Application of Natural Antibacterial Plants in the Extraction of Uranium from Seawater.

Marine biofouling directly affects the performance and efficiency of uranium (U(VI)) extraction from seawater. Compared to traditional chemical methods, natural plant extracts are generally biodegradable and nontoxic, making them an environmentally friendly alternative to synthetic chemicals in solving the marine biofouling problem. The effectiveness of natural antibacterial plants (i.e., pine needle, peppermint, Acorus gramineus Soland, Cacumen platycladi, and wormwood) in solving the marine biofouling problem was evaluated in this work. Experimental results showed that natural antibacterial plants could kill Vibrio alginolyticus in solution and effectively solve the marine biofouling problem of U(VI) extraction. To improve the adsorption capacity of natural plants for U(VI) in seawater, poly(vinylphosphonic acid) (PVPA) was modified on natural antibacterial plant surfaces by irradiation grafting technology. PVPA and natural antibacterial plants work as active sites and base materials for the U(VI) extraction material, respectively. The recovery performance of PVPA/pine needle for U(VI) was preliminarily studied. Results show that the adsorption of U(VI) on PVPA/pine needle follows pseudo-second-order and Langmuir models, and the maximum adsorption capacity is 111 mg/g at 298 K and pH 8.2.

Elimination of uranium pollution from coastal nuclear power plant by marine microorganisms: Capability and mechanism.

Uranium is one of the sensitive radionuclides in the wastewater of nuclear powers. Due to the fact that nuclear powers are mainly located in coastal areas, the elimination of uranium (U(VI)) pollution from coastal nuclear power is ultimately rely on marine microorganisms. The fixing of U(VI) on V. alginolyticus surface or converting it into sediments is an effective elimination strategy for U(VI) pollution. In this work, typical marine microorganism V. alginolyticus was used to evaluate the elimination of U(VI) pollution by marine microorganisms. Effects of solution conditions (such as pH, temperature, and bacterium concentrations) on the physicochemical properties and elimination capabilities of V. alginolyticus were studied in detail. FT-IR, XPS and XRD results reveal that COOH, NH2, OH and PO4 on V. alginolyticus were main functional groups for U(VI) elimination and formed (UO2)3(PO4)2·H2O. The elimination of U(VI) by V. alginolyticus includes two stages of adsorption and biomineralization. The theoretical maximum adsorption capacity (Cs,max) of V. alginolyticus for U(VI) can reach up to 133 mg/g at pH 5 and 298 K, and the process reached equilibrium in 3 h. Results show that V. alginolyticus play important role in the elimination of U(VI) pollution in seawater.

Retraction: A carboxymethyl cellulose modified magnetic bentonite composite for efficient enrichment of radionuclides.

[This retracts the article DOI: 10.1039/C6RA10990J.].

Application of poly(amidoxime)/scrap facemasks in extraction of uranium from seawater: from dangerous waste to nuclear power.

To effectively kill microorganisms on scrap facemasks (FMs) surface and provide new material for extracting uranium (U(VI)) from seawater, scrap FMs was treated by N2 capacitance coupled (CCP) plasma and modified with polyamidoxime (PAO). The obtained PAO/FMs was well characterized and applied as an adsorbent in the extraction of U(VI) from seawater. The effects of environmental conditions on the adsorption capability of PAO/FMs for U(VI) were briefly studied. Results showed that plasma technique can synchronously kill microorganisms and induce acrylonitrile (AN) polymerization on FMs surface. The prepared PAO/FMs presented excellent adsorption capability for U(VI). The experimental results highlighted the application of plasma technique in the management of scrap FMs, and PAO/FMs in the extraction of U(VI) from seawater.

Bismuth Coordinates with Iodine Atoms to Form Chemical Bonds for Existing Stabilization in Boron Glass.

Stabilizing radioactive iodine in boron glass for disposal was the ultimate goal of this study. In this study, bismuth was used near a monument. Thermogravimetric analysis showed that bismuth could remarkably stabilize iodine atoms in boron glass (only 3.74% of the mass was lost at 850 °C). Scanning electron microscopy-energy dispersive spectrometry images showed that most of the AgI was uniformly immobilized in the glass network. X-ray photoelectron spectrometry and NMR results confirmed the change in the coordination number of boron in the samples. The density functional theory calculation helped to understand the reason for the stable presence of iodine in boron glass. Iodine atoms were difficult to bond directly with boron atoms but tended to bond with bismuth atoms. From the spatial distribution of the structural molecular orbitals, it was observed that the bismuth atom releases electrons when stimulated, and the iodine atom needs to gain an electron to reach stability. At a low treatment temperature of 550 °C, the maximum density of the immobilized sample containing bismuth is 2.42 g·cm-3, and its iodine leaching rate at day 7 can be as low as 3.77 × 10-6 g·m-2·d-1. This study provides a way to improve the properties of boron glass microscopically in the future.

Application of poly(vinylphosphonic acid) modified poly(amidoxime) in uptake of uranium from seawater.

To enhance the anti-biofouling properties and adsorption capability of poly(amidoxime) (PAO), vinylphosphonic acid (VPA, CH2[double bond, length as m-dash]CH-PO3H2) was polymerized on poly(acrylonitrile) (PAN) surface by plasma technique, followed by amidoximation treatment to convert the cyano group (-C[triple bond, length as m-dash]N) into an amidoxime group (AO, -C(NH2)[double bond, length as m-dash]N-OH). The obtained poly(vinylphosphonic acid)/PAO (PVPA/PAO) was used as an adsorbent in the uptake of U(vi) from seawater. The effect of environmental conditions on the anti-biofouling property and adsorption capability of PVPA/PAO for U(vi) were studied. Results show that the modified PVPA enhances the anti-biofouling properties and adsorption capability of PAO for U(vi). The adsorption process is well described by the pseudo-second-order kinetic model and reached equilibrium in 24 h. Adsorption isotherms of U(vi) on PVPA/PAO can be well fitted by the Langmuir model, and the maximum adsorption capability was calculated to be 145 mg g-1 at pH 8.2 and 298 K. Experimental results highlight the application of PVPA/PAO in the extraction of U(vi) from seawater.

Rapid solidification of Sr-contaminated soil by consecutive microwave sintering: mechanism and stability evaluation.

Consecutive microwave sintering is a method proposed in this study to dispose soil contaminated by Sr during a nuclear accident by rapidly solidifying the contaminated soil. The results show that soil contaminated with 20 wt% SrSO4 and 30 wt% SrSO4 can be completely solidified by microwave sintering at 1100-1200 and 1300 â„ƒ, respectively, for 30 min. Sr was found to be cured into slawsonite (SrAl2Si2O8) and glass structures. Moreover, soil sintered at 1300 â„ƒ has large cured solubility (30 wt.%), good uniformity, and excellent hardness (6.9-7.2 GPa) and chemical durability (below 1.46 × 10-5 g m-2 d-1 at 28 d). Thus, consecutive microwave sintering technology may provide a new method for treating Sr-contaminated soil in case of a nuclear accident emergency.

Transformation details of poly(acrylonitrile) to poly(amidoxime) during the amidoximation process.

During the amidoximation process, transformation details of poly(acrylonitrile) (PAN) to poly(amidoxime) (PAO) is critical for optimizing amidoximation conditions, which determine the physicochemical properties and adsorption capabilities of PAO-based materials. Although the optimization of amidoximation conditions can be reported in the literature, a detailed research on the transformation is still missing. Herein, the effect of the amidoximation conditions (i.e. temperature, time, and NH2OH concentration) on the physicochemical properties and adsorption capabilities of PAO was studied in detail. The results showed that the extent of amidoximation reaction increased with increasing temperature, time, and NH2OH concentration. However, a considerably high temperature (>60 °C) and a considerably long time (>3 h) could result in the degradation and decomposition of PAO's surface topologies and functional groups, and then decrease its adsorption capability for U(vi). The optimal amidoximation condition was 3 h, 60 °C and 50 g L-1 NH2OH. At this condition, the PAO obtained presented the highest adsorption capability for U(vi) under experimental conditions. These results provide pivotal information on the transformation of PAO-based materials during the amidoximation process.

A review of biopolymer (Poly-ß-hydroxybutyrate) synthesis in microbes cultivated on wastewater.

The large quantities of non-degradable single use plastics, production and disposal, in addition to increasing amounts of municipal and industrial wastewaters are among the major global issues known today. Biodegradable plastics from biopolymers such as Poly-ß-hydroxybutyrates (PHB) produced by microorganisms are potential substitutes for non-degradable petroleum-based plastics. This paper reviews the current status of wastewater-cultivated microbes utilized in PHB production, including the various types of wastewaters suitable for either pure or mixed culture PHB production. PHB-producing strains that have the potential for commercialization are also highlighted with proposed selection criteria for choosing the appropriate PHB microbe for optimization of processes. The biosynthetic pathways involved in producing microbial PHB are also discussed to highlight the advancements in genetic engineering techniques. Additionally, the paper outlines the factors influencing PHB production while exploring other metabolic pathways and metabolites simultaneously produced along with PHB in a bio-refinery context. Furthermore, the paper explores the effects of extraction methods on PHB yield and quality to ultimately facilitate the commercial production of biodegradable plastics. This review uniquely discusses the developments in research on microbial biopolymers, specifically PHB and also gives an overview of current commercial PHB companies making strides in cutting down plastic pollution and greenhouse gases.

Harvesting the vibration energy of α-MnO2 nanostructures for complete catalytic oxidation of carcinogenic airborne formaldehyde at ambient temperature.

Vibration is one of the most prevalent energy sources in natural environment, which can also be harvested and utilized to drive chemical reaction. Herein, mechanical vibration is used for enhancing the catalytic decomposition of formaldehyde at ambient temperature with the assistance of four well-defined morphologies α-MnO2 (nanowire, nanotube, nanorod and nanoflower). In particular, α-MnO2 nanowire exhibits the best catalytic activity, which can completely mineralize formaldehyde into carbon dioxide at ambient temperature by harvesting the vibration energy. To the best of our knowledge, this may be the first report that α-MnO2, as a non-noble metal catalyst, can completely decompose formaldehyde to carbon dioxide at ambient temperature. The characterization results show that α-MnO2 nanowire has a much higher oxygen vacancy concentration than other three catalysts. In addition, thermal effect generated from friction between nanoparticles induced by ultrasonic vibration may enhance its catalytic activity. More importantly, it is the vibration that effectively promotes the activation of O2 adsorbed on the surface oxygen vacancy to produce more , thus increasing the catalytic decomposition performance. The strategy presented herein demonstrates a new approach for efficient use of mechanical vibration to improve catalytic activity of traditional catalysts.

Retraction: Enhanced adsorption of Eu(iii) on mesoporous Al2O3/expanded graphite composites investigated by macroscopic and microscopic techniques.

Retraction of 'Enhanced adsorption of Eu(iii) on mesoporous Al2O3/expanded graphite composites investigated by macroscopic and microscopic techniques' by Yubing Sun et al., Dalton Trans., 2012, 41, 13388-13394.

Correction: Plasma-induced grafting of polyacrylamide on graphene oxide nanosheets for simultaneous removal of radionuclides.

Correction for 'Plasma-induced grafting of polyacrylamide on graphene oxide nanosheets for simultaneous removal of radionuclides' by Wencheng Song et al., Phys. Chem. Chem. Phys., 2015, 17, 398-406.

Retraction: Enhanced adsorption of ionizable aromatic compounds on humic acid-coated carbonaceous adsorbents.

[This retracts the article DOI: 10.1039/C2RA21713A.].

Correction: Preconcentration of U(vi) ions on few-layered graphene oxide nanosheets from aqueous solutions.

Correction for 'Preconcentration of U(vi) ions on few-layered graphene oxide nanosheets from aqueous solutions' by Guixia Zhao et al., Dalton Trans., 2012, 41, 6182-6188.

Correction: Efficient removal of cobalt from aqueous solution using ß-cyclodextrin modified graphene oxide.

[This corrects the article DOI: 10.1039/C3RA41434E.].

Heavy-ion irradiation effects on U3O8 incorporated Gd2Zr2O7 waste forms.

In this research, the heavy-ion irradiation effects of U-bearing Gd2Zr2O7 ceramics were explored for nuclear waste immobilization. U3O8 was designed to be incorporated into Gd2Zr2O7 from two different routes in the form of (Gd1-4xU2x)2(Zr1-xUx)2O7 (x = 0.1, 0.14). The self-irradiation of actinide nuclides was simulated by Xe20+ heavy-ion radiation under different fluences. Grazing incidence X-ray diffraction (GIXRD) analysis reveals the relationship between radiation dose, damage and depth. The radiation tolerance is promoted with the increment of U3O8 content in the discussed range. Raman spectroscopy testifies the enhancement of radiation tolerance and microscopically existed phase evolution from the chemical bond vibrations. In addition, the microstructure and elemental distribution of the irradiated samples were analyzed as well. The amorphization degree of the sample surface declines as the U content was elevated from x = 0.1 to x = 0.14.

Exploring the Sorption Mechanism of Ni(II) on Illite: Batch Sorption, Modelling, EXAFS and Extraction Investigations.

The sorption mechanism of nickel (Ni) at the illite/water interface was investigated using batch, sorption modelling, extended X-ray absorption fine structure (EXAFS), and extraction approaches. The results showed that Ni(II) sorption on illite was strongly dependent on pH, contact time, temperature, and initial Ni(II) concentration. At a low initial Ni(II) concentration, the ion exchange species of ≡X2Ni° and the inner-sphere complexes including ≡SsONi+, ≡SwONi+ and ≡SwONiOH° species are observed on the sorption edges of Ni(II) on illite. As the initial Ni(II) concentration increased to 1.7 × 10-3 mol/L, precipitates including surface-induced precipitation of s-Ni(OH)2 and amorphous Ni(OH)2 became more significant, especially under neutral to alkaline conditions. EXAFS analysis confirmed that Ni-Al layered double hydroxide (LDH) can gradually form with an increase in the contact time. At pH 7.0, α-Ni(OH)2 was produced in the initial stage and then transformed to the more stable form of Ni-Al LDH with increasing contact time because of the increased Al3+ dissolution. With an increase in temperatures, α-Ni(OH)2 phase on illite transformed to Ni-Al LDH phase, indicating a lower thermodynamic stability compared to Ni-Al LDH phase. These results are important to understand the geochemical behaviors to effectively remediate soil contaminated with Ni(II).

Sorption of Nickel(II) on a Calcareous Aridisol Soil, China: Batch, XPS, and EXAFS Spectroscopic Investigations.

The sorption of Ni(II) on a calcareous aridisol (CA) soil, one of the major soil types in northwestern China, was investigated using batch and extended X-ray absorption fine structure (EXAFS) approaches in a 0.01 mol/L NaClO4 solution at different pH values (6.0-10.0), temperatures (25-60 °C) and contact times (2-15 days). Under alkaline conditions, EXAFS analysis showed that the interatomic distances between Ni and O atoms (RNi-O) were approximately 2.04 Å with a typical coordination number (CN) of ~6.0 O atoms in the contact time range from 2 to 15 days. The RNi-Ni (~3.07 Å) suggested that the structure of the Ni(II) adsorbed on the CA soil was basically the same as that of Ni(OH)2(s), while the Ni-Al shell (RNi-Al ~3.16 Å) gradually formed and grew with the increasing contact time. Under weakly acidic conditions, the sorption mechanism of Ni(II) on the CA soil possibly included at least two processes: (i) a fast accumulation dominated by ion exchange and surface complexation and (ii) the formation of a Ni-Al LDH phase over the long term. A high temperature is beneficial to the fixation of Ni(II) on the CA soil and the formation of a Ni-Al LDH.