Effect of pH on sorption ⁸⁵Sr, ¹³⁷Cs and ⁶⁰Co on chitosan, activated carbon and composite chitosan-activated carbon

For the environment, the pollution of water resources by anthropogenic radionuclides is very dangerous. Such radionuclides include ²³⁹Np, ²³⁹Pu, ¹³⁷Cs, ⁶⁰Co, ⁹⁹Tc, ¹³¹I, ⁸⁹Sr or ⁸⁵Sr. These are nuclear medicine products or nuclear plant products. Anthropogenic radionuclides were also produced by nuclear weapons tests. Suitable adsorbent materials capable of adsorbing radionuclides and heavy metals include carbon-based adsorbents or chitosan. This work studied the effect of pH on sorption of ⁸⁵Sr, ¹³7Cs and ⁶0Co on chitosan (CH 0.01 g), activated carbon (CA 0.01 g) and chitosan activated carbon (CH-CA 1: 1). It was found that the sorption of all the radioisotopes under investigation for the materials concerned was that R % increased with the increasing pH of the solution. The percentage of sorption in dependence on the used material, increased in order of CH 0.01 g < CA 0.01 g < CH-CA 1:1. The R % values were for CH-CA 1:1 higher than 91% for ⁶⁰Co-sorption for composite material, 94% for ⁸⁵Sr-sorption for composite material and 64% for sorption of ¹³⁷Cs for composite material. CH-CA 1:1 exhibited buffering properties ranging from pH 4 to 8 where the pH values after sorption were in ranged from 6.0 to 6.5. The measurement error was less than 5%. (authors)