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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Additional information

Transport and distribution

Adsorption / desorption


The log of the adsorption coefficient (KOC) of Dipotassium oxide/Potassium oxide was estimated to be log KOC = 1.1211which is equal to a KOC value of 13.22 using the KOCWIN v2.00 QSAR method.


CHEM  : Potash (potassium oxide)


MOL WT : 94.20

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

Koc Estimate from MCI:


        First Order Molecular Connectivity Index ........... : 1.000

        Non-Corrected Log Koc (0.5213 MCI + 0.60) .......... : 1.1211

        Fragment Correction(s) --> NONE                     :  ---

        Corrected Log Koc .................................. : 1.1211


                        Estimated Koc: 13.22 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 2.814E-023 atm-m3/mole (2.851E-018 Pa-m3/mole) This is Exposure Assessment Tools and Models made from EPA (Environmental Protection Agency).

Distribution modelling.


Dipotassium oxide/ Potassium oxide has no affinity to be in air and sediment. The direct emissions to soil and surface water are significant, therefore Dipotassium oxide/ Potassium oxide 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 8.49e-028 (atm), in air (atm) 2.99e-026 and soil 3.73e-026 (atm) and sediment to be  7.69e-028 (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 Dipotassium oxide/Potassium oxide 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: Potash (potassium oxide)


Molecular Weight   : 94.20 g/mole

Water Solubility      : 1E+006 ppm

Vapor Pressure      : 2.27E-016 mm Hg

Henry's Law Constant: 2.81E-023 atm-m3/mole (calculated from VP/WS)


                                 RIVER            LAKE

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

Water Depth    (meters):   1                1         

Wind Velocity   (m/sec):   5                0.5       

Current Velocity (m/sec): 1                0.05      


     HALF-LIFE (hours) : 2.02E+019        2.203E+020

     HALF-LIFE (days ) :  8.415E+017       9.18E+018 

     HALF-LIFE (years) :  2.304E+015       2.513E+016



STP Fugacity Model: Predicted Fate in a Wastewater Treatment Facility


  (using 10000 hr Bio P,A,S)

PROPERTIES OF: Potash (potassium oxide)


Molecular weight (g/mol)                              94.2

Aqueous solubility (mg/l)                             1E+006

Vapour pressure (Pa)                                  3.02642E-014

               (atm)                                              2.98684E-019

               (mm Hg)                                        2.27E-016

Henry 's law constant (Atm-m3/mol)      2.8136E-023

Air-water partition coefficient                  1.15068E-021

Octanol-water partition coefficient (Kow)      8.31764E-006

Log Kow                                                          -5.08

Biomass to water partition coefficient                0.800002

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       15.97      10000.00

         -Aeration tank      0.04       15.97      10000.00

         -Settling tank        0.04       15.97      10000.00


                                     STP Overall Chemical Mass Balance:


                                          g/h              mol/h         percent


Influent                           1.00E+001        1.1E-001       100.00


Primary sludge                 2.50E-002        2.6E-004        0.25

Waste sludge                   1.50E-001        1.6E-003        1.50

Primary volatilization        1.53E-020        1.6E-022        0.00

Settling volatilization         4.18E-020        4.4E-022        0.00

Aeration off gas               1.03E-019        1.1E-021        0.00


Primary biodegradation      1.76E-003        1.9E-005        0.02

Settling biodegradation      5.27E-004        5.6E-006        0.01

Aeration biodegradation    6.93E-003        7.4E-005        0.07


Final water effluent            9.82E+000        1.0E-001       98.15


Total removal                     1.85E-001        2.0E-003        1.85

Total biodegradation          9.22E-003        9.8E-005        0.09