Metal Affinities in Single and Multiple Ion Adsorption Reaction at Sulfide Mineral Surfaces

摘要

The sulfide mineral is an important constituent in soil and aquifer material. It plays a dramatic role in controlling of transport and transformation of heavy metal in soil and ground water. Sulfide minerals are found in porous media in both aerobic and anaerobic environments. The relative binding affinities and reaction products for ten metal-metalloid irons reacting with four sulfide minerals have been defined. For any particular metal and mineral, the greater reactivity occurs in the single-ion metal system except Ag(I) on pyrite and Cu(II) on galena. Both precipitation and adsorption reactions can decrease metal ion mobility on porous media. The order of metal mobility in the presence of chalcocite, pyrite, galena, and sphalerite is predicted to be: Zn(II), Cd(II) and Ni(II)--mobile; Cu(II), Pb(II), Fe(II), As(III) and Cr(III)--variable mobility; and Ag(I)--immobile. MINTEQA1 predictions on metal phase distribution-partitioning compared quite well with those observed experimentally. Solubility product considerations, intrinsic acidity constant of the mineral, Eh, pH and the carbonate equilibrium are major factors controlling the phase distribution of metals reacting singularly or in combination with sulfide mineral surfaces.