Chemical Fate of Brass Dust in Waters of Varying Hardness Levels

摘要

The chemical fate of brass dust was examined at four levels of water hardness ranging from very soft to very hard water. The brass dust was added at a concentration of 10 mg/L to two set of test water at each hardness level. In the first set, the brass was applied on the water surface; in the second set, the brass was mixed into the water by sonication. Atomic absorption analysis, conducted over 21 days, to determine the rate of brass breakdown into soluble copper (Cu) and zinc (Zn), disclosed that the greatest dissociation occurred in the very soft water. The percentage of soluble metal dissociated from the brass at other hardness levels was comparable, ranging from 5 to 11% Cu and 6 to 8% for Zn. The effects of mixing the brass into the water accelerated the initial release of soluble Cu and Zn and increase the dissociation of Zn. Any associated toxicity of the brass to aquatic organisms would probably occur soon after the brass entered the aqueous environment. Keywords: Brass dust; Copper; Zinc; Water hardness; Half life; Kinetics. (mjm)