Hydrogen cyanide

CAS RN: 74-90-8

Soil Adsorption / Mobility

The Koc of hydrogen cyanide is estimated as 15(SRC), using a log Kow of -0.25(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that hydrogen cyanide is expected to have very high mobility in soil. The pKa of hydrogen cyanide is 9.2(4), indicating that this compound will exist partially in the anion form in the environment and anions generally do not adsorb more strongly to soils containing organic carbon and clay than their neutral counterparts(5).
Hydrogen cyanide is only weakly absorbed by organic matter(1). Hydrogen cyanide is not strongly partitioned into the sediments or suspended adsorbents, primarily due to its high solubility in water. Cyanide mobility is least where soils exhibit low pH, high concn of free iron oxides, and positively charged particles (eg, kaolin, chlorite, gibbsite). Mobility is greatest at high pH, high concentration of free calcium carbonate (high negative charge) and low clay content. Adsorption of hydrogen cyanide by montmorillonitic clays is fairly weak and is decreased by the presence of water(2).
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