Biosorption of U(VI) from aqueous systems by malt spent rootlets. Kinetic, equilibrium and speciation studies|
Anagnostopoulos, V.; Symeopoulos, B.; Bourikas, K. & Bekatorou, A.
A low-cost and environmentally friendly cleanup
technique is evaluated in this study, based on the use of
a brewery by-product, malt spent rootlets, as potential
biosorbent for U(VI) sequestration from aquatic systems.
Uranium uptake was rapid (2.5 h at 25 °C), and MSR
exhibited capability of removing U(VI) from effluents of
high acidity (pH 1.5) and salinity (0.5 M NaCl and
NaNO3). Maximum uptake was 157 mg U(VI) g-1 at
25 °C. The pseudo-second-order model gave the best fit for
kinetic data, whereas film diffusion was the rate-controlling
step. Langmuir adsorption isotherm was the best fitting
model. Activation energy, thermodynamic data and the
extent of sorption reversibility implied that sorption of
U(VI) is predominantly chemical. FTIR studies showed
that lignin moieties are mainly responsible for U(VI)
uptake. Speciation modeling showed that only positively
charged and uncharged uranium species can be retained on
the biomass. Finally, desorption studies revealed that
Na2CO3 was the most efficient eluent with 78 % of U(VI),
previously bound on the biosorbent’s surface, recovered.
Uranium; Uptake; Isotherm; Kinetics; Titration; Modelling