Inorganic chemistry of chromium and its speciation in Whetlerite

Chromium compounds are among the impregnants that enhance the ability of carbon air filters to absorb and destroy toxic agents such as CK and AC. The possibility of inhaling chromium-containing carbon dust from such filters has caused concern because, in addition to being an essential nutrient, chromium has been identified as a chemical carcinogen in humans. The essentiality or carcinogenicity of chromium depends upon its chemical speciation. Solubility and oxidation state are particularly important factors in assessing the potential hazards associated with the possible inhalation of chromium-containing dusts from these impregnated carbons or Whetlerites. The chemical speciation of the chromium in Whetlerite was found to be: from 0.6 to 1.3% insoluble trivalent chromium; from 1.0 to 1.3% insoluble hexavalent chromium; and from 0.7 to 0.9% soluble hexavalent chromium. The impregnation process, and the resulting speciation of chromium in Whetlerite, is consistent with the inorganic chemistry of chromium.