Fate and effects of xanthates in laboratory freshwater systems.

Xanthates (salts of the dithiocarbon acid-O-ester with ~ a C-O-alkyl or aryl chain and C-S-metal ion) are mostly of technical s[gnificance as "samplers" of metal sul[ides in mining flotation. Alkali-metal-xanthates are stable, crystalline substances. The Na-salts are slightly hygroscopic and form dihydrates, while the Ksalts crystallize free of water. More than ii 000 metric tons of Na-isopropyl (49 %), Na-ethyl-(30 %), Nasec. butyl-(15 %) and K-isopentyl-xanthates (i0 %) are consumed in flotation processes per year worldwide. Alkali-xanthates are of mlnor toxicity to mammals (LD50 for mice ranged from 400-700 mg/kg; Edelmann 1983). As Xanthates are hydrolyzed by stomach acid, poisoning is mainly caused by the hydrolysis products alcohol and carbon disulfide. Xanthates, however, are known to be strong fish poisons (Edelmann 1983; Webb et al. 1976). LD50 values were round between i0 and i00 mg/L water. Recently xanthates are being discussed as helpful agents in environmental protection because of their ability to remove harmful heavy metals from contaminated waters (Edelmann 1983). The present work was undertaken, to provide more information on the rate and effects on aquatic organisms of these environmental chemicals.