Accumulation of heavy metals by Pseudomonas fluorescens 4F39 was rapid and pH dependent. The affinity series for bacterial accumulation of metal cations decreased in the order Ni>>Hg>U>>As>Cu>Cd>Co>Cr>Pb. Metal cations were grouped into those whose accumulation increased as the pH increased, with a mzximum accumulation at the pH before precipitation (Ni, Cu, Pb, Cd, Co), and those whose maximum accumulation was not associated with precipitation (Cr, As, U, Hg). High Ni++ accumulation was studied. Electron microscopy indicated that at pH 9, Ni++ accumulated on the cell surface as needle and hexagon-like precipitates, whose crystalline structure was confirmed by electron diffraction analysis and corresponded to two different orientations of the nickel hydroxide crystals. Crystals on cells showed marked anisotropy by X-ray powder diffraction, which differentiated them from crystals observed in nickel solution at pH 10 and 11 and from commercial nickel hydroxide. Nickel biosorption by Pseudomonas fluorescens 4F39 was a microprecipitation consequence of an ion exchange.
Mendeley saves you time finding and organizing research
Choose a citation style from the tabs below