Nanostructured surfaces 

Effect of Rhizobium leguminosarum bv Trifolii exopolysaccharide on the cadmium(II) adsorption on nanostructured montmorillonite particles
Szewczuk-Karpisz K. 1, Bajda T.2
1 Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, 20-290 Lublin, Poland.
E-mail: k.szewczuk-karpisz@ipan.lublin.pl
2 AGH University of Science and Technology, Faculty of Geology, Geophysics and Environmental Protection, Mickiewicza 30, 30-059 Krakow, Poland.

Exopolysaccharides (EPS) are macromolecular compounds synthesized by soil bacteria. They are excreted into the environment and involved in establishing symbiosis between these microorganisms and Fabaceae plants enabling the fixation of atmospheric nitrogen. Exopolysaccharides can also affect the accumulation of toxic compounds in soil, e.g. contribute to a strong immobilization of heavy metal ions on the surface of soil minerals and thus reduce their availability for plants and animals [1]. What is more, EPS can significantly limit the leaching of micro- and macroelements to groundwater and ensure their gradual release at the same time. 
The main aim of this study was to determine the impact of exopolysaccharide (EPS), synthesized by soil bacteria Rhizobium leguminosarum bv Trifolii, on the accumulation of cadmium(II) ions on the surface of the selected clay mineral –  montmorillonite from the smectite group. The applied solid was separated from natural bentonite derived from the Jelsovy Potok deposit in Slovakia. The obtained results indicated that experimental Cd(II) adsorbed amount on smectite equaled 8.34 mg/g (41%). The EPS addition increased the ion adsorption to the value of 10.8 mg/g (50.4%). It was probably dictated by formation of polymer-metal ions complexes of intramolecular character.

1.	Palansooriya K.N., Shaheen S.M., Chen S.S., Tsang D.C.W., Hashimoto Y., Hou D., Bolan N.S., Rinklebe J., Ok Y.S. Soil amendments for immobilization of potentially toxic elements in contaminated soils: A critical review// Environ. Int.-2020-134.-105046.
 
This research was partly financed by National Science Center, Poland (2020/04/X/NZ9/00275).