Progressive adsorption of uranium by Biomass modified montmorillonite.

M. OLIVELLI; G. CURUTCHET; R. M. TORRES SÁNCHEZ

San Salvador Bahia, Brasil

Conferencia; Environmental Health Conference; 2011

Uranium is a heavy metal, with noticeable toxicity associated with nuclear energy processes and acidic mine drainage.Montmorillonite clays have known metal sorption capacity. The main technological drawback in using clays as sorbent materials is the difficulty in separating them from the solution. The same problem appears in biosorption processes.  A novel methodology for immobilization of the biomass and system coagulation is to generate clay biopolymers matrices.The objective of this study is to evaluate the progressive accumulation of Uranyl ions in matrices generated from Acremonium sp. and Aphanocladium sp. (two air-borne)grown on a natural Montmorillonite (B-MMT) by repeated treatments with dilute solutions, in order to approach more closely to natural conditions where there is a continued percolation of dilute solutions.The generated clay biopolymers (B-MMT) were characterized through X ray diffraction (XRD), measurement of the specific surface and electrophoretic mobility. The Uranium sorption capacity was determined in batch systems. The progressive adsorption was carried out by dispersing the different B-MMT in the Uranil nitrate solution containing 50 ppm uranium. After 2 hr the B-MMT was centrifuged, the supernatant solution poured off and measured, and a second quantity of solution was added. This procedure was repeated several times.B-MMT systems showed higher maximum Uranium adsorption than those obtained for microorganisms or MMT alone. The progressive adsorption indicated that B-MMT reached its maximum when the equilibrium is achieved. This confirms that even with very dilute uranyl solutions, complete saturation of the clay is possible after several adsorption cycles.Specific surface area (Sw) did not indicate any differences for B-MMT respect to the MMT.The XRD analysis of the reflection peak d(001) indicated interlayer space collapse for B-MMT respect of that of MMT.Uranium adsorption shift the MMT reflection peak d(001) around 3.5Å, indicating an Uranium entrance in the interlayer clay space.