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Nanoscale zero-valent iron (nZVI or Fe

The synergistic effect between strong interaction of pores with H2 and spillover effect for Pd@HKUST-1-DS brings high hydrogen storage capacity at a low and ambient temperature.

Recent progress in environmental remediation, colloidal behavior and biological effects of MXene was summarized.

A crystalline zirconium fluorophosphonate with K+ as charge-balancing ions exhibits superior Eu3+ adsorption capacities under strongly acidic conditions.

Retraction of ‘Magnetic polydopamine decorated with Mg–Al LDH nanoflakes as a novel bio-based adsorbent for simultaneous removal of potentially toxic metals and anionic dyes’ by Jie Li et al., J. Mater. Chem. A, 2016, 4, 1737–1746, https://doi.org/10.1039/C5TA09132B.

Magnetic Fe3O4 nanoparticles were coated by polyethyleneimine (PEI), and then Fe3O4@PEI was further modified with MoS2 by the hydrothermal method to fabricate 3D flower-like structured magnetic polyethyleneimine@MoS2 (MP@MoS2) composites, and the composites were served as efficient adsorbents to capture Cr(VI) and Pb(II) from aqueous solution. The effects of temperature, pH, shaking time and environmental conditions on adsorption performance of MP@MoS2 towards Cr(VI) and Pb(II) have been conducted by batch adsorption experiments. The prepared MP@MoS2 exhibited high adsorption capacities (192.30 mg/g for Cr(VI) at pH 3.0 and 256.41 mg/g for Pb(II) at pH 6.0) and the adsorption equilibrium could be achieved in a short time. Moreover, MP@MoS2 composites with high saturation magnetization could be simply separated under an external magnet. Combined experiments and spectral analysis, the underlying adsorption mechanism for Cr(VI) on MP@MoS2 was mainly attributed to the reduction of Cr(VI) to Cr(III), and the removal of Pb(II) was due to the complexation with sulfur groups and amino-groups. Consequently, the prepared 3D flower-like structured MP@MoS2 has a great potential for the practical application in removing Cr(VI) and Pb(II) from the aquatic environment.

In this work, nitrogen-doped carbon nanoshell structure with the encased Fe0/Fe3C nanoparticles (Fe@NC) was synthesized with a solvent-free method via direct carbonizing the ground mixture of dicyandiamide and ferric chloride hexahydrate. The morphology, structure, and surface properties of as-synthesized Fe@NC were characterized systematically, and the removal performance of Fe@NC towards U(VI) was studied in detail. The results manifested that the Fe@NC possessed large surface area (127.0 m2/g) with mesoporosity and the encapsulated Fe0/Fe3C nanoparticles were concentrated at the tip of N-doped carbon nanotubes. Moreover, the Fe@NC hybrid material exhibited the maximum removal capacities of 0.85 and 0.44 mg/m2 at pH 4.5 and 1.5, respectively. The mechanism of U(VI) removal by the Fe@NC was attributed to the synergistic effects of adsorption via nitrogen/oxygen-containing groups and redox reaction between Fe0/Fe2+ and U(VI).

Although two-dimensional titanium carbide (Ti3C2Tx MXene) has emerged as a shining star material in various communities, its environmental behaviors and fate remain unknown. Herein, the colloidal properties and stability of Ti3C2Tx MXene are explored in aquatic systems for the first time, considering the roles of solution chemistry conditions (e.g., pH, ionic types, and strength). It was found that pH had no effect on the stability of Ti3C2Tx in the range of 5.0-11.0, whereas ionic valence and concentrations displayed significant effects on the aggregation behavior of Ti3C2Tx. By employing time-resolved dynamic light scattering measurements, the critical coagulation concentration (CCC) value of Ti3C2Tx was determined to be 12 mM for NaCl. The divalent cations Ca2+ and Mg2+ exhibited higher destabilizing capacity to Ti3C2Tx, as evidenced by the lower CCC values (0.3 and 0.4 mM for CaCl2 and MgCl2, respectively) and faster coagulation rates. Long-term stability studies implied that Ti3C2Tx MXene was less likely to be transported over long distances in the synthetic or natural waters. These findings provided significant insights into the fate and transport of Ti3C2Tx in the aquatic environment.

A series of novel sandwich-like GO@SiO2@C@Ni composites were developed. The morphologies and adsorption capacities of the materials sintered at different carbonization temperatures were investigated. The formed GO@SiO2@C@Ni-400 possessed of wonderful dispersion, large surface area (229.88 m2/g) and high saturation magnetization. Batch experimental results revealed that maximum adsorption capacities of these materials towards Cr(VI) were as follows: GO@SiO2@C@Ni-400 (299.20 mg/g) > GO@SiO2@C@Ni-500 (244.05 mg/g) > GO (202.39 mg/g) > Graphene@C@Ni (188.80 mg/g) > GO@SiO2@C@Ni-600 (165.51 mg/g) > GO@SiO2@C@Ni-700 (93.36 mg/g). Moreover, the influence of hydrochemistry, such as contact time, pH, co-existing ions and solution temperature, on Cr(VI) adsorption was researched as well. It was demonstrated that GO@SiO2@C@Ni-400 had remarkable adsorption capacity for Cr(VI) removal under the acidic condition, hardly disturbed by other anions, and showed better adsorption performance at 328 K. Besides, On the base of X-ray photoelectron spectroscopy analysis, mechanisms of adsorption could be explained that Cr(VI) was reduced to Cr(III) by nitrogen dopant, and the complexation was existed between Cr(VI) and oxygen-containing functional groups. Additionally, GO@SiO2@C@Ni-400 could be easily separated under the external magnetic field and displayed outstanding reusability. Herein, GO@SiO2@C@Ni-400 opens up the possibility of future practical applications.

With the development of MXene as the efficient adsorbent for U(VI), the tendency of MXene coming into contact with U(VI) in wastewaters increases. Motivated by UV light irradiation applied in wastewater treatments, the UV light induced photochemical co-transformation of Ti

An ultrastable zirconium phosphonate framework (SZ-7) exhibits superior Sr2+ ion-exchange properties in 1 M NaOH solution with high adsorption capacity (183 mg g−1) and in-depth removal performance (Kd = 3.9 × 105 mL g−1).

Magnetic carbon materials promise distinct advantages in the decontamination of heavy metal ions. In this work, a novel interconnected hierarchical nickel-carbon (Ni@IHC) hybrid was synthesized by combining the solvothermal method with a one-step pyrolysis under argon atmosphere. Benefitting from 3D flower-like morphology, interconnected porous nanosheets, large surface area, and abundant Ni nanoparticles, Ni@IHC hybrids can remove Cr(VI) within 25 min by using formic acid (FA) as a reductant at 25 ℃. Furthermore, the experimental parameters that can affect the material catalytic performance such as initial Cr(VI) concentration, catalyst dosage, FA concentration, and temperature were also investigated in detail. It was found that highly dispersed Ni nanoparticles contributed significantly to the reduction process. More importantly, the embedded Ni nanoparticles favor fast separation by a magnet and were helpful for the recycles use. This Ni@IHC hybrid was obtained by a facile and easy scale-up method, resulting in the fast transformation of Cr(VI) into Cr(III).

Correction for ‘Synthesis of porous Fe3O4 hollow microspheres/graphene oxide composite for Cr(vi) removal’ by Mancheng Liu et al., Dalton Trans., 2013, 42, 14710–14717, https://doi.org/10.1039/C3DT50955A.

In this study, chitosan (CS) loading well-dispersed nanoscale zero-valent iron (NZVI/CS) was successfully prepared via the liquid-phase reduction method. Characterizations of the NZVI/CS with high-resolution transmission electron microscopy and X-ray diffraction suggested that the as-prepared NZVI/CS comprised numerous dispersed Fe0 nanoparticles. Synergistic adsorption and reduction occurred during the removal process based on X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Influence of pH, contract time and temperature on U(VI) removal were investigated. The high removal capacity and rapid removal kinetics were predominately ascribed to the existence of well-distributed NZVI, which could rapidly reduce U(VI) into U(IV). The removal process could be better depicted by the Langmuir isotherm model and the pseudo-second-order kinetic model. The thermodynamic parameters showed that the removal process was exothermic. These findings indicate that the synthesized NZVI/CS composites have potential application for the removal of U(VI) from the sewage water.

In this research, the Fe–Ni/graphene oxide composite (Fe–Ni/GO) was synthesized by the hydrothermal way and investigated to remove uranium(VI) from aqueous solution under various environmental conditions. Loading Fe–Ni on GO could obviously enhance the stability of Fe–Ni/GO. X-ray diffractometer analysis confirmed that the crystallization of Fe0 and Ni0 was formed in Fe–Ni/GO. The sorption and reduction of U(VI) by Fe–Ni/GO nanoparticles were confirmed by using Fourier transform infrared and X-ray photoelectron spectroscopy (XPS) analysis. Batch experiments displayed the sorption of U(VI) obtained equilibrium within 25 min following the second order reaction kinetics. Based on XPS analysis before and after sorption, the Fe–Ni could simultaneously involve the sorption and reduction of U(VI), and played a dominating impact on U(VI) removal. The introduction of Ni metal could promote U(VI) reduction through catalytic hydrogenation and electron transfer. Thus, Fe–Ni/GO exhibited more efficiency towards U(VI) removal compared to Fe/GO and Fe–Ni, and Fe–Ni/GO displayed outstanding maximum U(VI) removal capacity (384.62 mg/g). The results demonstrated that Fe–Ni/GO was a promising and feasible material for U(VI) removal from wastewater.

Porous carbonized polydopamine nanospheres encapsulated with Fe0-dominated Fe3O4/Fe0/Fe3C nanoparticles (Fe@C-PDA) were feasibly fabricated by a one-step pyrolysis of the Fe-PDA polymer, which was employed to activate persulfate (PS) toward degrading tetracycline (TC). The morphology, structure, chemical compositions and textural properties of the resulting catalyst were characterized systematically, and effects of catalyst dosages, PS concentration, inorganic anions (HCO3− and Cl−), natural organic matter and practical water body were studied in detail. The N-doping derived from C-PDA not only enhanced TC adsorption capacity, but also worked as active sites for PS excitation. Moreover, Fe@C-PDA displayed an excellent efficiency and stability in the 5th cycle tests. Electron paramagnetic resonance, classical radical scavenging experiments and X-ray photoelectron spectroscopy analysis disclosed that the active species in the system were identified as sulfate radicals (SO4 −) and hydroxyl radicals ( OH), and the variable chemical valences of Fe3O4/Fe0/Fe3C nanoparticles as well as N-doping in the C-PDA nanospheres contributed to the outstanding catalytic activity. This work can provide new insight of making this kind of Fe-based materials as the promising catalysts for application in eliminating organic pollutants.

Currently, there is little comparative data on the colloidal stability and the toxicity of ultraviolet (UV)- and visible-light (VL)-transformed graphene oxide (GO). In order to identify this knowledge gap, the physicochemical properties of UV/VL-transformed GO are investigated in detail. Attempts are made to correlate the physicochemical alterations of UV/VL-transformed GO to the observed changes in its colloidal properties and toxicity. The results show that both UV and VL irradiations induce the significant change in the color, UV-vis absorbance, morphology, surface charge, size, oxygen containing functional groups, total of carbon, and photoluminescence properties of GO. The photo-reaction behavior of GO under UV exposure is different from that under VL irradiation in terms of reaction rate, order, and extent. Finally, the UV and VL irradiations show different effects not only on the colloidal stability of GO in the City water and Dongpu Lake water, but also on the toxicity of GO to Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria. This study clearly shows how the environmental fate and risk of GO are modified by UV and VL irradiations.

In this study, graphene aerogel (GA) was successfully prepared through a simple hydrothermal method. The resulting GA exhibited a porous network structure with a large specific surface area (350.8 m2/g), ultra-light mass and easy separation from water. The pHIEP value of the GA was estimated to be 3.5. The adsorption process and the factors that affect adsorption capacity were studied. The adsorption could be conducted in a wide pH range from 2.0 to 7.0. The maximum adsorption capacity of GA towards U(VI) at pH 4.0 and T = 298 K was 238.67 mg/g calculated from the Langmuir model. The GA had greatly rapid adsorption property for the removal of U(VI) at pH 4.0. Kinetic data showed good correlation with pseudo-second-order equation. Fourier transform infrared spectroscopy and X-ray photoelectron spectrometry characterizations showed that GA adsorbed U(VI) through chemical interaction by oxygen-containing and nitrogen-containing groups functional groups. The results show that GA has excellent application potential as an adsorbent material for removing U(VI) from aqueous solution.

Uranium is not merely a momentous resource for nuclear energy, but also a highly toxic pollutant which has aroused global attention. The efficient handling of uranium from contaminated water is urgent. Herein, to acquire the improved performance of MOFs for U(VI) capture, a 2D/3D hybrid NH2-UiO-66/g-C3N4 (NU6CN) adsorbent was designed and fabricated through one-step hydrothermal approach. With the newly synthesized efficient NU6CN composite, the U(VI) loading amount could reach 195.55 mg·g−1, which significantly outperformed that of the individual NH2-UiO-66 (134.09 mg·g−1) and g-C3N4 (53.69 mg·g−1) at pH 5.0 and 298 K. The adsorption process conformed to the Langmuir and pseudo-second-order model. Subsequently, based on this system, the underlying interaction mechanism between U(VI) and NU6CN was carefully investigated. The formation of an inner-sphere complex on NU6CN surface was determined by the macroscopic and microscopic data. In the light of XPS analysis, the adsorption of U(VI) on NU6CN was attributable to the synergism of the ample nitrogen- and oxygen-bearing functional groups (e.g., N C N, O C O, C O) derived from g-C3N4 and NH2-UiO-66. Additionally, NU6CN revealed good recoverability and recyclability by adsorption/desorption test. These findings presented herein demonstrated the remarkable potential of as-prepared adsorbents for the uranium-contaminated water remediation.

Recently, nitrogen-doped carbon encapsulating with transition metal hybrids has attracted extensive interests in catalysis because of its unique microstructure and promising properties. In this work, three dimensional N-doped graphene-CNT frameworks with well encapsulated ultrafine Ni nanoparticles (Ni@N-CNTs/N-G) were developed by a facile two-stage encapsulation strategy by combining Ni-MOFs with melamine as the precursor. In terms of Cr(VI) reduction by using formic acid (HCOOH) as the reductant, N-CNTs/N-G matrix not only protected the encapsulated Ni nanoparticles from poisoning or leaching in strong acid media, but also provided enhanced active sites for Cr(VI) by its rich mesopores and high N content. Among all the products obtained after thermal treatments at different temperatures, Ni@N-CNTs/N-G-800 (pyrolyzed at 800 °C) exhibited superb reduction performance with the efficiency of approximately 99.6%, ascribing to the synergistic effects including the porous 3D framework with large specific surface area, high N-doping level, and large amount of ultrafine Ni nanoparticles. More importantly, its catalytic activity and microstructure rarely changed after 10 times of recycling, suggesting that Ni@N-CNTs/N-G-800 processes excellent stability. This study provides a new strategy of synthesizing transition metal-based catalyst, which can broaden the applicability of MOF materials for heavy metal pollution cleanup.

With the development of nuclear energy, large amounts of radionuclides are inevitably released into the natural environment. It is necessary to eliminate radionuclides from wastewater for the protection of environment. Nanomaterials have been considered as the potential candidates for the effective and selective removal of radionuclides from aqueous solutions under complicated conditions because of their high specific surface area, large amounts of binding sites, abundant functional groups, pore-size controllable and easily surface modification. This review mainly summarized the recent studies for the synthesis, fabrication and surface modification of novel nanomaterials and their applications in the efficient elimination and solidification of radionuclides, and discussed the interaction mechanisms from batch experiments, spectroscopy analysis and theoretical calculations. The sorption capacities with other materials, advantages and disadvantages of different nanomaterials are compared, and at last the perspective of the novel nanomaterials is summarized.

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.

Well-ordered, hollow, magnetic, high specific surface area composites have recently received enormous attention for the treatment of pollutants containing heavy metal ions. Herein, a serious of magnetic chestnut shell-like hollow sphere structure composites (NiOx/Ni@C) were derived via pyrolyzing a MOF containing nickel as self-sacrificed template and served as adsorbent materials for arsenic(V) (As(V)) removal from aqueous solutions. The experimental results indicated that the adsorption capacity of NiO/Ni@C400 towards As(V) (454.94 mg/g) was higher than that of Ni@C600 (342.77 mg/g), Ni@C500 (290.89 mg/g), NiO@C300 (210.40 mg/g), and Ni-MOFs (133.93 mg/g), which could be ascribed to NiO/Ni@C400-rich oxygen-containing functional groups and high specific surface area. The NiO/Ni@C400 had a high magnetization intensity and could be easily separated under external magnetic field. In addition, the NiO/Ni@C400 had an excellent As(V) removal performance over a broad pH range from 1 to 10. The significant adsorption capacity and reusability of the NiO/Ni@C400 coupled with the easy separation property indicated that the NiO/Ni@C400 has great potential in As(V) purification industry.

TiO2 with different exposed facets often shows different adsorption and photoreduction performances in environmental pollutant treatment, but the latent mechanisms are not fully understood. In this work, {0 0 1}, {1 0 0} and {1 0 1} facet-dominated anatase TiO2 was prepared and studied for its effectiveness in U(VI) removal, and the molecular level surface chemistry was studied by density functional theory (DFT) calculations. The experimental results indicated that {0 0 1} facet TiO2 exhibited the best adsorption capacity and photoreduction ability compared to {1 0 0} and {1 0 1} facet TiO2. DFT calculation results showed that the adsorption of U(VI) on the three surfaces leaded to the formation of inner-sphere complexes, in which the monodentate complex was most favored for {0 0 1} facet TiO2, whereas bidentate complexes were most favored for {1 0 0} and {1 0 1} facet TiO2. The results from experimental techniques, such as steady fluorescence emission spectra, time-resolved photoluminescence spectra, photocurrent density, electro-chemical impedance spectroscopy, Mott-Schottky plots suggested that the higher photocatalytic activity could be ascribed to higher electron-hole separation efficiency for three facets TiO2. Furthermore, the dissolved oxygen played different roles in U(VI) photoreduction on the three types of TiO2 in the experiments due to different surface structure arrangement. This work provides knowledge of toxic metal ion removal by facet-dependent metal oxides and a basis for the design and synthesis of other reactive facet-dependent materials for environmental management.

The elimination and safe treatment of U(VI) from radioactive wastewater has attracted widespread attention with the development of the nuclear power industry. In this work, a MgO/carbon adsorbent was successfully prepared by one-step Mg-MOF-74 pyrolyzation and used for U(VI) removal from aqueous solution. Characteristic results indicated that the as-prepared composite was a typical porous structure. The adsorption performance of the MgO/carbon towards U(VI) was studied by batch experiments. The results indicated that the MgO/carbon can rapidly and effectively remove U(VI) and showed an excellent adsorption capacity (777.51 mg/g), which is much higher than other reported adsorbent materials. In addition, the intraparticle diffusion model provides a good explanation for each adsorption process. The adsorption capacity of the MgO/carbon towards U(VI) is greatly promoted by the large specific surface area and well-defined porous structure. Based on the zeta potential and XPS analysis, the possible mechanism for U(VI) removal involved the surface complexation and electrostatic attraction. The results indicate that the MgO/carbon can be regarded as an efficient adsorbent for U(VI) removal from wastewater, which has a very broad application prospect.

Nanoscale zerovalent iron/magnetic carbon (NZVI/MC) composites were successfully synthesized by simply calcining yellow pine and iron precursors. NZVI/MC pyrolyzed at 800°C (NZVI/MC800) had a higher percentage of NZVI and displayed better resistance to aggregation and oxidation of NZVI than samples prepared at other temperatures. The NZVI/MC800 material was applied for the elimination of U(VI) from aqueous solutions. The results suggested that the NZVI/MC800 displayed excellent adsorption capacity (203.94 mg/g) toward U(VI). The significant adsorption capacity and fast adsorption kinetics were attributed to the presence of well-dispersed NZVI, which could quickly reduce U(VI) into U(IV), trapping the guest U(IV) in the porous biocarbon matrix. The removal of U(VI) on the NZVI/MC samples was strongly affected by solution pH. The NZVI/MC samples also displayed outstanding reusability for U(VI) removal after multiple cycles. These findings indicate that NZVI/MC has great potential for remediation of wastewater containing U(VI).

A novel interconnected hierarchically nitrogen-doped porous carbon (IHNPC) derived from metal-organic framework-based composites was obtained via a facile method and applied as a superior material for the capture of 17β-estradiol (E2) from aqueous solution. The adsorption kinetic and isotherm behaviors were well described by the pseudo-second-order and Langmuir models. Various thermodynamic parameters uncovered that E2 adsorption onto IHNPC was spontaneous and exothermic. Moreover, the adsorption rate of E2 by IHNPC didn’t decrease with increasing water salinity in the presence of electrolyte ions and humic acids. Naturally occurring aquatic particles can enhance (i.e., Al2O3), decrease (i.e., kaolin and SiO2) or have no obvious effects (i.e., montmorillonite) on the adsorption rate of E2 by IHNPC. The high adsorption capacity and remarkable adsorption selectivity of IHNPC highlighted the application of IHNPC for the capture of E2 and provided understanding of the fate and transport of E2 in natural aquatic environments.

Metal−organic frameworks (MOFs) combined with adsorptive materials have proven their prospect for radionuclide sequestration. To achieve more void space of MOFs as active sites for U(VI) capture, ZIF-8 (zeolitic imidazolate framework-8) nanoparticles were decorated on the polypyrrole (PPy) nanotubes (denoted as PPy/ZIF-8) via an easy and green method. X-ray diffraction, transmission electron microscopy, and Fourier transform infrared spectroscopy were applied to evaluate the effectiveness of the preparation of PPy/ZIF-8. This novel PPy/ZIF-8 was evaluated for the capture of U(VI) from the simulated wastewater. Based on the Langmuir model, the adsorption capacity was 534.0 mg/g at pH 3.5, which surpassed many other MOF-based adsorbents. The kinetic analysis disclosed that 90 min was enough for PPy/ZIF-8 to reach the adsorption equilibrium. In addition, the introduction of polypyrrole nanotubes endowed PPy/ZIF-8 high adsorption performance in a relatively wide pH range from 3.0 to 7.0. The superior adsorption performance was predominately traceable to the coordination of U(VI) with pyrrolic NH groups and Zn terminal hydroxyl groups based on the systematic spectroscopy characterization. PPy/ZIF-8 also showed excellent selectivity and regeneration ability. The excellent adsorption performance endows this novel composite a promising scavenger for the purification of U(VI)-polluted wastewater.

In this article, LDH@MOF-76 composite was successfully prepared by using a hydrothermal method and applied for the sorption of U(VI) from aqueous solution. The as-prepared composite displayed a typical porous and rod-like structure. The sorption performance of LDH@MOF-76 toward U(VI) was investigated by batch experiments. The results indicated that the LDH@MOF-76 could rapidly and effectively remove U(VI) from aqueous solution, with an excellent sorption capacity (433.91 mg/g), which is much higher than pure LDH (107.21 mg/g) and MOF-76 (269.14 mg/g). The high sorption capacity of the LDH@MOF-76 toward U(VI) resulted from the special one-dimensional channels of MOF-76 and the electrostatic attraction between U(VI) and LDH@MOF-76. Regeneration experiments revealed the LDH@MOF-76 had a good recycle performance. Based on the zeta potential and XPS analysis, the possible mechanism of U(VI) sorption involved the surface complexation and electrostatic attraction. In addition, the intraparticle diffusion model provided a good explanation for the sorption process. In summary, LDH@MOF-76 material can be a promising material to efficiently remove U(VI) from aqueous solution.

A denitrifying strain with high efficiency at low carbon to nitrogen (C/N) ratio of 2.0 was isolated and characterized. It belongs to the genus Pseudomonas. Scanning electron microscopy (SEM) showed that GF2 was rod-shaped. The nitrate removal efficiency reached up to 92.41% (1.85 mg L−1 h−1) with the C/N ratio of 2.0 and the nitrite accumulation eventually decreased to 0.88 mg L−1. By response surface method (RSM) method, three reaction conditions of strain GF2 were optimized, including pH, C/N ratio, and nitrate concentration. Nitrogen balance and gas detection revealed that 88.03% of nitrogen was removed in gaseous form (included 98.80% nitrogen gas), which confirmed its efficient denitrification ability and pathway. 3D fluorescence spectrum (3D-EEM) manifested that in the absence of organic matter, strain GF2 can utilize extracellular polymeric substance (EPS) as carbon source for efficient denitrification. This research strived to provide new research ideas for low C/N ratio sewage treatment.

A novel magnetic flower-shaped yolk-shell like structure composite Fe3O4@NC@MnO2 (Fe3O4 nanostructures coupled with N-doped carbon and MnO2, denoted as FNCM) was successfully fabricated through a facile and scalable tactic. By batch experiments, the maximal removal capacites of FNCM towards Re(VII) and As(V) can reach 110.9 and 236.3 mg/g at 293 K, respectively. Besides, the formed FNCM had excel dispersion, moderate specific surface area (46.23 m2/g) and saturation magnetization (∼20 emu/g). Next, the adsorption performance of FNCM towards Re(VII) and As(V) was investigated as function of contact time, pH, interfering ions and solution temperature. It was indicated that FNCM possessed wonderful adsorption performance towards Re(VII) and As(V) elimination under the acidic condition, rarely affected by other co-existing ions under the same concentration, and exhibited higher removal capacity. Furthermore, On the base of zeta potential and microscopic spectra analysis, the adsorption mechanism of FNCM towards Re(VII) and As(V) can be drown to three aspects: complexation between Re(VII)/As(V) and oxygen-containing functional groups (oxide–metal bonds (O–M bonds)), electrostatic interaction, and protonated N adsorption. In all, these results imply that the FNCM could be as a potential candidate for remediating water contaminated with practical applications.

Correction for ‘Graphene oxide-iron oxide and reduced graphene oxide-iron oxide hybrid materials for the removal of organic and inorganic pollutants’ by Xin Yang et al., RSC Adv., 2012, 2, 8821–8826, https://doi.org/10.1039/C2RA20885G.

Retraction of 'Enhanced adsorption of Eu(iii) on mesoporous Al