Preferential adsorption of uranium by functional groups of the marine unicellular cyanobacterium Synechococcus elongatus BDU130911

This study reports the surface interaction of the chemically modified marine unicellular cyanobacterium Synechococcus elongatus BDU130911 with uranium. The selective functional groups of the control (dead biomass) for binding with uranium in unicellular marine cyanobacteria were identified as carboxyl groups. The adsorption capacity of the biomass in a 1 mM uranium solution was found to be 92% in the control, 85% in the amine-blocked treatments, and 20% in the carboxyl-blocked treatments. The Langmuir isotherm provided a good fit to the data, suggesting a monolayer of uranium adsorption on all the tested biomass. The functional groups involved in the adsorption of uranium by the control and modified biomass were assessed by Fourier transform infrared spectroscopy, energy dispersive X-ray fluorescence and X-ray diffractive analysis. The results of this study identify, carboxyl groups as the dominant anionic functional group involved in uranium adsorption, which validates an ionic interaction between the biomass and uranium, a cationic metal.