Sodium hydrogensulphate

Endpoint summary

Additional information

Sodium hydrogensulfate:

The aquatic effect and risk assessment focuses on the effects due to possible pHchanges related to H⁺discharges, because of the assumption that the toxicity of ubiquitous Na⁺and SO₄^2-ions is expected to be negligible compared to the (potential) pHeffect. The high water solubility and very low vapour pressure indicate that NaHSO₄will be found practically exclusively in water. Significant emissions or exposure to air are not expected due to the low vapour pressure of NaHSO₄. Significant emissions or exposure to the terrestrial environment are similarly not expected either for the industrial uses.

Environmental fate:

When NaHSO₄is emitted to wastewater or surface water, sorption to particulate matter and sediment will be negligible. Howevere, the pHmay decrease, depending on the buffer capacity of the water. In general, the buffer capacity prevents minor shifts in acidity or alkalinity in natural waters, because it is regulated by the equilibrium between carbon dioxide (CO₂), the bicarbonate ion (HCO₃^-) and the carbonate ion (CO₃^2-):

 

CO₂+ H₂O <-> HCO₃^-+ H⁺(pKa1 = 6.35)

HCO₃^-<-> CO₃^2-+ H⁺(pKa2 = 10.33)

 

If the pHis < 6, un-ionised CO₂is the predominant species and the first equilibrium reaction is most important for the buffer capacity. At pHvalues of 6-10, the bicarbonate ion (HCO₃^-) is the predominant species and at pHvalues > 10 the carbonate ion (CO₃^2-) is the predominant species. In the majority of natural waters the pH values are between 6 and 10, thus theNaHSO₄concentration and the second equilibrium reaction are most important for the buffer capacity.

Sodium sulfate:

In water, sodium sulfate completely dissociates into sodium and sulfate ions. The ions cannot hydrolyse. In anaerobic environments sulfate is biologically reduced to (hydrogen) sulfide by sulfate reducing bacteria, or incorporated into living organisms as source of sulfur, and thereby included in the natural sulfur cycle. Sodium sulfate is not reactive in aqueous solution at room temperature.

 

Significant bioconcentration is not expected. Sodium and sulfate ions are essential to all living organisms and their intracellular and extracellular concentrations are actively regulated. Sodium sulfate is not expected to adsorb onto soil and sediment. From Source: SODIUM SULFATE CAS N°: 7757-82-6 OECD SIDS April 2005

Environmental Exposure and Fate.

In anaerobic environments sulfate is biologically reduced to (hydrogen) sulfide by sulfate reducing bacteria, or incorporated into living organisms as source of sulfur. Sodium sulfate is not reactive in aqueous solution at room temperature. In moist air sodium sulfate will take up water (hygroscopic) to form hydrates. Sodium sulfate is also soluble in glycerol, but insoluble in alcohol. Sodium sulfate has no oxidising properties, is not explosive and is non-flammable.