6hoursand test temperature was maintained at 20 deg C.

 

In the study of Kubodera T, Muto T and Yamamoto T 1978 Dodecylbenzenesulfonate 14C (DBS-14C) was tested as model compound.

Biodegradation of Dodecylbenzenesulfonate 14C(DBS-14C)at76ppmwas measured>90% after90hoursand test temperature was maintained at 24deg C.

DBS decreased from 76.0 ppm to less than 0.6 ppm at 90h (Readily degradation).The biodegradation of DBS-14C has three periods of rapid adsorption period, acclimation period, and degradation process. 1-Tetralone, 1-indanone, 4-methyl-1-tetralone, naphthalene were the decomposition products

 

Biodegradation in soil

 

Ward and Larson (1989) conducted a laboratory study and observed the biodegradation rate constant and half-life for C12-LAS in sludge-amended soil. The biodegradation rate constant for C12-LAS is 0.030 day-1and half-life for C12-LAS is 23.1 days. Scheunertet al., (1987) measured the biomineralization rate of dodecylbenzenesulfonate in soil/water suspension under anaerobic and aerobic conditions for 42 days. The results (40.6%14CO2: aerobic, 51.9%14CO2: anaerobic) showed that the substance was readily biodegradable by the micro-organisms present in soil.

 

Table     Summary of Biodegradationin soil

 

Type/ Method

Test material

Degradation

Duration

References

Aerobic/

Other

C12-LAS

50%

23.1 days

Ward and Larson, 1989

Aerobic and Anaerobic/

Other

Dodecylbenzenesulfonate

40.6%14CO2of mineralization

(aerobic),

51.9%14CO2of mineralization (anaerobic)

42 days

Scheunertet al., 1987

 

Transport and distribution

Adsorption / desorption

 

The log of the adsorption coefficient(KOC) ofSodium dodecylbenzenesulfonate was estimated to be log KOC = 2.0092which is equal to a KOC value of 102.1 using the KOCWIN v2.00 QSARmethod.

   

KOCWIN Program (v2.00) Results:

==============================

SMILES : O([Na])S(=O)(=O)c1ccc(cc1)CCCCCCCCCCCC

CHEM  : Benzenesulfonic acid, dodecyl-, sodium salt

MOL FOR: C18 H29 O3 S1 Na1

                Koc may be sensitive to pH!

--------------------------- KOCWIN v2.00 Results ---------------------------

NOTE: METAL (Na, Li or K) HAS BEEN REMOVED TO ALLOW ESTIMATION via MCI!

 Koc Estimate from MCI:

 ---------------------

        First Order Molecular Connectivity Index ........... : 10.537

        Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 6.0928

        Fragment Correction(s):

                 1  Sulfonic acid (-S(=O)-OH) ............. : -2.0000

        Corrected Log Koc .................................. : 4.0928

 

                        Estimated Koc: 1.238e+004 L/kg  <===========

 

 Koc Estimate from Log Kow:

 -------------------------

        Log Kow (experimental DB) ......................... : 1.96

        Non-Corrected Log Koc (0.55313 logKow + 0.9251) .... : 2.0092

        Fragment Correction(s):

                 1  Sulfonic acid (-S(=O)-OH) ............. : 0.0000

        Corrected Log Koc .................................. : 2.0092

 

                        Estimated Koc: 102.1 L/kg  <==========

 

 

 

  

 Henry's Law constant

 

 

 The estimated Henrys Law Constant (25 deg C) measured by calculation from EPI SuiteTM v4.1, HENRYWIN v3.20 Program was 6.29E-008 atm-m3/mole (6.38E-003 Pa-m3/mole , which is almost zero.

This is Exposure Assessment Tools and Models made from EPA (Environmental Protection Agency).

 

Distribution modelling.

 

Sodium dodecylbenzenesulfonate has no affinity to be in air and sediment. The direct emissions to soil and surface water are significant, therefore Sodium dodecylbenzenesulfonate will be almost exclusively be found in soil and surface water.

 

Mackay fugacity modelling (level 3) indicates that, taking into account degradation and using inflow parameters which are consistent with the known production tonnage of this substance in, fugacity coefficient indicates that environmental concentrations in water are predicted to be 3.05e-013 (atm), in air (atm) 8.43e-018 and soil 4.63e-014 (atm) and sediment to be  1.91e-013 (atm).

These are negligible low levels. This can be considered a worse case prediction as it assumes all product is emitted with no emission control systems used.

 

   

 

Other distribution data

 

These results suggest for Sodium dodecylbenzenesulfonate that direct and indirect exposure from distribution in media is unlikely.

Based on low vapor pressure and low estimated log Pow, expected to partition to water and soil. Not expected to partition to air, sediments or biota.

 

Therefore testing for distribution in media does not need to be performed.

 

The estimated STP Fugacity Model and Volatilization From Water were measured by calculation from EPI SuiteTM v4.1 Program.

This is Exposure Assessment Tools and Models made from EPA (Environmental Protection Agency) .

 

                                              Volatilization From Water

                           =========================

 

Chemical Name: Benzenesulfonic acid, dodecyl-, sodium salt

 

Molecular Weight   : 348.48 g/mole

Water Solubility   : -----

Vapor Pressure     : -----

Henry's Law Constant: 6.29E-008 atm-m3/mole (estimated by Bond SAR Method)

 

                                               RIVER            

                                          ---------        ---------

Water Depth    (meters):      1                1         

Wind Velocity   (m/sec):      5                0.5       

Current Velocity (m/sec):    1                0.05      

 

     HALF-LIFE (hours) :  1.738E+004       1.897E+005

     HALF-LIFE (days ) :   724.1            7906      

     HALF-LIFE (years) :   1.982            21.64     

 

 

STP Fugacity Model: Predicted Fate in a Wastewater Treatment Facility

===============================================

  (using 10000 hr Bio P,A,S)

PROPERTIES OF: Benzenesulfonic acid, dodecyl-, sodium salt

 

Molecular weight (g/mol)                              348.48

Aqueous solubility (mg/l)                             0

Vapour pressure (Pa)                                     0

               (atm)                                                 0

               (mm Hg)                                           0

Henry 's law constant (Atm-m3/mol)                    6.29E-008

Air-water partition coefficient                                2.57242E-006

Octanol-water partition coefficient (Kow)             91.2011

Log Kow                                                                      1.96

Biomass to water partition coefficient                19.0402

Temperature [deg C]                                             25

Biodeg rate constants (h^-1),half life in biomass (h) and in 2000 mg/L MLSS (h):

         -Primary tank        0.00      366.84      10000.00

         -Aeration tank      0.00      366.84      10000.00

         -Settling tank        0.00      366.84      10000.00

 

                                         STP Overall Chemical Mass Balance:

                                      ---------------------------------

                                                   g/h              mol/h         percent

 

Influent                              1.00E+001        2.9E-002       100.00

 

Primary sludge                4.67E-002        1.3E-004        0.47

Waste sludge                   1.65E-001        4.7E-004        1.65

Primary volatilization     3.42E-005        9.8E-008        0.00

Settling volatilization      9.30E-005        2.7E-007        0.00

Aeration off gas              2.29E-004        6.6E-007        0.00

 

Primary biodegradation    1.82E-003        5.2E-006        0.02

Settling biodegradation    5.44E-004        1.6E-006        0.01

Aeration biodegradation  7.16E-003        2.1E-005        0.07

 

Final water effluent           9.78E+000        2.8E-002       97.79

 

Total removal                    2.21E-001        6.4E-004        2.21

Total biodegradation       9.52E-003        2.7E-005        0.10

 

 

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