Removal of the radionuclides from aqueous solutions by biosorption on the roots of the dandelion ( Taraxacum officinale  )

A novel biosorbent—dandelion root (DRB)—was investigated as adsorbent for removal of Sr(II) and Am(III) from aqueous solutions. Batch equilibrium experiments were carried out to study the effect of contact time, initial concentration of the metal and pH of the media as well as of the sorbent amount. The equilibrium time was found to be 90 min for adsorption of both radionuclides. The kinetic model can be described by the pseudo-second-order model well, and the isotherm model is fitted to Freundlich model the best. The maximum adsorption capacity of the DRB at pH about 6.0 was calculated to be 63.7 and 80.6 g kg^-1 for Sr(II) and Eu(III), respectively. About 90 % of Am(III) and 80 % of Sr(II) were removed when 30 mg of the biosorbent was used in 1 mL of the solution. Use of the sequential portions of the fresh sorbent is expected to increase efficiency of the process. Complexation of Sr(II) and Am(III) by strong chelating agents, e.g., citrate, oxalate and EDTA, did not diminish significantly the sorption efficiency of the sorbent. Once sorbed, <1 % of each radionuclide was desorbed by water.
Graphical Abstract Low-cost biomass obtained from the dandelions’ roots (DRB) was investigated as adsorbent for removal of strontium and americium from aqueous solutions.

Keywords
Americium-241; Aqueous contaminated solutions; Dandelion root; Isotherms; Metal ions biosorption; Radioactive wastes; Radionuclides; Strontium-85