Abiotic schwertmannite transformation kinetics and the role of sorbed As(III)

摘要: Abstract Schwertmannite (SHM) precipitated from acid mine drainage often contains high levels of As(III). The present study is aimed at understanding the fate As(III) preadsorbed to bio-synthesized schwertmannite (0.92 wt% As(III)) during transformation, compared with SHM devoid Ageing experiments were conducted room temperature in controlled reactors for 120 days pH 5, 6, 7 and 8. Transformation was indicated by a steady SO 4 2 - release of ⩾90% solid phase pH 8 after 75 days both specimens. correlated OH− consumption, indicating OH – exchange facilitated as pH increased 5 No significant structural change could be using XRD, IR spectroscopy scanning electron microscopy, suggesting formation an initial transformation product low crystallinity. Incomplete ripening determined traces ferrihydrite goethite As(III)-free specimens, which more prominent higher pH. Significant sorbed As (1.9 wt% pH 5) detected As-containing rapidly readsorbed probably new phase. detectable occurred lower values case As(III)-sorbed specimens inhibitory effect on nucleation phases.