Adsorption of Radionuclides (134Cs, 85Sr, 226Ra, 241Am) by Extracted Biomasses of Cyanobacteria (Nostoc Carneum, N. Insulare, Oscillatoria Geminata and Spirulina Laxis-Sima) and Phaeophyceae (Laminaria Digitata and L. Japonica; Waste Products from Alginate Production) at Different pH

Abstract

The extracted biomasses of four cyanobacteria (Nostoc carneum, Nostoc insulare, Oscillatoria geminata, and Spirulina laxissima) grown in axenic mass cultures, and of four samples of Laminaria obtained from different locations (L. digitata I and II, France; L. japonica I and II, China; all waste products from alginate production) were tested for their ability to adsorb four radionuclides (134Cs, 85Sr, 226Ra, and 241Am) under different pH regimes. In addition, two of the cyanobacterial biomasses (N. carneum. and O. geminata) and the four Laminaria biomasses were phosphorylated before being tested as radionuclide adsorbers. The non-phosphorylated cyanobacterial biomasses showed very low adsorption of 134Cs but substantially higher removal of 85Sr and 226Ra, which increased with increasing pH. 241Am was almost completely removed from the solution at low pH, but less at higher pH. After phosphorylation, removal of 134Cs, 85Sr and 226Ra by the cyanobacterial biomasses was improved, particularly at lower pH, but there was almost no adsorption of 241Am. The non-phosphorylated Laminaria biomasses showed good removal of 134Cs and very good adsorption of 85Sr and 226Ra. Removal of 241Am was high at low pH but decreased with increasing pH. After phosphorylation, adsorption of 134Cs by Laminaria samples was slightly improved; removal of 85Sr and 226Ra was increased at low pH with a tendency towards decrease in adsorption with increasing pH; but almost no 241Am was adsorbed. The origin of the cyanobacterial and Laminaria materials appeared to have little effect on the adsorption of the radionuclides.