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Global Modeling of Microplastics in the AtmosphereShanye Yang, Guy Brasseur, Stacy Walters, Pablo Lichtig, Cathy Wing Yi Li, Xiaofei WangGlobal model simulations driven by bottom-up emissions show that more than 100 kilotons of microplastic particles are suspended in the atmosphere. The calculations are based on estimated emissions associated to traffic, agriculture, domestic activities and ocean exchanges. They make use of our laboratory measurements of microplastic exchanges at the water-air interface that is considerably less intensive than the emissions from land. Approximately 20 million tons are deposited each year on the Earth’s surface, and 3 million tons in the oceans. These model simulations show that the microplastic particle abundance is considerably higher over the continents, which is consistent with current observations. Exposure risks are highest in the most populated areas. Worldwide, adults inhale 2.4 × 107 - 1.5 × 109 microplastic particles per year. Remote areas including Antarctica and the Arctic are also important receptor regions for the particles with a diameter smaller than 1.5 μm.

With the wide use of nuclear energy, radioactive pollution has become a public environmental concern. In this study, the sodium dodecyl sulfate modified molybdenum disulfide (SDS/MoS2) was used to ...

Peanut shell, a widely available agricultural waste, was successfully grafted with quaternary ammine groups on its surface by using amination modification. The sorption mechanism of U(VI) on the amine cross-linked peanut shell (PNN) was examined by batch experiments and spectroscopy analysis. The physical adsorption was dominated by the liquid film diffusion and the intra-particle diffusion, whereas the chemical adsorption was dominated by surface complexation with quaternary amine groups and carboxyl groups. The maximum adsorption capacity of U(VI) on PNN was calculated to be 574.81 mg g−1 at pH = 6.0 and T = 298 K, which was much higher than that of U(VI) on pristine pure peanut shell and many other materials. Consideration of the high sorption efficiency and eco-friendliness of peanut shell, PNN presented promising potential in the preconcentration of radionuclides in radioactive pollution management.

The nanoscale zero valent iron (NZVI) modified coal fly ash (CFA) magnetic composites (NZVI/CFA) were synthesized from the waste CFA and applied for the high-efficiency sequestration of U(VI) ions from water solution. The sequestration capacity of U(VI) ions on NZVI/CFA (0.62 mmol·g−1) was larger than that on bare CFA (0.25 mmol·g−1) or NZVI (0.38 mmol·g−1). The sequestration of U(VI) on NZVI and NZVI/CFA was primary controlled by outer-sphere surface complexation at low pH, and by inner-sphere surface complexation at high pH. According to the thermodynamic data and the adsorption isotherms' analysis, the U(VI) sorption process to the NZVI/CFA was spontaneous and endothermic. The main reaction mechanism was that, most of the soluble U(VI) ions were firstly adsorbed to NZVI/CFA and then the surface adsorbed U(VI) was partly reduced to U(VI) on the porous NZVI/CFA composites, and this synergistically affected U(VI) removal from solution to NZVI/CFA. The results of DFT calculation indicated that the NZVI/CFA had a strong sequestration capacity towards U(VI) and U(IV) ions, and the binding energy of U(IV) species was larger than that of U(VI) species, which evidenced the higher sorption of U(IV) than U(VI) on NZVI/CFA. The results showed that NZVI/CFA was an appropriate material for U(VI) sequestration from large volumes of actual effluent in wastewater cleanup.

In this investigation, two novel magnetic core-shell Fe

With the development and utilization of nuclear energy, radioactive contamination has caused special concern. Herein, the sodium laurylsulfonate modified silicon dioxide (SLS/SiO2) was prepared to eliminate europium (Eu) from aqueous solution. The SLS/SiO2 composite revealed a uniform spherical structure. The results showed that Eu(III) removal onto SLS/SiO2 was monolayer adsorption, and the elevated temperature was advantageous to Eu(III) removal. The adsorption capacity of SLS/SiO2 at 298 K reached 52.5 mg/g for Eu(III), and the adsorption of Eu(III) was dependent on solution pH and independent on coexisting ions. The adsorption of Eu(III) reached the adsorption equilibrium within 120 min, showing a great advantage. The retention of Eu(III) onto SLS/SiO2 only occurred at the surface of the composite. According to the characterization analysis, the removal mechanism was the strong surface complexation of Eu(III) at the surface of SLS/SiO2. The results in this study can offer significant information for the radioactive pollution control.

In this study, the simultaneous removal of U(VI) cations and Cr(VI) anions on flower-like greigite (Fe3S4) micro-crystal was investigated by batch experiments and characterized by spectroscopy techniques. Fe3S4 micro-crystal has good removal potentials for both positive U(VI) ions (423.0 mg/g) and negative Cr(VI) ions (231.3 mg/g) at pH 5.0, and T = 298 K. Furthermore, it is interesting to note that simultaneous U(VI) and Cr(VI) removal resulted in a better removal performance (505.4 mg/g for U(VI) and 274.1 mg/g for Cr(VI) when U(VI) and Cr(VI) were removed simultaneously) than their single removal system under the same condition. The XPS, Raman, and XRD lattice analyses indicated that the synergistic removal mechanisms of U(VI) and Cr(VI) by Fe3S4 were attributed to: (1) Fe3S4 micro-crystal could adsorb U(VI) and Cr(VI) ions via its different functional groups, i.e., U(VI) ions mainly complexed with sulfide functional groups, while Cr(VI) ions mainly complexed with oxygen functional groups; (2) The simultaneous sequestration of U(VI) cations and Cr(VI) anions by Fe3S4 could enhance electrostatic attraction for each other. The higher U(VI) than Cr(VI) sorption performance is owing to the electrostatic cation–anion interaction and complexation of uranium to chromium; (3) U(VI) and Cr(VI) ions could be reduced to less toxic U(IV) and Cr(III) species with the help of reducing Fe(II) and S(-II) components in Fe3S4. The electron-accepting ability of Cr(VI) was stronger than that of U(VI) on Fe3S4. This work is of great importance for the understanding of the synergistic removal mechanisms of uranium cations and chromium anions on Fe3S4, and the usage of Fe3S4 micro-crystal in toxic metal ions removal, especially the efficient elimination of both cations and anions from wastewater.

In this investigation, two novel magnetic core-shell Fe3O4@MoS2 (F@M) and MoS2@Fe3O4 (M@F) composites were synthesized and exploited for Cr(VI) elimination. Eco-friendly preparation methods were applied for the synthesis of Fe3O4 and MoS2 composites. The experimental results showed that both F@M and M@F have high saturation magnetization values (43.2 emu/g for F@M and 49.9 emu/g for M@F), excellent maximum sorption capacities of Cr(VI) at pH 5.0 and 298 K (324.3 mg/g for F@M, 290.2 mg/g for M@F), remarkable Cr(VI) removal efficiencies (Cr(VI) sorption equilibrium by both F@M and M@F can be reached in 90 min) and nice regeneration properties (the sorption capabilities of F@M and M@F decreased slightly after five consecutive sorption/desorption cycles). Chemical reduction of Cr(VI) to Cr(III) occurred on the surface of F@M and M@F, and the synergetic reduction of sulfur and ferrous ions made F@M an outstanding material for Cr(VI) removal. This paper highlights F@M and M@F as potential, eco-friendly and ultrahigh-efficiency materials for Cr(VI) pollution cleanup.