This work was carried out to study methods of sulfide analysis to obtain a fast, accurate and reproducible procedure to evaluate acid drainage in samples of rocks and sediments.The samples were submitted to oxidative digestions with H2O2 and nitric-hydrochloric acid solutions (3:1, v/v).The S in the extracts was determined by gravimetry, atomic absorption spectrophotometry (AAS) for remaining Ba, turbidimetry and colorimetry.The Fe and Pb contents in the extracts were determined by AAS.Acidity was also determined by titration with NaOH in the H2O2 extracts.The nitric-hydrochloric oxidative digestion followed by S determination by AAS for remaining Ba, after BaCl2 treatment of the extracts, was the most suitable technique for measuring the sulfide contents of the samples.On the other hand, H2O2 digestion was not efficient for the total oxidation of the sulfides, underestimating the acid drainage potential in rock and sediment samples.
acid drainage; potential acidity; sulfide oxidation; S analytical techniques