Liquid Phase Reduction Method Research Articles

Synthesis of bare and modified zerovalent iron nanoparticles and their use in porous polylactic acid composites for methyl orange removal

The main objective of this study was to assess the efficacy of two types of immobilised zerovalent iron nanoparticles (nZVI) incorporated into a porous biopolymer matrix of polylactic acid (PLA) as a novel multifunctional composite system for potential use in dye wastewater treatment. The study involved the preparation of unmodified and 2,6-pyridinedicarboxylic acid (PDCA) modified nZVI material using liquid phase reduction method. Zeta potential measurement and UV-Vis spectrophotometry revealed that the ligand-modified nZVI particles exhibited better dispersion stability in aqueous media than bare particles. SEM-EDS analysis showed a higher oxidation state of the ligand-modified nZVI particles and good dispersion and adhesion of nZVI particles in the mesoporous structure of PLA matrix. The removal efficiency of methyl orange was determined spectrophotometrically where a high efficiency (above 90%) for high concentration of bare nZVI was detected. Its composites also showed an efficiency of 75 – 100%. However, modified nZVI showed much lower efficiency, especially after embedding in the PLA matrix.

The Synthesis of Copper Nanoparticles for Printed Electronic Materials Using Liquid Phase Reduction Method.

This text discusses the synthesis of copper nanoparticles via a liquid phase reduction method, using ascorbic acid as a reducing agent and CuSO4·5H2O as the copper source. The synthesized copper nanoparticles are small in size, uniformly distributed, are mostly between 100-200 nm with clear boundaries between particles, and exhibit excellent dispersibility, making them suitable for metal conductive inks. 1. The copper nanoparticles are analyzed for good antioxidation properties, because their surface is coated with PVP and ascorbic acid. This organic layer somewhat isolates the particle surface from contact with air, preventing oxidation, and accounts for about 9% of the total weight. 2. When the prepared copper nanoparticles are spread on a polyimide substrate and sintered at 250 °C for 120 min, the resistivity can be as low as 23.5 μΩ·cm, and at 350 °C for 30 min, the resistivity is only three times that of bulk copper. 3. The prepared conductive ink, printed on a polyimide substrate using a direct writing tool, shows good flexibility before and after sintering. After sintering at 300 °C for 30 min and connecting the pattern to a circuit with a diode lamp, the diode lamp is successfully lit. 4. This method produces copper nanoparticles with small size, good dispersion, and antioxidation capabilities, and the conductive ink prepared from them demonstrates good conductivity after sintering.

Granular activated carbon supported polyethylene glycol modified nano-zero-valent iron immobilized microbial removal of 2,4-dichlorophenol in water

In recent years, the remediation of 2,4-DCP pollution using immobilized microbial technology has attracted increasing attention. Using granular activated carbon (GAC), polyethylene glycol 4000 (PEG-4000), ferrous sulfate, and sodium borohydride as raw materials, granular activated carbon loaded polyethylene glycol modified nano zero-valent iron composite material (PEG-nZVI/GAC) was prepared via a liquid-phase reduction method. Bacillus marisflavi, capable of degrading phenolic compounds, was immobilized on PEG-nZVI/GAC using an adsorption method to prepare immobilization of microorganisms by granular activated carbon loaded polyethylene glycol modified nano zero-valent iron (PEG-nZVI/GAC@B) for 2,4-DCP removal. Characterization analysis of immobilized microbes was conducted using transmission electron microscopy (TEM) and other methods to determine their physicochemical properties. Response surface methodology (RSM) was employed to optimize the conditions for 2,4-DCP removal, and the performance and mechanism of 2,4-DCP removal by PEG-nZVI/GAC@B were studied. The results indicate that nanoscale zero-valent iron (nZVI) was uniformly distributed in granular activated carbon, Bacillus marisflavi was successfully loaded onto PEG-nZVI/GAC, PEG-nZVI/GAC@B had a higher content of oxygen-containing groups on its surface, and exhibits good dispersibility, stability, and reusability. When the immobilized microbial dosage was 270.32 mg/L, the initial concentration of 2,4-DCP was 50.51 mg/L, and pH was 6.58, the predicted removal rate of 2,4-DCP was 96.53 %. Under these conditions, the actual removal rate of 2,4-DCP was 94.68 %. The removal of 2,4-DCP by PEG-nZVI/GAC@B involved adsorption by granular activated carbon, reductive dechlorination by nanoscale zero-valent iron, and degradation by Bacillus marisflavi. In conclusion, PEG-nZVI/GAC@B is an excellent immobilized microorganism for the removal of 2,4-DCP.

Directional control of electromagnetic parameters of Fe@Ni nanowires for ultrathin and low-frequency microwave absorbing

How to prepare materials according to the target properties has been a hot research topic. In this paper, the target electromagnetic parameters are obtained according to the performance requirements, and the nanoflower rod-like, low-density mulberry-like and high-density mulberry-like one-dimensional (1D) core–shell structured Fe@Ni(x) nanowires (NWs) are prepared by liquid-phase reduction method. The effective absorption bandwidth (EAB) of sample Fe@Ni(40) in the low-frequency (2–8 GHz) is up to 1.89 GHz (3.1 mm). Sample Fe@Ni(60) is able to reach a maximum EAB of 3.18 GHz at a thickness of 0.9 mm. Concisely, the sample has the ability to absorb microwaves in low frequency bands and ultra-thin thicknesses. The reason can be attributed to the strong magnetic coupling brought by the bimetallic composition to strengthen the resonance level and the excellent 1D core–shell structure to enhance the efficiency of polarization loss. In conclusion, Fe@Ni(x) provides a technological route for the preparation of low-frequency and ultra-thin-thickness absorbers.

A new attempt to remove toluene using nickel–iron bimetallic particle electrode reactor

A new attempt of removing toluene waste gas using a three-dimensional electrode reaction device with nickel–iron bimetallic particle electrode is presented in this paper. The particle electrode was prepared by a simple liquid phase reduction method. Through bimetal modification, the particle electrode mass transfer rate is increased to 1.29 times, and the degradation efficiency of the reactor is increased by nearly 40%, which makes it possible to remove toluene waste gas by other electrochemical methods in addition to plasma method. The removal efficiency of the particle electrode can be stabilized at more than 80% after 5 cycles (50 h). At the same time, the relationship between independent working parameters and dependent variables is analyzed using the central composite design, and the operating parameters are optimized. Based on this study, the removal mechanism and possible degradation pathway of toluene were investigated. This study provides a supplement to the possibility and theoretical basis of new technology application for electrocatalytic oxidation removal of VOCs.

Nano zero-valent iron/montmorillonite composite for the removal of Cr(VI) from aqueous solutions: Characterization, performance, and mechanistic insights

Infiltration of hexavalent chromium (Cr(VI)) into the human body poses significant health risks, including the risk of developing cancer and increased mortality rates. The discharge of chromium-contaminated wastewater from industrial processes exacerbates environmental pollution, highlighting the necessity for efficient, cost-effective, and environmentally friendly treatment methods. In recent years, there has been a growing emphasis on the application of nanoscale zero-valent iron particles (NZVI) for mitigating Cr(VI) water pollution. In the present study, NZVI was synthesized using a liquid-phase reduction method employing sodium borohydride (NaBH4), and natural montmorillonite (Mt) was incorporated as a carrier, resulting in the creation of NZVI/Mt., a composite material. Characterization of this composite was performed using scanning electron microscopy (SEM), Transmission Electron Microscope (TEM), Specific surface area and pore size (BET), X-ray diffraction (XRD), and Fourier-transform infrared (FT-IR) techniques. The investigation encompassed an exploration of the influence of initial pollutant pH levels, adsorbent dosages, and initial pollutant concentrations on the adsorption process. The research findings indicate that, at an initial pH of 4.0, NZVI/Mt. achieves a removal efficiency of 92.41% for a Cr(VI) solution with an initial concentration of 40 mg/L. The NZVI/Mt. composite adheres to both a pseudo-second-order kinetic model and the Langmuir isotherm model, showcasing a significant maximum adsorption capacity of 67.75 mg/g for Cr(VI). Furthermore, thermodynamic analysis revealed an exothermic nature of the adsorption process. This experimental approach effectively resolved issues related to NZVI particle agglomeration, offering a simplified, cost-effective, and environmentally friendly preparation method. Consequently, the NZVI/Mt. composite material demonstrates effective treatment of Cr(VI) mildly contaminated wastewater.

Clay minerals modified nickel boride for electrochemical supercapacitor electrode application

Nickel boride has attracted great interest in the field of energy storage due to its superior electrochemical performance, However, particles agglomeration and poor electability have limited its wider application. Clay minerals with high specific surface area and excellent wettability can reduce the agglomeration of particles. We synthesized eight kinds of composites Ni3B@montmorillonite (Ni3B@Mt), Ni3B@chlorite (Ni3B@Chl), Ni3B@vermiculite (Ni3B@Ver), Ni3B@kaolinite (Ni3B@Kaol), Ni3B@palygorskite (Ni3B@Pal), Ni3B@halloysite (Ni3B@Hal), Ni3B@sepiolite (Ni3B@Sep), and Ni3B@talc (Ni3B@Tal) materials with different morphologies and structures by simple liquid phase reduction method. We explored the influence of a series of clay minerals on the electrochemical performance of Ni3B. The results show that the specific capacitance of the Ni3B@clay minerals composites has been improved in different degrees. In addition, the Ni3B@Mt. shows the best specific capacitance of 1406 F g−1 at a current density of 0.5 A g−1, and still maintains a high specific capacitance of 944 F g−1 at a current density of 5 A g−1. The assembled asymmetric supercapacitor Ni3B@Mt.//AC using an activated carbon (AC) and the Ni3B@Mt. showed excellent electrochemical performance with achieving the maximum energy density of 92.60 W h kg−1 at the power density of 350 W kg−1, which suggests the practical application of clay minerals in the electrochemical energy storage field.

A novel Cu@Ag nano paste with low porosity for rapidly sintering in air condition

The emergence of Cu@Ag core-shell nanoparticles presents a promising solution to address issues such as copper oxidation, the high cost of silver, and electro-chemical migration in high-power electronic devices, showcasing their potential for practical applications. In this study, Cu@Ag nanoparticles were synthesized via a liquid-phase reduction method, resulting in an average size of 30 nm. A low-boiling-point mixed organic solvent was meticulously prepared following Raoult's law, enabling the creation of a nano paste utilizing Cu@Ag nanoparticles. This innovation facilitated the sintering of fully dense joints under ambient air conditions, effectively mitigating the oxidation issue caused by silver dewetting behavior in Cu@Ag core-shell nanoparticles. Subsequently, the shear strength and microstructure of the joints were comprehensively studied under various sintering temperatures and durations. Notably, the joint exhibited a shear strength of 17.3 MPa when sintered at 250 °C for 30 min, while achieving full density at a sintering temperature of 300 °C for 30 min. These findings underscore the capacity of Cu@Ag core-shell nano paste to enable the production of high-performance joints under air conditions, utilizing thoughtfully selected organic components.

NiCoCrFeY High Entropy Alloy Nanopowders and Their Soft Magnetic Properties.

High entropy alloy nanopowders were successfully prepared by liquid-phase reduction methods and their applications were preliminarily discussed. The prepared high entropy alloy nanopowders consisted of FeNi alloy spherical powders and NiFeCoCrY alloy spherical powders with a particle size of about 100 nm. The powders have soft magnetic properties, the saturation magnetization field strength were up to 5000 Qe and the saturation magnetization strength Ms was about 17.3 emu/g. The powders have the excellent property of low high-frequency loss in the frequency range of 0.3-8.5 GHz. When the thickness of the powders coating was 5 mm, the powders showed excellent absorption performance in the Ku band; and when the thickness of the powders coating was 10 mm; the powders showed good wave-absorbing performance in the X band. The powders have good moulding, and the powders have large specific surface area, so that the magnetic powder core composites could be prepared under low pressure and without coating insulators, and the magnetic powder cores showed excellent frequency-constant magnetization and magnetic field-constant magnetization characteristics. In the frequency range of 1~100 KHz; the μm of the magnetic powder core heat-treated at 800 °C reached 359, the μe was about 4.6 and the change rate of μe with frequency was less than 1%, meanwhile; the magnetic powder core still maintains constant μe value under the action of the external magnetic field from 0 to 12,000 A/m. The high entropy alloy nanopowders have a broad application prospect in soft magnetic composites.

The Design and Preparation of Permittivity-Adjustable FeNi@SrFe-MOF Composite Powders

When the thickness of the wave-absorbing material is low, there exists the problem of the narrow wave-absorbing frequency band, making it difficult to regulate the position of the wave-absorbing peak. In this study, FeNi@SrFe-MOF composite powders were synthesized using a hydrothermal method and a liquid-phase reduction method. The composite powder was spherical, with a particle size of about 50 μm–60 μm; the core layers of the powders were porous SrFe-MOF powders with permanent magnetization, and the outer layers were FeNi alloy nano-powder coatings with a particle size of 100 nm–120 nm, which took into account both the soft magnetization and the permanent magnetization properties of the composite powders. Additionally, a directional magnetic field was applied to the powder coating. By regulating the intensity and direction of the magnetic field, the electromagnetic parameters of the composite powder coating underwent sensitive changes, allowing for the precise regulation of the electromagnetic wave absorption performance of the composite powders. With the increase in magnetic field intensity, the ε′ value decreased significantly. The ε′ values were 8.56–7.35 for H453mT and 6.73–6.12 for H472mT. When no magnetic field was applied, the Snoke limit frequency of the μ′ value was 6.0 GHz. When the magnetic field intensity increased, the Snoke limit frequency of the μ′ value increased from 6.0 GHz, without the magnetic field, to 8.3 GHz; the Snoke limit of the composite powders was shattered. After the H453mT magnetic field regulation treatment, the powder coating exhibited good impedance matching characteristics with air. When the magnetic field intensity was 453mT and the thickness of the composite powders coating was 3.5 mm, the composite powders coating showed the strongest absorption peak when the R-value was −59 dB at 7.8 GHz, and the effective absorption bandwidth reached 3.2 GHz, exhibiting superb absorbent qualities. The wave absorption property of the coating can be sensitively changed by the magnetic field regulation treatment at the condition without changing the powder structure or coating structure, which provides a new strategy for the regulation of the wave absorption property and has broad application prospects.

Efficacy and mechanism of Microcystis aeruginosa removal by activated carbon fiber/nanoscale zero-valent iron/nickel foam cathodic electrochemical system

ABSTRACT Cyanobacterial outbreaks seriously affect drinking water safety. Therefore, developing effective algal removal technologies is urgently needed. The study aims to investigate the effects of pH, electrode distance, current density, and initial algal concentration on electrochemical algae collection. Consequently, we loaded nanoscale zero-valent iron (nZVI) on activated carbon fiber/nickel foam (ACF/Ni) to form an ACF/nZVI/Ni composite cathode using the liquid phase reduction method and used titanium-based platinum plating (Pt/Ti) as the anode to construct a novel Pt/Ti- ACF/nZVI/Ni electrochemical system. The results showed that on pH of 6.0, the electrode distance was 10 mm, the current density was 75 mA/cm2, and the initial algal concentration was OD680 = 0.100; the algal cell removal rate was 94.20% after electrolysis for 30 min. This paper provides an efficient and environmentally friendly electrochemical algal removal technology for protecting the safety of drinking water and dealing with cyanobacterial outbreaks.

Preparation and mechanical properties of Ni/RGO reinforced epoxy resin composites

The graphene/nanonickel composites(Ni/RGO) were prepared by liquid phase reduction method, and the graphene/nanonickel epoxy composites(Ni/RGO/EP) were prepared by in-situ polymerization method. The glass transition temperature (Tg) of the modified epoxy resin was increased by 19°C compared to EP with 2.1 wt% Ni/RGO loading. The tensile strength and hardness increased by 65% and 18%, the impact strength is increased by 10.053 KJ·m−2 compared to EP, and the shear strength reaches 34.78 MPa for the Ni/RGO/EP with 1.7 wt% Ni/RGO loading. It can be seen, that the addition of Ni/RGO greatly improves the heat resistance and mechanical properties of epoxy resin when the Ni/RGO are evenly dispersed into the epoxy resin by emulsion dispersion method.

Optimization on removal of 2,4-dichlorophenol by sodium carboxymethyl cellulose modified nanoscale Pd/Fe bimetal with response surface methodology

2,4-dichlorophenol (2,4-DCP) is a toxic and harmful organic intermediate widely used in industrial production. Recently, the utilization of nano-zero-valent iron (NZVI) for 2,4-DCP treatment has gained significant popularity, but the deactivation and agglomeration of NZVI always appear and continue to present challenges. To address these issues, sodium carboxymethyl cellulose (CMC) and noble metal catalyst Pd are used as stabilizers to improve the removal efficiency of NZVI on 2,4-DCP. The CMC-modified nanoscale Pd/Fe bimetal (CMC-Pd/Fe) particles were prepared by the liquid phase reduction method and characterized by scanning electron microscopy (SEM), Fourier infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The results showed that the addition of Pd and CMC succeeded in ameliorating the aggregation of NZVI. A five-level-four-factor central composite design (CCD) of response surface methodology (RSM) was used to optimize the removal of 2,4-DCP by CMC-Pd/Fe and explored the factors influencing the removal of 2,4-DCP, including the amount of catalyst, the initial pH of the system, the time of reaction, and the initial concentration of 2,4-DCP. A statistically significant and well-fitting quadratic regression model was successfully constructed to predict 2,4-DCP removal efficiency. The high F-value of 14.35, very low p-value (<0.0001), nonsignificant Lack of Fit, and appropriate coefficient of determination of 0.9399 demonstrate a good correlation between the experimental and predicted values of the proposed model. The analyses of variance reveal catalyst amount and reaction time have a positive effect on the removal efficiency of 2,4-DCP and the CMC-Pd/Fe catalyst amount shows the most apparent significance, with PC (percent contribution) greater than 26. Conversely, pH and 2,4-DCP concentration have a negative impact on the removal process. The optimum condition is 1.10 g/L of catalyst amount, 5.63 of pH, 2.31 h of reaction time, and 20 mg/L of initial 2,4-DCP concentration. The validation results from parallel experiments showed that the average removal efficiency of 2,4-DCP reached 96.32% under the optimal conditions.

Mechanistic insight into near-infrared light-driven Cu2O/WO2 Ohmic contact photothermal catalysts for high-efficiency antibiotic wastewater purification.

Near-infrared (NIR) light-induced photothermal effect is beneficial for accelerating catalytic processes; thus, it is imperative to develop novel photothermal catalysts for promoting practical application. Herein, we synthesized NIR-responsive Cu2O/WO2 Ohmic contact photothermal catalysts through a facile ethylene glycol-assisted liquid-phase reduction method. In this photothermal catalyst, a new-type NIR-responsive Cu2O semiconductor is integrated with an NIR-responsive WO2 semimetal component to form an Ohmic contact, which is more beneficial for simultaneously promoting photocharge separation and enhancing NIR light absorption for a high-efficiency photothermal effect. As expected, the Cu2O/WO2 composite displays higher NIR light-driven photothermal catalytic performance for tetracycline removal from wastewater. Various characterization methods and density functional theory calculations were performed to obtain in-depth mechanistic insights into the NIR light-driven Cu2O/WO2 Ohmic contact photothermal catalysts. Hopefully, this research could provide a useful guideline for researchers focusing on the photothermal engineering of new composite photocatalysts.

A silver and manganese dioxide composite with oxygen vacancies as a high-performance cathode material for aqueous zinc-ion batteries.

Aqueous zinc ion batteries (AZIBs) are regarded as a promising alternative for energy storage due to their safety, cost-effectiveness and environmental friendliness. Manganese dioxide is considered a promising cathode material for energy storage because of its abundant reserves and high energy density. However, its inherent low electronic conductivity and limited cycling performance due to structural instability hinder its further development. Herein, a silver and manganese dioxide composite (Ag@MnO2) enriched with oxygen vacancies was prepared by a simple liquid-phase reduction method. The introduction of silver particles facilitates the improvement of electrical conductivity, and the incorporation of oxygen vacancies helps change the surface properties of manganese dioxide, providing additional active sites for ion transport, enhancing the overall electrochemical kinetics, and further improving the battery performance. As a result, the Ag@MnO2 cathode exhibits an astonishingly high capacity of 353 mAh g-1 at a current density of 0.1 A g-1 and a capacity retention of 78% after 1500 cycles. Additionally, electrochemical and structural analyses have revealed that the Ag@MnO2 cathode undergoes a reversible and stable process of H+ and Zn2+ insertion/extraction.

Synthesis of Cobalt Particles and Investigation of Their Electromagnetic Wave Absorption Characteristics.

As the integration technology for integrated circuit (IC) packaging continues to advance, the issue of electromagnetic interference in IC packaging becomes increasingly prominent. Magnetic materials, acknowledged for their superior electromagnetic absorption capabilities, play a pivotal role in mitigating electromagnetic interference problems. In this study, we employed a liquid-phase reduction method. We prepared three types of cobalt (Co) particles with distinct morphologies. Through variations in the synthesis process conditions, we were able to control the aspect ratio of protrusions on the surface of the Co particles. It was found that the sword-like Co particles exhibit superior electromagnetic wave absorption capabilities, showing a reflection loss value of up to -50.96 dB. Notably, when the coating thickness is only 1.6 mm, the effective absorption bandwidth is extended up to 7.6 GHz. The spatially expansive sword-like Co particles, with their unique structure featuring dipole polarization and interfacial polarization, demonstrated enhanced dielectric and magnetic loss capabilities, concurrently showcasing superior impedance-matching performance.

Peroxymonosulfate activation by walnut shell activated carbon supported nano zero-valent iron for the degradation of tetracycline: Performance, degradation pathway and mechanism

In this study, activated carbon (WS-AC) was prepared from walnut shell. Nano-zero-valent iron (nZVI) was loaded on walnut shell activated carbon by liquid phase reduction method and used as catalyst (WS-AC/nZVI) to activate peroxymonosulfate (PMS) to efficiently degrade tetracycline (TC) in solution. The composite material with a mass ratio of WS-AC to nZVI of 1:1 has the highest catalytic performance for activating PMS to degrade TC. The results showed that under the conditions of TC concentration of 100 ppm, PMS dosage of 0.2 mM and WS-AC/nZVI dosage of 0.1 g/L, the removal efficiency of TC could reach 81%. Based on quenching experiments and electron spin resonance (EPR), it was verified that •OH, SO4•− and 1O2 bound on the catalyst surface were the main reactive oxygen species during the reaction. The intermediate products of TC were identified by liquid chromatography-mass spectrometry (HPLC-MS) and DFT calculation, and the possible degradation pathway of TC was proposed. The catalyst still maintained high removal efficiency of TC after four cycles of experiments, and the minimal iron loss on the surface of the catalyst indicated that it had good stability. The efficient and stable WS-AC/nZVI activated PMS showed great potential in the degradation of antibiotics.

Biochar supported nanoscale zerovalent iron-calcium alginate composite for simultaneous removal of Mn(II) and Cr(VI) from wastewater: Sorption performance and mechanisms

Heavy metal pollution in water caused by industrial activities has become a global environmental issue. Among them, manganese mining and smelting activities have caused the combined pollution of Cr(VI) and Mn(II) in water, posing a serious ecotoxicological risk to ecological environments and human health. To efficiently remove Cr(VI) and Mn(II) from wastewater, a novel biochar supported nanoscale zerovalent iron-calcium alginate composite (CA/nZVI/RSBC) was synthesized by liquid-phase reduction and calcium alginate embedding methods. The adsorption performance and mechanisms of Cr(VI) and Mn(II) by CA/nZVI/RSBC were investigated. The maximum adsorption capacities of Cr(VI) and Mn(II) onto CA/nZVI/RSBC fitted by the Langmuir model were 5.38 and 39.78 mg/g, respectively, which were much higher than the pristine biochar. The iron release from CA/nZVI/RSBC was comparatively lower than that of nZVI/RSBC. Mn(II) presence enhanced the reduction of Cr(VI) by CA/nZVI/RSBC. The results of XRD, XPS, and site energy distribution analysis indicated that redox was the predominant mechanism of Cr(VI) adsorption, while electrostatic attraction dominated Mn(II) adsorption. This study provides a novel alternative way for the simultaneous removal of Cr(VI) and Mn(II) in wastewater.

Air-Stable Ni Catalysts Prepared by Liquid-Phase Reduction Using Hydrosilanes for Reactions with Hydrogen.

The liquid-phase reduction method for the preparation of metal nanoparticles (NPs) by the reduction of metal salts or metal complexes in a solvent with a reducing agent is widely used to prepare Ni NPs that exhibit high catalytic activity in various organic transformations. Intensive research has been conducted on control of the morphology and size of Ni NPs by the addition of polymers and long-chain compounds as protective agents; however, these agents typically cause a decrease in catalytic activity. Here, we report on the preparation of Ni NPs using hydrosilane (Ni-Si) as a reducing agent and a size-controlling agent. The substituents on silicon can control not only the size but also the crystal phase of the Ni NPs. The prepared Ni NPs exhibited high catalytic performance for the hydrogenation of unsaturated compounds, aromatics, and heteroaromatics to give the corresponding hydrogenated products in high yields. The unique feature of Ni catalysts prepared by the hydrosilane-assisted method is that the catalysts can be handled under air as opposed to conventional Ni catalysts such as Raney Ni. Characterization studies indicated that the surface hydroxide was reduced under the catalytic reaction conditions with H2 at around 100 °C and with the assistance of organosilicon compounds deposited on the catalyst surface. The hydrosilane-assisted method presented here could be applied to the preparation of supported Ni catalysts (Ni-Si/support). The interaction between the Ni NPs and a metal oxide support enabled the direct amination of alcohols with ammonia to afford the primary amine selectively.

Pd/Cu bimetallic nano-catalyst supported on anion exchange resin (A520E) for nitrate removal from water: High property and stability

High nitrate concentration in water can lead to eutrophication and the disruption of healthy aquatic ecosystems. Additionally, in the human digestive system, it has the potential to be reduced to nitrite, which can be damaging to people's physical health. Catalytic hydrogenation of nitrate is one of the strategies for removing nitrate from water. Using A520E resin as support, we prepared Pd/Cu nano-catalyst (Pd/Cu@A520E) according to a liquid phase reduction method. A520E could improve the transfer process of nitrate in the solution to the activity sites of Pd/Cu nanoparticles, thus increase the reaction rate of nitrate reduction. Pd/Cu bimetallic nano-particles were evenly distributed on/in the resin with a size range from 2 nm to 10 nm. The External Circulating System equipped with Venturi tube (ECSV) was designed to improve the utilization efficiency of H2 in both batch tests and long-term continuous-flow tests. Nearly 100% of nitrate removal efficiency and above 90% of N2 selectivity were achieved in both batch tests and continuous-flow tests. Coexisting Cl− and SO42− at 300 mg/L showed little impact on the property of Pd/Cu@A520E. Pd/Cu@A520E also showed high nitrate removal property and stability in continuous-flow tests of more than 800 h. NO3− was adsorbed onto the active sites (functional groups and Pd/Cu particle sites), meanwhile H2 was adsorbed onto the active sites of Pd/Cu@A520E to form Pd [H]. Then the adsorbed NO3− was reduced into N2 (main product) or NH4+ by Pd [H]. In addition, Pd/Cu@A520E showed high nitrate removal property from municipal waste water.