Studies of internal gelation for the production of microspheres: sonication assisted gelation

Internal gelation studies are carried out with mixed oxides of uranium and plutonium (MOX) and HMUR (i.e. mixture of hexamethylene tetramine (HMTA) and urea in 1:1 proportion). It is necessary to find surrogate of MOX for the detailed experimental work. Hence, the studies have been carried out with aluminium nitrate and magnesium nitrate. Important parameters of gelation such as temperature and concentration of precursors and the effect of sonication and drying on the gelled particles have been studied using these nitrates and HMUR. It has been found that micromixing (sonication) provides narrow and compact size distribution as compared to macromixing (using magnetic stirrer) and temperature of the precursors does not affect the size distribution of the gelled particles. The effect of drying has been studied using IR (infrared) dryer and oven dryer and it was found that IR drying augments the performance as compared to oven drying. Depending on the solubility of the gel in water and its appearance (as pasty mass which is similar to uranyl nitrate gel) aluminium nitrate is chosen as an appropriate surrogate for MOX. FTIR studies have been carried out for characterization of the gel.