As(V) and As(III) reactions on pristine pyrite and on surface-oxidized pyrite

作者：Sun Fenglong; Dempsey Brian A^*; Osseo Asare Kwadwo A

来源：Journal of Colloid and Interface Science, 2012, 388(1): 170-175.

DOI：10.1016/j.jcis.2012.08.019

• Pyrite
• Arsenic
• Arsenate
• Arsenite
• Adsorption
• Reduction
• XANES

Reactions of As(III) and As(V) with pyrite were investigated using pristine pyrite (produced and reacted in a rigorously anoxic environment with P-O2 < 10(-8) atm) and using surface-oxidized pyrite (produced under anoxic conditions, exposed to air, then stored and reacted under rigorously anoxic conditions). Results with surface-oxidized pyrite were similar to previously reported arsenic-pyrite results. However As(III) adsorbed over a broader pH range on pristine pyrite than on surface-oxidized pyrite, As(V) adsorbed over a narrower pH range on pristine pyrite than on surface-oxidized pyrite, and adsorbed As(V) on pristine pyrite was reduced to As(III) but adsorbed As(V) was not reduced with surface-oxidized pyrite. Reduction of As(V) with pristine pyrite was first-order in total As(V), Fe(II) was released, and sulfur was oxidized. The proposed mechanism for pyrite oxidation by As(V) was similar to the published mechanism for oxidation by O-2 and rates were compared. The results can be used to predict the removals of As(V) and As(III) on pyrite in continuously anoxic environments or on pyrite in intermittently oxic/anoxic environments. Rigorous cleanup and continuous maintenance of strictly anoxic conditions are required if commercial or produced pyrites are to be used as surrogates for pristine pyrite.

• 出版日期2012-12-15