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Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Transport and distribution

Adsorption / desorption

 

 According to “ANNEX IX- STANDARD INFORMATION REQUIREMENTS FOR SUBSTANCES MANUFACTURED OR IMPORTED IN QUANTITIES OF 100 TONNES OR MORE , an adsorption study need not be conducted if:

— based on the physicochemical properties the substance can be expected to have a low potential for adsorption (e.g. the substance has a low octanol water partition coefficient), or

— the substance and its degradation products decompose rapidly.

 

The log of the adsorption coefficient (KOC) ofSodiumethyl xanthate was estimated to be log KOC = 0.602 which is equal to a KOC value of 4 using the KOCWIN v2.00 QSAR method. This value indicates that Reaction mass of SEX will be adsorbed by organic carbon in soil. Reaction mass of SEX can be classified to be of very high mobility in soil according these results and does not have a high potential for adsorption to soil

 

Reaction mass of SEX and xanthates in general adsorbs strongly to sulphide minerals but has less affinity for surfaces in general.

The KOC value of 4 also suggest this conclusion.

 

The estimated Soil Adsorption Coefficient was 4L/kg measured by calculation from EPI SuiteTM v4.1 Program. This is Exposure Assessment Tools and Models made from EPA (Environmental Protection Agency

 

SMILES : S=C(S([Na]))OCC

CHEM  : Carbonodithioic acid, O-ethyl ester, sodium salt

MOL FOR: C3 H5 O1 S2 Na1

MOL WT : 144.18

 Koc Estimate from MCI:

        First Order Molecular Connectivity Index ........... : 2.770

        Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 2.0438

        Fragment Correction(s):

                 1  Thiocarbonyl (C=S) .................. : -0.5701

                 1  Ether, aliphatic (-C-O-C-) .......... : -0.8716

        Corrected Log Koc .................................. : 0.6021

 

                        Estimated Koc: 4 L/kg  <===========

 

 Koc Estimate from Log Kow:

 -------------------------

        Log Kow (Kowwin estimate) ......................... : -2.24

        Non-Corrected Log Koc (0.55313 logKow + 0.9251) .... : -0.3139

        Fragment Correction(s):

                 1  Thiocarbonyl (C=S) .................. : 0.3004

                 1  Ether, aliphatic (-C-O-C-) .......... : -0.0906

        Corrected Log Koc .................................. : -0.1041

 

                        Estimated Koc: 0.7869 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  7.494E-016 atm-m3/mole (7.593E-011 Pa-m3/mole) , which is almost zero.

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

 

Distribution modelling.

 

 Reaction mass of SEX has no affinity to be in air and sediment. The direct emissions to soil and surface water are significant, therefore Reaction mass of SEX 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 5.2e-019   (atm), in air (atm)   1.65e-020   and soil   8.69e-019    (atm) and sediment to be  1.5e-020  (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 Reaction mass of SEX 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: Carbonodithioic acid, O-ethyl ester, sodium salt

 

Molecular Weight   :     144.18 g/mole

Water Solubility   :       1E+006 ppm

Vapor Pressure     :      3.95E-009 mm Hg

Henry's Law Constant: 7.49E-016 atm-m3/mole (calculated from VP/WS)

 

                                            RIVER            

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

Water Depth    (meters):      1                1         

Wind Velocity   (m/sec):      5                0.5       

Current Velocity (m/sec):     1                0.05      

 

     HALF-LIFE (hours) :  9.382E+011       1.023E+013

     HALF-LIFE (days ) :   3.909E+010       4.264E+011

     HALF-LIFE (years) :   1.07E+008        1.168E+009

 

 

STP Fugacity Model: Predicted Fate in a Wastewater Treatment Facility

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

  (using 10000 hr Bio P,A,S)

PROPERTIES OF: Carbonodithioic acid, O-ethyl ester, sodium salt

Molecular weight (g/mol)                              144.18

Aqueous solubility (mg/l)                             1E+006

Vapour pressure (Pa)                                   5.26623E-007

               (atm)                                             5.19737E-012

               (mm Hg)                                       3.95E-009

Henry 's law constant (Atm-m3/mol)             7.49354E-016

Air-water partition coefficient                       3.06464E-014

Octanol-water partition coefficient (Kow)    0.0057544

Log Kow                                               -2.24

Biomass to water partition coefficient                0.801151

Temperature [deg C]                                   25

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

         -Primary tank         0.04       16.00      10000.00

         -Aeration tank        0.04       16.00      10000.00

         -Settling tank          0.04       16.00      10000.00

 

                                     STP Overall Chemical Mass Balance:

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

                                            g/h              mol/h         percent

 

Influent                            1.00E+001        6.9E-002       100.00

 

Primary sludge                2.50E-002        1.7E-004         0.25

Waste sludge                   1.50E-001        1.0E-003        1.50

Primary volatilization      4.08E-013        2.8E-015        0.00

Settling volatilization      1.11E-012        7.7E-015        0.00

Aeration off gas              2.74E-012        1.9E-014        0.00

 

Primary biodegradation    1.76E-003        1.2E-005       0.02

Settling biodegradation    5.27E-004        3.7E-006       0.01

Aeration biodegradation  6.93E-003        4.8E-005       0.07

 

Final water effluent            9.82E+000        6.8E-002       98.15

 

Total removal                    1.85E-001        1.3E-003        1.85

Total biodegradation          9.22E-003        6.4E-005        0.09