No abstract

Cryptomelane-type (potassium) and todorokite-type (magnesium and calcium) manganese oxides were prepared and studied for the removal of radionuclides from aqueous solutions containing inactive metal ions of interest in radionuclide-bearing nuclear waste effluents. Batch distribution coefficients were measured as a function of pH and sodium, potassium, magnesium, and calcium ion concentrations. Trace strontium (89Sr) and cesium (137Cs) ions were taken up by ion-exchange mechanisms. Selectivity coefficients were estimated as K Cs/K = 0.6 and K Sr/K = 1.0 for cryptomelane and K Cs/Mg = 7550, K Sr/Mg = 50, and K Sr/Ca = 10 for todorokite. The cryptomelane analogue was particularly effective for the separation of trace silver ions (110Ag) in low-pH solutions. Todorokite analogues were effective for a wider range of radionuclides, including 57Co across a wide pH range (1−10) and 137Cs in acidic solution. The affinity sequence for magnesium and calcium ion-extracted (acid-treated) todorokites in 0.1 HNO3 was 137Cs > 59Fe > 51Cr ≈ 57Co ≈ 241Am > 54Mn > 63Ni > 65Zn > 236Pu > 89Sr.

This work examines the ability of commerical zeolite Y to act as a slow release agent for a number of anthelmintic drugs. Administration to rats, dosed with Nippostrongylus brasiliensis, of pyrantel and/or fenbendazole and pigs, dosed with Ascaris and Oesophagostomum, of dichlorvos (DDVP) loaded onto zeolite Y was more sucessful in killing adult worms than administration of the pure drug alone. The zeolite Y was used as supplied for initial studies and then later dealuminated for further studies. The drug loadings were monitored by thermal analysis and the loaded zeolites were used in several field trials. The results indicate that zeolite Y is a suitable vehicle for the slow release of some anthelmintics. The slow release of drug from the zeolite matrix improved its efficacy.