APPLICATION OF SILICA-GEL TO METAL-ION SORPTION - STATIC AND DYNAMIC REMOVAL OF URANYL IONS

As an alternative to standard processes for the removal of heavy metals from low content effluents, silica gel was used experimentally to sorb dissolved uranium. Batch experiments show that rapid sorption occurs with a first phenomenon instantaneously reducing the metal concentration followed by a second sorption phenomenon of surface precipitation. This conclusion is in agreement with the sorption isotherms observed and with the effect of pH, related to the correlation existing between pH of hydrolysis and pH of effective sorption. Column studies show a good correlation between the experimental data and the calculated break-through curves obtained by the Adams-Bohart or related derived models, and the Clark model. An empirical method of prediction of 10% breakpoint, based on the estimated slope of the break-through curve obtained at 50% of the influent and on the saturation batch concentration in the sorbent, gives a good correlation, for both models cited above, between empirical calculated values and experimental data.