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Electrochemical conversion of nitrate offers an efficient solution to nitrate pollution and a sustainable strategy for ammonia generation. Cu and Fe bimetallic electrocatalysts exhibit excellent electrochemical reduction of nitrate (NO3RR) reactivity but the conventional preparation strategy is complex and time‐consuming and this reaction is still suffers from unsatisfied kinetic and unidentified mechanisms. Herein, in situ electrodeposition strategy is employed to induce Cu to modify the Fe active sites of iron‐based N‐doping carbon nanofiber electrode (Fe/Fe3C@NCNFs) during NO3RR in Cu‐contained nitrate solution. Benefiting from the synergistic effect between Cu and Fe sites of Cu─Fe/Fe3C@NCNFs electrode, superior activity of rate‐determining reaction (*NO3 to *NO2) and reduced energy barriers of the following deoxidation and hydrogenation steps are achieved. Compared with Fe/Fe3C@NCNFs‐500, the pseudo‐first‐order (PFO) rate constant for NO3RR by Cu─Fe/Fe3C@NCNFs demonstrates nearly two‐fold improvement with high current efficiencies over wide pH and voltage range. Furthermore, the maximum NO3─N removal capacity and N2 selectivity of Cu─Fe/Fe3C@NCNFs reach 15593.8 mg N g−1 Fe and ca. 92% after twenty cycles. This work offers an avenue for highly active bimetallic electrode design, paving more insights into the interactions between active site construction and NO3RR performance. [ABSTRACT FROM AUTHOR]

Mining wastewater with heavy metals poses a serious threat to the ecological environment. However, the acute single and combined ecological effects of heavy metals, such as chromium (Cr) and nickel (Ni), on freshwater ostracods, and the development of relevant prediction models, remain poorly understood. In this study, Heterocypris sp. was chosen to investigate the single and combined acute toxicity of Cr and Ni. Then, the quantitative structure-activity relationship (QSAR) model was used to predict the combined toxicity of Cr and Ni. The single acute toxicity experiments revealed high toxicity for both Cr and Ni. In addition, Cr exhibited greater toxicity compared to Ni, as evidenced by its lower 96-hour half-lethal concentration (LC50) of 1.07 mg/L compared to 4.7 mg/L for Ni. Furthermore, the combined acute toxicity experiments showed that the toxicity of Cr-Ni was higher than Ni but lower than Cr. Compared with the concentration addition (CA) and independent action (IA) models, the predicted results of the QSAR model were more consistent with the experimental results for the Cr-Ni combined acute toxicity. So, the high accuracy of QSAR model identified its feasibility to predict the toxicity of heavy metal pollutants in mining wastewater. [ABSTRACT FROM AUTHOR]

This study proposes a new Pr 0.25 Nd 0.25 Ca 0.5 MnO 3-δ (PNCM) cathode material for protonic ceramic fuel cells (PCFCs). As demonstrated by first-principles calculations, the Ca-doping strategy can promote oxygen vacancy formation and accelerate the oxygen reduction reaction (ORR) compared to the conventional Sr-doping method. Additional experiments reveal the doping of Ca can enhance the proton and oxygen diffusion abilities compared with the traditional Sr-doped material. Consequently, the PCFC with single-phase PNCM cathode produces a high peak power density of 1232 mW cm-2 at 700 °C, which is significantly greater than the cell with Sr-doped cathode, which only produces 749 mW cm-2 under the same testing conditions. The PNCM cathode inherits the excellent stability of manganate cathodes, allowing the fuel cell to exhibit good stability under operational conditions. PNCM is a new and promising cathode material for PCFCs due to its excellent fuel cell performance and stability. [ABSTRACT FROM AUTHOR]

Sintering aids are commonly used to improve the sinterability of proton-conducting oxides, whereas the sintering aid elements are being used alone in previous research. In this study, a high-entropy design method for the BaCe 0.4 Zr 0.4 Y 0.2 O 3 (BCZY) proton-conducting oxides sintering aid is proposed. In contrast to the use of sintering aids such as Ni, Fe, Cu, Co, and Zn alone, the high-entropy design allows for the simultaneous use of all five elements, resulting in the new composition BaCe 0.4 Zr 0.4 Y 0.15 Ni 0.01 Cu 0.01 Co 0.01 Fe 0.01 Zn 0.01 O 3 (HE-BCZY). Compared to conventional BaCe 0.4 Zr 0.4 Y 0.15 M 0.05 O 3 (BCZYM, M = Ni, Cu, Co, Fe, Zn) materials, the sinterability of the new HE-BCZY material is significantly greater than that of BCZYM, despite the fact that the concentration of sintering aids is the same. Following sintering at 1300 °C, the HE-BCZY electrolyte membrane is completely dense. In addition, the HE-BCZY electrolyte has a higher conductivity than BCZYM. The low sintering temperature allows the successful preparation of proton ceramic fuel cells (PCFCs) with the HE-BCZY electrolyte, and the fuel cell reaches a high peak power density of 1218 mW cm−2 at 700 °C, which is much higher than that of PCFCs using BCZY-based electrolytes. In addition, the excellent chemical stability of HE-BCZY is maintained under both H 2 O and CO 2 conditions. Consequently, a fuel cell employing the HE-BCZY electrolyte operates without detectable degradation for 200 h. This study demonstrates that although the high-entropy design is seldom used for sintering aids of proton-conducting oxides, it is an intriguing and promising strategy for creating high-performance electrolyte materials with good sinterability, high conductivity, and excellent stability. [ABSTRACT FROM AUTHOR]

Bicarbonate, ubiquitous in natural and waste waters is an important factor regulating the rate and efficiency of pollutant separation and transformation. For example, it can form complexes with U(VI) in the aqueous phase and at the solid-water interface. In this work, we investigated the effect of bicarbonate on the aging of nanoscale zero-valent (nZVI) in the context of U(VI) reduction and removal from wastewater. For fresh nZVI, over 99% aqueous uranium was separated in less than 10 min, of which 83% was reduced from U(VI) to U(IV). When nZVI was aged in water, its activity for U(VI) sequestration and reduction was significantly reduced. Batch experiments showed that for nZVI aged in the presence of 10 mM bicarbonate, only 20.3% uranium was reduced to U(IV) after 6 h reactions. Characterizations of the iron nanoparticles with spherical aberration corrected scanning transmission electron microscopy (Cs-STEM) suggest that in fresh nZVI, uranium was concentrated at the nanoparticle center; whereas in nZVI aged in bicarbonate, uranium was largely deposited on the outer surface of the nanoparticles. Furthermore, aged nZVI without bicarbonate contained more lepidocrocite (γ-FeOOH) while aged nZVI in the presence of bicarbonate had more magnetite/maghemite (Fe 3 O 4 /γ-Fe 2 O 3 ). This could be attributed to the formation of carbonate green rust and pH buffer effect of . Primary mechanisms for U(VI) removal with nZVI include reduction, sorption and/or precipitation. Results demonstrate that bicarbonate alter the aging products of nZVI, and reduces the separation efficiency and reduction capability for uranium removal. [ABSTRACT FROM AUTHOR]

[Display omitted] • Stability of immobilized uranium by nZVI was investigated. • nZVI transformed to ferrihydrite and then stable iron oxides. • More than 90% U(VI) was reduced. • Key uranium uptake mechanism changed from reduction to adsorption. • E h could be used to control uranium uptake efficiency and its stability. Uranium is a carbon dioxide free nuclear energy, and uranium-contained wastewater poses serious chronic health effects toward human. Nanoscale zero-valent iron (nZVI) separates uranium from wastewater with ultrafast kinetic, high capacity and selectivity. However, the dynamic interfacial uranium binding mechanisms and its stability, controlled by the phase transformation of nZVI, is important but poorly understood. After 120 h reaction, the fresh nZVI was oxidized and transformed to ferrihydrite and then lepidocrocite and hematite. Analysis for the structures and valence states of U, Fe species indicated that the dominate U(VI) uptake mechanism changed from Fe0 induced reduction to adsorption as nZVI transformed to iron (oxyhydr)oxides. Density functional theory calculation revealed that uranyl formed corner-sharing configurations on the surface of iron nanoparticles, and some uranium ions prefer to incorporate into the structure of lepidocrocite than hematite during the crystallization processes of ferrihydrite. Meanwhile, 100 ∼ 10000 μg/L uranyl ions were quickly captured, the residual uranium could be maintained at ∼9.31 μg/L and the content of uranium in reacted iron nanoparticles reached ∼24.16 wt%. Interestingly, the oxidization reduction potential (E h) was a potential parameter to control uranium immobilization in the CSTR system, and the E h control strategy could be used to increase the fraction of U(IV)/U(V), sparingly soluble and highly stable, higher than 90 %. The findings augment our understanding of U-nZVI reactions and guide nZVI technology to remedy real uranium-contained wastewater. [ABSTRACT FROM AUTHOR]

A common concern in the approval of nanotechnology for water treatment is whether there are advantages of these nanomaterials over conventional water treatment reagents. In this work, nanoscale zero-valent iron (nZVI) is compared with lime (Ca(OH) 2 ), the most widely used heavy metal precipitant, for Pb(II) and Zn(II) removal, in laboratory and field experiments. Water chemistry, treatment efficiencies and reaction products of the two reagents are compared and the study shows that the moderate solution pH of nZVI and its seed effect play vital roles in producing high-quality effluents. The results are then verified in a field continuous-flow experiment using tons of lime and kilos of nZVI. The results show that sub-ppm levels (∼0.1 mg/L) of Pb(II) and Zn(II) could not be achieved via lime precipitation alone, due to the solubility limits of metal hydroxides and their re-dissolution caused by the strong alkalinity of lime. In comparison, stable and lower levels of Pb(II) and Zn(II) were easily attained using nZVI, due to its multifunctional properties and good tolerance for influent fluctuation enabled by its inherent pH-stabilizing nature. SEM characterizations, particle size analyses and quiescent settling experiments show the ability of nZVI to generate large and consolidated solids that are amenable to gravitational separation. The study shows several key advantages of nZVI over lime technology in Pb(II) and Zn(II) removal. As lime is widely used for heavy metal removal, this work provides an effective advanced treatment process to supplement lime-based treatment methods. [ABSTRACT FROM AUTHOR]

Based on the stable Zr6O4(OH)4 metal clusters, UiO-67 was first applied to the adsorption of U(VI), and its stability and adsorption performance for U(VI) were compared with UiO-66. As the organic ligand was lengthened, UiO-67 had a larger specific surface area and pore volume than UiO-66. The adsorption capacity of UiO-67 for uranium was 1.68 times that of UiO-66 under the same conditions. The chemical stability of UiO series decreased with the extension of organic ligands; for example, the crystalline structure of UiO-67 disintegrated in methanol, ethanol and water. Through the infrared spectra, adsorption isotherms and kinetics fitting, it is concluded that the carboxyl groups of UiO-67 participated in the chemisorption of U(VI), and uranyl ions adsorbed on UiO-67 were not desorbed with the collapse of UiO-67 crystal. This work represents the extension of organic chains reduces the chemical stability of MOFs but improves the adsorption performance of U(VI), which may be applied to predict the structural stability and adsorption capacity of other MOFs containing aromatic dicarboxylate organic linkers. [ABSTRACT FROM AUTHOR]

As an emerging versatile technology for separating uranium from uranium-containing wastewater (UCW), microbial fuel cell (MFC) offers a novel approach to UCW treatment. Its cathode is essential for the treatment of UCW. To thoroughly investigate the efficacy of MFC in treating UCW, investigations were conducted using MFCs with five materials (containing iron sheet (IP), stainless steel mesh (SSM), carbon cloth (CC), carbon brush (CB), and nickel foam (NF)) as cathodes. The results revealed that each MFC system performed differently in terms of carbon source degradation, uranium removal, and electricity production. In terms of carbon source degradation, CB-MFC showed the best performance. The best uranium removal method was NF-MFC, and the best electricity production method was carbon-based cathode MFC. Five MFC systems demonstrated stable performance and consistent difference over five cycles, with CC-MFC outperforming the others. Furthermore, SEM and XPS characterization of the cathode materials before and after the experiment revealed that a significant amount of U(IV) was generated during the uranium removal process, indicating that uranium ions were primarily removed by electrochemical reduction precipitation. This study confirmed that abiotic cathode MFC had a high UCW removal potential and served as a good guideline for obtaining the best cathode for MFC. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (CN) as an adsorbent exhibit promising potential for the removal of uranium in water. However, the lack of active sites seriously restricts its practical application. In contrast to the traditional method of introducing new ligands, we propose a strategy to activate original ligands on CN by injecting π electrons, which can be realized by grafting 4-phenoxyphenol (PP) on CN (PCN). Compared with CN, the maximum adsorption capacity of PCN for uranium increased from 150.9 mg/g to 380.6 mg/g. Furthermore, PCN maintains good adsorption properties over a wide range of uranium concentrations (1 ∼ 60 mg/L) and pH (4 ∼ 8). After 5 consecutive cycles, PCN exhibited sustained uranium removal performance with a little of losses. The experimental and theoretical results show that the enhancement of adsorption performance is mainly due to the ligands activation of CN by delocalization of π electrons from PP. Furthermore, this activation can be enhanced by irradiation, as the CN can be photoexcited to provide additional photoelectrons for PP. As a result, dormant ligands such as N-C N, C-O-C, C-N-H and N-(C) 3 can be activated to participate in coordination with uranium. This work provides theoretical guidance for the design and preparation of high efficiency uranium adsorbent. [Display omitted] • PCN was demonstrated to be an efficient adsorbent for removal of uranium. • PP can activate CN surface ligands by injecting π electrons for UO 2 2+ coordination. • N-C N, C-O-C, C-N-H and N-C 3 were activated for efficient uranium adsorption. • π electrons activation mechanism can be enhanced by light irradiation. [ABSTRACT FROM AUTHOR]

• Iron particle formation under different chlorine concentrations were studied. • High initial chlorine would prevent particle formation under a long hydraulic retention time. • EPS provided better protection for pipe corrosion under higher initial residual chlorine. • High initial chlorine may unexpectly increase the risk of microorganisms. Unlined iron pipe (UIP) is still widely in use in drinking water distribution systems (DWDS), discoloration easily happens after a long-time retention due to iron release, but the influence of initial chlorine on water quality under this condition is not clear. Here, we studied the water quality changes in UIP section reactors under different initial chlorine dosages. Results showed that chlorine could disappeared rapidly within 0.5 h in the UIP. The water with higher initial chlorine (5 mg/L) had higher turbidity in a short time (within 1.5 h), but for a longer retention time (2∼12 h), the highest turbidity was in the iron pipe without initial chlorine. Interestingly, a clear increase in adenosine triphosphate in the UIPs was observed with the increase of initial chlorine, which was in accordance with the results of heterotrophic plate count. Polysaccharide and protein increased with the increase of initial chlorine, which would benefit the formation of a protective layer to inhibit corrosion. This study reflects that during the overnight retention in UIP, raising chlorine would be effective to control discoloration, but chemical and microbiological risks may increase. [Display omitted] [ABSTRACT FROM AUTHOR]

Reduction of the migratory ability of uranium via reduction, co-precipitation or immobilization is a widely used technology for remediation of uranium contaminated groundwater (UCG). However, the re-released uranium due to environmental alterations such as oxidation, acid dissolution, or microbial decomposition limits the long-term effect of UCG remediation. Here, we developed a novel solar-powered electrochemical mineralization (SPEM) system for persistent remediation of UCG under laboratory conditions. The SPEM system incorporates uranium into magnetite crystal to achieve long-term stability of uranium. The effects of photoelectric conversion, subsurface void fraction, groundwater seepage velocity, and electrode configuration on uranium removal were systematically analyzed. The results showed that the remediation system had excellent adaptability to complex water quality and geological conditions, and could remediate large-area contamination. After 12 h of persistent treatment, the system with newly hexagonal two-dimensional electrode configuration (1A6C) reduced uranium concentration by more than 85% in simulated subsurface environment. The mineralized uranium was not re-released within continuous rinsing of treated regions using an acid solution (pH = 3.0), for 370 h. The developed method solely requires metallic iron as a raw material, which has high and long-term efficiency, is eco-friendly, simple, and widely applicable, thus reliable for the remediation of deep UCG. [Display omitted] • A SPEM system was constructed for persistent remediation of U from groundwater. • Effects of illumination and hydrogeological conditions on U removal were clarified. • The SPEM with a 1A6C electrode arrangement efficiently removed U from groundwater. • U remains stable in remediated regions and is not re-released under acidic condition. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new nFe 3 O 4 /PA/CB cathode for uranium separation in MFC was prepared by CVST. • nFe 3 O 4 /PA/CB cathode can efficiently and consistently isolate uranium from UCW. • The combination of nFe 3 O 4 and PA improves MFC power generation and uranium separation significantly. Microbial fuel cells (MFCs) have gained increasing attention in the field of uranium-containing wastewater (UCW) treatment as a self-powered bioelectrochemical system (BES) due to its advantages of recovering uranium resources and generating electricity. However, the lack of catalytic active sites on the carbon fiber cathode significantly hinders the reaction performance of surface electrons with uranium ions in solution, thereby limiting the application of MFC. In this study, we propose a carbon brush (CB) cathode modification process that utilizes cyclic voltammetry synthesis technique (CVS) to polymerize aniline (PA) on the surface of carbon fibers and uniformly load nano-Fe 3 O 4 particles (nFe 3 O 4). The loading of PA/nFe 3 O 4 not only significantly improve the catalytic active sites but also enhance the synergistic effect of adsorption and conductivity of CB cathode. Consequently, the nFe 3 O 4 /PA/CB-MFC showed excellent ability to continuous power generation and uranium separation. Over eight cycles of uranium separation, the nFe 3 O 4 /PA/CB-MFC exhibited an average maximum power density of 15.17 mW/m2 and a uranium separation efficiency of 95.52 %, showcasing substantial enhancements by 2.10-fold and 1.44-fold compared to the CB-MFC, respectively. Our study presents an efficient approach to enhance the efficiency of uranium separation and boost power density of MFC by increase catalytic active sites on carbon-based cathode. [ABSTRACT FROM AUTHOR]

Metals and glyphosate (GPS) herbicides adsorbed on minerals affects their mobility and environmental effects. In this study, using goethite as a model soil mineral, GPS and uranium as contaminants to investigate the effects of GPS on adsorption of uranium. The effects of solution pH, initial concentration and contact time on adsorption were investigated. When the initial pH is 4.0, the highest adsorption capacity of goethite for uranium with the absence GPS and the presence of GPS are 69.39 mg g−1 and 78.84 mg g−1 respectively. The adsorption kinetics can be well described by quasi second-order model, and the adsorption process can be described by Langmuir isotherm. Additional evidence for the uptake mechanism was obtained using FTIR and XPS. The carboxylic acid and phosphonic acid groups of the GPS molecule participated in the reaction with goethite and uranium to form goethite-GPS-U(VI) ternary complex. [ABSTRACT FROM AUTHOR]

Nanoscale zerovalent iron (Fe0)-based materials have been demonstrated to be a effective method for the U(VI) removal. However, limited research has been conducted on the long-term immobilization efficiency and mechanism of Fe0-based materials for U(VI), which are essential for achieving safe handling and disposal of U(VI) on a large scale. In this study, the prepared carboxymethyl cellulose (CMC) and sulfurization dual stabilized Fe0 (CMC-Fe0/FeS) exhibited excellent long-term immobilization performances for U(VI) under both anoxic and oxic conditions, with the immobilization efficiencies were respectively reached over 98.0 % and 94.8 % after 180 days of aging. Most importantly, different from the immobilization mechanisms of the fresh CMC-Fe0/FeS for U(VI) (the adsorption effect of –COOH and –OH groups, coordination effect with sulfur species, as well as reduction effect of Fe0), the re-mobilized U(VI) were finally re-immobilized by the formed FeOOH and Fe 3 O 4 on the aged CMC-Fe0/FeS. Under anoxic conditions, more Fe 3 O 4 was produced, which may be the main reason for the long-term immobilization U(VI). Under oxic conditions, the production of Fe 3 O 4 and FeOOH were relatively high, which both played significant roles in re-immobilizing U(VI) through surface complexation, reduction and incorporation effects. Long-term immobilization of U(VI) was achieved by CMC-Fe0/FeS and its removal and long-term immobilization mechanisms were further revealed. [Display omitted] • CMC-Fe0/FeS showed excellent long-term stability under oxic and anoxic conditions. • After 180 days of oxic or anoxic aging, the immobilization efficiencies exceed 94.8 %. • After aging for 180 days, the iron leaching rates were less than 2.5 ‱. • The formation of Fe 3 O 4 and FeOOH during aging were account for the long stability. • More FeOOH taken part in the long-term immobilization of U(VI) under oxic conditions. [ABSTRACT FROM AUTHOR]

Efficient degradation of antibiotic by peroxydisulfate (PDS)-based advanced oxidation processes in complex water environment is challenging due to the interference of impurities and the low activation efficiency of PDS caused by its symmetric structure. Herein, a novel Cu 7 S 4 /PDS system was developed, which can selectively remove tetracycline hydrochloride (TC) without interference of inorganic ions (e.g., Cl- and HCO 3 -) and natural organic matter (e.g., humic acid). The results of quenching and probe experiments demonstrated that surface high-valent copper species (Cu(III)), rather than radicals and 1O 2 , are main active species for TC degradation. Cu(III) can be generated via Cu(I)/O 2 and Cu(II)/ Cu(I)/PDS systems and the S species on the surface of Cu 7 S 4 promotes the cycle of Cu(II)/ Cu(I) and Cu(III)/ Cu(II), resulting in continuous generation of Cu(III). In addition, the degradation pathways of TC were proposed based on product analysis and DFT theory calculations. The acute toxicity, developmental toxicity and mutagenicity of treated TC were significantly reduced according to the results of toxicity estimation software tool. This study shows a promising Cu 7 S 4 /PDS system for the degradation and detoxication of antibiotic in complex water environment, while also providing a comprehensive understanding of PDS activation by Cu 7 S 4 to generate active Cu(III) species. [Display omitted] • Cu(III) was identified as main active species in a novel Cu 7 S 4 /PMS system. • Cu 7 S 4 /PMS system showed high reactivity and selectivity to degrade electron-rich antibiotic. • Common water components such as chloride ions did not influence the degradation. • Toxicity of degradation intermediates decreased based on QSAR analysis. • Activation mechanism and degradation pathway were proposed. [ABSTRACT FROM AUTHOR]

Doping uranium into a room-temperature stable Fe 3 O 4 lattice structure effectively reduces its migration. However, the synergistic or competitive effects of coexisting ions in an aqueous solution directly affect the uranium mineralization efficiency and the structural stability of uranium-bearing Fe 3 O 4. The effects of calcium, carbonate, and phosphate on uranium electromineralization were investigated via batch experiments and theoretical calculations. Calcium incorporated into the Fe 3 O 4 lattice increased the level and stability of doped uranium in Fe 3 O 4. Uranium and calcium occupied the octahedral and tetrahedral sites of Fe 3 O 4 , respectively; the formation energy was only −10.23 eV due to strong hybridization effects between Fe1s, U4f, O2p, and Ca3d orbitals. Compared to the uranium-doped Fe 3 O 4 , uranium leaching ratios decreased by 19.2 % and 48.9 % under strongly acidic and alkaline conditions after 120 days. However, high concentrations of phosphate inhibited Fe 3 O 4 crystallization. These results should provide new avenues for the development of multi-metal co-doping technologies and mineralization optimization to treat uranium-containing complex wastewater. [Display omitted] • Ca enhanced electromineralization rate and extent of U by Fe 3 O 4. • Ca and U co-doped into the Fe 3 O 4 lattice. • Lattice formation energy decreased for Ca and U co-doped Fe 3 O 4. • (Fe, Ca, U) 3 O 4 was more resilient to be corroded than (Fe, U) 3 O 4. [ABSTRACT FROM AUTHOR]

[Display omitted] • Roles of O groups in U adsorption by aged PS MPs were assessed for the first time. • Aging process improves U adsorption capacity of PS MPs. • O functional groups in aged PS MPs can serve as adsorption sites for uranyl. • PS MPs affinity to U ordered as PS═O–OHm > PS═O > PS–COOH > PS–OH > PS–OHm > virgin PS. • O groups facilitates U adsorption via HB from electrostatic and polarization effects. Although oxygen-containing functional groups generated during unavoidable aging play a key role in improving the adsorption performance of heavy metals by microplastics (MPs), little is known about the contribution of such groups to the interactions between highly toxic radioactive heavy metals and aged MPs. Here, we used a combination of batch experiments and density functional theory calculations to examine the effects and mechanisms of aging and the produced oxygen-containing functional groups, i.e., C═O, –OH, phenolic hydroxyl (–OHm), and –COOH, on the adsorption behavior of representative radionuclide uranium (U) on polystyrene (PS) MPs. The kinetic experimental results showed that the amount of U adsorption by the aged PS MPs was significantly higher than that of virgin PS MPs (P < 0.05). Binding-energy and thermodynamic data indicated that the affinity of PS MPs to a typical U species, i.e., uranyl, followed the order of PS═O–OHm > PS═O > PS–COOH > PS–OH > PS–OHm > virgin PS. Characterization and surface potential analyses demonstrated that the electronegative oxygen atoms in oxygen-containing functional groups in the aged PS MPs increased along with the aging time, and could serve as potential sites for electrostatic interactions with uranyl. Intramolecular interaction calculations confirmed that hydrogen bonding by oxygen-containing functional groups could strengthen the interactions between uranyl and aged PS MPs via electrostatic and polarization effects. Our findings provide an in-depth understanding of the role of aging in U adsorption by MPs, which is critical for assessing the fate of coexisting radionuclides and MPs in the environment, and their associated risks. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe0@SGB-NH 2 composites filled with semi-porous volume Fe0 were successfully prepared. • The content of Fe0 in Fe0@SGB-NH 2 was only 1/28 times that of unmodified Fe0 to reach the same U(Ⅵ) removal rate. • Fe0@SGB-NH 2 exhibited extraordinary selective capture and removal ability for uranium. • The sediment after the reaction of Fe0@SGB-NH 2 and uranium exhibited excellent resistance to the risk of secondary release. Developing a materials to realize the selective adsorption and long-term immobilization of uranium is of great significance for the effective remediation of uranium-containing wastewater. Herein, we half-filled Fe0 into SGB-NH 2 mesoporous channels to prepare a composite of Fe0 and amino-functionalized silica (Fe0@SGB-NH 2), and used to the selective removal of uranium in solution under aerobic conditions. It was found that solutions containing 10 mg/L U(VI) could be purified 98.96% by Fe0@SGB-NH 2 in the presence or absence of Na+, K+, Mg2+, SO 4 2 −, NO 3 −, HCO 3 − and Cl− at pH 5–9. Compared with Fe0, its saturation magnetization decreased from 81.24 emu/g to 0.78 emu/g, while the specific surface area increased from 47.895 m2/g to 504.404 m2/g, successfully preventing the agglomeration and rapid corrosion of Fe0 without reducing its activity. More interestingly, the consumption of Fe0@SGB-NH 2 was only 1/28 of untreated Fe0 when identical uranium removal efficiency was achieved. Further mechanistic studies indicated that U(VI) was firstly selectively captured by amino groups on the surface of the material and then reduction or adsorption in the pore, the long and narrow mesoporous channels reduce the possibility of uranium re-oxidation, thereby significantly reducing its re-release efficiency from 21.5% to only 1.73%. Encapsulation of Fe0 within SGB-NH 2 channels was found to facilitate faster removal rate and higher U(VI) reduction ratio, and reduce uranium re-oxidation, thus benefit the long-term immobilization of uranium in contaminated groundwater. [ABSTRACT FROM AUTHOR]

Resourcization has become a popular research topic for the final disposal of municipal solid waste incineration fly ash (MSWI FA). However, the current research is limited to building material preparation or valuable chloride recovery, which may cause resource waste and secondary pollution. A unique process, heat treatment with the addition of kaolin (KL), was presented to achieve complete resource utilization of MSWI FA. The physical properties of ceramsite could be improved by adding KL, and dioxin removal, heavy metals, and valuable chloride separation could be achieved via sintering at 1150 °C. The separation and purification of dust carried by the flue gas during thermal treatment (secondary fly ash) was achieved via wet separation. A building ceramsite with a compressive strength of 24.8 MPa was obtained, whereas dioxin and heavy metal toxicity were far below the standard limits. Heavy metal content was enriched by 12 times, approximately 59.6%, achieved after secondary fly ash separation and purification. A heavy metal product containing 39.5% Zn, 19.1% Pb, and chloride salt containing 41.8% KCl were obtained. This showed a high potential for the developed process to separate multiple valuable elements from ashes. This novel process will further promote the development and application of harmless and resourceful technologies for MSWI FA. [Display omitted] • Heat treatment eliminated heavy metals and dioxin of MSWI FA to non-hazardous waste. • Heat treatment with kaolin attains complete resource utilization of MSWI FA. • The technological process of complete resource utilization of MSWI FA is proposed. [ABSTRACT FROM AUTHOR]