BACKGROUNDIn nuclear medicine, the discharge of the radionuclides waste into the environment can cause serious environmental problems. It is preferable to remove these radionuclides from aqueous waste before discharging. Biosorption as an alternative has been becoming more important. The aim of the present work is to remove radioactive Tl-201 by biosorption from the aqueous media using the solid waste of an oleum rosea processing plant as a biosorbent. RESULTSRadioactive Tl-201 was removed from aqueous solution by biosorption in a stirred batch process with experimental parameters pH, temperature, adsorbent dose, nominal adsorbent size, and stirring speed. The effectiveness of the parameters in decreasing order was found to be initial pH, particle size and adsorbent dose. The biosorption yield is slightly reduced with increasing temperature, and no considerable effect of stirring speed was observed. The process is multi-layered on the heterogeneous surface and has a physical character. Negative G showed that the process is spontaneous, and negative H indicates that the process has exothermic character. CONCLUSIONSThe process has serious potential because of its fast biosorption rate with an equilibrium period of about 10min and high biosorption yields up to 93%. (c) 2013 Society of Chemical Industry