Mg-Fe Layered Double Hydroxide Research Articles

Synergistic adsorption of real phosphorus-containing domestic wastewater by in-situ growth of MgFe-layered double hydroxides co-doped with dual-functional lignosulfonate and La(OH)3 on wood-derived cellulose aerogel

Recovering and reusing of phosphorus (P) in wastewater is the optimal solution to address mineral shortages and eutrophication. Here, the layered double hydroxides (LDHs) grown on wood-derived aerogels (WAs) were prepared after screening the powdered precursors and named La/MgFe-LDH(LS)@WAs. The intricate pore structure and surface morphology of the WAs formed a fibrous network with ultra-low density, good strength and elasticity, allowing for uniform loading. The sample exhibited excellent adsorption capacity of 139.5 mg P/g at pH 4.0, and over 100.0 mg P/g within a wide pH range (3.0–8.0). Thomas and Yoon-Nelson models could effectively describe the dynamic adsorption process. Microscopic morphology and textural characteristics of the samples were characterized and molecular dynamics (MD) simulations and theoretical calculations based on density functional theory (DFT) were used to study the interaction mechanisms. The coordination bonds and weak interactions between the active component LS and La(OH)3 with phosphates were characterized using interaction region indicator (IRI) and independent gradient model based on Hirshfeld molecular density partitioning (IGMH) methods. The atomic δg index mapped to the molecular structure vividly illustrated the maximum contribution of hydroxyl hydrogen to phosphate deprotonation oxygen in inter-fragment interactions on LS. Combining the formation of Me-O-P bonds characterized by X-ray photoelectron spectroscopy (XPS), the mechanism involves weak interactions (hydrogen bond) and chemical adsorption via ligand exchange. High removal efficiency was demonstrated in real wastewater. A method for waste reuse was also proposed. Plant cultivation experiments showed that La/MgFe-LDH(LS)@WAs could sustain wheat growth with slowly degrade and maintain high phosphate availability. The composite shows potential for water restoration, waste treatment, and value-added conversion in the production of controlled-release fertilizers.

Enhancing iron content and growth of cucumber seedlings with MgFe-LDHs under low-temperature stress.

The development of cost-effective and eco-friendly fertilizers is crucial for enhancing iron (Fe) uptake in crops and can help alleviate dietary Fe deficiencies, especially in populations with limited access to meat. This study focused on the application of MgFe-layered double hydroxide nanoparticles (MgFe-LDHs) as a potential solution. We successfully synthesized and characterized MgFe-LDHs and observed that 1-10mg/L MgFe-LDHs improved cucumber seed germination and water uptake. Notably, the application of 10mg/L MgFe-LDHs to roots significantly increased the seedling emergence rate and growth under low-temperature stress. The application of 10mg/L MgFe-LDHs during sowing increased the root length, lateral root number, root fresh weight, aboveground fresh weight, and hypocotyl length under low-temperature stress. A comprehensive analysis integrating plant physiology, nutrition, and transcriptomics suggested that MgFe-LDHs improve cold tolerance by upregulating SA to stimulate CsFAD3 expression, elevating GA3 levels for enhanced nitrogen metabolism and protein synthesis, and reducing levels of ABA and JA to support seedling emergence rate and growth, along with increasing the expression and activity of peroxidase genes. SEM and FTIR further confirmed the adsorption of MgFe-LDHs onto the root hairs in the mature zone of the root apex. Remarkably, MgFe-LDHs application led to a 46% increase (p < 0.05) in the Fe content within cucumber seedlings, a phenomenon not observed with comparable iron salt solutions, suggesting that the nanocrystalline nature of MgFe-LDHs enhances their absorption efficiency in plants. Additionally, MgFe-LDHs significantly increased the nitrogen (N) content of the seedlings by 12% (p < 0.05), promoting nitrogen fixation in the cucumber seedlings. These results pave the way for the development and use of LDH-based Fe fertilizers.

Calcined MgFe layered double hydroxides for magnetic separation and enhanced adsorption performance of methyl orange: Mechanism based on the memory effect

This study successfully synthesized magnetic MgFe-layered double oxides (MgFe-LDO-500 °C) by calcining MgFe-layered double hydroxides (MgFe-LDHs) at 500 °C. Calcination temperature was identified as a critical factor for optimizing adsorption capacity and activating a memory effect, with 500 °C being particularly effective. The adsorption performance of MgFe-LDO-500 °C towards methyl orange (MO) in aqueous solutions was evaluated across varying pH levels (2–12), initial MO concentrations (50–1800 mg/L), contact times (0–1440 min), and temperatures (25–45 °C). The results indicated that MgFe-LDO-500 °C adsorption conforms to the pseudo-second-order kinetic and Langmuir models, achieving a theoretical maximum adsorption capacity of 5087.76 mg/g. Characterization through scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Zeta potential analysis revealed that the outstanding adsorption performance of MgFe-LDO-500 °C towards MO involves a combination of electrostatic attraction, memory effect, and surface complexation. Moreover, after four regeneration cycles, the material maintained a 73 % MO removal efficiency and could be efficiently separated using magnetic separation technology. In conclusion, MgFe-LDO-500 °C represents a promising adsorbent for wastewater treatment.

Using CuMgFe layered double oxide to replace laccase as a catalyst for abiotic humification

Humification offers a promising avenue for sequestering dissolved organic carbon while facilitating environmental cleanup. In this study, CuMgFe layered double oxides (LDO) were applied as a catalyst to replace conventional enzymes, such as laccase, thereby enhancing the in vitro polyphenol-Maillard humification reaction. CuMgFe LDO was synthesized through calcination of CuMgFe layered double hydroxides (LDH) at 500 °C for 5 h. A suite of characterization methods confirmed the successful formation into mixed oxides (Cu2O, CuO, MgO, FeO, and Fe2O3) after thermal treatment. A rapid humification reaction was observed with CuMgFe LDO, occurring within a two-week span, likely due to a distinct synergy between copper and iron elements. Subsequent analyses identified that MgO in CuMgFe LDO also played a pivotal role in humification by stabilizing the pH of the reaction. In the absence of magnesium, LDO's humification activity was more pronounced in the early stages of the reaction, but it rapidly diminished as the reaction progressed. The efficiency of CuMgFe LDO was heightened at elevated temperatures (35 °C), while light conditions manifested a discernible effect, with a modest decrease in humification efficacy under indoor light exposure. CuMgFe LDO surpassed both laccase and MgFe LDH in performance, boasting a superior humification efficiency relative to its precursor, CuMgFe LDH. The catalysts' humification activity was modulated by their crystallinity and valence dynamics. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) results suggested that introducing the amino acid, glycine, expedited the CuMgFe LDO-fueled humification, enhancing the formation of C–N and C–C bonds in the resultant products. The humic-like substances derived from the catalyst-enhanced reaction displayed an elevated presence of aromatic configurations and a richer array of oxygen functional groups in comparison to a typical commercial humic material.

La-doped MgFe-layered double hydroxides and their sorption properties towards tungsten oxyanions (WO42-) at alkaline pH’s

The present study focuses on the tungsten recovery from alkaline solutions using for the first time La-doped MgFe-LDH type sorbents (pH ≥ 13). A small-scale synthesis procedure was optimized, and further upscaled (20x) to produce up to 200 g batches with reproducibility degree close to 100%. The chemical composition, structural and textural characteristics of the as-synthesized materials were investigated by ICP-OES, X-ray Diffraction, N2 physisorption and IR spectroscopy techniques. The materials were applied for sorption of WO42- anions in aqueous media under relevant conditions. Parameters influencing the sorption process, such as the LDH composition, pH of the sorption media, adsorption capacity, kinetics and desorption solution composition were thoroughly investigated. Multi-cycling tests in different desorption solutions combined with IR and XRD characterization of the La-MgFe-LDH solids in different steps of the process, allowed us to elucidate the WO42- recovery mechanism. Further, the La-doping in the LDH structure increases the sorption capacity and assures the material stability throughout the WO42- recovery process in high pH media. The alkaline stability was demonstrated by powder post characterization by X-ray Diffraction as well as performing alkaline stability test and follow up of any leaching elements by ICP-OES in alkaline solutions. The results indicate that the as-developed La-MgFe-LDH are suitable candidates for WO42- recovery from aqueous solutions, including highly alkaline solutions compatible with the current hydrometallurgical processes.

Arsenate and phosphate adsorption onto Mg-Fe layered double hydroxides: The charge-distribution multisite complexation (CD-MUSIC) modeling as a tool to predict competitive oxyanion behavior

The adsorption of arsenate and phosphate onto natural or synthetic layered double hydroxides (LDHs) has emerged as a promising solution to minimize the environmental effects of these compounds in soils and waters. In the present work, the adsorption of these oxyanions onto Mg-Fe LDHs in both single-ion and competitive systems was studied through wet chemistry experiments, solid-state analyses, and advanced surface complexation modeling (SCM). The Mg-Fe LDH showed a good efficiency to remove both As and P, being the pH of the system a major driver for the adsorption levels observed. Adsorption results for competitive systems showed a decrease for both oxyanions compared to the single-ion adsorption systems. The adsorption behavior is mechanistically described using two types of SCM, namely the diffusion layer model (DLM) and the charge-distribution multisite complexation model (CD-MUSIC). The later model captures better the influence of pH and ionic strength on the adsorption of arsenate and phosphate onto LDH in both single-ion and multicomponent systems. The best description of the experimental results was obtained when combining two types of surface complexes, namely monodentate inner-sphere complex at lower pH values and monodentate outer-sphere complex at higher pH values. This model approach provides more detailed information about the surface properties of LDHs, which may be beneficial for future studies dealing with LDHs as reactive phases influencing metal(loid) mobility in water or soil systems.

Enhancing Cd(II) and U(VI) remediation through synergistic utilization of GCN-supported MgFe-layered double hydroxide

Due to the significant concentration of heavy metals in the contaminated area, it presents an imminent threat to both living organisms and the environment. In this research, we concentrate on finding an effective solution for eliminating Cd(II) and U(VI) from water. Our approach involves utilizing MgFe-layered double hydroxide (LDH) nanosheets combined with graphitic carbon nitride (GCN) nanosheets to ensure the effective elimination of these hazardous metal ions. The characterization techniques, including SEM, XPS, XRD, and BET analysis, confirmed the hierarchical layered structure of GCN/MgFe LDH with a significant surface area of 127.91 m2/g. Batch investigations demonstrated that the pH of the solution influences the elimination of both metal ions, while kinetics and equilibrium data well align with a pseudo-second-order model and the Langmuir model (R2 = 0.996–1.0), respectively. GCN/MgFe LDH demonstrated impressive removal capacities of 312.30 mg/g and 273.42 mg/g for Cd(II) and U(VI) respectively. A thermodynamic analysis indicated that the adsorption process of both metal ions was endothermic and spontaneous. Furthermore, the GCN/MgFe LDH can be reused for over five cycles. In the fourth cycle, it maintained a removal percentage of over 95 % for both metal ions when 0.1 M HNO3 was used for desorption. In continuous column tests, the GCN/MgFe LDH reduced metal ion concentrations to levels below USEPA standards (<0.005 mg/L and 0.003 mg/L for Cd(II) and U(VI), respectively) for up to 4000 bed volumes, demonstrating its potential for wastewater treatment.

In Situ Growth of Mg-Fe Layered Double Hydroxides (LDH) Film on Titanium Dental Implant Substrates for pH Regulation in Oral Environments

Layered double hydroxides (LDHs) consist of two-dimensional, positively charged lamellar structures with the ability to host various anions in the interlayer spaces, which grants them unique properties and tunable characteristics. LDHs, a class of versatile inorganic compounds, have recently emerged as promising candidates for enhancing osseointegration. A suitable alkaline microenvironment is thought to be beneficial for stimulating osteoblasts’ differentiation (responsible for bone matrix formation) while suppressing osteoclast generation (responsible for bone matrix disintegration). LDHs are prone to adjusting their alkalinity and thus offering us the chance to study how pH affects cellular behavior. LDHs can indeed modulate the local pH, inflammatory responses, and oxidative stress levels, factors that profoundly influence the behavior of osteogenic cells and their interactions with the implant surface. Herein, we deposited Mg–Fe LDH films on titanium substrates for dental implants. The modified Ti substrates was more alkaline in comparison to the bare ones, with a pH higher than 8 after hydrolysis in an aqueous environment.

Blocked Autophagy is Involved in Layered Double Hydroxide-Induced Repolarization and ImmuneActivation in Tumor-Associated Macrophages.

Tumor-associated macrophages (TAMs) are important immune cells in the tumor microenvironment (TME). The polar plasticity of TAMs makes them important targets for improving the immunosuppressive microenvironment of tumors. The previous study reveals that layered double hydroxides (LDHs) can effectively promote the polarization of TAMs from the anti-inflammatory M2 type to the pro-inflammatory M1 type. However, their mechanisms of action remain unexplored. This study reveals that LDHs composed of different cations exhibit distinct abilities to regulate the polarity of TAMs. Compared to Mg-Fe LDH, Mg-Al LDH has a stronger ability to promote the repolarization of TAMs from M2 to M1 and inhibit the formation of myeloid-derived suppressor cells (MDSCs). In addition, Mg-Al LDH restrains the growth of tumors in vivo and promotes the infiltration of activated immune cells into the TME more effectively. Interestingly, Mg-Al LDH influences the autophagy of TAMs; this negatively correlates with the pro-inflammatory ability of TAMs. Therefore, LDHs exert their polarization ability by inhibiting the autophagy of TAMs, and this mechanism might be related to the ionic composition of LDHs. This study lays the foundation for optimizing the performance of LDH-based immune adjuvants, which display excellent application prospects for tumor immunotherapy.

Hybridize magnesium-iron layered double hydroxide with biopolymers to develop multiple pathways for phosphate sorption and release: A potential slow release phosphorus fertilizer

The intensive use of chemical fertilizers presents a dilemma for sustaining food production or causing soil degradation and posing agricultural contamination. The reduction of phosphorus (P) fertilizer usage is particularly crucial because it is a limited resource. This situation calls for the development of efficient P fertilizers to address the impending P deficiency. Mg-Fe layered double hydroxides (LDH) with 0.5 and 2.5 M metal precursors were hybridized with chitosan (CTS) and carboxymethyl cellulose (CMC) to design alternatives of slow release P fertilizers. While phosphate (PO4) sorption capacities were in the order of Mg-Fe LDH > 2.5LDH-CTS/CMC > 0.5LDH-CTS/CMC, PO4 release from 0.5LDH-CTS exhibited a rate constant ∼2.6–7.6 times lower than that of other samples, which had not reached equilibration even after 2688 h. Fe-EXAFS data implied the greatest degree of isomorphic substitution into LDH interlayer of 0.5LDH-CTS. In addition to intercalated PO4, P-XANES data also suggested the organic-P and Fe(III)-P on 0.5LDH-CTS, causing versatile retention processes. After 2688 h of PO4 release, LDH structure gradually weathered and transformed primarily into a structure dominated by ferric (oxyhydrox)oxides. On 0.5LDH-CTS, however, 14.3% of Fe inventory was contributed by Fe(II) species. The Fe(II) domains in conjunction with the likely remaining Mg-Fe LDH structure and amorphous Mg(OH)2 provided bonding sites for PO4, serving as the key factor for the continuous PO4 release beyond 2688 h. Such extended duration of PO4 release warrants the use of LDHs hybridized with biopolymers as promising substitutes for slow release P fertilizers.

LDH-doped gelatin-chitosan scaffold with aligned microchannels improves anti-inflammation and neuronal regeneration with guided axonal growth for effectively recovering spinal cord injury

Spinal cord injury (SCI) causes immune cell infiltration, neuronal death and permanent motor dysfunction. Effective treatment for SCI requires simultaneous suppression of the inhibitory and inflammatory microenvironment and enhancement of the pro-regenerative potential at SCI sites. However, realizing neuronal regeneration with guided axon growth and anti-inflammation simultaneously is currently challenging. In this study, a layered double hydroxides (LDH)-doped gelatin-chitosan scaffold with aligned microchannels (GC-LDH/A scaffold) combined with chemical and structural repair effects was developed to regulate immune microenvironment and promote directional neurogenesis. The GC-LDH/A scaffold was prepared by anisotropic freezing of a mixture of Mg-Fe layered double hydroxides (Mg-Fe LDH), gelatin and chitosan. The LDH, gelatin and aligned microchannel structure work together to promote neuronal regeneration. Chitosan and the aligned microchannel structure have a function of anti-inflammation while the latter also guides axonal growth. The repair effect of this scaffold was assessed by restoring a completely transected spinal cord injury, and the results showed that the GC-LDH/A scaffold effectively activated the anti-inflammatory polarization of macrophages and microglia, promoted neurogenesis and guided axonal growth from the rostral to caudal of the lesion site. The key mediator of functional recovery in SCI is Myosin II, which negatively regulates axonal growth; however, the aligned microchannel structure inhibits its activity and reverses the repair effect. This study provides a promising strategy for addressing the repair challenges for effective SCI treatment.

Efficient Adsorption Capacity of MgFe-Layered Double Hydroxide Loaded on Pomelo Peel Biochar for Cd (II) from Aqueous Solutions: Adsorption Behaviour and Mechanism.

A novel pomelo peel biochar/MgFe-layered double hydroxide composite (PPBC/MgFe-LDH) was synthesised using a facile coprecipitation approach and applied to remove cadmium ions (Cd (II)). The adsorption isotherm demonstrated that the Cd (II) adsorption by the PPBC/MgFe-LDH composite fit the Langmuir model well, and the adsorption behaviour was a monolayer chemisorption. The maximum adsorption capacity of Cd (II) was determined to be 448.961 (±12.3) mg·g-1 from the Langmuir model, which was close to the actual experimental adsorption capacity 448.302 (±1.41) mg·g-1. The results also demonstrated that the chemical adsorption controlled the rate of reaction in the Cd (II) adsorption process of PPBC/MgFe-LDH. Piecewise fitting of the intra-particle diffusion model revealed multi-linearity during the adsorption process. Through associative characterization analysis, the adsorption mechanism of Cd (II) of PPBC/MgFe-LDH involved (i) hydroxide formation or carbonate precipitation; (ii) an isomorphic substitution of Fe (III) by Cd (II); (iii) surface complexation of Cd (II) by functional groups (-OH); and (iv) electrostatic attraction. The PPBC/MgFe-LDH composite demonstrated great potential for removing Cd (II) from wastewater, with the advantages of facile synthesis and excellent adsorption capacity.

Effect of MgFe-LDH with Reduction Pretreatment on the Catalytic Performance in Syngas to Light Olefins

MgFe-layered double hydroxides (LDH) were widely used as catalysts for Fischer–Tropsch synthesis to produce light olefins, in which the state of Fe-species may affect the resulting catalytic active sites. Herein, the typical MgFe-LDH was hydrothermally synthesized and the obtained MgFe-LDH was pretreated with H2 at different temperatures to reveal the effects of the state of Fe-species on the catalytic performance in Fischer–Tropsch synthesis. MgFe-LDH materials were characterized by X-ray diffraction (XRD), N2 adsorption–desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), H2 temperature-programmed reduction (H2-TPR), and X-ray photoelectron spectroscopy (XPS). It was found that a MgO-FeO solid solution would be formed with the increase of the reduction temperature, which made the electrons transfer from Mg atoms to Fe atoms and strengthened the adsorption of CO. The pre-reduced treatment toward Mg-Fe-LDH enabled the FeCx active sites to be easily formed in situ during the reaction process, leading to the high conversion of CO. CO2 temperature-programmed desorption (CO2-TPD) and H2 temperature-programmed desorption (H2-TPD) analysis confirmed that the surface basicity of the catalysts was increased and the hydrogenation capacity was weakened, the secondary hydrogenation of the olefins was inhibited, and therefore as were the enhancement of O/P in the product and the high selectivity of light olefins (42.7%).

Surface Modified MgFe Layered Double Hydroxide: An Efficient Photo Catalyst for Degradation of Methyl Orange

Surface Modified MgFe Layered Double Hydroxide: An Efficient Photo Catalyst for Degradation of Methyl Orange

Preparation, corrosion behavior and biocompatibility of MgFe-layered double hydroxides and calcium hydroxyapatite composite films on 316L stainless steel

Preparation, corrosion behavior and biocompatibility of MgFe-layered double hydroxides and calcium hydroxyapatite composite films on 316L stainless steel

An improved method of MgFe-layered double hydroxide/ biochar composite synthesis

Layered double hydroxides (LDHs) and their composites are a promising platform for a wide range of applications, especially in the environmental field. However, the facile and efficient synthesis of high-quality LDHs and their composites remains a challenge. Here, an improved co-pyrolysis method has been developed to synthesize LDH/biochar composites. A composite material was prepared by directly anchoring MgFe-LDH on corn stover by co-precipitation with FeCl3 and Mg(OH)2, and then through pyrolysis. The main features of this improved method are the use of the solubility product Mg(OH)2 to maintain the pH of the mixture at ∼10 (the optimum for LDH precipitation), eliminating the cumbersome pH control steps of the traditional co-precipitation method, and the low rate of solid-liquid reaction to obtain high LDH crystallinity and purity. This produces improved properties of the MgFe-LDH/biochar composite after pyrolysis: higher loading of MgFe-LDH, larger specific surface area of the composite, a more stable layered structure, and a more customizable LDH. The theoretical maximum adsorption capacity of phosphorus for the composite was 379.4 mg L−1 according to an adsorption isotherm study, and the dominant adsorption mechanism is chemical adsorption accompanied by physical adsorption. In actual wastewater applications, >80% of total phosphorus in biogas slurry was removed via adsorption, indicating that the composite is highly efficient in phosphorus selectivity in wastewaters with complex components. Here, a more sustainable synthesis method of LDH/biochar composite has been developed with high application potential.

Hydrothermal assisted ultrasonic synthesis of MgFe-LDH as a simple and eco-friendly method for electrochemical detection of vitamin B6

A new eco-friendly electrochemical sensor with high sensitivity and selectivity has been introduced in the present work. The proposed sensor is a MgFe-layered double hydroxide (MgFe -LDH) synthesizing via a very simple method. This sensor for the first time was used to determine pyridoxine hydrochloride (vitamin B6) using the differential pulse voltammetry (DPV) technique. The morphology and chemical composition of the MgFe-LDH was recognized using field emission scanning electron microscope (FESEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), energy dispersive spectroscopy (EDX), X-ray diffraction (XRD), and Brunauer-Emmett-Teller (BET). Under optimal conditions, the calibration curve was plotted using the DPV technique. The limit of detection (LOD) was 131 nM and a linear range of 900 nM–2300 μM was obtained for vitamin B6 oxidation. Therefore, the method is sensitive, simple, and specific with a short analysis time, and the main advantages of this sensor are easy synthesis, low detection limit, excellent stability, repeatability, and good selectivity in vitamin B6. This sensor has been successfully utilized in determining vitamin B6 in human plasma, rice flour, and tablet samples.

Enhanced Bactericidal Effect of Calcinated Mg-Fe Layered Double Hydroxide Films Driven by the Fenton Reaction.

Osteogenic and antibacterial abilities are the permanent pursuit of titanium (Ti)-based orthopedic implants. However, it is difficult to strike the right balance between these two properties. It has been proved that an appropriate alkaline microenvironment formed by Ti modified by magnesium-aluminum layered double hydroxides (Mg-Al LDHs) could achieve the selective killing of bacteria and promote osteogenesis. However, the existence of Al induces biosafety concerns. In this study, iron (Fe), an essential trace element in the human body, was used to substitute Al, and a calcinated Mg-Fe LDH film was constructed on Ti. The results showed that a proper local alkaline environment created by the constructed film could enhance the antibacterial and osteogenic properties of the material. In addition, the introduction of Fe promoted the Fenton reaction and could produce reactive oxygen species in the infection environment, which might further strengthen the in vivo bactericidal effect.

A MgFe-LDH Nanosheet-Incorporated Smart Thermo-Responsive Hydrogel with Controllable Growth Factor Releasing Capability for Bone Regeneration.

Although growth factor (GF)-loaded hydrogels have been explored as promising materials in repairing bone defects, it still remains challenging to construct smart hydrogels with excellent gelation/mechanical properties as well as controllable GF releasing capability. Herein, the incorporation of bone morphogenetic protein 2 (BMP-2)-functionalized MgFe-layered double hydroxide (LDH) nanosheets into chitosan/silk fibroin (CS) hydrogels loaded with platelet-derived growth factor-BB (PDGF-BB) to construct a smart injectable thermo-responsive hydrogel (denoted as CSP-LB), which can achieve a burst release of PDGF-BB and a sustained release of BMP-2, for highly efficient bone regeneration is reported. The incorporation of MgFe-LDH in CS hydrogel not only shortens the gelation time and decreases sol-gel transition temperature, but also enhances the mechanical property of the hydrogel. Because of the sequential release of dual-GFs and sustained release of bioactive Mg2+ /Fe3+ ions, the in vitro experiments prove that the CSP-LB hydrogel exhibits excellent angiogenic and osteogenic properties compared with the CS hydrogel. In vivo experiments further prove that the CSP-LB hydrogel can significantly enhance bone regeneration with higher bone volume and mineral density than that of the CS hydrogel. This smart thermo-sensitive CSP-LB hydrogel possesses excellent gelation capability and angiogenic and osteogenic properties, thus providing a promising minimally invasive solution for bone defect treatment.

Adsorption of nitrate in water by CTAB-modified MgFe layered double hydroxide composite biochar at low temperature: Adsorption characteristics and mechanisms

In this study, for the purpose of improving the removal effect of biochar on nitrate in wastewater at lower temperature, MgFe layered double hydroxides (MgFe-LDHs) were precipitated on the surface and in the pores of corn stover biochar (BC) in the presence of surfactant cetyltrimethylammonium bromide (CTAB) to prepare a novel adsorbent MgFe-CTAB-LDHs/BC. The result shows that BC has abundant pore structure and MgFe-LDHs has been uniformly loaded on the surface of BC and in the pores, which greatly reduced the agglomeration of LDHs. Part of CTAB was on the surface of BC, making it more positively charged, and the other part entered the interlayer of LDHs, changing the interlayer spacing, which is beneficial to adsorption. Meanwhile, the hydroxyl groups and metal hydroxides in LDHs and numerous active groups of BC enhanced the adsorption capacity through synergistic effect. The successful preparation of MgFe-CTAB-LDHs/BC was proved by various characterization analyses and the adsorption mechanism of nitrate on MgFe-CTAB-LDHs/BC was investigated through experimental demonstration and characterization analysis. The adsorption kinetics and isotherm studies also showed that the adsorption rate of MgFe-CTAB-LDHs/BC for nitrate was improved, and it still had a good adsorption effect at lower temperature. This study aims to provide a novel environmentally friendly adsorbent for nitrate adsorption at lower temperature.