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Selected samples of waste microbial biomass used in industrial fermentation processes and wastewater biological treatment plants have been studied for their radium biosorption ability from aqueous solutions. Equilibrium biosorption isotherms have been used to quantify the radium uptake capacity of the various types of biomass which were also compared to two types of activated carbon. Solution pH affected the observed uptake significantly. In general, the biomass types that showed appreciable sorption capacity exhibited maximum uptake between pH 7 and 10. The uptake was reduced considerably at pH 4 and little or no uptake was observed at pH 2. Radium biosorptive uptake capacities of the order of 4.5 x 10(4) nCi/g, at pH 7 and at an equilibrium radium concentration of 1000 pCi/L, were determined for a mixed culture, while the biomass of Penicillium chrysogenum adsorbed 5 x 10(4) nCi/g radium under the same conditions. The highest uptake value for a sample of F-400 granular activated carbon was 3600 nCi/g at pH 7 and 1000 pCi/L radium concentration. The biosorptive radium uptake of microbial biomass is compared to literature values for other types of adsorbents. The most effective biomass types studied exhibited radium removals in excess of 99% of the radium in solution.

Can. J. Chem. 56, 831 (1978). The results of a set of experiments designed to delineate the nucleation rate, supersaturation, temperature surface for the system CaS04.2H20/H20 are reported. The data were obtained using the droplet technique coupled with i t~ sitrc generation of SO4'-under the conditions that dS/dt was large during the early part of the induction period and it was zero during the actual nucleation events. The observed shape of the surface is compared with that suggested by the classical theory of nucleation and differences are commented on. The critical parameters important in classical nucleation theory are reported.D. M. KELLER, RONALD E. MASSEY et 0. E. HILEMAN, JR. Can. J. Chem. 56, 831 (1978). On rapporte les risultats d'un ensemble d'exptriences ayant pour but de dtlimiter la vitesse de nucltation, la sursaturation et la surface de temptrature du systkrne CaS04.2H20/Hz0. On a obtenu les donntes en utilisant la technique des goutellettes de concert avec la formation itz sit11 de SO4'-dans des conditions telles que la valeur dS/dr est plus grande durant la partie initiale de la ptriode d'induction et qu'elle est tgale a ztro lorsque la nucleation s'effectue. On a compart la forme observte pour la surface avec celle qui est suggtrie par la thtorie classique de la nucliation et on prtsente des commentaires au sujet des differences. On rapporte les paramttres critiques importants dans la thtorie de nucltation classique.[Traduit par le journal]

Nucleation rates from solutions of calcium sulfate dihydrate were measured at constant supersaturation but at varying cation:anion ratios. Induction times were also measured. The values of each were found to be dependent on the Ca:SO4 ratio. The results of empirical modeling studies are reported. These suggest that ion pair formation has an impact on the nucleation event beyond that of ion removal.

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