The elimination of selenium(IV) from aqueous solution by precipitation with sodium sulfide

摘要: In this study, the removal/precipitation of selenium with sodium sulfide from initially weakly acidic sulfate solutions containing 300 mg/L selenium(IV) at 23 °C was studied. The results showed that, below a pH approximately 7.0, precipitation reaction complete to ratio above 1.8 and less than 11 0.005 soluble remaining in solution. When rose between 7.0 9.5 incomplete. Above solution turned dark red but no apparent. started as soon added selenium-bearing completed 10 min. orange "selenium sulfide" precipitates, characterized using X-ray diffraction, scanning electron microscopy chemical analysis, were crystalline form aggregated dense particles their sulfur/selenium molar varying 1.7 2.3. precipitate deduced be Se-S solid consisting ring molecules following Se(n)S(8-n) formula, where n = 2.5-3. Long term leachability tests (>2 month equilibration) under ambient conditions 7 produced essentially insoluble (<0.005 mg/L).