Biosorption and biomineralization of U(VI) by Kocuria rosea: Involvement of phosphorus and formation of U-P minerals.

The biosorption and biomineralization behavior of U(VI) by Kocuria rosea with uranium resistance higher than other general microorganisms was investigated in this study. The results showed the obvious effects of initial U(VI) concentration, biomass, time, and especially pH, and presented that U(VI) was immobilized to K. rosea by physical and chemical action. The characterization results for the precipitation proved that U-P minerals with U(VI) (H3OUO2PO4·3H2O, H2(UO2)2(PO4)2·8H2O) or U(IV) (CaU(PO4)2) were dominant, and the crystallization level increased with time. In the process, the phosphorous containing groups, amino, hydroxyl and carboxyl groups played important roles in adsorption of U(VI), and the phosphate groups were crucial in immobilization of uranium, showing the importance of groups containing phosphorus in both biosorption and biomineralization processes. Our findings focus on the biosorption and biomineralization mechanism of U(VI) by K. rosea, emphasize the synergy of physical adsorption and chemical immobilization in the process and formation of U(VI)-P and U(IV)-P minerals, and highlight the significance of phosphorus involvement in the reaction.

Organic acid mediated photoelectrochemical reduction of U(vi) to U(iv) in waste water: electrochemical parameters and spectroscopy.

The photoelectrochemical reduction of U(vi) is recognized as an economical and effective way to eliminate radioactive pollution. In this study, we construct a α-Fe2O3/TiO2 film electrode-based photoelectrochemical cell to remove U(vi) and recover uranium from aqueous solution. Citric acid and oxalic acid could act as hole scavengers, being favorable for the photocatalytic reduction of U(vi). In the presence of 0.5 mM citric acid and oxalic acid, the uranium removal capacity reached 70% and 58%, respectively, while 24% was achieved for the system in the absence of acid. The XRD, SEM, FT-IR and XPS results revealed that a proportion of U(iv) was also precipitated as surface associated metastudtite. These novel observations have significant implications for the behavior of uranium within engineered and natural environments.

Removal of lead(II) and copper(II) from aqueous solution using foitite from Linshou mine in Hebei, China.

Foitite from Linshou mine in China's Hebei province was investigated as an adsorbent to remove Pb(II) and Cu(II) from aqueous solution. The results showed that foitite can readily remove heavy metal ions from aqueous solution. The data shows that the metal uptake for Pb(II) increases rapidly, accounting for 74.47% when contact time was 2 min. In contrast to Pb(ll), there was a worse capability for adsorption of Cu(II). In the first 4 min, the metal uptake accounted for 34.7%. According to the analytical results obtained from X-ray diffraction, laser Raman spectrum, X-ray energy dispersive spectrometer, and Zeta potential, the removal mechanism of Pb(II) and Cu(II) by using foitite can be explained as following: firstly, the existence of an electrostatic field around foitite particles can attract heavy metal ions and consequently combine heavy metal ions with OH; secondly, heavy metal ions in the solution are exchanged with the Fe3+ and Al3+ in the foitite.

Research on the additives to reduce radioactive pollutants in the building materials containing fly ash.

Several kinds of functional additives such as barite, zeolite, ferric oxide, gypsum, and high alumina cement were introduced to prepare a low-radiation cement-based composite to reduce radioactive pollutants contained in fly ash. The effect of content and granularity of the functional additives on the release of radioactive pollutants were investigated. Composites were characterized by X-ray diffraction, Scan electron microscopy. The results indicate that the radioactive pollutants contained in the fly ash can be reduced by adding a proper amount of zeolite, ferric oxide, gypsum, and high alumina cement. The release of radon from fly ash decreases with a decrease in the granularity of additives. Compared with traditional cement-based composite containing fly ash, the release of radon can be reduced 64.8% in these composites, and the release of gamma-ray is decreased 45%. Based on the microstructure and phase analysis, we think that by added functional additives, there are favorable to form self-absorption of radioactivity in the interior composites. This cement-based composite will conducive to fly ash are large-scale applied in the field of building materials.