4-Phosphoryl Pyrazolones for Highly Selective Lithium Separation from Alkali Metal Ions.

Effective receptors for the separation of Li+ from a mixture with other alkali metal ions under mild conditions remains an important challenge that could benefit from new approaches. In this study, it is demonstrated that the 4-phosphoryl pyrazolones, HL2 -HL4 , in the presence of the typical industrial organophosphorus co-ligands tributylphosphine oxide (TBPO), tributylphosphate (TBP) and trioctylphosphine oxide (TOPO), are able to selectively recognise and extract lithium ions from aqueous solution. Structural investigations in solution as well as in the solid state reveal the existence of a series of multinuclear Li+ complexes that include dimers (TBPO, TBP) as well as rarely observed trimers (TOPO) and represent the first clear evidence for the synergistic role of the co-ligands in the extraction process. Our findings are supported by detailed NMR, MS and extraction studies. Liquid-liquid extraction in the presence of TOPO revealed an unprecedented high Li+ extraction efficiency (78 %) for HL4 compared to the use of the industrially employed acylpyrazolone HL1 (15 %) and benzoyl-1,1,1-trifluoroacetone (52 %) extractants. In addition, a high selectivity for Li+ over Na+ , K+ and Cs+ under mild conditions (pH ∼8.2) confirms that HL2 -HL4 represent a new class of ligands that are very effective extractants for use in lithium separation.

Crystallization and Phase Transformations of Aluminum (Oxy)hydroxide Polymorphs in Caustic Aqueous Solution.

Gibbsite, bayerite, and boehmite are important aluminum (oxy)hydroxide minerals in nature and have been widely deployed in various industrial applications. They are also major components in caustic nuclear wastes stored at various U.S. locations. Knowledge of their crystallization and phase transformation processes contributes to understanding their occurrence and could help optimize waste treatment processes. While it has been reported that partial conversion of bayerite and gibbsite to boehmite occurs in basic solutions at elevated temperatures, systematic studies of factors affecting the phase transformation as well as the underlying reaction mechanisms are nonexistent, particularly in highly alkaline solutions. We explored the effects of sodium hydroxide concentrations (0.1-3 M), reaction temperatures (60-100 °C), and aluminum concentrations (0.1-1 M) on the crystallization and transformation of these aluminum (oxy)hydroxides. Detailed structural and morphological characterization by X-ray diffraction (XRD), scanning electron microscopy (SEM), and nuclear magnetic resonance (NMR) spectrometry revealed that these processes depend largely on the reaction temperature and the Al/OH- ratio. When 1 ≤ Al/OH- ≤ 2.5, the reactions favor formation of high-crystallinity precipitates, whereas at an Al/OH- ratio of ≥2.5 precipitation ceases unless the Al concentration is higher than 1 M. We identified pseudoboehmite, bayerite, and gibbsite as intermediate phases to bayerite, gibbsite and boehmite, respectively, all of which transform via dissolution-reprecipitation. Gibbsite transforms to boehmite in both acidic and weak caustic environments at temperatures above 80 °C. However, a "bar-shaped" gibbsite morphology dominates in highly caustic environments (3 M NaOH). The findings enable a robust basis for the selection of various solid phases by tuning the reaction conditions.

Effect of Cr(III) Adsorption on the Dissolution of Boehmite Nanoparticles in Caustic Solution.

The incorporation of relatively minor impurity metals onto metal (oxy)hydroxides can strongly impact solubility. In complex highly alkaline multicomponent radioactive tank wastes such as those at the Hanford Nuclear Reservation, tests indicate that the surface area-normalized dissolution rate of boehmite (γ-AlOOH) nanomaterials is at least an order of magnitude lower than that predicted for the pure phase. Here, we examine the dissolution kinetics of boehmite coated by adsorbed Cr(III), which adheres at saturation coverages as sparse chemisorbed monolayer clusters. Using 40 nm boehmite nanoplates as a model system, temperature-dependent dissolution rates of pure versus Cr(III)-adsorbed boehmite showed that the initial rate for the latter is consistently several times lower, with an apparent activation energy 16 kJ·mol-1 higher. Although the surface coverage is only around 50%, solution analysis coupled to multimethod solids characterization reveal a phyicochemical armoring effect by adsorbed Cr(III) that substantially reduces the number of dissolution-active sites on particle surfaces. Such findings could help improve kinetics models of boehmite and/or metal ion adsorbed boehmite nanomaterials, ultimately providing a stronger foundation for the development of more robust complex radioactive liquid waste processing strategies.

Cr(III) Adsorption by Cluster Formation on Boehmite Nanoplates in Highly Alkaline Solution.

The development of advanced functional nanomaterials for selective adsorption in complex chemical environments requires partner studies of binding mechanisms. Motivated by observations of selective Cr(III) adsorption on boehmite nanoplates (γ-AlOOH) in highly caustic multicomponent solutions of nuclear tank waste, here we unravel the adsorption mechanism in molecular detail. We examined Cr(III) adsorption to synthetic boehmite nanoplates in sodium hydroxide solutions up to 3 M, using a combination of X-ray diffraction (XRD), Raman, X-ray photoelectron spectroscopy (XPS), scanning/transmission electron microscopy (S/TEM), electron energy loss spectroscopy (EELS), high-resolution atomic force microscopy (HR-AFM), time-of-fight secondary ion mass spectrometry (ToF-SIMS), Cr K-edge X-ray absorption near edge structure (XANES)/extended X-ray absorption fine structure (EXAFS), and electron paramagnetic resonance (EPR). Adsorption isotherms and kinetics were successfully fit to Langmuir and pseudo-second-order kinetic models, respectively, consistent with monotonic uptake of Cr(OH)4- monomers until saturation coverage of approximately half the aluminum surface site density. High resolution AFM revealed monolayer cluster self-assembly on the (010) basal surfaces with increasing Cr(III) loading, possessing a structural motif similar to guyanaite (ß-CrOOH), stabilized by corner-sharing Cr-O-Cr bonds and attached to the surface with edge-sharing Cr-O-Al bonds. The selective uptake appears related to short-range surface templating effects, with bridging metal connections likely enabled by hydroxyl anion ligand exchange reactions at the surface. Such a cluster formation mechanism, which stops short of more laterally extensive heteroepitaxy, could be a metal uptake discrimination mechanism more prevalent than currently recognized.

Adsorption behaviors and vibrational spectra of hydrogen peroxide molecules at quartz/water interfaces.

The effect of H2O2 concentration on the change of H-bonds at a water/quartz interface was systematically examined by surface-specific sum-frequency generation (SFG) spectroscopy. Molecular dynamics (MD) simulation was further utilized to interpret the specific molecular dynamics as well as the configuration and evolution of water and H2O2 molecules at the interface. The results from this study demonstrated the important role of surface H-bonds on determination of the stability of adsorbed H2O2 at solvated, silica, xerogel surfaces. It was revealed that prior to reaching the surface saturation with H2O2 molecules (less than 20% in bulk solution), multiple H-bonds were formed with silanols at relatively short interactive distances. These H-bonds proved to be strong enough to enable the overall stability of adsorbed H2O2. However, once saturated, the H2O2 molecules would be adsorbed at longer distances away from the surface, and could easily migrate to the bulk solution; therefore, in this case, the bonds failed to support stable H2O2 adsorption. These new findings explained the detailed molecular mechanism of the relationship between H2O2 concentration and H2O2 stability in H2O2-silica xerogels. This solves the current challenge of effective H2O2 storage, and provides fundamental insight for predicting the adsorption behavior of H2O2 at the silica surface.

[Effect of diets with different fat levels on the body size and development of Lucilia sericata].

OBJECTIVE: To observe the effect of diets with different fat levels on the body size and development of Lucilia sericata. METHODS: Under the constant temperature of 28 degrees C, the larvae were reared on the diets containing 0% (G0), 10% (G1), 30% (G3), 50% (G5) and 80% (G8) fat tissues (fat/muscle ratio), respectively. Length and weight of larvae and pupae were measured at 12 h interval since 16 h after eclosion. Length of inter-medial cross vein (m-m) of adult left wing was measured. 10 samples were collected in each group. The developmental duration time, mortality and sex ratios of adults were recorded. RESULTS: The mean maximal larval length [(13.3 +/- 1.2), (12.0 +/- 1.1), (10.2 +/- 0.9) and (8.8 +/- 0.8) mm, respectively] and mean maximal larval weight [(72.8 +/- 6.1), (62.2 +/- 5.7), (47.2 +/- 4.3), and (34.9 +/- 5.7) mg] in G1, G3, G5 and G8 groups were significantly less than that of the G0 group [(14.8 +/- 1.3) mm and (80.4 +/- 8.1) mg](P < 0.01). The body size of pupae and adults was also significantly less than that of G0 group (P < 0.01). The total duration time of G5 and G8 groups [(293.3 +/- 22.2) and (285.2 +/- 24.6) h] were significantly shorter than that of G0 group [(312.8 +/- 20.1)h] (P < 0.01). The mortality of larvae [(32.6 +/- 5.6)% and (44.3 +/- 7.7)%] and pupae [(28.6 +/- 5.5)% and (43.5 +/- 6.2)%] of G5 and G8 group were also significantly higher than that of G0 group [(5.7 +/- 3.3)% and (4.5 +/- 1.9)%] (P < 0.01). There was no significant difference in sex ratio among the 5 groups (P > 0.05). CONCLUSION: The body size of larvae, pupae and adults of Lucilia sericata is smaller, the development time is shorter and mortality is higher when the food substrate contains more fat tissues.

Synthesis, biological evaluation and molecular docking studies of resveratrol derivatives possessing curcumin moiety as potent antitubulin agents.

A series of resveratrol derivatives possessing curcumin moiety were synthesized and evaluated for their antiproliferative activity against three cancer cell lines including murine melanoma B16-F10, human hepatoma HepG2 and human lung carcinoma A549. Among them, compound C5 displayed the most potent in vitro antiproliferative activity against B16-F10 with IC(50) value of 0.71 µg/mL. Compound C5 also exhibited good tubulin polymerization inhibitory activity with IC(50) value of 1.45 µg/mL. Furthermore, docking simulation was carried out to position C5 into the tubulin-colchicine binding site to determine the probable binding mode.

Sulfuric acid leaching of ball-milling activated FePO4 residue after lithium extraction from spent lithium iron phosphate cathode powder.

A mechanical-chemical process is proposed to recover the iron phosphate residue(IPR)of spent lithium iron phosphate(LFP)after lithium extraction. In this process, the IPR was pretreated by ball-milling and leached with the sulfuric acid solution. The results showed that, under the optimized ball-milling conditions (a mass ratio of the stainless-steel-ball to material to water of 2:1:2.5, a milling time of 20 min), the maximum particle size of IPR decreased from 34.265 um to 13.102 um, the specific surface increased from 11.41 m2/g to 13.74 m2/g, and the cell volume distortion rate could reach 0.331 %. Under the optimized leaching conditions (a temperature of 333 K, a concentrated acid-to-material ratio of 0.46 mL/g, a liquid-to-solid ratio of 5:1 mL/g, and a stirring speed of 600 rpm), the leaching efficiency of iron phosphate could reach 98 %. The kinetic study indicated that the leaching was controlled by diffusion and chemical reaction with the apparent activation energy of 29 kJ/mol. The dissolution-precipitation phase transition of IPR was also found at high temperatures. This study illustrates that such a mechanical-chemical process is an effective way to improve the leaching efficiency of IPR with a lower sulfuric acid dosage, which has great potential in industrial applications.

Utilization of coal fly ash in China: a mini-review on challenges and future directions.

The rapid economic development in China places a large demand for energy, and as a result, thermal power plants in China are producing an enormous amount of coal fly ash (CFA) which causes severe environmental pollution. This paper briefly describes the current production and utilization status of CFA in China and identifies the challenges confronting sustainable CFA utilization as the Chinese economy is being transformed. These issues include a regional imbalance in supply and demand, reducing demand in the real estate industry as well as stricter laws for environmental protection. Viable directions for future CFA utilization are proposed, for example, production of CFA-based ceramic tiles, recovery of elemental resources, agricultural melioration, treatment of wastewater and flue gas, and production of high-volume CFA concretes. This paper has some guiding significance for sustainable and cleaner utilization of CFA in China and even worldwide. Graphical abstract.

[Qualitative and quantitative analysis of various elements in chromite ore by ICP-AES].

Kind of the elements in chromite ore was firstly determined by ICP-AES. Twenty nine elements, such as Cr, Fe, Al, Mg, Zn, Ca and Ni, were contained in the chromite sample based on the qualitative analysis. Then the contents of main elements Cr, Fe, Al, Mg, Ca, T, Si, Mn and V were measured. The chromite samples processing procedures have two steps, the first is decomposition by nitrate carbonate and sodium tetraborate at 950 degrees C for 30 min, then leaching by dilute hydrochloric acid at 80 degrees C for 10 min. The method showed satisfactory precision and accuracy with the RSDs between 0.48% and 2.05% and the recovery rates between 90.5% and 111.3%.

NiFe-Layered Double Hydroxide Synchronously Activated by Heterojunctions and Vacancies for the Oxygen Evolution Reaction.

The development of earth-abundant transition-metal-based electrocatalysts with bifunctional properties (oxygen evolution reaction (OER) and hydrogen evolution reaction (HER)) is crucial to commercial hydrogen production. In this work, layered double hydroxide (LDH)-zinc oxide (ZnO) heterostructures and oxygen vacancies are constructed synchronously by plasma magnetron sputtering of NiFe-LDH. Using the optimal conditions, ZnO nanoparticles are uniformly distributed on the NiFe-LDH nanoflowers, which are prepared uniformly on the three-dimensional porous Ni foam. In the LDH-ZnO heterostructures and oxygen vacancies, electrons are depleted at the Ni cations on the NiFe-LDH surface and the active sites change from Fe cations to Ni cations during OER. Our theoretical assessment confirms the change of active sites after the deposition of ZnO and reveals the charge-transfer mechanism. Owing to the significant improvement in the OER dynamics, overall water splitting can be achieved at only 1.603 V in 1 M KOH when the Ni/LDH-ZnO and Ni/LDH are used as the anode and cathode, respectively. The work reveals a novel design of self-supported catalytic electrodes for efficient water splitting and also provides insights into the surface modification of catalytic materials.

[Spectroscopy research on synthesis of new desilication reagent-calcium hydroferrocarbonate].

For removing silica from high concentration medium after digestion of the diasporic bauxite by sub-molten salt, the research used calcium hydroferrocarbonate with the new desilication reagent. In the reaction, calcium carbonate, calcium hydroxide and calcium ferrite were by-product, therefore the reaction factors showed significant influence on the synthesis and disilicating efficiency. To explore the synthesis mechanism and optimize the reaction factors, the composition of the intermediate obtained from the synthesis reaction was investigated through the combination of FTIR, ICP-AES and desilication reaction. The FTIR and desilication reaction results revealed that calcium hydroferrocarbonate is metastable compound in solution, and the reaction temperature and reaction time have significant influence on the systhesis. With the temperature and reaction time increasing, the content of calcium hydroferrocarbonate in the composition first increased and then reduced. The optimal factors were: temperature of 30 degrees C, reaction time of 16 hours, the liquid to solid mass ratio of 20 and rpm of 500 r x min(-1). The crystal structure of calcium hydroferrocarbonate was investigated, and was found to be rhombohedral, including H2O bond, -OH bond and Fe-O bond.

[Analysis of metallic elements in refractory tantalum-niobium slag by ICP-AES].

A new method for analysing the contents of many metalic elements, such as Ta, Nb, Sn, Ti, W, Fe, Mn, Al, Pb, Ce, Y, Sc, Pr, Sm, Nd, U, Th etc, in refractory tantalum-niobium slag by ICP-AES was developed. The samples processing procedures involve two steps, being first decomposed by potassium carbonate and boric acid at 950 degrees C for 15 min, then leached by hydrochloride and tartaric acid at 90 degrees C for 30 min. The interference of flux and tin matrix in analyzing the other elements was eliminated by the utilization of matrix matching method. This method showed satisfactory precision and accuracy with the RSDs between 0.27% and 5.48% and the recovery rates between 94.0% and 109.6%. The analysis results indicated that highly valuable metals of Sn, Ta, Nb, Ti, W and Ce are rich in the refractory tantalum-niobium slag, showing that it has the great potential for comprehensive utilization. However, the analysis result also showed that the slag is a radioactive pollution source due to a small amount of U and Th. This method is simple and fast, and has the advantage of analyzing many elements simultaneously. The accurate analytic results provided a basis for the future researches on the comprehensive utilization of refractory tantalum-niobium slag.

[Acupuncture combined with Jingtong granule for nerve-root type cervical spondylosis and its effects on IL-6、TNF-α、IL-1ß and hemorheological indexes].

OBJECTIVE: To explore the clinical efficacy of acupuncture combined with Jingtong granule for nerve-root type cervical spondylosis and its effects on serum interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1ß) and hemorheological indexes. METHODS: A total of 114 patients with nerve-root type cervical spondylosis were randomly divided into an observation group and a control group, 57 cases in each group. The patients in both groups were treated with traction. The patients in the control group were treated with oral administration of Jingtong granule, 4 g each time, 3 times a day, while based on the treatment of control group, the patients in the observation group were treated with acupuncture at Dazhui (GV 14), Tianzhu (BL 10), Houxi (SI 3), cervical Jiaji (EX-B 2), Quchi (LI 11), Hegu (LI 4) and Waiguan (TE 5), once a day. Both groups were treated for 4 weeks. The simplified McGill pain questionnaire (MPQ), neck disability index (NDI), numbness score, levels of IL-6, TNF-α, IL-1ß in serum and hemorheological indexes were observed before and after treatment, and the clinical efficacy was compared between the two groups. RESULTS: The total effective rate was 91.2% (52/57) in the observation group, which was higher than 71.9% (41/57) in the control group (P<0.05). Compared before treatment, the scores of MPQ, NDI and numbness in the two groups were reduced after treatment (P<0.05). After treatment, the scores of MPQ, NDI and numbness in the observation group were lower than those in the control group (P<0.05). After treatment, the serum levels of IL-6, TNF-α and IL-1ß in the two groups were reduced (P<0.05), and those in the observation group were lower than the control group (P<0.05). After treatment, the plasma viscosity, fibrinogen, low shear rate of whole blood viscosity and high shear rate of whole blood viscosity in the two groups were lower than before treatment (P<0.05), and those in the observation group were lower than the control group (P<0.05). CONCLUSION: Acupuncture combined with Jingtong granule have significant clinical efficacy for nerve-root type cervical spondylosis, which could reduce the serum levels of IL-6, TNF-α and IL-1ß and improve hemorheology.

Hierarchical oxygen-implanted MoS2 nanoparticle decorated graphene for the non-enzymatic electrochemical sensing of hydrogen peroxide in alkaline media.

Owing to the extensive applications of hydrogen peroxide (H2O2) in biological, environmental and chemical engineering, it is of great importance to investigate sensitive and selective sensing platform towards the detection of H2O2. Herein, oxygen-implanted MoS2 nanoparticles decorated graphene nanocomposite is synthesized via a facile one-pot solvothermal method for the sensitive detection of H2O2 in alkaline media. The structure and morphology of the MoS2/graphene nanocomposites were systematically characterized, showing that Mo-O bonds are formed and oxygen is implanted into the crystal structure in the nanocomposite. As a result, the MoS2/graphene composite exhibited enhanced electron transfer kinetics and excellent electro-reduction performance towards H2O2 in alkaline media. Under optimum conditions, the fabricated sensor demonstrated a wide linear response towards H2O2 in the range of 0.25-16mM with a low detection limit of 0.12µM and high sensitivity of 269.7µAmM-1cm-2. Besides, the constructed sensor presented a good selectivity to H2O2 with the presence of other interfering species. Therefore, the proposed sensor was successfully applied for the detection and determination of H2O2 in real sample, indicating great potential for the practical applications.

Adsorption study of selenium ions from aqueous solutions using MgO nanosheets synthesized by ultrasonic method.

MgO nanosheets with thickness ranges of 3-10 molecule layers and high specific area (166.44m2g-1) were successfully fabricated by an ultrasound-assisted exfoliation method and used as adsorbent for the removal of both selenite (Se(IV)) and selenate (Se(VI)) from aqueous solutions. The resulting MgO nanosheets displayed high maximum adsorption capacities of 103.52 and 10.28mgg-1 for Se(IV) and Se(VI), respectively. ATR-FTIR and XPS spectroscopic results suggested that both Se(IV) and Se(VI) formed inner-sphere surface complexes on MgO nanosheets under the present experimental conditions. Furthermore, high adsorption capacity for Se(IV/VI) in the presence of coexistent anions (SO42-, PO43-, Cl-, and F-) and efficient regeneratability of adsorbent by NaOH solution were observed in the competitive adsorption and regeneration steps. The simple one-step synthesis process of MgO nanosheets and high adsorption capacities offer a promising method for Se(IV/VI) removal in water treatment.

Alkaline electrochemical advanced oxidation process for chromium oxidation at graphitized multi-walled carbon nanotubes.

Alkaline electrochemical advanced oxidation processes for chromium oxidation and Cr-contaminated waste disposal were reported in this study. The highly graphitized multi-walled carbon nanotubes g-MWCNTs modified electrode was prepared for the in-situ electrochemical generation of HO2-. RRDE test results illustrated that g-MWCNTs exhibited much higher two-electron oxygen reduction activity than other nanocarbon materials with peak current density of 1.24 mA cm-2, %HO2- of 77.0% and onset potential of -0.15 V (vs. Hg/HgO). It was originated from the highly graphitized structure and good electrical conductivity as illustrated from the Raman, XRD and EIS characterizations, respectively. Large amount of reactive oxygen species (HO2- and ·OH) were in-situ electro-generated from the two-electron oxygen reduction and chromium-induced alkaline electro-Fenton-like reaction. The oxidation of Cr(III) was efficiently achieved within 90 min and the conversion ratio maintained more than 95% of the original value after stability test, offering an efficient and green approach for the utilization of Cr-containing wastes.

Research and industrialization progress of recovering alumina from fly ash: A concise review.

Fly ash, a by-product of high temperature combustion of coal in coal-fired power plants, is one of the most complex and largest amount of industrial solid wastes generated in China. Its improper disposal has become an environmental problem. Now it is widely realized that fly ash should be considered as a useful and potential mineral resource. Fly ash is rich in alumina, making it a potential substitute for bauxite. With the diminishing reserves of bauxite resources, as well as the increasing demand for alumina, recovery of alumina from fly ash has attracted extensive attention world-wide. The present review describes, firstly, the generation and physicochemical properties of high alumina fly ash found in northern China and then focuses on the various alumina recovery technologies, the advantages and disadvantages of these processes, and in particular, the latest industrial developments. Finally, the directions for future research are also considered.

Enhanced boron adsorption onto synthesized MgO nanosheets by ultrasonic method.

MgO nanosheets with high adsorption performance were fabricated by an ultrasonic method. It was revealed that, nest-like MgO was formed from the magnesium salt solution precipitation and further calcination. Then the nest-like MgO was exfoliated by ultrasonic waves to obtain MgO nanosheets with approximately a lateral of 200-600nm and a thickness of 10nm. Adjusting the ultrasonic time and power, the specific surface areas of MgO nanosheets could be tuned in a range of 79-168m2/g. The synthesized MgO nanosheets were used as adsorbents to remove boron from aqueous solution, and the maximum boron adsorption capacity of these MgO nanosheets reached 87mgg-1. The high uptake capability of the MgO nanosheets makes it potentially adsorbent for the removal of boron from wastewaters.

The leaching kinetics of cadmium from hazardous Cu-Cd zinc plant residues.

A large amount of Cu-Cd zinc plant residues (CZPR) are produced from the hydrometallurgical zinc plant operations. Since these residues contain substantial amount of heavy metals including Cd, Zn and Cu, therefore, they are considered as hazardous wastes. In order to realize decontamination treatment and efficient extraction of the valuable metals from the CZPR, a comprehensive recovery process using sulfuric acid as the leaching reagent and air as the oxidizing reagent has been proposed. The effect of temperature, sulfuric acid concentration, particle size, solid/liquid ratio and stirring speed on the cadmium extraction efficiency was investigated. The leaching kinetics of cadmium was also studied. It was concluded that the cadmium leaching process was controlled by the solid film diffusion process. Moreover, the order of the reaction rate constant versus H2SO4 concentration, particle size, solid/liquid ratio and stirring speed was calculated. The XRD and SEM-EDS analysis results showed that the main phases of the secondary sulfuric acid leaching residues were lead sulfate and calcium sulfate.