Complicated Spinal Stenosis and Spinal Deformity in Patients with Achondroplasia: Case Series and Review of the Literature.

OBJECTIVE: Due to the low incidence of achondroplasia (Ach), there is a relative lack of research on the treatment and management of spinal complications of Ach. Characteristics and interventions for spinal complications in patients with Ach are in urgent need of investigation. This study aimed to summarize the common spinal complications in patients with Ach and the corresponding treatment strategies. METHODS: This study is a retrospective case series. We retrospectively collected and analyzed Ach cases who presented to our hospital with neurological symptoms due to skeletal anomalies between February 2003 and October 2023. A total of seven patients were included, four males (57.1%) and three females (42.9%) with a mean age of 38.57 years. Patient pain/numbness visual analog scale (VAS), preoperative Oswestry disability index (ODI), development of neurological complaints, and presentation of skeletal abnormalities were collected and followed up routinely at 3, 6, 12 and 24 months postoperatively. The relevant literature was reviewed. RESULTS: Seven patients were included in this series. The mean preoperative VAS was 4, and the mean preoperative ODI was 50.98%. All patients had concomitant spinal stenosis, four with thoracolumbar kyphosis (TLK), and one with scoliosis. Six of the seven patients underwent surgery, and one patient received conservative treatment. In the routine follow-ups, all patients experienced satisfactory relief of symptoms. Only one of the seven patients developed a new rare lesion adjacent to the primary segments. Six months after the first surgery, a follow-up visit revealed thoracic spinal stenosis caused by ossification of the ligamentum flavum, and his symptoms were relieved after thoracic decompression surgery. CONCLUSIONS: Ach seriously affects the skeletal development of patients and can lead to the development of spinal stenosis, spinal deformities, and other complications of the locomotor system. Surgery remains the primary treatment for complications of the musculoskeletal system. Specific surgical approaches and comprehensive, long-term management are critical to the treatment of patients with spinal complications.

The establishment of a novel upper cervical complex fracture classification system.

BACKGROUND CONTEXT: Upper cervical complex fractures are associated with high rates of neurological damage and mortality. The Dickman's classification is widely used in the diagnosis of upper cervical complex fractures. However, it falls short of covering the full spectrum of complex fractures. This limitation hinders effective diagnosis and treatment of these injuries. PURPOSE: To address the diagnostic gap in upper cervical complex fractures, the study introduces a novel classification system for these injuries, assessing its reliability and usability. STUDY DESIGN: Proposal of a new classification system for upper cervical complex fractures. PATIENT SAMPLE: The study comprised the clinical data of 242 patients with upper cervical complex fractures, including 32 patients treated at our hospital, along with an additional 210 cases from the literature. OUTCOME MEASURES: The inter-observer and intra-observer reliability (kappa coefficient, κ) of this classification system were investigated by 3 spine surgeons. The 3 researchers independently re-evaluated the upper cervical complex fracture classification system 3 months later. METHODS: The proposed classification categorizes upper cervical complex fractures into 3 main types: Type I combines odontoid and Hangman's fractures into 2 subtypes; Type II merges C1 with odontoid/Hangman's fractures into 3 subtypes; and Type III encompasses a combination of C1, odontoid, and Hangman's fractures, divided into 2 subtypes. Meanwhile, a questionnaire was administered in 15 assessors to evaluate the system's ease of use and clinical applicability. RESULTS: A total of 45 cases (18.6%) unclassifiable by Dickman's classification were successfully categorized using our system. The mean κ value of inter-observer reliability was 0.783, indicating substantial reliability. The mean κ value of intra-observer reliability was 0.862, indicating almost perfect reliability. Meanwhile, thirteen assessors (87.7%) stated that the classification system is easy to remember, easy to apply, and they expressed intentions to apply it in clinical practice in the future. CONCLUSIONS: This system not only offers high confidence and reproducibility but also serves as a precise guide for clinicians in formulating treatment plans. Future prospective applications are warranted to further evaluate this classification system.

The Role of Paraspinal Muscle in Postoperative Coronal Balance Transition in Degenerative Lumbar Scoliosis: A 2-year Follow-up Study.

STUDY DESIGN: Retrospective observational study. OBJECTIVE: The purpose of this study was to determine whether paraspinal muscle could influence postoperative coronal balance and its transition in degenerative lumbar scoliosis (DLS). SUMMARY OF BACKGROUND DATA: Although the importance of the paraspinal muscles (PSM) in sagittal alignment is well recognized, there is no information about its role in coronal balance. METHODS: The study included 102 DLS patients. Evaluation of the PSM on magnetic resonance imaging were conducted at baseline. Coronal measurements included coronal balance distance (CBD), major Cobb angle, L4 coronal tilt, and L5 coronal tilt. The cohort was divided based on postoperative parameters into persistent coronal balance (PCB), worsened coronal imbalance (WCIB), recurrent coronal balance (RCB), and persistent coronal imbalance (PCIB) according to immediate postoperative and follow-up coronal balance. Multivariate logistic regression models for postoperative CIB, follow-up WCIB and follow-up RCB were utilized to identify statistically significant associations while accounting for confounders. RESULTS: The cohort was divided into 57 with PCB, 13 with WCIB, 10 with RCB, and 22 with PCIB. The follow-up groups with CIB exhibited more severe fatty infiltration in the extensor muscle compared to the balanced groups. Specifically, the WCIB group demonstrated the most severe extensor muscle degeneration, particularly on the concave sides, and the most prominent asymmetrical degeneration of the PSM among the four groups. Furthermore, patients with CIB had worse sagittal malalignment compared to those with CB at the last follow up. CONCLUSION: Patients exhibiting stronger extensor muscle mass were prone to immediate postoperative CB and more likely to experience spontaneous improvement or recurrence of coronal balance during follow-up. Severe extensor muscle degeneration and prominent asymmetrical bilateral PSM degeneration represent potential risk factors for persistent CIB and recurrent CIB. It is crucial to assess the dynamic change during the follow-up period as long-term prognosis may be impacted if CB deteriorates, or otherwise develops during follow-up. LEVEL OF EVIDENCE: 3.

Can the 6-minute Walking Test Assess Ambulatory Function Impairment in Patients with Cervical Spondylotic Myelopathy?

STUDY DESIGN: Prospective cohort study. OBJECTIVE: Investigating the ability of a 6-minute walking test (6MWT) to assess functional status in patients with cervical spondylotic myelopathy (CSM). SUMMARY OF BACKGROUND DATA: The 6MWT provides an objective assessment of a patient's ability to walk. There is the potential for its application to the assessment of functional status in patients with CSM. MATERIALS AND METHODS: One hundred and thirty-five patients from our institution were prospectively enrolled from July 2022 to August 2023. A control group of age- and sex-matched healthy individuals was established. The 6MWT was conducted in strict accordance with established guidelines. The Nurick score, the Prolo score, the Cooper-myelopathy-scale score (CMS), the Japanese Orthopedic Association score (JOA) and the European-myelopathy-scale score (EMS) were assessed preoperatively. Visual Analog Scale (VAS) for pain or numbness and Oswestry Neck Disability Index (NDI) were also collected. Radiographic parameters were measured and recorded. Continuous variables between patients and controls were compared by applying the t-test. The chi-square test was used to compare gender ratios between groups. Pearson's correlation analysis was used to analyze the association between continuous variables and ordinal variables. Subgroups of CSM patients were analyzed according to global spinal alignment types, based on whether the SVA was greater than or equal to 50 mm. Clinical scores and imaging parameters were compared by t-test. RESULTS: The preoperative 6-minute walking distance (6MWD) of CSM patients was 309.34 ± 116.71 m, which was significantly lower than that of the controls (464.30 ± 52.59 m, P<.01). The 6MWD was significantly correlated with scores on all clinical scales except the VAS. CMS Lower extremity score had the strongest correlation with preoperative 6MWD in CSM patients (r=-.794 , P<.01). Of the sagittal alignment parameters, only C7 sagittal vertical axis (SVA) and T1 slope were significantly correlated with 6MWD(r=-.510,-0.360, respectively). CSM patients with SVA greater than 50 mm had significantly lower 6MWD than CSM patients with SVA less than or equal to 50 mm (168.00 ± 137.26 vs 346.24 ± 84.27 m, P<.01). CONCLUSIONS: The 6MWD of CSM patients was significantly lower than that of the healthy population and correlated well with commonly used clinical scales. The 6MWD can potentially assist in the assessment of functional status in patients with CSM.

Piezo1 channel exaggerates ferroptosis of nucleus pulposus cells by mediating mechanical stress-induced iron influx.

To date, several molecules have been found to facilitate iron influx, while the types of iron influx channels remain to be elucidated. Here, Piezo1 channel was identified as a key iron transporter in response to mechanical stress. Piezo1-mediated iron overload disturbed iron metabolism and exaggerated ferroptosis in nucleus pulposus cells (NPCs). Importantly, Piezo1-induced iron influx was independent of the transferrin receptor (TFRC), a well-recognized iron gatekeeper. Furthermore, pharmacological inactivation of Piezo1 profoundly reduced iron accumulation, alleviated mitochondrial ROS, and suppressed ferroptotic alterations in stimulation of mechanical stress. Moreover, conditional knockout of Piezo1 (Col2a1-CreERT Piezo1flox/flox) attenuated the mechanical injury-induced intervertebral disc degeneration (IVDD). Notably, the protective effect of Piezo1 deficiency in IVDD was dampened in Piezo1/Gpx4 conditional double knockout (cDKO) mice (Col2a1-CreERT Piezo1flox/flox/Gpx4flox/flox). These findings suggest that Piezo1 is a potential determinant of iron influx, indicating that the Piezo1-iron-ferroptosis axis might shed light on the treatment of mechanical stress-induced diseases.

Electronic Structure Optimization and Proton-Transfer Enhancement on Titanium Oxide-Supported Copper Nanoparticles for Enhanced Nitrogen Recycling from Nitrate-Contaminated Water.

Electrocatalytic reduction of nitrate to NH3 (NO3RR) on Cu offers sustainable NH3 production and nitrogen recycling from nitrate-contaminated water. However, Cu affords limited NO3RR activity owing to its unfavorable electronic state and the slow proton transfer on its surface, especially in neutral/alkaline media. Furthermore, although a synchronous "NO3RR and NH3 collection" system has been developed for nitrogen recycling from nitrate-laden water, no system is designed for natural water that generally contains low-concentration nitrate. Herein, we demonstrate that depositing Cu nanoparticles on a TiO2 support enables the formation of electron-deficient Cuδ+ species (0 < δ ≤ 2), which are more active than Cu0 in NO3RR. Furthermore, TiO2-Cu coupling induces local electric-field enhancement that intensifies water adsorption/dissociation at the interface, accelerating proton transfer for NO3RR on Cu. With the dual enhancements, TiO2-Cu delivers an NH3-N selectivity of 90.5%, mass activity of 41.4 mg-N h gCu-1, specific activity of 377.8 mg-N h-1 m-2, and minimal Cu leaching (<25.4 µg L-1) when treating 22.5 mg L-1 of NO3--N at -0.40 V, outperforming most of the reported Cu-based catalysts. A sequential NO3RR and NH3 collection system based on TiO2-Cu was then proposed, which could recycle nitrogen from nitrate-contaminated water under a wide concentration window of 22.5-112.5 mg L-1 at a rate of 209-630 mgN m-2 h-1. We also demonstrated this system could collect 83.9% of nitrogen from NO3--N (19.3 mg L-1) in natural lake water.

FeMo@porous carbon derived from MIL-53(Fe)@MoO3 as excellent heterogeneous electro-Fenton catalyst: Co-catalysis of Mo.

An ultra-efficient electro-Fenton catalyst with porous carbon coated Fe-Mo metal (FeMo@PC), was prepared by calcining MIL-53(Fe)@MoO3. This FeMo@PC-2 exhibited impressive catalytic performance for sulfamethazine (SMT) degradation with a high turnover frequency value (7.89 L/(g·min)), much better than most of reported catalysts. The mineralization current efficiency and electric energy consumption were 83.2% and 0.03 kWh/gTOC, respectively, at low current (5 mA) and small dosage of catalyst (25.0 mg/L). The removal rate of heterogeneous electro-Fenton (Hetero-EF) process catalyzed by FeMo@PC-2 was 4.58 times that of Fe@PC/Hetero-EF process. Because the internal-micro-electrolysis occurred between PC and Fe0, while the co-catalysis of Mo accelerated the rate-limiting step of the Fe3+/Fe2+ cycle and greatly improved the H2O2 utilization efficiency. The results of radical scavenger experiments and electron paramagnetic resonance confirmed the main role of surface-bound hydroxyl radical oxidation. This process was feasible to remove diverse organic contaminants such as phenol, 2,4-dichlorophenoxyacetic acid, carbamazepine and SMT. This paper enlightened the importance of the doped Mo, which could greatly improve the activity of the iron-carbon heterogeneous catalyst derived from metal-organic frameworks in EF process for efficient removal of organic contaminants.

Building dual active sites Co3O4/Cu electrode to break scaling relations for enhancement of electrochemical reduction of nitrate to high-value ammonia.

The electrochemical reduction of nitrate to ammonia (ERNA) has become a green treatment technology for nitrate wastewater. However, strong adsorption for product caused high activation energy for product desorption in scaling relations, blocking activity of electrocatalyst in ERNA. Density functional theory (DFT) calculations indicated that constructing dual active sites (Cu and Co3O4) could achieve strong adsorption of nitrate (-2.91 eV) with low desorbing energy barrier of ammonia (0.13 eV), breaking scaling relations. This dual active sites Co3O4/Cu electrode achieved a high ammonia yield rate of 684 µg mgcat-1 h-1 with 94.6% faradic efficiency, surpassing single active site Co3O4 and Cu electrodes. For mechanism, In-situ electrochemical characterization found the vital intermediates of *NH and *NH2, demonstrating that indirect reduction was the main pathway on Co3O4/Cu electrode. Thus, it is believed that building dual active sites on electrode is a reliable strategy to enhance ERNA for purifying industrial wastewater polluted by nitrate.

Aminopolycarboxylic acids modified oxygen reduction by zero valent iron: Proton-coupled electron transfer, role of iron ion and reactive oxidant generation.

The oxygen reduction reaction (ORR) activated by Fe0 in the presence of three aminopolycarboxylic acids (CAs), i.e. nitrilotriacetic acid (NTA), ethylenediamine-N,N'-disuccinic acid (EDDS) and ethylenediaminetetraacetic acid (EDTA), for the degradation of sulfamethazine (SMT) was investigated. At optimum conditions, Fe0/EDDS/O2, Fe0/EDTA/O2 and Fe0/NTA/O2 systems presented SMT removal of 58.2%, 75.3% and 93.8%, respectively, being much higher than that in the Fe0/O2 system (1.36%). The generation of surface-bound Fe2+ (Fe2+) and dissolved iron ion was enhanced by CAs. ORR through a two-electron transfer pathway was mainly responsible for H2O2 generation in NTA and EDTA systems, while a single-electron ORR was the major source for producing H2O2 in EDDS system. •OH produced by the homogeneous reaction of Fe2+ and H2O2 was the main species for SMT degradation. Fe0/EDDS/O2 produced more 1O2 than Fe0/EDTA/O2 and Fe0/NTA/O2; however, the radical contributed negligibly to SMT removal. The caging effect of CAs might be a major factor influencing the reaction rate of Fe2+ and O2. CAs provided protons to accelerate the electron transfer, the production of Fe2+ and thus the contaminant removal. This study is of great significance for revealing ORR mechanisms in the Fe0-chelate system.

S-doped MIL-53 as efficient heterogeneous electro-Fenton catalyst for degradation of sulfamethazine at circumneutral pH.

The reduced S-modified MIL-53(Fe) was prepared by sulfurizing MIL-53(Fe) at low temperature, which was an efficient electro-Fenton catalyst at wide pH range (3-9) for sulfamethazine (SMT) degradation. The best temperature and MIL-53(Fe)/S ratio were 350 °C and 1:2, at which the BET surface area was much enlarged. The MIL-53(Fe) surface was etched by S to many 2D nanosheets with the thickness of ~50 nm, while S2-2 replaced OH- to coordinate with Fe2+ and increased the Fe2+ content, which improved the catalytic performance. Even at initial pH of 7.0, the SMT removal was 95.8%, and the rate constant (k) in the Hetero-EF process was 16-folds of that in the Homo-EF process. The turnover frequency (TOFd) value of MIL-53(Fe)/S(1:2)-350 was 0.48 L g-1 min-1, which was 6.8 times that of commercial FeS2. The S2-2in catalyst adjusted the pH superfast, and promoted the generation of Fe2+ and thus efficiently activating H2O2 to form surface ·OH, which was verified to be the main radical by EPR and radical scavenger experiments. This catalyst showed promising prospect for environmental application and could be regenerated by sulfidation method. S-doped MIL-53(Fe) was an excellent pH regulator, thus promoting promising application in Hetero-EF processes.

Prenatal maternal depressive symptoms of Chinese pregnant women and twin newborns' physical health: the moderating role of infant sex.

Consequences of prenatal maternal depressive symptoms on infant health are well established. But the results of infants' sex differences of such consequences are mixed. The current study examines whether any association exists between prenatal maternal depressive symptoms and infant physical health different for the sex of newborns. A sample of 84 women pregnant with twins reported depressive symptoms using the Edinburgh Postnatal Depression Scale (EPDS) in the late gestational stage. The Apgar scores of newborns were assessed by healthcare providers at 1, 5, and 10 minutes after birth. The relationship of maternal prenatal depressive symptoms and newborns' physical health was moderated by infant sex. Higher depressive symptoms were associated with a lower Apgar index among newborn boys but not girls. Fetus environment or biomarkers related to sex may be a key mechanism of the effect of prenatal depression symptoms on newborns' health. Tailored interventions targeting maternal depression symptoms may be warranted.

Synergistic Effect of Co(III) and Co(II) in a 3D Structured Co3O4/Carbon Felt Electrode for Enhanced Electrochemical Nitrate Reduction Reaction.

As nitrate contamination causes serious environmental problems, it is necessary to develop stable and efficient electrocatalysts for efficient electrochemical nitrate reduction reaction (ENRR). Here, a nonprecious Co3O4/carbon felt (CF) electrode with a 3D structure was prepared by integrating electrodeposition with calcination methods. This 3D structured Co3O4/CF electrode exhibits a high-rate constant of 1.18 × 10-4 s-1 cm-2 for the ENRR, surpassing other Co3O4 electrodes in previous literature. Moreover, it also has an excellent stability with a decrease of 6.4% after 10 cycles. Density functional theory calculations, electron spin resonance analysis, and cyclic voltammetry were performed to study the mechanism of the ENRR on the Co3O4/CF electrode, proving that atomic H* (indirect pathway) plays a prominent role in NO3- reduction and clarifying the synergistic effect of Co(III) and Co(II) in the Co(II)-Co(III)-Co(II) redox cycle for the ENRR: Co(III) prefers the adsorption of NO3- and Co(II) favors the production of H*. Based on this synergy, a relatively large amounts of Co(II) on the surface of the Co3O4/CF electrode (1.3 Co(II)/Co(III) ratio) was maintained by controlling the temperature of calcination to 200 °C with a lower energy barrier of H* formation of 0.46 eV than other ratios, which is beneficial for forming H* and enhancing the performance of the ENRR. Thus, this study suggests that building 3D structure and optimizing Co(II)/Co(III) ratio are important for designing efficient Co3O4 electrocatalyst for ENRR.

Emotional intelligence and dyadic satisfaction buffer the negative effect of stress on prenatal anxiety and depressive symptoms in Chinese women who are pregnant with twins.

Background: Pregnancy-related stress in women who are pregnant with twins, may increase the risk of adverse emotional outcomes such as depressive symptoms and anxiety. Possible protective coping resources of pregnant women could be their socio-economic background, their marital relationship quality (dyadic satisfaction), or their emotional intelligence. Objectives: The study aims at exploring the mechanisms by which protective factors are associated with pregnancy-related stress and adverse emotional outcomes such as depression and anxiety. Methods and Design: Hospitals in Beijing, China, provided questionnaire data from 134 women who were pregnant with twins. Pregnancy-related stress, anxiety, depression, and three resource factors (socio-economic status, emotional intelligence, and dyadic marital satisfaction) were measured. Results: The experience of pregnancy-related stress mediated between resource factors and adverse consequences. While some socio-economic background variables had a main effect, personal and social resources exerted a buffer effect: emotional intelligence as well as dyadic satisfaction buffered the negative effects of stress on prenatal anxiety and depressive symptoms, respectively. Conclusions: A unique mechanism was identified that may explain how protective coping resources are associated with psychosocial stress and adverse outcomes in pregnant at-risk women. Future studies should substantiate this finding using longitudinal research designs.

Identifying the rate-determining step of the electrocatalytic hydrodechlorination reaction on palladium nanoparticles.

Identifying the rate-determining step over the catalysts and clarifying the underlying mechanisms are crucial for maximizing the electrocatalytic hydrodechlorination (EHDC) efficiency for detoxification of the chlorophenol pollutants in water. Here, monodisperse palladium nanoparticles (Pd NPs) separately supported on carbon (C) and titanium nitride (TiN) were synthesized as two model catalysts. The support effects on EHDC efficiency, kinetics and current efficiency towards 2,4-dichlorophenol (2,4-DCP), and the electronic structure of Pd and its binding strengths with 2,4-DCP, phenol and Cl- (the primary EHDC product) were investigated by experimental and density functional theory (DFT) analyses. The low current efficiency (<30%) of both catalysts and the good description of EHDC kinetics by the Langmuir-Hinshelwood model suggest that the 2,4-DCP coverage on Pd, rather than the well-known adsorbed hydrogen generation, determines EHDC efficiency. Furthermore, the superior EHDC efficiency on TiN-Pd (96.4% vs. 80.9% on C-Pd), coupled with the weakened adsorption of 2,4-DCP and phenol on TiN-supported Pd, demonstrates that the 2,4-DCP coverage is largely influenced by phenol due to its poisoning effect by blocking active sites, and phenol desorption is the rate-determining step of EHDC on the catalyst. The support TiN enables alleviation of the phenol poisoning by modulating the electronic structure of Pd. The d band center of Pd can serve as a potential descriptor of EHDC efficiency, and its optimization for balancing 2,4-DCP and phenol adsorption should be an effective strategy to enhance EHDC.

MgAl layered double oxide: One powerful sweeper of emulsified water and acid for oil purification.

We exploit a novel role of MgAl-layered double oxide (LDO) as a powerful sweeper to remove trace emulsified water and organic acids from contaminated oil. Notably, 0.4 g of LDO enable to purify 20 mL of contaminated oil with 0.2 g of water and 0.1 mL of octanoic acid, and the separation efficiency reaches 94.6 and 28.2%, respectively. The separation process is initiated with the immobilization of water droplets at the crystalline matrix of LDO (driven by the unique water memory effect), accompanied by the LDO converted to MgAl-layered double hydroxide (LDH). LDH possesses a high point of zero charge and abundant OH- and Mg2+/Al3+ on its layered surface, which enables it to remove the acids via neutralization and complexing reactions. The immobilized water and adsorbed acids are eventually swept by collecting the solids. The collected solids, mainly composed of LDH, can be regenerated to LDO for recycle through a calcination process. Economy evaluation reveals it takes $6.7 for LDO to purify every cubic meters of emulsion, much more cost-effective than the reported CaSO4•0.5H2O and Fe3O4-based adsorbents. The robust performance with the competitive economy points to the high potential of LDO for oil regeneration.

Calcium Sulfate Hemihydrate Nanowires: One Robust Material in Separation of Water from Water-in-Oil Emulsion.

Here we report a facile and cost-effective wet-chemical approach to the synthesis of calcium sulfate hemihydrate nanowires (HH NWs, CaSO4·0.5H2O), and their robust performance in immobilizing water molecules to the crystal lattice of CaSO4 and then separating them from a surfactant-stabilized water-in-oil emulsion (mean droplet size of around 1.2 µm). Every gram of HH NWs are capable of treating 20 mL emulsion (water content: 10.00 mg mL-1) with a separation efficiency of 99.23% at room temperature, and this efficiency can be further improved by tuning the surface charge density of HH. Along with the water immobilization, HH NWs are converted to large cubic-like calcium sulfate dihydrate microparticles (DH, CaSO4·2H2O, mean size: 50 µm), and the accompanied size increment enables efficient collection of the solid phase from oil. DH microparticles can be regenerated into HH NWs, which retain the high performance of the original NWs. Such a unique renewable feature improves the economics of our method and simultaneously prevents the secondary pollution. Further economic evaluation finds that purification of every cubic meters of emulsion (water content: 10.00 mg mL-1) will cost about $34.18 for HH NWs, much lower than the $490.78 for the previously reported HH NPs, and $11 052.05-$23 420.32 Fe3O4 NP-based adsorbents, respectively. With the high efficiency, easy collection, low cost, and renewable feature, HH NWs show highly promising applications in the field of oil purification and recycle.

Zero-valent iron nanoparticles embedded into reduced graphene oxide-alginate beads for efficient chromium (VI) removal.

Zero-valent iron nanoparticles (Fe0 NPs) technologies are often challenged by poor dispersibility, chemical instability to oxidation, and mobility during processing, storage and use. This work reports a facile approach to synthesize Fe0 NPs embedded reduced graphene oxide-alginate beads (Fe@GA beads) via the immobilization of pre-synthesized Fe0 NPs into graphene oxide modified alginate gel followed by a modelling and in-situ reduction process. The structure/composition characterization of the beads finds that the graphene sheets and the Fe0 NPs (a shape of ellipsoid and a size of <100nm) are uniformly dispersed within the alginate beads. We demonstrate that these Fe@GA beads show a robust performance in aqueous Cr(VI) removal. With a optimized Fe and alginate content, Fe@GA bead can achieve a high Cr(VI) removal efficiency and an excellent mechanical strength. The initial Cr(VI) concentration, ionic strength, temperature and especially solution pH are all critical factors to control the Fe@GA beads performance in Cr(VI) removal. Fitness of the pseudo second-order adsorption model with data suggests adsorption is the rate-controlling step, and both Langmuir and Freundlich adsorption isotherm are suitable to describe the removal behavior. The possible Cr(VI) removal path by Fe@GA beads is put forward, and the synergistic effect in this ternary system implies the potentials of Fe@GA beads in pollutant removal from water body.