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The rapid growth in nuclear industries such as uranium ores mining, nuclear energy generation, spent-fuel treatment and nuclear weapon manufacture has caused a legacy of uranium contamination in the aquatic environment, which poses a potential threat to the ecological environment and human health. The safe and effective disposal of uranium-contaminated water has thus been an urgent requirement. For decades, various materials have been shown to be capable for removing uranium from aqueous solution by adsorption technique, namely inorganic materials (e.g., clay minerals, metal oxides, mesoporous silica), organic polymers (e.g., resins, cellulose, chitosan), carbon family materials (e.g., mesoporous carbon, carbon nanotubes, graphene oxides), and porous framework materials (e.g., covalent organic frameworks, metal-organic frameworks). In this review, we provide a systematic and comprehensive overview of the researches conducted from 2005 to 2018 for uranium removal from aqueous solution by these emerging materials. The different approaches in the determination of the adsorption mechanisms between uranium and adsorbents are also briefly summarized, involving macroscopic experimental approaches, microscopic spectroscopic and computational approaches. Finally, we discuss the current limitations and propose future research perspectives in hopes of inspiring more dramatic advancements in the material and environment remediation fields.

Extraction of Eu(III) from wastewater has recently received extensive attention in environmental water pollution improvement because Eu(III) is the chemical analogue of trivalent lanthanides [Ln(III)] and actinides [An(III)]. In this work, UiO-66-AO with remarkable physicochemical properties was designed through introducing amidoxime groups (C(NOH)NH2) on the surface of UiO-66-CN which was derived from UiO-66-Br through introducing cyano groups (C N). SEM, TEM, BET, FT-IR, XRD, and TGA techniques demonstrated the effective synthesis and excellent structural performances of target materials. The outstanding sorption efficiency of UiO-66-AO (∼253.8 mg/g within 2 h) was verified through kinetic and thermodynamic analyses, showing that the kinetics data were well fitted by pseudo-second-order kinetic model, and the sorption isotherms were effectively fitted by Langmuir model. Based on macroscopic experiments and spectroscopic analyses (FT-IR and XPS), the removal mechanisms of Eu(III) onto UiO-66-AO were electrostatic interaction and inner-sphere surface complexation. In addition, the environmental application assessment had proved that UiO-66-AO owned excellent stability, outstanding selectivity, and remarkable Eu(III) removal percentage in simulated wastewater systems, demonstrating the great potential of UiO-66-AO to remove radionuclides from the actual wastewater.

Nanoscale zero-valent iron (NZVI) has been considered as a potential scavenger for U(VI) elimination from aqueous environment. To decrease the aggregation and to improve antioxidation, sulfidation technology and biochar were applied to modify NZVI. In this work, Dictyophora indusiate-derived biochar supported sulfide NZVI (DI-SNZVI) was synthesized and applied for U(VI) elimination. The excellent behaviors of kinetics (3 h for equilibrium), thermodynamic research and maximum removal amounts (427.9 mg·g−1 at pH = 5.0 and 298 K) revealed the outstanding performances of DI-SNZVI in U(VI) removal. The cycle experiments and different water system investigations further illustrated its potential ability for real applications. Moreover, the abundant functional groups and FeSx shell of DI-SNZVI were proved to be responsible for the enhanced removal of U(VI). In the end, the macroscopic and XPS study revealed that U(VI) elimination mechanisms were synergistic attributed to the adsorptive and reductive processes. This paper highlighted the biochar-based sulfide NZVI for efficient U(VI) elimination in environmental pollution management.

In this study, nanoscale zero-valent iron (nZVI) supported on layered double hydroxide (LDH) composite (LDH@nZVI) was prepared, characterized and applied to U(VI) scavenging in water. Removal of U(VI) as a function of pH, ionic strength, reaction time, initial concentrations of U(VI), and temperature were studied and compared with pure LDH and nZVI, the LDH@nZVI had best U(VI) removal efficiency owning to the excellent synergistic combination of LDH adsorption and nZVI reduction. XPS analysis found that surface oxygen functional groups and surface-bound Fe(II) played a critical role in U(VI) remediation. The large surface areas (334.0 m2/g), abundant functional groups (i.e., M O, C O and OH), rapid kinetics (adsorption equilibrium within 1 h) and excellent adsorption capacities (176 mg/g) indicating that LDH@nZVI can be considered as a potential material for preconcentration of U(VI) from sewage water.

The bioaccumulation and transformation of U(VI) by sporangiospores of Mucor circinelloides under different environmental conditions (e.g., reaction time, pH, carbonate, sporangiospores concentration, and temperature) was investigated by batch, XPS and EXAFS techniques. The bioaccumulation kinetics and isotherms can be fitted by the pseudo-second-order kinetic mode and Langmuir model, respectively, due to the high correlation coefficient. The maximum bioaccumulation capacity of sporangiospores for U(VI) was 166.13 mg/g at pH 6.0, which was significantly higher than that of other mycelia or spores. The intracellular and extracellular morphology of sporangiospores were significantly changed after U(VI) bioaccumulation, and levels of intracellular H2O2, O3−, GPx and SOD compounds in sporangiospores increased significantly. XANES analysis confirmed that the intracellular U(VI) was reduced to U(IV) by sporangiospores, and U(IV) might be stably associated with oxygen-bearing functional groups by EXAFS analysis. These results show that the sporangiospores can be used a promising adsorbent for the bioaccumulation and transformation of U(VI) from aqueous solutions, which has important scientific significance for the immobilization of U(VI) in environmental remediation.

The binding of metal ions with humic acid (HA) plays an important role in the aggregation of HA and the migration of metal ions in the environments. The effects of common cations (Na+, Mg2+, Ca2+ and Al3+) and heavy metal ions (Ag+, Cd2+, Cu2+, Cr3+ and Eu3+) on the aggregation of HA were investigated systematically by aggregation kinetics, spectroscopic techniques and molecular dynamic (MD) simulations. The critical coagulation concentration (CCC) of mono-, di- and trivalent cations could be predicted by the Schulze-Hardy rule. The aggregation of HA in the presence of Na+ and Ag+ was mainly due to the reduction of repulsive force and the hydrogen bonds between HA molecules. While the complexation of di- and trivalent cations with carboxylic/phenolic groups, or the cation-π interactions enhanced the intra- or inter-molecular bridges in HA and then contributed greatly to the aggregation of HA. Heavy metal ions could easily pass through the electric double-layer of HA compared with common cations. MD simulations further signified the strong aggregation ability of HA molecules in solutions containing high valence metal ions. These findings are important for understanding not only how the influence of metal ions on the aggregation of HA, but also the conditions which ions more efficient for aggregation.

Purpose: The presence of a high degree of tumor-infiltrating lymphocytes (TIL) has been proven to be associated with outcome in patients with non–small cell lung cancer (NSCLC). However, recent evidence indicates that tissue architecture is also prognostic of disease-specific survival and recurrence. We show a set of descriptors (spatial TIL, SpaTIL) that capture density, and spatial colocalization of TILs and tumor cells across digital images that can predict likelihood of recurrence in early-stage NSCLC. Experimental Design: The association between recurrence in early-stage NSCLC and SpaTIL features was explored on 301 patients across four different cohorts. Cohort D1 (n = 70) was used to identify the most prognostic SpaTIL features and to train a classifier to predict the likelihood of recurrence. The classifier performance was evaluated in cohorts D2 (n = 119), D3 (n = 112), and D4 (n = 112). Two pathologists graded each sample of D1 and D2; intraobserver agreement and association between manual grading and likelihood of recurrence were analyzed. Results: SpaTIL was associated with likelihood of recurrence in all test sets (log-rank P < 0.02). A multivariate Cox proportional hazards analysis revealed an HR of 3.08 (95% confidence interval, 2.1–4.5, P = 7.3 × 10−5). In contrast, agreement among expert pathologists using tumor grade was moderate (Kappa = 0.5), and the manual TIL grading was only prognostic for one reader in D2 (P = 8.0 × 10−3). Conclusions: A set of features related to density and spatial architecture of TILs was found to be associated with a likelihood of recurrence of early-stage NSCLC. This information could potentially be used for helping in treatment planning and management of early-stage NSCLC. See related commentary by Peled et al., p. 1449

Designing and fabricating environmental friendly adsorbents with more accessible active sites and higher specific surface area for achieving rapid kinetics and high efficiency have become an impending challenge in radionuclides’ pollution remediation. To overcome these issues, we rationally designed the hierarchical structured layered double hydroxides with mesoporous carbon template (CMK-3@LDHs) by in situ hydrothermal method. The adsorption data could be well simulated with pseudo-second-order and Langmuir model, and the results indicated that the CMK-3@LDHs exhibited higher adsorption capacities (171 mg·g−1 for CMK-3@Mg-Al LDHs and 301 mg·g−1 for CMK-3@Ni-Al LDHs at pH = 5.0) and more rapid kinetics (achieved equilibrium within 30 min) than SBA-15@LDHs towards U(VI). The kinetic model simulation demonstrated that the adsorption rate was dominated by intra-particle and film diffusion models simultaneously. In addition, the interaction between U(VI) and LDHs was pH-dependent and weakly related with ionic strength at pH

Two-dimensional (2D) nanomaterials have been identified as one of the promising materials due to their great promise for waste treatment. Currently, the investigation of wastewater remediation is highly imperative and still remains challenging. Here, a novel class of 2D MAX@titanate nanocomposites was fabricated by a simple oxidation and alkalization method, and they exhibited different morphologies and impressive elimination performance. The Pb(ii) uptake processes were dramatically affected by the solution pH and reached equilibrium quickly. Abundant functional groups and enhanced specific surface areas endowed T-NTO nanofibers with outstanding adsorption capacity of 328.9 mg g-1 at pH = 5.0 and T = 298 K, which was much higher than that of T-KTO nanoribbons. Moreover, the possible mechanism was expounded with the aid of Raman, FT-IR, XRD and XPS analyses, in which the synergistic effect of surface complexation and ion exchange significantly contributed to the adsorption performance. On the basis of above analyses, this study not only presents a novel and facile strategy for preparing T-NTO and T-KTO nanostructures with superior adsorption capacity, but also broadens the prospective applications of other functional MAX-derived nanostructures in environmental cleanup.

Nitrogen, phosphorus, and sulfur co-doped 3D inverse opal structured graphene-like carbon nanospheres (denoted as NPS-IOC) are reported for the first time by graphitization of highly cross-linked poly (cyclo-triphosphazene-co-4,4′-sulfonyldiphenol) (PZS). The resulting NPS-IOC possessed hierarchical interconnected spherical voids with a diameter of about 400 nm, which not only offered a short diffusion distance for mass transportation, but also aggrandized the surface area to increase active sites. NPS-IOC400 exhibited excellent BPA capture performance with a maximum adsorption capacity of 255.39 mg g−1 at 298.15 K, ultrafast removal rate, especially stable under high ionic strengths and suitable for wide pH environments. Our systematic spectroscopic characterizations and theoretical calculations demonstrated that the adsorption mechanism was mainly driven by π–π stacking interaction. Meanwhile, electrostatic interaction, hydrophobic interactions and hydrogen-bonding also played roles in the adsorption mechanism. Most importantly, the doped N, P, S heteroatoms played a synergistic effect which promoted the adsorption process. Its unique structure and excellent performance endowed NPS-IOC with a great promising future for governing organic pollutants in aquatic environments.

Because the pollutants produced by human activities have destroyed the ecological balance of natural water environment, and caused severe impact on human life safety and environmental security. Hence the task of water environment restoration is imminent. Metal-organic frameworks (MOFs), structured from organic ligands and inorganic metal ions, are notable for their outstanding crystallinity, diverse structures, large surface areas, adsorption performance, and excellent component tunability. The water stability of MOFs is a key requisite for their possible actual applications in separation, catalysis, adsorption, and other water environment remediation areas because it is necessary to safeguard the integrity of the material structure during utilization. In this article, we comprehensively review state-of-the-art research progress on the promising potential of MOFs as excellent nanomaterials to remove contaminants from the water environment. Firstly, the fundamental characteristics and preparation methods of several typical water-stable MOFs include UiO, MIL, and ZIF are introduced. Then, the removal property and mechanism of heavy metal ions, radionuclide contaminants, drugs, and organic dyes by different MOFs were compared. Finally, the application prospect of MOFs in pollutant remediation prospected. In this review, the synthesis methods and application in water pollutant removal are explored, which provide ways toward the effective use of water-stable MOFs in materials design and environmental remediation.

Background Intratumoural heterogeneity has been previously shown to be related to clonal evolution and genetic instability and associated with tumour progression. Phenotypically, it is reflected in the diversity of appearance and morphology within cell populations. Computer-extracted features relating to tumour cellular diversity on routine tissue images might correlate with outcome. This study investigated the prognostic ability of computer-extracted features of tumour cellular diversity (CellDiv) from haematoxylin and eosin (H&E)-stained histology images of non-small cell lung carcinomas (NSCLCs). Methods In this multicentre, retrospective study, we included 1057 patients with early-stage NSCLC with corresponding diagnostic histology slides and overall survival information from four different centres. CellDiv features quantifying local cellular morphological diversity from H&E-stained histology images were extracted from the tumour epithelium region. A Cox proportional hazards model based on CellDiv was used to construct risk scores for lung adenocarcinoma (LUAD; 270 patients) and lung squamous cell carcinoma (LUSC; 216 patients) separately using data from two of the cohorts, and was validated in the two remaining independent cohorts (comprising 236 patients with LUAD and 335 patients with LUSC). We used multivariable Cox regression analysis to examine the predictive ability of CellDiv features for 5-year overall survival, controlling for the effects of clinical and pathological parameters. We did a gene set enrichment and Gene Ontology analysis on 405 patients to identify associations with differentially expressed biological pathways implicated in lung cancer pathogenesis. Findings For prognosis of patients with early-stage LUSC, the CellDiv LUSC model included 11 discriminative CellDiv features, whereas for patients with early-stage LUAD, the model included 23 features. In the independent validation cohorts, patients predicted to be at a higher risk by the univariable CellDiv model had significantly worse 5-year overall survival (hazard ratio 1·48 [95% CI 1·06-2·08]; p=0·022 for The Cancer Genome Atlas [TCGA] LUSC group, 2·24 [1·04-4·80]; p=0·039 for the University of Bern LUSC group, and 1·62 [1·15-2·30]; p=0·0058 for the TCGA LUAD group). The identified CellDiv features were also found to be strongly associated with apoptotic signalling and cell differentiation pathways. Interpretation CellDiv features were strongly prognostic of 5-year overall survival in patients with early-stage NSCLC and also associated with apoptotic signalling and cell differentiation pathways. The CellDiv-based risk stratification model could potentially help to determine which patients with early-stage NSCLC might receive added benefit from adjuvant therapy. Funding National Institue of Health and US Department of Defense.

Carbon materials derived from metal organic frameworks (MOFs) have excellent properties of high surface area, high porosity, adjustable pore size, high conductivity and stability, and their applications in catalysis have become a rapidly expanding research field. In this review, we have summarized the synthesis strategies of MOF-derived carbons with different physical and chemical properties, obtained through direct carbonization, co-pyrolysis and post-treatment. The potential applications of derived carbons, especially monometal-, bimetal-, nonmetal-doped and metal-free carbons in organo-catalysis, photocatalysis and electrocatalysis are analyzed in detail from the environmental perspective. In addition, the improvement of catalytic efficiency is also considered from the aspects of increasing active sites, enhancing the activity of reactants and promoting free electron transfer. The function and synergy of various species of the composites in the catalytic reaction are summarized. The reaction paths and mechanisms are analyzed, and research ideas or trends are proposed for further development.

With the fast development of industrial and human activity, large amounts of persistent organic pollutants, heavy metal ions and radionuclides are released into the natural environment, which results in environmental pollution. The efficient elimination of the natural environment is crucial for the protection of environment to against the pollutants' toxicity to human beings and living organisms. Graphitic carbon nitride (g-C

Adsorbents with the combination of magnetic separation and removal performance are expected for reducing the adverse impact of nuclear pollution. In this study, the core-shell Fe

Correction for ‘Plasma-induced grafting of polyacrylamide on graphene oxide nanosheets for simultaneous removal of radionuclides’ by Wencheng Song et al., Phys. Chem. Chem. Phys., 2015, 17, 398–406.

Retraction of ‘Reductive immobilization of uranium by PAAM–FeS/Fe3O4 magnetic composites’ by Dadong Shao et al., Environ. Sci.: Water Res. Technol., 2015, 1, 169–176, https://doi.org/10.1039/C4EW00014E

Correction for ‘Heteroaggregation behavior of graphene oxide on Zr-based metal–organic frameworks in aqueous solutions: a combined experimental and theoretical study’ by Jie Li et al., J. Mater. Chem. A, 2017, 5, 20398–20406, https://doi.org/10.1039/C7TA06462D.

To enhance the electron–hole separation and boost the practical performance of commercial titania (Degussa P25) under natural solar light, in this work, P25 was modified with Co(II) species (CoP25) through post-treatment with decomposition of Co-ethylenediaminetetraacetic acid precursors in a wet chemical anchoring process. With appropriate Co(II) loading amount as molecular cocatalyst, the resulted CoP25-4 showed significantly improved photocatalytic performance for Cr(VI) reduction and bisphenol A (BPA) oxidation under UV-light irradiation. The coexistence of Cr(VI) and BPA promoted mutually the degradation of both pollutants. Under simulated solar light (AM 1.5G) illumination, the Cr(VI) reduction rate over CoP25-4 was 8.5 times enhanced compared with that over P25, whereas the simultaneous degradation rate of BPA over CoP25-4 was 8 times higher than that over P25. Further investigations indicated that the covalent atomic Co(II) anchoring on P25 significantly promoted the photogenerated electron–hole s...

The increased release and accumulation of Bisphenol A (BPA) in contaminated wastewater has resulted in the world wide concerns because of its potential negative effects on human health and aquatic ecosystems. Starting with metal-organic frameworks, we present a simple method to synthesize magnetic porous microcubes (N-doped Fe0/Fe3C@C) with graphitized shell and highly dispersed active kernel via the pyrolysis process under N2 atmosphere. Batch adsorption experimental results showed that N-doped Fe0/Fe3C@C had high adsorption capacity for BPA (∼138 mg g−1 at pH = 7 and 298 K). Degradation of BPA adsorbed on N-doped Fe0/Fe3C@C was further investigated as a function of BPA concentration, persulfate amount, temperature and solution pH. It was found that potassium peroxodisulfate could be activated by N-doped Fe0/Fe3C@C, and a large number of free radicals were generated which was crucial for the degradation of BPA. The concentration of BPA was barely changed in the individual persulfate system. BPA (10 mg L−1) was almost completely degraded within 60 min in the presence of N-doped Fe0/Fe3C@C (∼0.2 g L−1). When the BPA content increased to 25 mg L−1, the removal efficiency of BPA achieved to 98.4% after 150 min. From the XRD, Raman, and XPS analysis, the main adsorption mechanism of BPA was π-π interactions between the π orbital on the carbon basal planes and the electronic density in the BPA aromatic rings. While the superior degradation was attributed to the radical generation and evolution in phenol oxidation. This work not only proved the potential application of N-doped Fe0/Fe3C@C in the adsorption and degradation of BPA, but also opened the new possibilities to eliminate organic pollutants using this kind of magnetic materials in organic pollutants’ cleanup.

With the rapid development of nuclear industry, radioactive wastes have been directly/indirectly released into the natural environment, threatening the health of human being and ecological balance. As one of the renewable materials, biochar has attracted increasing attention and been extensively applied to eliminate pollutants from aqueous solution, owing to its abundant pore structures and unique chemical properties. In this study, we used the carbonized coffee ground (CG) and acid-oxidized coffee ground (CG-AO) to remove U(VI) from solutions to evaluate their sorption performances. The sorption of U(VI) was investigated under various conditions (e.g., contact time, pH, initial U(VI) concentration and temperature). The results showed that the sorption process was strongly influenced by pH. The thermodynamic parameters derived from sorption isotherms revealed that the sorption of U(VI) on CG-AO was a spontaneous and endothermic process. The maximum sorption capacity of U(VI) on CG-AO was calculated to be 251.71 mg g−1 from Langmuir model at T = 298 K and pH 5.0, which was almost three times relative to the untreated CG (80.93 mg g−1). Combined with the X-ray photoelectron spectroscopy (XPS) analysis, the removal of U(VI) on CG-AO was mainly attributed to the formation of (O=C–O)2UO2, while the removal of U(VI) on CG was mainly via a combined effect of carboxyl and H2O molecules, resulting in the coordination of O=C–OUO2(OH).

The three-dimensional (3D) carbonaceous nanofiber and Ni-Al layered double hydroxide (CNF/LDH) nanocomposite was successfully prepared by a facile one-step hydrothermal methodology. Characterization of scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), XRD, and Fourier transformed infrared spectroscopy (FTIR) provided a demonstration that the modified CNF/LDH nanocomposite possessed abundant functional groups, for instance, metal-oxygen surface bonding sites (Ni–O as well as Al–O) and free-metal surface bonding sites (C–O, C–O–C, as well as O–C=O). The elimination of representative radionuclide (i.e. U(VI)) on the CNF/LDH nanocomposite from aqueous solutions was explored as a key function of pH, ionic strength, contact time, reaction temperature as well as radionuclide preliminary concentrations with the use of the batch methodology. As revealed by the findings, the sorption of radionuclides on CNF/LDH nanocomposite adhered to the pseudo-second-order kinetic model as well as Langmuir model. The maximum elimination capacity of U(VI) amounted to be 0.7 mmol/g. The independent of ionic strength shed light on the fact that inner-sphere surface complexation mainly overpowered radionuclide uptake by the CNF/LDH nanocomposite, which was further verified through the combination of FTIR and XPS spectral analyses. The abovementioned analyses shed light on the fact that the CNF/LDH nanocomposite can be regarded as a latent material to preconcentration radionuclides for environmental remediation.

Early-stage estrogen receptor-positive (ER+) breast cancer (BCa) is the most common type of BCa in the United States. One critical question with these tumors is identifying which patients will receive added benefit from adjuvant chemotherapy. Nuclear pleomorphism (variance in nuclear shape and morphology) is an important constituent of breast grading schemes, and in ER+ cases, the grade is highly correlated with disease outcome. This study aimed to investigate whether quantitative computer-extracted image features of nuclear shape and orientation on digitized images of hematoxylin-stained and eosinstained tissue of lymph node-negative (LN−), ER+ BCa could help stratify patients into discrete (10 years long-term survival) outcome groups independent of standard clinical and pathological parameters. We considered a tissue microarray (TMA) cohort of 276 ER+, LN− patients comprising 150 patients with long-term and 126 patients with short-term overall survival, wherein 177 randomly chosen cases formed the modeling set, and 99 remaining cases the test set. Segmentation of individual nuclei was performed using multiresolution watershed; subsequently, 615 features relating to nuclear shape/texture and orientation disorder were extracted from each TMA spot. The Wilcoxon’s rank-sum test identified the 15 most prognostic quantitative histomorphometric features within the modeling set. These features were then subsequently combined via a linear discriminant analysis classifier and evaluated on the test set to assign a probability of long-term vs. short-term disease-specific survival. In univariate survival analysis, patients identified by the image classifier as high risk had significantly poorer survival outcome: hazard ratio (95% confident interval) = 2.91(1.23–6.92), p = 0.02786. Multivariate analysis controlling for T-stage, histology grade, and nuclear grade showed the classifier to be independently predictive of poorer survival: hazard ratio (95% confident interval) = 3.17(0.33–30.46), p = 0.01039. Our results suggest that quantitative histomorphometric features of nuclear shape and orientation are strongly and independently predictive of patient survival in ER+, LN− BCa.

Uranium is considered to be a strategic means for the nuclear power as well as a worldwide highly toxic pollutant. For the enhanced U(VI) elimination from wastewater, novel Co-Mo-Ni ternary hydroxide (CMN) and calcined CMN (CCMN) nanocomposites were prepared via a simplistic single-step hydrothermal technique and calcination process. The elimination process and adsorption property of U(VI) on CMN and CCMN were analysed by batch experiment as well as spectroscopy analysis, and the researches showed that U(VI) was formed stable and strong complexes with the surface groups of CMN and CCMN. The maximal removal capacities of U(VI) on CMN and CCMN amounted to be 585.6 and 973.7 mg/g at pH = 5.0 and T = 298 K, correspondingly, that exhibited competitiveness with the majority of the reported adsorbents. The U(VI) uptake was substantially impacted by the tested solution pH and not affected by the ionic strength, which revealed that the interaction mechanism was primarily inner-sphere surface complexation, which received further confirmation by the XPS analysis. Based on the above analyses, the facile synthesis process and excellent U(VI) elimination performance denoted that the ternary (hydr)oxide materials were applicable as an attractive adsorbent for the radionuclides preconcentration and removal from aqueous solutions in natural environmental management.

Heavy metal pollution of water sources has raised global environmental sustainability concerns, calling for the development of high-performance materials for effective pollution treatment. Herein, we report a facile approach to synthesize carbonaceous nanofiber/Ni Al layered double hydroxide (CNF/LDH) nanocomposites for high-efficiency elimination of heavy metals from aqueous solutions. The CNF/LDH nanocomposites were characterized by three-dimensional architectures formed by the gradual self-assembly of flower-like LDH on CNF. The nanocomposites exhibited excellent hydrophilicity and high structural stability in aqueous solutions, guaranteeing the high availability of active sites in these environments. High-efficiency elimination of heavy metal ions by the CNF/LDH nanocomposites was demonstrated by the high uptake capacities of Cu(II) (219.6 mg/g) and Cr(VI) (341.2 mg/g). The sorption isotherms coincided with the Freundlich model, most likely because of the presence of heterogeneous binding sites. The dominant interaction mechanisms consisted of surface complexation and electrostatic interaction, as verified by a combination of X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy analyses and density functional theory calculations. The results presented herein confirm the importance of CNF/LDH nanocomposites as emerging and promising materials for the efficient removal of heavy metal ions and other environmental pollutants.

In this article, polyaniline modified carbon nanofiber (PANI@CNF) composites were synthesized by in situ polymerization technique, and applied to highly efficient removal of radioactive uranium (U(VI)) from aqueous solutions. The prepared materials had abundant functional groups and excellent physical and chemical properties, which was confirmed by scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The adsorption of U(VI) from aqueous solutions as a function of pH, ionic strength, reaction time and temperature on the materials were investigated by batch experiments. The elimination of U(VI) was strongly dependent on pH but independent of ionic strength, indicating that the interaction was mainly dominant by inner-sphere surface complexation. The adsorption kinetics were well simulated by pseudo-second-order model and reached reaction equilibrium within 30 min. The adsorption isotherms were well described by Langmuir isotherm model, implying that the elimination of U(VI) was monolayer coverage. At pH=5.0 and T =298 K, the maximum adsorption capacity of U(VI) on PANI@CNF (319.4 mg/g) was higher than those of U(VI) on CNF (133.9 mg/g), which was attributed to the synergistic effects between oxygen functional groups and nitrogen functional groups. Such a facile preparation method and efficient removal performance highlighted the application of PANI@CNF as a candidate for rapid and efficient radionuclide contamination’s elimination in practical applications.

Layered double hydroxides (LDHs), one of the most important two-dimensional layered compounds, have enabled massive developments in effective pollution treatments. Over the past few decades, their derivative materials have also applied to the efficient removal of radionuclides owing to the intrinsic advantages of their low cost, easy preparation, large surface areas, topological transformation, and environment-friendly. In this review, we give an overview of the recent advances in LDH-based nanomaterials, from a brief introduction to their preparation and modification methods to an overview of their application in the removal of radionuclides and an exploration of their underlying adsorption mechanisms. In the end, a summary and outlook are also briefly addressed. This review intends to provide deep insight into the design of high-performance LDH-based materials for the potential elimination of radionuclides from aqueous solutions during environmental pollution cleanup.

Nowadays, more and more researchers pay close attention to the decontamination of radioactive uranium because of its high toxicity and long half-life in the environment. Although many strategies fo...

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.

Graphene oxide (GO) was applied as adsorbent to efficiently eliminate the heavy metal ions from wastewater because of its large amount of functional surface groups and high surface areas. However, the contribution of different functional surface groups on the high preconcentration of heavy metal ions to GO is still unclear. Herein the GO was applied as adsorbent for the efficient preconcentration of Co(II) and the effect of functional surface groups on Co(II) removal was studied by batch sorption experiments. The results showed that the maximum sorption capacities of Co(II) on GO, NGO, MGO and NMGO were 43.6, 27.3, 23.2 and 14.6 mg/g, respectively. The elimination of Co(II) was significantly influenced by ionic strength and pH, indicated that the interaction mechanism was primarily controlled by strong surface complexation. The DFT calculation further evidenced that the oxygen-containing surface groups could form shorter bond distance with Co(II) ions than the nitrogen-containing functional groups, and the calculated adsorption energies (Ead) for GO–COOH–Co (44.05 kcal/mol) and GO–OH–Co (16.44 kcal/mol) were much higher than that for NGO–Co (6.33 kcal/mol). The density of states (DOS) and charge density differences of combined complexes further illustrated the strong surface complexes were formed between Co(II) and the oxygen-containing surface groups of GO surfaces. This work highlighted that the oxygen-containing surface groups played a vital role in the formation of surface complexes with Co(II) on GO, which is crucial for the preparation and application of GO in the radioactive pollution cleanup.

l -cysteine intercalated Mg/Al layered double hydroxide (Cys-LDH) composites were fabricated and applied for treating the U(VI) contaminated wastewater under various conditions. Interaction mechanisms and adsorption properties were investigated by using batch experiments with spectroscopy analysis. The adsorption isotherms and kinetics were fitted perfectly with the Langmuir isotherm and the pseudo-second-order model, respectively. The significant maximum adsorption capacity of Cys-LDH (211.58 mg/g) compared to LDH was attributed to the larger number of functional groups on Cys-LDH. The presence of humic acid (HA) decreased U(VI) elimination on Cys-LDH at high pH but increased U(VI) removal at low pH. Typically, the presence of various anions (such as NO3−, Cl−, ClO4− and SO42−) did not obviously affect U(VI) adsorption on Cys-LDH, while the coexisted CO32− significantly affected U(VI) elimination. The predominate adsorption were determined to be the formation of Cys-U(VI)-Cys complexes with cysteine in the Cys-LDH interlayers. The results demonstrated that the Cys-LDH are promising adsorbents for efficient elimination and extraction of radionuclides in actual environmental contamination management.

The hierarchical core-shell and yolk-shell magnetic titanate nanosheets (Fe3O4@TNS) were successfully synthesized by employing magnetic nanoparticles (NPs) as interior core and intercrossed titanate nanostructures (NSs) as exterior shell. The as-prepared magnetic Fe3O4@TNS nanosheets had high specific areas (114.9 m2 g−1 for core-shell Fe3O4@TNS and 130.1 m2 g−1 for yolk-shell Fe3O4@TNS). Taking advantage of the unique multilayer structure, the nanosheets were suitable for eliminating U(VI) from polluted water environment. The sorption was strongly affected by pH values and weakly influenced by ionic strength, suggesting that the sorption of U(VI) on Fe3O4@TNS was mainly dominated by ion exchange and outer-sphere surface complexion. The maximum sorption capacities (Qmax) calculated from the Langmuir model were 68.59, 121.36 and 264.55 mg g−1 for core-shell Fe3O4@TNS and 82.85, 173.01 and 283.29 mg g−1 for yolk-shell Fe3O4@TNS, at 298 K, 313 K and 328 K, respectively. Thermodynamic parameters (ΔH0, ΔS0 and ΔG0) demonstrated that the sorption process was endothermic and spontaneous. Based on X-ray photoelectron spectroscopy (XPS) analyses, the sorption mechanism was confirmed to be cation-exchange between interlayered Na+ and UO22+. The yolk-shell Fe3O4@TNS had more extraordinary sorption efficiency than core-shell Fe3O4@TNS since the yolk-shell structure provided internal void space inside the titanate shell to accommodate more exchangeable active sites. The flexible recollection and high efficient sorption capacity made core-shell and yolk-shell Fe3O4@TNS nanosheets promising materials to eliminate U(VI) or other actinides in wastewater cleanup applications.

With the widespread application of radionuclide 235U(VI), it is inevitable that part of U(VI) is released into the natural environment. The potential toxicity and irreversibility impact on the natural environment has become one of the most forefront pollution problems in nuclear energy utilization. In this work, rod-like metal-organic framework (MOF-5) nanomaterial was synthesized by a solvothermal method and applied to efficiently adsorb U(VI) from aqueous solutions. The batch experimental results showed that the sorption of U(VI) on MOF-5 was strongly dependent on pH and independent of ionic strength, indicating that the dominant interaction mechanism was inner-sphere surface complexation and electrostatic interaction. The maximum sorption capacity of U(VI) on MOF-5 was 237.0 mg/g at pH 5.0 and T = 298 K, and the sorption equilibrium reached within 5 min. The thermodynamic parameters indicated that the removal of U(VI) on MOF-5 was a spontaneous and endothermic process. Additionally, the FT-IR and XPS analyses implied that the high sorption capacity of U(VI) on MOF-5 was mainly attributed to the abundant oxygen-containing functional groups (i.e., C O and C O). Such a facile preparation method and efficient removal performance highlighted the application of MOF-5 as a candidate for rapid and efficient radionuclide contaminations elimination in practical applications.

Ordered mesoporous polymer-carbon composites containing amidoxime groups (AO-OMC) were successfully synthesized via in-situ polymerizing 2-Butenenitrile onto the external and internal surface of ordered mesoporous carbon (CMK-3). The characterization of small-angle X-ray diffraction, N2 adsorption–desorption isotherms and TEM confirmed that the polyacrylamidoxime was only coated on the mesopore walls with a thin layer rather than occupied the whole pores. The AO-OMC containing 16.8% polyacrylamidoxime (0.2AO-OMC) showed the highest adsorption capacity for U(VI) (322.6 mg·g−1 at pH = 5.0 and T = 298.15 K), which was significantly higher than CMK-3 (43.4 mg·g−1). XPS analysis suggested that the high adsorption capacity of 0.2AO-OMC was mainly attributed to the combination of U(VI) with abundant amidoxime groups via surface complexation and electrostatic interactions. The U(VI) selectivity was above 60% in a wide pH range from 3.0 to 5.0, which has not been reported to date, and reached the highest selectivity of 72.4% at pH = 4.0. The thermodynamic parameters calculated from temperature-dependent adsorption isotherms suggested that uranium adsorption onto 0.2AO-OMC was an endothermic and spontaneous process, and the 0.2AO-OMC exhibited excellent reusability and structural stability without any significant changes in the adsorption capacity after ten cycles. This work highlighted the simple synthesis and application of AO-OMC as an efficient material for the high elimination of U(VI) from large volumes of aqueous solutions in environmental pollution cleanup.

Hydrangea-like carbon sphere@layered double hydroxide (CS@LDH) nanocomposite was fabricated by one-step hydrothermal synthesis strategy using carbon sphere and Ni-Al LDH as monomer molecules. The CS@LDH nanocomposites were then applied as adsorbents to eliminate U(VI) from aqueous solutions and showed excellent elimination performance to U(VI) from aqueous solutions because of its strong synergistic effects between metal-oxygen functional groups (Ni-O and Al-O) and free-metal functional groups (C O, C O C, and O C O). The removal of U(VI) on CS@LDH was mainly dominated by inner-sphere surface complexation, which was confirmed with batch sorption experiments, FTIR and XPS analysis. Furthermore, the maximum sorption capacity of U(VI) on CS@LDH (0.6 mmol/g) was 2.0 times higher than that of U(VI) on Ni-Al LDH (0.3 mmol/g) and approximately 1.5 times higher than that of U(VI) on CS (0.4 mmol/g) at pH = 5.0 and T = 298 K. The thermodynamic parameters suggested that the sorption of U(VI) was a typical spontaneous and endothermic process. The sorption isotherms were well simulated by Langmuir model, suggesting that the sorption was monolayer coverage. The CS@LDH can be used as superior adsorbent for efficient elimination of radionuclides in environmental pollution remediation. This study also demonstrated a new strategy to improve the physicochemical properties of other low efficiency adsorbents through polymerization reaction.

Magnetic Fe/Zn layered double oxide decorated carbon nanotubes (M-Fe/Zn-LDO@CNTs) composites were synthesized via a hydrothermal method with further calcination treatment. The fabricated M-Fe/Zn-LDO@CNTs were characterized by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, UV–vis spectroscopy, scanning electron microscopy, and transmission electron microscopy and then applied for U(VI) elimination under diversiform experimental conditions, such as pH, temperature, ionic strength, contact time, and coexisting ions. The experimental results demonstrated that the U(VI) adsorption performance of M-Fe/Zn-LDO@CNTs was much higher than bare CNTs. The thermodynamic parameters revealed that U(VI) adsorption on M-Fe/Zn-LDO@CNTs was endothermic and spontaneous. More importantly, the adsorption performance of U(VI) on M-Fe/Zn-LDO@CNTs was still higher than ∼89% after five cycles. Furthermore, ∼95.9% of 241Am(III) could be removed by M-Fe/Zn-LDO@CNTs from solution at pH = ...

Uranium has attracted sustained attention due to its high mobility and biotoxicity. Among various techniques, sorption is considered as the most effective technique to treat the U(VI)-containing wastewater. In serving for low-cost adsorbents, layered double hydroxides (LDHs) have been proved to be promising candidates. However, the interaction mechanism of U(VI) with LDHs is still unclear, although plenty of LDHs have been used in this field. Herein, we developed two novel methods to fabricate ternary LDHs (MgFeAl LDHs and NiFeAl LDHs) and applied the ternary LDHs as adsorbents to investigate their sorption performance towards U(VI). The results showed that the sorption was endothermic and followed the pseudo-second-order kinetics through the formation of inner-sphere surface complexes, and the sorption isotherms were simulated by the Langmuir model well. Furthermore, systematic spectroscopy characterization indicated that the sorption occurred on the surface sites of Mg-OH and Ni2+–OH, while the CO32− in the gallery space also played an important role. This work highlighted the synthesis of high-efficient materials and their application in wastewater treatment.

The nanoscaled zero-valent iron (nZVI) supported zeolite MCM-41 composites (nZVI/MCM) were synthesized, and applied for the immobilization of Cr(VI) from aqueous solutions. The precise role of MCM-41 and nZVI in the immobilization and reduction of Cr(VI) was characterized using SEM, TEM, HRTEM, HRTEM-EDS, XPS and EXAFS techniques. Comparing to the bare nZVI nanoparticles, the as-synthesized nZVI/MCM composites showed higher efficiency on Cr(VI) immobilization due to the high synergistic effect of Cr(VI) reduction by nZVI and sorption by MCM-41. The morphology and visualizing analysis indicated that nZVI was uniformly distributed on the surfaces of MCM-41, which reduced the aggregation of nZVI apparently and thereby increased the reduction activity. XPS and EXAFS analysis showed that nZVI could promote Cr(VI) reduction into Cr(III), and the sorption and reduction reactions were occurred on bare nZVI. MCM-41 acted as a scavenger for the insoluble products, which could improve the reduction activity of nZVI. The high performance of nZVI/MCM composites showed the promising strategy for the efficient decontamination of Cr(VI) pollution in environmental pollution cleanup.

Radionuclides with long half-life are toxic, and thereby result in serious threat to human beings and ecological balance. Herein, a simple two-step synthesis method was used to prepare manganese dioxide@polypyrrole (MnO2@PPy) core/shell structures for efficient removal of U(VI) and Eu(III) from aqueous solutions. The adsorption of U(VI) and Eu(III) were investigated under different kinds of experimental conditions. The experimental results suggested that the adsorption of U(VI) and Eu(III) on MnO2@PPy were greatly affected by pH. U(VI) adsorption on MnO2@PPy was independent of ionic strength at pH 6.0. However, Eu(III) adsorption on MnO2@PPy was independent of ionic strength at the whole pH range of experimental conditions. The maximum adsorption capacities ( q max) of U(VI) and Eu(III) were 63.04 and 54.74 mg g−1 at T = 298 K, respectively. The BET, XRD, FTIR and XPS analysis evidenced that high adsorption capacities of U(VI) and Eu(III) on MnO2@PPy were mainly due to high surface area and rich metal oxygen-containing group (i.e., Mn–OH and Mn–O), and the interaction was mainly attributed to strong surface complexation and electrostatic interaction. This study highlighted the excellent adsorption performance of U(VI) and Eu(III) on MnO2@PPy and could provide the reference for the elimination of radionuclides in real wastewater management.

Increasing specific surface area and functional groups are two key ways to improve the adsorption performance of adsorbent materials. Herein, porous Fe2O3 (P-Fe2O3) microcubes composed of fine Fe2O3 nanoparticles (NPs) were facilely synthesized through the simultaneous oxidative decomposition of Prussian blue (PB) microcubes. Owing to their integrated features (i.e., large specific surface area of ∼155 m2 g−1 and large amount of Fe2O3 NPs), the synthesized P-Fe2O3 exhibited excellent adsorption capacities for heavy metal ions (175.5 mg g−1 for Cr(VI) and 97.8 mg g−1 for Pb(II)) and organic contaminants (159.4 mg g−1 for humic acid and 425.9 mg g−1 for methyl blue) from aqueous solutions. Based on the batch experiments, the adsorption isotherms could significantly conform to the Langmuir models. Combined with the microscopic analysis, the results suggested that the enrichment of Pb(II) on P-Fe2O3 was mainly attributed to the chemical binding between the electron donating oxygen ions of P-Fe2O3 surface and Pb(II), while the large available positive charge density could facilitate the effective adsorption of Cr(VI) due to ion exchange and electrostatic attraction. Furthermore, the surface complexation of organic pollutants on P-Fe2O3 was depended on the dipole moment and molar volume of the organic pollutant molecules. The consequences indicated that P-Fe2O3 could be served as a promising material for the decontamination of organic contaminants as well as the elimination of heavy metal ions from aqueous solutions. The findings presented herein played important roles in the purification of inorganic and organic contaminants on the available of inexpensive P-Fe2O3 NPs in natural environmental pollution cleanup applications.

Water pollution, a worldwide issue for the human society, has raised global concerns on environmental sustainability, calling for high-performance materials in effective pollution treatments. Boron nitride (BN) with a structure similar to graphene possesses many extraordinary properties such as high surface areas, high oxidization resistance at high temperature, and high chemical stability. This review presents the outstanding removal percentage and environmental restoration of BN-based nanomaterials for the elimination of various pollutants from the last ten years. Notably, recent advances in the removal of organic/inorganic pollutants and interaction mechanism are outlined. BN-based materials can not only preferably remove contaminants, but also can be directly regenerated by burning in air. The BN-based materials have satisfactory sorption capacities for inorganic pollutants (e.g. heavy metal ions) and organic pollutants (e.g. dyes and pharmaceutical molecules). The interaction mechanisms between pollutants and BN-based materials are mainly surface complexation, π-π stacking, and electrostatic interactions. This paper is beneficial to further comprehend the interactions of pollutants with BN-based materials, which is also helpful for the improvement of BN-based materials and potential areas for future applications in environment remediation.

With the rapid expansion of industrialization, it is inevitable that heavy metal ion (such as chromium, Cr(VI)) is released into the ecological systems, which has become a potential threat to public health. Herein, polyvinylpyrrolidone intercalated molybdenum disulfide composites and polyacrylamide intercalated molybdenum disulfide composites were synthesized for the efficient removal of Cr(VI) from aqueous solutions. The sorption of Cr(VI) on the composites was studied by batch technique and the macroscopic sorption results revealed that the removal of Cr(VI) was strongly dependent on ionic strength and pH. The removal capacities of Cr(VI) achieved 142.24 mg/g on PVP/MoS2 and 84.91 mg/g on PAM/MoS2 at pH = 5.0. The thermodynamic study indicated that the interaction was a spontaneous and endothermic process. According to the batch experimental results combined with XPS spectra analysis, it can be considered that the interaction of Cr(VI) with the composites was that Cr(VI) ions were fixed on the composite surfaces by electrostatic attraction and then entered into the interlayer and combined with amide groups at the interlamination of the composites. The findings can provide a new perspective for the rational design of MoS2 composites with high performance and excellent chemical stability for Cr(VI) removal in extreme conditions, which would not cause secondary pollution.

The construction of heterogeneous catalysts with high efficiency is important for the degradation of organic pollutants. Catalysts with small cluster dispersions are thus highly desirable to maximize the amount of active sites and enhance the atom efficiency. Here, a simple and scalable method was designed to fabricate amorphous sub-nanometer Cu-doped FeOOH clusters/ultrathin g-C3N4 nanosheet (Cu-FeOOH/CNNS) hybrids as heterogeneous photo-Fenton catalysts. The fabricated hybrids possess a unique hierarchical nanostructure, comprising abundant uniformly dispersed ultrafine Cu-FeOOH clusters tightly anchored on the CNNS surface. The optimal loading content of Cu-FeOOH clusters decolorized ∼98.7% methylene blue (MB) within 40 min in a wide pH value range of 4.8–10.1, which is more than 8.1 times faster than pristine CNNS. Moreover, influential factors, including the initial MB concentration, H2O2 concentration, initial pH and multiform organic contaminants, such as azo dyes, nitrophenol and antibiotics, were investigated and analyzed in detail. The degradation efficiency remained the same even after 10 cycles, suggesting the robustness and stability of the fabricated hybrids. The excellent degradation efficiency is attributed to the cluster active sites and the synergistic activation of Fe/Cu/CNNS promoting the generation of ˙OH for MB degradation. A practical application of water remediation on a 15 L scale was also performed with expected MB degradation efficiency under the coexisting dyes. The fabricated hybrid is expected for practical industrialization applications and this design and fabrication strategy provided a generic route for further design of catalysts with high activities for PFR.

With the increasing demand of nuclear power plant, the depleted uranium is inevitably emitted and causes environmental risk, hence it is crucial to develop new methods to efficiently eliminate uranium compounds from water. In this work, a bifunctional material core-shell-shell layered double hydroxide (LDH) decorated hollow magnetic polydopamine (MP) microspheres (defined as MPL) were synthesized and evaluated for the cleanup of uranium (VI) from aqueous solutions through specific adsorption. The experimental results showed that the adsorption was significantly affected by pH value rather than ionic strength, reflecting that the interaction was mainly governed by inner-sphere surface complexation owing to the multiple functional groups including imine, catechol, amine, and hydroxyl groups. The adsorption kinetics can be perfectly depicted by the pseudo-second-order model with high uptake percentage of 94.8%, which was superior to the previously reported materials. Interestingly, the maximum adsorption performance can be tuned by changing the thickness of polydopamine shell and the content of LDH, in the order of MP2L2 (344 mg/g) > MP2L3 (291 mg/g) > MP3L2 (245 mg/g) > MP2L1 (211 mg/g) > ML2 (142 mg/g) > MP1L2 (141 mg/g) > MP2 (71 mg/g) > Fe3O4 (34 mg/g) at 298.15 K and pH 5.0. The adsorption mechanism has been thoroughly investigated with techniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM), X-ray diffraction (XRD), thermo-gravimetric analyses (TGA), Fourier transformed infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS). In summary, the bifunctional material could be applied as promising building block for the enrichment and recovery of uranium (VI) from aqueous solutions in environmental pollution cleanup.

Potentially toxic metals in sewage and industrial effluents pose a serious threat to human health and the environment. Herein, core–shell hollow magnetic polydopamine nanoparticles (denoted as Fe3O4@PDA) were fabricated via a simple one-pot synthesis method and applied for the elimination of Pb(II) and Cu(II) from wastewater. The versatile polydopamine (PDA) layer with abundant functional groups (amine, imine and catechol groups) provided favourable sites to bind metal ions. The experimental results showed that the adsorption processes were significantly affected by the pH values of the suspension. The ionic strength-independent adsorption processes indicated the existence of inner-sphere surface complexes of Pb(II) and Cu(II) on Fe3O4@PDA. The results showed that Fe3O4@PDA exhibited fast removal kinetics for Pb(II) and Cu(II), which achieved equilibrium within 3 h. The adsorption processes were well fitted by the pseudo-second-order kinetic model and Langmuir isotherm model. Furthermore, the removal capacities of Fe3O4@PDA were calculated to be 57.25 mg g−1 for Pb(II) and 86.35 mg g−1 for Cu(II), which were much higher than those of pure Fe3O4 and other materials. Most importantly, the adsorption efficiencies of Pb(II) and Cu(II) on Fe3O4@PDA were still ∼71% and ∼70% after five cycles, respectively. In summary, the hollow Fe3O4@PDA nanoparticles can be used as outstanding materials for the elimination of Pb(II) and Cu(II), which is beneficial to reduce the toxic effects of heavy metal ion contaminated water.

The toxicity and radioactivity of uranium [235,238U(VI)] has resulted in serious environmental issues in recent years. Polyethyleneimine-decorated waste fly ash (FA@PEI) from thermal power plants has been fabricated via a novel and cost-efficient method and applied to the U(VI) elimination from aqueous solutions by batch experiments. The U(VI) removal was found to be dramatically influenced by pH whilst being ionic strength-independent, which indicated that the interaction was primarily controlled by inner-sphere surface complexation. Kinetic studies showed that the FA@PEI had an ultrafast removal rate (1.5 h to achieve adsorption equilibration) for U(VI) and a pseudo-second-order model fitted the adsorption process. The maximum removal capacity of U(VI) by FA@PEI was 70.3 mg g−1 at 298 K and pH 5.0. Based on the thermodynamics data (ΔH° > 0, ΔS° > 0 and ΔG° < 0), the U(VI) removal process is typically spontaneous and endothermic. According to the XPS analysis, the enhanced U(VI) adsorption was mainly attributed to the abundant metal–oxide bonds and amine groups (–NH2, –NH–). Furthermore, the FA@PEI material also demonstrated an outstanding regeneration ability. This paper highlights FA@PEI as an environmentally-friendly and economical alternative for U(VI) elimination from waste water.