Progressive Adsorption of Uranium by Biomass Modified Montmorillonite

OLIVELLI, MELISA SOLEDAD; CURUTCHET, GUSTAVO; TORRES SÁNCHEZ, ROSA MARÍA

Salvador de Bahia

Congreso; Environmental Health 2011; 2011

Uranium is a heavy metal associated to 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 fungi biomass (Acremonium sp. and Aphanocladium sp.) grown on a natural Montmorillonite 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, specific surface area (Sw) and electrophoretic mobility. The progressive Uranium adsorption was carried out in batch systems. The B-MMT was dispersed in the Uranil nitrate solution containing 50 ppm Uranium. After 2 hr, the B-MMT suspension was centrifuged, the supernatant solution poured off and measured, and a second quantity of solution was added. This procedure was repeated several times. MMT systems showed higher maximum Uranium adsorption than MMT. The progressive adsorption indicated that B-MMT reached its maximum of sorption after several cycles. This confirms that even with very dilute uranyl solutions, complete saturation of the clay is possible. Sw did not indicate any differences for B-MMT respect to the MMT. XRD analysis indicated interlayer clay space collapse for B-MMT. Uranium adsorption shift the MMT reflection peak d(001) around 3.5Å, indicating the entrance of uranium in the interlayer space. These preliminary studies conclude that these biofilm-clay systems have a great potentiality for Uranium biosorption processes given its high cationic exchange capacity and its ability to adapt the process to different situations.