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Excellent column packing is a precondition for efficient separation of radioactive 90Sr from high level liquid waste (HLLW). α-ZrP particles are traditionally used as column packing for capturing radioactive nuclides from HLLW due to their excellent stability and adsorption ability. However, there remains room for improvement in terms of capacity and selectivity. Here, the traditional α-ZrP column packing was exfoliated and further modified by anchoring sulfonic groups on its surface to improve its adsorption capacity for 90Sr. The resulting ZrP-SO3H not only retained the excellent properties of α-ZrP but also possessed a larger surface area and much more adsorption sites. Adsorption experiments indicated that ZrP-SO3H exhibited excellent adsorption ability for separating of Sr2+ from acidic condition, and the maximum adsorption capacity of Sr2+ fitted by a Langmuir model is 183.21 mg g−1, which is higher than that of traditional α-ZrP and other similar column packings. In addition, kinetic studies indicated that Sr2+ adsorption on ZrP-SO3H is fast, and surface chemical adsorption is the main interaction between Sr2+ and ZrP-SO3H. Remarkably, radioactive experiment proved that ZrP-SO3H is an excellent adsorbent, and shows good stability for high efficiency for selective removal of 90Sr under complicate radioactive environment. Our present results implied that the novel ZrP-SO3H is potential column packing and could be suggested as promising column packing for separation of 90Sr from HLLW.

Knowledge of uranyl (UO22+) aqueous speciation and chemical interactions with natural organic matter is the basis to mode the sorption and transport behavior of uranyl. Anserine is a natural dipeptide containing β-alanine and 1-methylhistidine, which can be found in the skeletal muscle of birds and certain species of mammals. The complexation of anserine with uranyl cation was studied thermodynamically and structurally at 25 °C, I = 0.5 mol·L−1 NaCl solution. Protonation of anserine was investigated by potentiometry, microcalorimetry and NMR spectroscopy. Experimental results confirmed that there are three successive proton reaction steps for a totally deproton anserine. The order of successive protonation sites are the terminal amine nitrogen atom of alanine, amine nitrogen atoms in imidazole ring, and finally carboxylate oxygen. This trend is in agreement with exothermic enthalpies of protonation reaction. Potentiometry was used to measure stability constant of uranyl complex in solution. Thermodynamic studies identified four uranyl/anserine complexes with different degrees of deprotonation, UO2(HL)2+, UO2L+, UO2L2(aq) and UO2(OH)L2−. Coordination modes of the three complexes [UO2(HL)2+, UO2L+ and UO2L2(aq)] were investigated by NMR spectroscopy. In these complexes, anserine holds a tridentate mode. Cyclic voltammetry was performed to understand the influence of anserine exert over redox response to uranium in solution. The results confirmed that oxidation state of uranyl cation is stabilized significantly and harder to be reduced by complex with anserine. Anserine could effectively suppress the hydrolysis of uranyl in aqueous solutions.

Glufosinate, an analogue of glutamic acid (also known as phosphinothricin), is an important herbicide. The protonation constants of glufosinate were determined by means of potentiometric titrations at variable temperatures with ionic strength 0.5 mol·L−1 (NaCl solution). The heat effects of the protonation reactions of glufosinate were measured by direct calorimetry. NMR spectroscopies have demonstrated that the first protonation site occurs on the nitrogen atom in the amino group, followed by one of the oxygen atoms in the phosphono group, and finally the carboxyl oxygen atom. This trend is in good agreement with the enthalpy of protonation and crystal structure results. These data will help to predict the speciation of glufosinate in physiological systems.

Recently, 2D-MXene materials have attracted much attention. However, their low adsorption capacities for metal ions have limited their application in nuclear wastewater disposal. Here, we describe the unprecedentedly high adsorption by Ti3C2Tx for the removal of radionuclides by a simple and efficient surface modification strategy. We have produced an Alk-Ti3C2Tx material possessing desirable properties such as wide layer spacing and abundant active adsorption sites, with excellent ability to remove barium ions from aqueous solution. Maximum Ba2+ adsorption by Alk-Ti3C2Tx is 46.46 mg g-1, almost three times higher than that of unmodified Ti3C2Tx and much higher than that reported in previous studies. The remarkable selectivity for the removal of Ba2+ from simulated mixed nuclear wastewater is highly desirable for application in environmental wastewater treatment.

O-Phospho-l-serine is one of the naturally occurring phosphorylated amino acids, having important pharmacological activity and bioactivity. The protonation constants of O-phospho-l-serine were determined by means of potentiometric titrations at 25 °C and ionic strength of 0.5 mol·L−1 (NaCl). The heat effects of the protonation reaction of the O-phospho-l-serine were measured by direct calorimetry. NMR spectroscopy has demonstrated that the first protonation site occurs at the nitrogen atom in the amino group, followed by one of the oxygen atoms in the phosphono group, and finally the carboxyl oxygen atom. This trend is in good agreement with the enthalpy of protonation and quantum chemical calculations. These data will help to predict the speciation of O-phospho-l-serine in physiological systems.

N-(phosphonomethyl)-l-proline is an analogue of glyphosate. The protonation for N-(phosphonomethyl)-l-proline was studied by potentiometry, calorimetry, 31P NMR spectroscopy and quantum chemical calculations to further understand the protonation process of glyphosate. The results confirmed that the order of successive protonation sites of totally deprotonated N-(phosphonomethyl)-l-proline are a phosphonate oxygen, amino nitrogen, and finally the carboxylate oxygen. The results can improve the understanding of the biological activity of these types of molecules in solution.

A novel layered functionalized zirconium phosphonate adsorbent (DB-ZrP) was prepared by intercalating of 3, 4-dibenzo-21-crown-7 into the interlamination of α-ZrP. DB-ZrP not only efficiently combined the advantages of α-ZrP and 3, 4-dibenzo-21-crown-7 including the good stability and strong adsorption ability, but also overcame their disadvantages such as the loss of crown ether in aqueous solution and the collapsing of the layered structure of α-ZrP under rigid condition. Remarkably, DB-ZrP exhibited preferential Cs+ adsorption from HNO3 media even in the presence of competing ions, and the maximum Cs+ adsorption capacity obtained from a Langmuir isotherm model was 177.98 mg g−1, which was attributed to the wider layer distance and abundant adsorption sites after intercalating of 3,4-dibenzo-21-crown-7. The kinetics dates indicated the adsorption process was slow and the intra-particle diffusion was the main rate-controlling step. The thermodynamic coefficients suggested the passage of Cs+ ions through the liquid solid boundary was endothermic and spontaneous. The adsorbent could be reused in several cycles without no significant loss. Moreover, this excellent adsorption performance of DB-ZrP had also been observed in radioactive experiment for 137Cs removal from HNO3 media, which further specified that as-prepared DB-ZrP was a sustainable as well as efficient adsorbent for practical decontamination of radioactive liquid waste.

Radioisotopes pose a potential mass threat to public heath if accidently released into the environment. To mitigate the consequences, effective methods must be developed for removal of radioactive ions from the environment. In this study, we show that nanofibers of sodium niobate with negatively charged layers and readily exchangeable sodium ions between the layers can efficiently remove radioactive Sr 2+ . The exchange of Sr 2+ ions with the interlayer Na + ions can cause structural deformation of layers, trapping the Sr 2+ in the nanofibers. Furthermore, silver oxide (Ag 2 O) nanocrystals can be firmly anchored on the surface of niobate nanofibers via coherent interfaces between Ag 2 O and niobate phases. I − anions in fluids can easily access the Ag 2 O nanocrystals and be efficiently trapped by forming an AgI precipitate that firmly attaches to the adsorbent. This bi-functional absorbent can be arranged to remove Sr 2+ and I − ions simultaneously by optimizing the Ag 2 O loading and Na + content of the niobate nanofibers. It can provide high adsorption capacity for both ions in basic media, unlike other adsorbents that can be used in acid or neutral media. The maximum adsorption capacities of Sr 2+ and I − for Ag 2 O anchored sodium niobate nanofibers were found to be 148.92 and 296 m 2 g −1 respectively. Furthermore, the niobate adsorbents can be readily dispersed in liquids and easily separated after purification due to their fibril morphology, which significantly enhances their adsorption efficiency and reduces separation costs. This study demonstrates that Ag 2 O anchored sodium niobate nanofibers with fibril morphology, negatively charged thin layers and readily exchangers are potential sorbent for the simultaneous uptake of cations and anions.

A series of Sr1–1.5x Y x TiO3 (x = 0–12) solid solutions were synthesized by a solid state reaction process. The effects of reaction temperature and dopant on the crystallinity, microstructure and morphology of Sr1–1.5x Y x TiO3 (x=0–0.12) were investigated. Pure and single-phase perovskite-type Sr1–1.5x Y x TiO3 (x

WO3 nanowires were fabricated by a hydrothermal method, which proceeded at 170 °C for 48 h in a solution containing C2H10N6H2SO4 as a dispersant and Na2WO4 as a starting material. The nanowires exhibit a well crystallized one-dimensional structure with 20 nm in diameter and several microns in length. The physicochemical properties of WO3 were compared using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) and UV-vis spectroscopy (UV-Vis). The photoactivity of the as-perpared WO3 nanowires was evaluated through the photodegradation of methylene blue (MB) in aqueous solution. The experimental results demonstrate that addition of C2H10N6H2SO4 salt in the WO3 nanowires synthesis process can enhance its photocatalytic activity obviously.

The intercalated α-ZrP materials have been extensively concerned due to their excellent properties for removal of metal ions from complex system. However, the relationship between the metal ions and the intercalated materials need be investigated to better imply the intercalation mechanism. In this paper, three intercalated α-ZrP materials were prepared, and their ability for adsorption of Sr2+ and Cs+ was studied systemically. Intercalation of guest molecules into the layered structure of α-ZrP could significantly improve its adsorption properties for removal of Sr2+ and Cs+ ions. However, Sr2+ and Cs+ showed different adsorption behaviors on the intercalated α-ZrP materials. Both of the size of the intercalated molecules and hydration radius of the Sr2+ ions had a notable influence on Sr2+ adsorption capacity due to much more space was needed for Sr2+ ions moving during adsorption process, while the adsorption capacity for Cs+ is little affected by the size of the guest molecules, due to the smaller hydrated radius of Cs+ which allows it to move easily.

Searching for new efficient, selective, and stable, adsorbents for 90Srgenerated in the nuclear fuel cycle remains important. In the last year, 18 crown 6ether and its derivatives have been intensively studied as highly efficient ion-exchangers for removal of 90Sr. However, one of the main problems for further application of these expensive macrocyclic ligands is loss in solid-liquid media due to their solubility. To overcome this problem, in this work, we have developed a new organic – inorganic layer α-ZrP composite by intercalation of 4-amino-benzo-18 crown 6. This new α-ZrP composite (AM-ZrP) not only inherits the advantages of 4-amino-benzo-18 crown 6 and α-ZrP, exhibiting excellent stability under acid and radioactive conditions, but also efficiently decreases the loss of valuable4-amino-benzo-18 crown 6 in the adsorption process. Furthermore, the preparation process for AM-ZrP is simple and it can be easily produced on a large-scale. Remarkably, having a pore size matching4-amino-benzo-18 crown 6, AM-ZrP shows high selectivity for capturing Sr2+ from complicated mixed solutions. The maximum adsorption capacity for Sr2+ onto AM-ZrP is 320.16 mg·g−1, which is about five times that of neat α-ZrP. Itsurpasses most other inorganic adsorbents, which can be attributed to the much higher number of adsorption sites and the wide interlayer spacing of α-ZrP after interactionwith4-amino-benzo-18 crown 6. Our present work not only poses a new way to promote crown ether compounds and α-ZrP materials, furthering their application in nuclear wastewater disposal, but also develops a new way of thinking about the design and preparation of new adsorbents for removal of difficult-to-capture ions from nuclear wastewater.

Efficient and irreversible capture of radioactive nuclides is an important environmental protection task when disposing of nuclear wastewater. This paper uses an "ion trapping" concept to design an efficient adsorbent based on a metal-organic framework (MOF), for removal of radioactive strontium from nuclear wastewater. Two functionalized MOFs were achieved by the introduction of sulfate or oxalate into the pore structure of MOF-808, giving MOF-808-SO4 and MOF-808-C2O4, respectively. These functionalized MOF-808 materials exhibit excellent ability to remove Sr2+ from acidic solution due to their particular trapping action, with the maximum Sr2+ adsorption capacities of 176.56 mg g-1 and 206.34 mg g-1 for MOF-808-SO4 and MOF-808-C2O4, respectively, surpassing most other inorganic materials. Additionally, 99% of Sr2+ is removed by MOF-808-SO4 and MOF-808-C2O4 after reaching the equilibrium. Remarkably, these two functionalized MOF-808 materials exhibited selectivity for the removal of Sr2+ from simulated mixed nuclear wastewater, even when there are 10 times as many co-existing ions as Sr2+ ions, demonstrating that anchoring of the trapping groups is a good way to improve Sr2+ adsorption capacity on MOFs. Moreover, both functionalized MOF-808 materials trap Sr2+ ions irreversibly, suggesting these trapping groups have strong ability to bind with Sr2+. A mechanism study indicated no proton ion exchange occurred during the adsorption process, so the functionalized groups anchored to MOFs play an important role in Sr2+ adsorption. Our present study provides an efficient way to design new adsorbents for the removal of radioactive strontium and other radionuclides from nuclear wastewater.

Glyphosate [N-(phosphonomethyl)glycine] has been described as the ideal herbicide because of its unique properties. There is some conflicting information concerning the structures and conformations involved in the protonation process of glyphosate. Protonation may influence the chemical and physical properties of glyphosate, modifying its structure and the chemical processes in which it is involved. To better understand the species in solution associated with changes in pH, thermodynamic study (potentiometry, calorimetry and NMR spectroscopy) about the protonation pathway of glyphosate is performed. Experimental results confirmed that the order of successive protonation sites of totally deprotonated glyphosate is phosphonate oxygen, amino nitrogen, and finally carboxylate oxygen. This trend is in agreement with the most recent theoretical work in the literature on the subject (J. Phys. Chem. A 2015, 119, 5241-5249). The result is important because it confirms that the protonated site of glyphosate in pH range 7-8, is not on the amino but on the phosphonate group instead. This corrected information can improve the understanding of the glyphosate chemical and biochemical action.

Radioactive iodine isotopes are released into the environment by the nuclear industry and medical research institutions using radioactive materials, and have negative effects on organisms living within the ecosystem. Thus, safe disposal of radioactive iodine is necessary and crucial. For this reason, the uptake of iodide ions was investigated in Ag2O nanocrystal grafted sodium niobate nanofibers, which were prepared by forming a well-matched phase coherent interface between them. The resulting composite was applied as an efficient adsorbent for I(-) anions by forming an AgI precipitate, which also remained firmly attached to the substrates. Due to their one-dimensional morphology, the new adsorbents can be easily dispersed in liquids and readily separated after purification. This significantly enhances the adsorption efficiency and reduces the separation costs. The change in structure from the pristine sodium niobate to Ag2O anchored sodium niobate and to the used adsorbent was examined by using various characterization techniques. The effects of Ag(+) concentration, pH, equilibration time, ionic strength and competing ions on the iodide ion removal ability of the composite were studied. The Ag2O nanocrystal grafted sodium niobate adsorbent showed a high adsorption capacity and excellent selectivity for I(-) anions in basic solutions. Our results are useful for the further development of improved adsorbents for removing I(-) anions from basic wastewater.

Iodine radioisotopes have been released into the environment both by the nuclear industry and as a result of medical treatment using radioactive materials, potentially posing a serious threat to human health. Thus, when developing applications of radioactive iodine, emergency procedures for dealing with it, and preventing its leakage, are constant concerns. In this study, nanofibers and cubes of Ag2O anchored sodium niobate composites were synthesized by a wet chemical process, and characterized by means of XRD, SEM, TEM and BET techniques. It was found that the well-dispersed Ag2O nanocrystals (3–5 nm) were firmly anchored on the external surface of sodium niobate along the planes with crystallographic similarity to those of Ag2O. These composites can efficiently capture I− anions by precipitating AgI, firmly attaching it to the substrate and allowing it to be recovered easily for safe disposal. Variations in the iodine removal abilities with differing pH value, adsorption time, adsorption temperature, initial I− concentration, and in the presence of competing ions, were studied. The maximum monolayer adsorption capacities of I− anions for Ag2O anchored sodium niobate nanofibers and cubes were found to be 296 and 193 m2 g−1 respectively. TEM, XRD, XPS and Raman results indicated that I− anion adsorption was mainly due to the Ag2O nanocrystals on the sodium niobate surfaces. We conclude that Ag2O deposited on sodium niobate hass a great potential for removal of radioactive iodine from waste water.

Hydrous antimony oxide Sb2O5·4H2O with a pyrochlore structure is an ion exchanger that is selective toward Sr2+ in mild solutions. The present study aims to improve the Sr2+ adsorption capacity of antimony oxide. Cubic pyrochlore non-doped and Ta-doped antimony oxide nanoparticles were prepared by a hydrothermal method. The particles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N2 gas sorption, Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Incorporation of Ta5+ into the sorbent led to an expansion of the pyrochlore structure, and increases in the surface hydroxyl group content and surface area of the sorbent, consequently improving the Sr2+ adsorption capacity considerably. A satisfactory correlation coefficient and a relatively low normalized standard deviation of the fit of the experimental data using the Freundlich model demonstrate that Sr2+ adsorption onto Ta-doped antimony oxide proceeds via a multilayer chemical adsorption process. Thermodynamic studies were conducted under different reaction temperatures. The results indicate that Sr2+ adsorption onto Ta-doped antimony oxide is an endothermic and a spontaneous process. Under the current experimental conditions, the maximal Sr2+ adsorption capacity of 26.37 mg g−1 was obtained at pH 4.

The molecule of glutaroimidedioxime, a cyclic imidedioxime moiety that can form during the synthesis of the poly(amidoxime)sorbent and is reputedly responsible for the extraction of uranium from seawater. Complexation of manganese (II) with glutarimidedioxime in aqueous solutions was investigated with potentiometry, calorimetry, ESI-mass spectrometry, electrochemical measurements and quantum chemical calculations. Results show that complexation reactions of manganese with glutarimidedioxime are both enthalpy and entropy driven processes, implying that the sorption of manganese on the glutarimidedioxime-functionalized sorbent would be enhanced at higher temperatures. Complex formation of manganese with glutarimidedioxime can assist redox of Mn(II/III). There are about ~15% of equilibrium manganese complex with the ligand in seawater pH(8.3), indicating that manganese could compete to some degree with uranium for sorption sites.

WO 3 has been identified as a promising candidate electrocatalyst for hydrogen evolution reaction (HER), because it can form a tungsten bronze (H x WO 3 ) which is highly electron and proton conducting. In this paper, we report that the electrocatalytic activity of WO 3 for HER can be enhanced by incorporation of tantalum ions (Ta 5+ ) into the lattice of WO 3 . The most active performance is achieved with the molar ratio of Ta/W being 0.01, which is two times more active than that of undoped WO 3 at an overpotential of -0.52 V. It is shown that incorporation of proper Ta 5+ into WO 3 can induce moderate defects and oxygen vacancies, as well as intercalate a higher amount of protons, which enhance the electron transfer and short the protons diffusion paths. These changes correlated positively with the enhanced catalytic HER activity. This study demonstrates, for the first time, that metal ions-doped WO 3 nanowires are promising electrocatalysts for HER.

Li-doped WO3 nanowires have been hydrothermally prepared and characterized mainly via spectroscopic methods. Both the hexagonal structure distortion and morphology evolution induced by Li doping reveal a lattice expansion of about 0.07 A. Also, the residence of oxygen vacancy and the enlargement of external surface areas positively correlate with the narrowing of energy band. Subsequently, the electrocatalytic oxidation of ascorbic acid using a Li-doped WO3 film-coated electrode performs a 13% and 21% negative shift of the oxidation overpotential compared with a WO3 film-coated electrode and a bare glassy carbon electrode, respectively. A preliminary mechanism has been proposed on the basis of relevant model analyses.

Hexagonal tungsten trioxide nanomaterials were synthesized from ammonium metatungstate using a solid-state method. The reaction temperature had a significant effect on the morphology, crystal phase and optical absorption properties of the tungsten trioxide nanomaterials. Increasing reaction temperature promoted the morphological evolution from hollow spheres to nanobelts. Hexagonal phase nanorods of width 300–600 nm and length 10–30 µm were obtained at a reaction temperature of 900 °C, and possessed the narrowest band gap among the obtained samples. This method is applicable for the large scale production of hexagonal tungsten trioxide particles with favorable optical absorption properties. It can also be used to fabricate various semiconductor oxides with advanced properties.

Large surface area hexagonal phase WO3 (h-WO3) nanowires were synthesized by a hydrothermal route with the assistance of C2H12N6O4S. They were characterized by XRD, SEM, TEM, BET, FT-IR and XPS. It is shown that C2H12N6O4S not only acts as a stabilizer to facilitate the generation of a metastable hexagonal phase, but also functions as a structure directing agent to assist the construction of nanowires. The obtained h-WO3 possesses a large specific surface area and numerous adsorption functional groups such as -OH groups. These characteristics result in an excellent adsorption performance for the removal of strontium from acidic aqueous solutions. A maximum adsorption capacity of 52.93 mg g(-1) was achieved on the h-WO3 prepared in the presence of C2H12N6O4S. This value is almost two times higher than that of bare h-WO3 (no C2H12N6O4S). The effects of pH, contact time, initial Sr(2+) concentration and ion strength on Sr(2+) removal from the solution by h-WO3 were systematically investigated. The adsorption mechanism involving the combination of electrostatic attraction and ion exchange for the adsorption of Sr(2+) is proposed. Based on our results, h-WO3 with high adsorption capacity and good surface characteristics exhibits great potential for the removal of Sr(2+) from radioactive wastewater.

Localization is very important for wireless sensor networks. Many applications require the location information. In this paper, we propose a range based Monte Carlo localization algorithm, which builds upon the Monte Carlo localization algorithm. We improve the localization accuracy and efficiency by introducing the RSSI (received signal strength indication) ranging technique, which is a low power, low cost and low complexity ranging method. The ranging error of RSSI is always very large and always varying with the change of the real environment. Although the low accuracy and high uncertainty of the range measurements would appear to make the localization more difficult, our approach exploits it to improve the accuracy and efficiency of localization. Simulation results show that its performance is better than some other localization algorithms.

In this paper, Nb-doped WO3 nanowires were successfully prepared using a low-temperature, hydrothermal method. The physicochemical properties of pristine and Nb-doped WO3 were determined by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy (UV-vis). The photocatalytic properties of those Nb-doped WO3 nanomaterials are evaluated on the basis of their ability to degrade methylene blue (MB) in an aqueous solution under simulated sunlight irradiation. It is demonstrated that the pristine nanowires tend to aggregate, whereas the energy band gap of those nanomaterials narrows as more niobium ions are doped. The photocatalytic experimental results indicated that the Nb-doped WO3 exhibited superior photocatalytic activities to that of the undoped WO3. The Nb-doped WO3 nanowires synthesized with an Nb/W molar ratio of 0.03 possessed the most effective photocatalytic activity among the tested samples.