Biosorption of U(VI) from aqueous systems by malt spent rootlets. Kinetic, equilibrium and speciation studies

Abstract

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 NaNO 3 ). 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 Na 2 CO 3 was the most efficient eluent with 78 % of U(VI), previously bound on the biosorbent's surface, recovered.

Sodium silicate treatment for the attenuation of U(VI) by iron‐bearing sediments in acidic groundwater plumes

“…Surface sorption is usually attributed to physical sorption, denoting no specificity of the adsorbate towards the adsorbent. In the opposite case, where no strong linear correlation between surface and sorption efficiency is observed, the involvement, to some degree, of chemical binding between the adsorbate and the active surface groups is assumed . Furthermore, the correlation of iron concentration with U(VI) removal is almost linear and this suggests that iron concentration drives uranium removal rather than surface area.…”

“…In the opposite case, where no strong linear correlation between surface and sorption efficiency is observed, the involvement, to some degree, of chemical binding between the adsorbate and the active surface groups is assumed. 1,21 Furthermore, the correlation of iron concentration with U(VI) removal is almost linear and this suggests that iron concentration drives uranium removal rather than surface area. The results imply that retention of U(VI) by SRS sediment under circumneutral conditions could be attributed to chemical binding between U(VI) and active groups of the minerals that SRS sediment comprises of and more specifically goethite.…”

“…Several human activities, such as uranium mining and minerals processing, for the requirements of nuclear industry, have released into the environment uranium and other radionuclides, such as uranium series decay products. They pose a severe, long‐term ecological and public health threat …”

“…They pose a severe, long-term ecological and public health threat. 1 More specifically, uranium mining may result in extensive contamination of groundwater and/or acidification, as a result of geochemical processes, like oxidation of sulfide bearing minerals. 2,3 A typical example of nuclear weapons production leading to groundwater contamination is the US Department of Energy's Savannah River Site (SRS) complex.…”

Valorization of brewery waste

“…[20] malt kökçüğünü atık sulardan civa ve Anagnostopoulos ve diğ. [21] ise uranyum uzaklaştırılması için biyosorbant olarak kullanmışlar ve malt kökçüğünün, bu metaller için önemli bir sorpsiyon kapasitesine sahip olduğunu belirlemişlerdir.…”