The standards selected for Mn were birnessite
The researchers reacted chromite with birnessite, a manganese-containing mineral that often forms in weathered rocks and soils containing chromite.
The researchers conclude that within 100 days, chromite and birnessite could generate chromium (VI) at concentrations above the World Health Organization's limit for drinking water--which is 50 micrograms per liter.
2]-adsorption surface area analyser after the mineral had been degassed under vacuum at 105[degrees]C overnight, except for the ferrihydrite and birnessite
, which were degassed under vacuum at room temperature.
The predominant mineral in the coatings is birnessite
, a manganese oxide compound that includes traces of sodium, calcium, and potassium.
Additionally, at soil pH [is greater than] 5-6, Mn adsorption onto aluminium and ferric oxides and birnessite
(Mn oxide) increases (McBride 1978; McKenzie 1980).