Accumulation of zirconium and nickel byCitrobacter sp

Abstract

Zirconium in aqueous¯ows was moderately biomineralized by immobilized Citrobacter N14 cells, in the form of gel-like deposits, probably comprising a mixture of zirconium hydrogen phosphate (Zr(HPO 4 ) 2 ) and hydrated zirconia (ZrO 2 ). The simultaneous presence of uranyl ion (UO P P ) did not facilitate zirconium deposition and the biomineralization of uranium itself as HUO 2 PO 4 was repressed by zirconium in the presence of excess inorganic phosphate, liberated enzymatically. Nickel (Ni 2+ ) was not signi®cantly removed from aqueous¯ows by sorption into cell-bound zirconium deposits, although cell-bound hydrogen uranyl phosphate (HUP) facilitated nickel removal via intercalative ion exchange into its polycrystalline lattice. A preformed layer of HUP also promoted zirconium removal, at 100% ef®ciency at pH 2.6, maintained over 38 column¯uid-volumes before saturation.

Microbial influence on metal mobility and application for bioremediation

“…to a mixture of Zr(HPO 4 ) 2 and hydrated zirconia (ZrO 2 ): biomineralization of uranium as HUO 2 PO 4 was repressed by zirconium in the presence of excess inorganic phosphate. Cell-bound HUO 2 PO 4 facilitated Ni 2 + removal by intercalative ion exchange into the polycrystalline lattice and also promoted Zr removal (Brasnakova and Macaskie, 1999).…”

Accumulation of zirconium phosphate by a Serratia sp.: a benign system for the removal of radionuclides from aqueous flows

“…Other factors influencing this crystallisation process are the solubility product of the metal phosphate, the nature and concentration of the complexing ligand(s) present and the pH of the solution. Previous studies showed that, despite the low solubility products quoted in the literature, in practice tetravalent metal phosphates tend not to desolubilise readily due to the extensive hydrolysis of the tetravalent ion in solution (Yong and Macaskie 1998;Basnakova and Macaskie 1999).…”

“…Determination of Zr was as described by Basnakova and Macaskie (1999), using Xylenol Orange, with a slight modification. The calibration was made from stock solution: ZrOCl 2 Á8H 2 O made to 1 mM in a solution comprising 1 ml conc.…”

“…Zirconium would be ideal for the remediation of wastes and potable water where nontoxicity is a pre-requisite. The Serratia metal phosphate deposition system has been demonstrated for tetravalent metals (Th(IV), Zr(IV)) (Yong and Macaskie 1998;Basnakova and Macaskie 1999) although Zr(IV) was deposited poorly (Basnakova and Macaskie 1999). Therefore the objective of this study was to develop effective biogenic ZrP deposition by the Serratia sp., working towards a method for use as an entrapment matrix for removal of metals such as Co 2?…”

Time-resolved luminescence studies in hydrogen uranyl phosphate intercalated with amines

“…HUP exhibits high proton conductivities and can be employed as a solid electrolyte in micro-ionic devices, such as sensors [1][2][3][4], batteries [5] and electrochromic displays [6][7]. Studies of this compound has been centered on the structure [8][9][10][11], reactivity [12][13][14][15], vibrational spectroscopy [16], synthesis and characterization of intercalation compounds with different cationic species [17][18][19], diffusion and protonic conductivity mechanism [20][21][22][23][24][25][26][27][28], and chemisorption properties of HUP bound to biomass of bacteria [29][30][31][32][33]. Photoluminescence properties [34][35][36][37][38][39], have also been investigated in the literature, but they are not analyzed in terms of restricted geometry [40][41][42][43][44][45]...…”