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 metal s from low content effluents, silica gel was used experimentally to so rb dissolved uranium. Batch experiments show that rapid sorption occur s with a first phenomenon instantaneously reducing the metal concentra tion 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 betwee n pH of hydrolysis and pH of effective sorption. Column studies show a good correlation between the experimental data and the calculated bre ak-through curves obtained by the Adams-Bohart or related derived mode ls, and the Clark model. An empirical method of prediction of 10% brea kpoint, based on the estimated slope of the break-through curve obtain ed at 50% of the influent and on the saturation batch concentration in the sorbent, gives a good correlation, for both models cited above, b etween empirical calculated values and experimental data.