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The importance of iodine to industry and humans cannot be overemphasized. It plays a crucial role in human metabolic processes. It is widely used for various applications in medicine, material sciences, environmental, and engineering sciences. During the deployment of nuclear technology, there is release of radioiodine in the environment through processes such as reprocessing of nuclear fuel and accidents. Thus, to safeguard the applications of iodine and prevent the leakage of radioiodine into the environment, the capturing and storage of radioiodine are very critical. In our work, ultrahigh radioiodine adsorption capacities of 454 wt% and 1508 mg g−1 were achieved for iodine vapor and iodine in cyclohexane solution, respectively; using Zinc oxide and nitrogen-doped hierarchical porous carbon (ZnO@NCs), which has a surface area of 1983 m2g−1 synthesized by ultra-sonication of ZIF-8 precursor. These ultrahigh adsorption capacities could be the result of large pore volume of the pores and area of the surface; as well as the electron donor groups such as OH− and O2−, which generated charge transfer between iodine and the adsorbent. The adsorption fits the Freundlich and pseudo-second-order models. These large surface area, ultrahigh adsorption capacity, easy preparation, and good regeneration are indicative of ZnO@NCs as a promising radioiodine adsorbent.

γ-Fe2O3 has an excellent low-temperature SCR deNOx performance, but its resistance to alkaline earth metal calcium (Ca) is poor. In particular, the detail mechanism of Ca poisoning on the γ-Fe2O3 catalyst at the atomic level is not clear. Hence, the density functional theory (DFT) method was used in this research to investigate the influence mechanism of Ca poisoning on the NH3-SCR over the γ-Fe2O3 catalyst surface. The findings reveal that NH3, NO, and O2 molecules can bind to the γ-Fe2O3 (001) surface to generate coordinated ammonia, monodentate nitroso, and adsorption oxygen species, respectively. The main active site is Fe1-top. For the γ-Fe2O3 with Ca poisoning, the Ca atom has a higher adsorption energy on the surface of γ-Fe2O3 (001), which covers the catalyst surface and reduces the active sites. The presence of Ca atom decreases the adsorption performance of NH3, while slightly improves the NO and O2 adsorption. In particular, The Ca atom restrains the NH3 activation and NH2 formation, which is detrimental to the NH3-SCR process.

γ-Fe

In this work, petal-like Fe-Mg layered double hydroxide (LDH) was fabricated by a simple solvothermal method. A well-defined petal-like shape was observed in SEM and TEM characterisations. The abil...

To further improve the removal ability of layered double hydroxide (LDH) for iodide (I−) anions from wastewater, we prepared hierarchically porous Cu5Mg10Al5-LDH and used as a matrix for in suit growth of Cu/Cu2O on its surface, forming Cu/Cu2O-LDH, which was characterized and applied as an adsorbent. Results displayed high I− saturation uptake capability (137.8 mg/g) of Cu/Cu2O-LDH compared with Cu5Mg10Al5-LDH (26.4 mg/g) even thermal activated LDH (76.1 mg/g). Thermodynamic analysis showed that the reaction between I− anions and Cu/Cu2O-LDH is a spontaneous and exothermic. Uptake kinetics analysis exhibited that adsorption equilibrium can be reached after 265 min. Additionally, the adsorbent showed satisfactory selectivity in the presence of competitive anions (e.g., SO42−), and could achieve good adsorption performance in a wide pH range of 3–8. A cooperative adsorption mechanism was proposed on the basis of the following two aspects: (1) ion exchange between iodide and interlayer anions; (2) the adsorption performance of Cu, Cu(II) and Cu2O for I−. Meanwhile, the difference between the adsorption mechanism of Cu/Cu2O-LDH, Cu5Mg10Al5-LDH and Cu5Mg10Al5-CLDH adsorbents was also elaborated and verified.

Iodine plays a significant role in industry and in chemical processes within living organisms. However, radioiodine exposure possess threats such as thyroid cancer to humans, when they are released into the environment when using nuclear technology and through nuclear accidents. Its capture and storage is critical to safeguard industrial applications while preventing environmental leakages. Herein we report efficient radioiodine capture using a hierarchical nitrogen-doped, large surface area, nanoporous carbon derived from ultrasonication of ZIF-8. The carbon exhibited high adsorption capacity of 434 wt% gravimetrically and 1418 mgg− 1 in cyclohexane solution with fast kinetics and high recoverability. We deduced the high adsorption capacity to be due to the large surface area with micro and mesopores, presence of hydroxyl groups acting as electron donors and the presence of nitrogen, which interacts strongly with the electron-deficient iodine (I2). Moreover, the process best fits the pseudo-second-order and Freundlich models with multilinearity observed with Webber-Morris model. Because of its comparatively lower cost, large surface area, facile preparation, good regeneration and fast kinetics, the as-prepared porous carbon shows exceptional promise as radioiodine adsorbent.

Specific tables and charts in the article“Research on the Digital Humanities Practices in Chinese Libraries: A Case Study of Shanghai Libraries&rdquo

Cardamine enshiensis (C. enshiensis) is a selenium (Se) hyperaccumulator plant found in Enshi, a typical seleniferous area in southwestern Hubei Province, central China. The aim of this work was to investigate the translocation and transformation of Se in C. enshiensis, which may help to elucidate the mechanism on the tolerance and hyperaccumulation of Se in C. enshiensis. The contents of Se in roots, shoots and leaves of C. enshiensis were measured by ICP-MS. The spatial distribution and chemical forms of Se in roots, shoots and leaves of C. enshiensis were studied using synchrotron radiation microfocused X-ray fluorescence analysis (μ-SRXRF) and in situ Se K-edge X-ray Absorption Near Edge Spectroscopy (μ-XANES). The Se species in roots, shoots and leaves were further studied by RP-HPLC-ICPMS. Roots, shoots and leaves of C. enshiensis contained an average of 2985, 3329 and 2491 mg/kg Se DW, respectively. μ-SRXRF found that Se was primarily located in the cortex, endodermis, and vascular cylinder in roots, while it was in the epidermis, cortex and vascular bundle of shoots and concentrated in the leaf veins and the peripheral parts. In situ μ-XANES analysis showed that the root vascular tissue contained 16% SeO42−, 19% C-Se− (using selenocystine, SeCys as model compound) and 65% C-Se-C (using methylselenocystine, MeSeCys as model compound), and shoot vascular bundle contained 10% SeO42−, 28% C-Se− and 62% C-Se-C while leaves had 84% C-Se− and 16% SeO32−. RP-HPLC-ICPMS confirmed that the major Se species were MeSeCys and SeCys. C. enshiensis is a hyperaccumulator plant with the majority of Se in it as organic Se species like MeSeCys and SeCys. Se was translocated from roots via shoots to leaves through vascular tissues, and was deposited in the cortex and endodermis of roots, epidermis and cortex of shoots and periphery of leaves. The high concentration of organic Se species like MeSeCys suggests that C. enshiensis may be used for health promotion in people suffered from cancer and other diseases. Besides, the hyperaccumulation of Se in C. enshiensis may also identify itself to be applied for phytoremediation in Se-contaminated areas.

The leakage of iodide (I−)-containing wastewater into environment could cause water pollution owing to the toxicity and radioactivity of iodine isotopes. Therefore, multifunctional adsorbents with high-efficiency removal toward iodide are in high demanded. In the present research, the hierarchically mesoporous mixed copper oxide anchored on calcined layered double hydroxide (Cu2O/CuO@CLDH) materials were synthesized by direct pyrolysis of Cu-BTC metal-organic framework @ layered double hydroxide (HKUST-1@LDH) under N2. Subsequently, the resultant materials were characterized and applied to remove iodide from simulated wastewater. The batch adsorption experiments showed a high I− adsorption amount of 120.9 ​mg/g with relatively fast kinetic removal process as well as good selectivity, and wide working pH range. The adsorption behavior, with spontaneity and exothermic, matched well with the Langmuir isotherm and pseudo-second-order kinetic models, which suggests a homogenous monolayer adsorption and chemisorption characteristics of the as-fabricated materials toward iodide. The outstanding adsorption performance of Cu2O/CuO@CLDH could be attributed to the reconstruction of the layered structures of CLDH and the strong chemical interaction between Cu2O and I−. This study proposes a promising material for iodide elimination.

Studies on the elimination of iodide anions (I−) by Cu-based adsorbents have been conducted for decades, however its unsatisfactory adsorption performance and its non-reusability are still the main obstacles for large-scale practical applications. Here, an efficient technique was proposed for the elimination of iodide using nanowhisker zero-valent copper (nwZVC) decorated ZnO nanocomposites obtained by two steps pyrolysis of Cu-Zn bimetal ZIFs precursors. The as-synthesized materials were extensively characterized and the results clearly revealed that nanoscale ZVC were well-dispersed in the ZnO matrix, and the morphology and the amount of nanoscale ZVC could be tuned by adjusting the molar ratio of Cu/Zn in ZIF precursors. The following batch adsorption experiments demonstrated that the resultant materials exhibited high adsorption capacity of 270.8 mg g−1 under condition of adequate oxygen, as well as high selectivity, strong acidity resistance and an excellent reusability. The mechanism investigations revealed that the elimination of I− by as-fabricated materials involved adsorption process coupled with oxidation, and the existence of nwZVC was responsible for this since nwZVC could activate molecular oxygen to generate H2O2 accompanied by the release of Cu+, thus leading to I− adsorbed by the released Cu+ and oxidized by the H2O2.

Iodine plays a significant role in industry and in chemical processes within living organisms. However, radioiodine exposure possess threats such as thyroid cancer to humans, when released into the environment through using nuclear technology, used nuclear fuel reprocessing and nuclear accidents. Its capture and storage is critical to safeguard industrial applications, prevent harm to human health, while preventing environmental damage. Herein we report efficient radioiodine capture using a large surface area, nanoporous carbon derived from ultra-sonication of ZIF-8. The carbon exhibited high adsorption capacity of 434 ​wt% gravimetrically with reusability of 96% after 3 cycles, and 1418 mgg-1 in cyclohexane solution with fast kinetics and high recoverability and reusability. We deduced the high adsorption capacity to be due to the large surface area with micro and mesopores, presence of OH- acting as electron donors and the presence of nitrogen, which interacts strongly with the electron-deficient iodine (I2). Moreover, the process best fits the pseudo-second-order and Freundlich models with multilinearity observed with Weber-Morris model. Because of its comparatively lower cost, large surface area, facile preparation, good regeneration and fast kinetics, the as-prepared porous carbon shows exceptional promise as radioiodine adsorbent.

To further improve the removal ability of layered double hydroxide (LDH) for iodide (I

Iodide anion (I−) is one of the most-problematic radioactive nuclides in used nuclear fuel due to its intrinsic characteristics of a high toxicity and environmental mobility. Therefore, effective and selective elimination of I− from nuclear contaminated solution is highly beneficial for the pollution remediation purposes in the development of nuclear power, but is of significant challenge owing to the extreme conditions of the high acidity, strong ionizing radiation field and high concentration of competing anions. Herein, a novel core–shell ZnO@Cu2O (ZC) encapsulated Ag nanoparticles (Ag NPs) nanocomposites have been fabricated via a facile one step self-assembly process and an environmentally friendly technique. The as-fabricated ZnO@Ag@Cu2O (ZAC) nanocomposites were characterized and applied to capture of I− from aqueous solution. Adsorption studies revealed that the ternary nanocomposites showed fast removal kinetics, high photooxidation-adsorption capacity (up to 217.4 mg g−1 at pH = 3 for ZAC-2), satisfactory selectivity and high acidity resistance. Furthermore, the nanocomposites also exhibited a good reusability, as no significant change in the uptake capacity was observed even after five adsorption-regeneration cycles. Inspired by the superior features, a possible mechanism (chemical adsorption coupled with photooxidations) was proposed based on XRD, XPS and Raman spectra analysis for the pre- and post-adsorbed samples as well as the detailed adsorption experimental evidence.

Elimination of radioactive iodide (I-) from complex solution of used nuclear fuel directly is the optimum scheme in the remediation of iodide released into the environment. However, this assignment represents a tremendous challenge given the combined harsh conditions of strong acidity, high ionic strength, and strong ionizing radiation field. Here, we surmount the challenge by applying silver-decorated ZIF-8 derived ZnO concave nanocubes (CNCs) (denoted as AZ) as a potential photocatalyst and adsorbent for photooxidation-adsorption of I- from simulated radioactive wastewater. The as-synthesized product showed a prominent I- uptake capacity of 129.3 ​mg g-1 under visible light with relatively fast kinetic adsorption process as well as remarkable selectivity, strong acid resistance and excellent γ radiation resistance. The uptake process, with spontaneity and exothermic, followed the pseudo-second-order kinetics and Langmuir isotherm models. The mechanism explaining the excellent properties was investigated systematically and could be epitomized into the following: AZ nanocomposites possessed the cumulative effects of the uptake performance of Ag2O for I-, the photooxidation property of Ag(0)@ZnO CNCs for oxidation of I- to I2 under visible light. Density functional theory (DFT) calculations further revealed that I2 was more likely to bind to nearby Ag site yielding AgI, or be trapped readily by AgI to form AgI3. Overall, our work provides a facile and useful pathway toward radioactive iodine elimination.

The high effective Ag/ZIF-8@ZIF-67 core-shell composite was fabricated by a convenient strategy and applied in the reduction of 4-nitrophenol. The obtained samples were fully characterized by transmission electron microcopy (TEM), element mapping, X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and the like. Catalytic experiments showed that the Ag/ZIF-8@ZIF-67 exhibit superior catalytic activity in the reduction of 4-nitrophenol and another two nitroaromatic compounds. The apparent rate constant (Kapp) and the conversion frequency (TOF) of Ag/ZIF-8@ZIF-670.4 for 4-nitrophenol were 12.22 × 10−3 s−1 and 5.611 min−1, respectively, and preserved high catalytic performance after four cycles. The catalytic activity of Ag/ZIF-8@ZIF-67 was significantly increased compared to Ag/ZIF-8, which was mainly attributed to the high specific surface area of ZIF-8@ZIF-67, the synergy of ZIF-8 core and ZIF-67 shell and the restriction of pores to Ag NPs.

Nano mixed-valence silver oxide (Ag2O-Ag2O3) modified the zeolitic imidazolate framework-8 (ZIF-8) composite (Ag2O-Ag2O3@ZIF-8) was firstly prepared via a simple and efficient method, characterized and applied for iodide ion (I−) uptake from simulated radioactive wastewater. The results showed that Ag2O-Ag2O3 nanoparticles doped and uniformly dispersed on the surface of ZIF-8 matrix. The adsorption capacity of the as-synthesized adsorbents increased with the increasing Ag doped amount, and the maximum adsorption capacity for 20%-Ag2O-Ag2O3@ZIF-8 was 232.12 mg/g. The calculated thermodynamic parameters indicating that the adsorption was a spontaneous and exothermic. It was worth mentioning that each Ag-based adsorbent exhibited high uptake rate of I−, and all the adsorption tests were equilibrated for a few minutes. This could be ascribed to its large specific surface area and the absolutely dominant position of chemical adsorption for as-prepared samples. Furthermore, the adsorption was barely affected by pH and competitive anions (e.g. Cl−, SO42−, CO32−), even in simulated salt lake water. Additionally, a mechanism explaining the excellent properties for adsorbents could be epitomized into three aspects, namely, the uptake performance of Ag2O for I−, the strong oxidization of Ag2O3 for I−, and the adsorption of AgI for I2.