Characterization, dissolution and solubility of the hydroxypyromorphite–hydroxyapatite solid solution [(PbxCa1−x)5(PO4)3OH] at 25 °C and pH 2–9

Additional file 1: Appendix A. Supplementary data—X-ray diffractograms (XRD) of the hydroxypyromorphite–hydroxyapatite solid solution [(PbxCa1−x)5(PO4)3(OH)] after dissolution at 25 ˚C and an initial pH of 5.60 and 9.00 for 300d

Fixed-bed column adsorption of arsenic(V) by porous composite of magnetite/hematite/carbon with eucalyptus wood microstructure

The fixed-bed column adsorption-desorption of As(V) by the porous composite of iron oxides and carbon with eucalyptus wood hierarchical microstructure (PC-Fe/C) was experimentally studied. The increase in the influent As(V) concentration and the inflow rate resulted in an earlier exhaustion of the column. The breakthrough curves indicated that a larger adsorbent mass, a smaller adsorbent grain size and a lower influent pH prolonged the column life span. The operating temperature had negligible effect. All breakthrough curves could be well fitted with the Thomas and Yoon–Nelson models. Under the condition of the influent flow rate of 5.136 mL/min, the influent As(V) concentration of 20 mg/L, the influent pH of 3, the adsorbent mass of 2 g, the adsorbent grain size of <100 mesh, and the operating temperature of 35 °C, the equilibrium adsorption capacity reached 10.49 mg/g, which was greater than those of natural/synthetic iron oxides adsorbents and iron-oxide-coated adsorbents

Unprecedented strength in pure iron via high-pressure induced nanotwinned martensite

Martensitic transformation can easily induce a maximum hardness value of 800–900 HV (Vickers hardness) for steels with carbon contents of 0.6 wt.% and above. However, the occurrence of martensitic transformation in pure iron requires exceptionally high cooling rates (105–106°C/s), and the maximum achievable hardness is only about 150 HV. Here we report an extreme hardness of 830 HV in pure iron obtained through high pressure induced martensitic transformation at a rather slow cooling rate of just 10°C/s. This unprecedented strength originates from the formation of twin-related martensitic laths with an average thickness of 3.8 nm

Target density effects on charge tansfer of laser-accelerated carbon ions in dense plasma

We report on charge state measurements of laser-accelerated carbon ions in the energy range of several MeV penetrating a dense partially ionized plasma. The plasma was generated by irradiation of a foam target with laser-induced hohlraum radiation in the soft X-ray regime. We used the tri-cellulose acetate (C$_{9}$H$_{16}$O$_{8}$) foam of 2 mg/cm$^{-3}$ density, and $1$-mm interaction length as target material. This kind of plasma is advantageous for high-precision measurements, due to good uniformity and long lifetime compared to the ion pulse length and the interaction duration. The plasma parameters were diagnosed to be T$_{e}$=17 eV and n$_{e}$=4 $\times$ 10$^{20}$ cm$^{-3}$. The average charge states passing through the plasma were observed to be higher than those predicted by the commonly-used semiempirical formula. Through solving the rate equations, we attribute the enhancement to the target density effects which will increase the ionization rates on one hand and reduce the electron capture rates on the other hand. In previsous measurement with partially ionized plasma from gas discharge and z-pinch to laser direct irradiation, no target density effects were ever demonstrated. For the first time, we were able to experimentally prove that target density effects start to play a significant role in plasma near the critical density of Nd-Glass laser radiation. The finding is important for heavy ion beam driven high energy density physics and fast ignitions.Comment: 7 pages, 4 figures, 35 conference

Two ultraviolet radiation datasets that cover China

Ultraviolet (UV) radiation has significant effects on ecosystems, environments, and human health, as well as atmospheric processes and climate change. Two ultraviolet radiation datasets are described in this paper. One contains hourly observations of UV radiation measured at 40 Chinese Ecosystem Research Network stations from 2005 to 2015. CUV3 broadband radiometers were used to observe the UV radiation, with an accuracy of 5%, which meets the World Meteorology Organization's measurement standards. The extremum method was used to control the quality of the measured datasets. The other dataset contains daily cumulative UV radiation estimates that were calculated using an all-sky estimation model combined with a hybrid model. The reconstructed daily UV radiation data span from 1961 to 2014. The mean absolute bias error and root-mean-square error are smaller than 30% at most stations, and most of the mean bias error values are negative, which indicates underestimation of the UV radiation intensity. These datasets can improve our basic knowledge of the spatial and temporal variations in UV radiation. Additionally, these datasets can be used in studies of potential ozone formation and atmospheric oxidation, as well as simulations of ecological processes

Dissolution, Stability and Solubility of Tooeleite [Fe6(AsO3)4(SO4)(OH)4·4H2O] at 25–45 °C and pH 2–12

Tooeleite [Fe6(AsO3)4(SO4)(OH)4&middot;4H2O] was synthesized and characterized to investigate its possible immobilization for arsenic in acidic and alkali environments by a long-term dissolution of 330 d. The synthetic tooeleite was platy crystallites of ~1&mu;m across, giving the lattice parameters of a = 6.4758 &Aring;, b = 19.3737 &Aring; and c = 8.9170 &Aring;. For the tooeleite dissolution, the dissolved arsenic concentration showed the lowest value of 427.3~435.8 mg/L As at initial pH 12 (final pH 5.54). The constituents were dissolved preferentially in the sequence of SO42&minus; &gt; AsO33&minus; &gt; Fe3+ in the aqueous medium at initial pH 2&ndash;12. The dissolved iron, arsenite and sulfate existed mainly as FeSO4+/Fe3+, H3AsO30 and SO42&minus; at initial pH 2, and in the form of Fe(OH)30/Fe(OH)2+, H3AsO30 and SO42&minus; at initial pH 12, respectively. The tooeleite dissolution was characterized by the preferential releases of SO42&minus; anions from solid surface into aqueous medium, which was fundamentally controlled by the Fe-O/OH bond breakages and the outer OH&minus; group layers. From the data of the dissolution at 25 &deg;C and initial pH 2 for 270&ndash;330 d, the ion-activity product [logˍIAP], which equaled the solubility product [Ksp] at the dissolution equilibrium, and the Gibbs free energy of formation [&Delta;Gfo] were estimated as &minus;200.28 &plusmn; 0.01 and &minus;5180.54 &plusmn; 0.07 kJ/mol for the synthetic tooeleite, respectively

Characterization, Dissolution, and Solubility of Lead Hydroxypyromorphite [Pb5(PO4)3OH] at 25–45°C

Dissolution of the hydroxypyromorphite [lead hydroxyapatite, Pb5(PO4)3OH] in HNO3 solution (pH = 2.00), ultrapure water (pH = 5.60), and NaOH solution (pH = 9.00) was experimentally studied at 25°C, 35°C, and 45°C. The XRD, FT-IR, and FE-SEM analyses indicated that the hydroxypyromorphite solids were observed to have indistinguishable change during dissolution. For the hydroxypyromorphite dissolution in aqueous acidic media at initial pH 2.00 and 25°C, the aqueous phosphate concentrations rose quickly and reached the peak values after 1 h dissolution, while the aqueous lead concentrations rose slowly and reached the peak values after 1440 h. The solution Pb/P molar ratio increased constantly from 1.10 to 1.65 near the stoichiometric ratio of 1.67 to 209.85~597.72 and then decreased to 74.76~237.26 for the dissolution at initial pH 2.00 and 25°C~45°C. The average Ksp values for Pb5(PO4)3OH were determined to be 10−80.77 (10−80.57−10−80.96) at 25°C, 10−80.65 (10−80.38−10−80.99) at 35°C, and 10−79.96 (10−79.38−10−80.71) at 45°C. From the obtained solubility data for the dissolution at initial pH 2.00 and 25°C, the Gibbs free energy of formation [ΔGfo] for Pb5(PO4)3OH was calculated to be −3796.71 kJ/mol (−3795.55~−3797.78 kJ/mol)

Prediction and Evaluation of the Mixture Toxicity of Twelve Phenols and Ten Anilines to the Freshwater Photobacterium Vibrio qinghaiensis sp.-Q67

Twelve substituted phenols and ten substituted anilines were chosen to investigate if the dose addition and independent action models can be used to evaluate the mixture toxicity of phenolic and aniline derivatives (PADs). Their photobacterium toxicity to the freshwater luminescent bacterium Vibrio qinghaiensis sp.-Q67 showed that the two-parameter Weibull or Logit function could be effectively applied to describe the dose-response relationships. The joint toxicity of three equivalent-effect concentration ratio (EECR) mixtures and twelve uniform design concentration ratio (UDCR) mixtures could be well evaluated using the dose addition (DA) or the independent action (IA) model within 95% confidence intervals

Applications of Biochar and Modified Biochar in Heavy Metal Contaminated Soil: A Descriptive Review

Given that the problem of contaminated soil continues to grow, the development of effective control and remediation measures has become imperative, especially for heavy-metal-contaminated soil. Biochar and modified biochar are eco-friendly and cost-effective remediation materials that are widely used in the remediation of contaminated soil. This review provides an overview of the different raw materials used in the preparation of biochar as well as the modification of biochar using various synthesis methods, highlighting their differences and providing recommendations for biochar and modified biochar as applied toward ameliorating pollution in soil contaminated by heavy metals. We also explore the effects of the physicochemical properties of raw materials, pyrolysis temperature, additives, and modification methods on the properties of the resulting biochar and modified biochar, and systematically present the types of soil and operating factors for repair. Moreover, the mechanisms involved in remediation of heavy-metal-contaminated soil by biochar and modified biochar are outlined in detail, and include adsorption, complexation, precipitation, ion exchange, and electrostatic attractions. Finally, the corresponding monitoring technologies after remediation are illustrated. Future directions for studies on biochar and modified biochar in the remediation of contaminated soil are also proposed to support the development of green environmental protection materials, simple preparation methods, and effective follow-up monitoring techniques

Applications of Biochar and Modified Biochar in Heavy Metal Contaminated Soil: A Descriptive Review

Given that the problem of contaminated soil continues to grow, the development of effective control and remediation measures has become imperative, especially for heavy-metal-contaminated soil. Biochar and modified biochar are eco-friendly and cost-effective remediation materials that are widely used in the remediation of contaminated soil. This review provides an overview of the different raw materials used in the preparation of biochar as well as the modification of biochar using various synthesis methods, highlighting their differences and providing recommendations for biochar and modified biochar as applied toward ameliorating pollution in soil contaminated by heavy metals. We also explore the effects of the physicochemical properties of raw materials, pyrolysis temperature, additives, and modification methods on the properties of the resulting biochar and modified biochar, and systematically present the types of soil and operating factors for repair. Moreover, the mechanisms involved in remediation of heavy-metal-contaminated soil by biochar and modified biochar are outlined in detail, and include adsorption, complexation, precipitation, ion exchange, and electrostatic attractions. Finally, the corresponding monitoring technologies after remediation are illustrated. Future directions for studies on biochar and modified biochar in the remediation of contaminated soil are also proposed to support the development of green environmental protection materials, simple preparation methods, and effective follow-up monitoring techniques