Search

HZSM-5 zeolite modified by rare earth was prepared with ion exchange method in the study. The effects of different types of rare earth elements, modification temperatures, pH, and rare earth contents on structural stability of the as-prepared zeolite were investigated. The as-prepared zeolite was characterized by XRD, SEM and FT-IR spectroscopy. The characterization results showed that the crystal structure of the zeolite was not changed by the modification of rare earth, which was evenly distributed on the surface or in the pore channel of zeolite. Sm/HZSM-5 zeolite with the highest structural stability was obtained under the following modification conditions: 2% rare earth Sm, modification temperature of 70 °C, 2 h of ion exchange, and pH 3. [ABSTRACT FROM AUTHOR]

In the study, MgAl binary water talc (MgAl-CO3-LDHs) was firstly synthesized by a steady-state co-precipitation method and then characterized by XRD, SEM and ICP-OES methods. The effects of n(Mg2+)/n(Al3+) in mixed salt solutions, pH and roasting temperature on the properties of MgAl-CO3-LDHs were mainly explored. The optimal adsorption condition of VO3- on MgAl-CO3-LDHs was determined as synthesis temperature of 25 °C, n(Mg2+)/n(Al3+) ratio of 3:1, pH 8 ± 0.1 and roasting temperature of 517 °C. The adsorption characteristics of MgAl-CO3-LDHs on VO3- were better fitted with Langmuir's isothermal equation and quasi-secondary kinetic equation. The adsorption mechanism was close to the monolayer adsorption with a saturated adsorption capacity of 53.73 mg/g. [ABSTRACT FROM AUTHOR]

In the study, MgAl binary water talc (MgAl-CO3-LDHs) was firstly synthesized by a steady-state co-precipitation method and then characterized by XRD, SEM and ICP-OES methods. The effects of n(Mg2+)/n(Al3+) in mixed salt solutions, pH and roasting temperature on the properties of MgAl-CO3-LDHs were mainly explored. The optimal adsorption condition of VO3- on MgAl-CO3-LDHs was determined as synthesis temperature of 25 °C, n(Mg2+)/n(Al3+) ratio of 3:1, pH 8 ± 0.1 and roasting temperature of 517 °C. The adsorption characteristics of MgAl-CO3-LDHs on VO3- were better fitted with Langmuir's isothermal equation and quasi-secondary kinetic equation. The adsorption mechanism was close to the monolayer adsorption with a saturated adsorption capacity of 53.73 mg/g. [ABSTRACT FROM AUTHOR]

With Miyi diatomite as the carrier and ferric nitrate as the modification agent, nano-micron vanadium adsorbent was prepared in the study. Then the adsorption properties of the prepared adsorbent were characterized by XRD, XRF, SEM, and ICP-OES analysis. The effects of adsorption time, initial pH value and initial vanadium concentration on VO3− adsorption performance were studied and the adsorption mechanism was discussed. The adsorption of VO3− on Miyi diatomite was significantly improved by the modification with ferric nitrate. The adsorption process of VO3− on nano-micron vanadium adsorbent was in accordance with Langmuir isothermal equation and quasi-second-order kinetic model. The saturated adsorption capacity was 43.38 mg/g. The adsorption capacity was higher in the weak acid environment and peaked at pH = 4. [ABSTRACT FROM AUTHOR]

In this study, the loaded diatomite was prepared with Changbai Mountain diatomite as the carrier according to different Fe/Al molar ratios. The structure and adsorption of the above materials were characterized by XRD, SEM, and ICP-OES. The effects of Fe/Al molar ratio, adsorption time, initial concentration of V(V), and the initial pH value of the solution on the adsorption performance of loaded diatomite were explored. The diatomite loaded with Fe/Al compounds could significantly improve the removal efficiency of V(V), and the removal efficiency of loaded diatomite prepared according to a Fe/Al molar ratio of 1:3 was better. Reaction equilibrium time is 24 h and the pseudo second-order kinetic equation can better describe the adsorption kinetic behavior of V(V) on loaded diatomite. When the initial concentration of V(V) increased from 15.85 mg/L to 122.5 mg/L, the unit adsorption capacity and removal rate of V(V) by loaded diatomite increased continuously. The adsorption behavior of V(V) on loaded diatomaceous earth belongs to the chemical adsorption via the multi-molecular layer, which is consistent with the Freundlich isotherm adsorption model. A weak acid environment is beneficial to the adsorption behavior of V(V) on loaded diatomaceous earth and the strong alkaline environment should be avoided. [ABSTRACT FROM AUTHOR]

The nanoakaganeite (β-FeOOH) was synthesized by the hydrothermal method in the study. The structural characterization and adsorption investigation of the produced materials were performed with powder X-ray diffractometer (XRD), scanning electron microscope (SEM), and inductively coupled plasma optical emission spectrometer (ICP-OES). Moreover, the influences of hydrothermal time, Fe3+ concentration, and hydrothermal temperature on the product structure and chromium adsorption were investigated. In addition, the influence of initial Cr(VI) concentration on chromium adsorption was investigated. The investigation results confirmed the optimal synthesis conditions of β-FeOOH as follows: 72 h hydrothermal reaction, 0.20 M Fe3+, and hydrothermal temperature at 70 °C. The as-synthesized β-FeOOH was spindle-shaped akaganeite. When the initial Cr(VI) concentration increased from 9.91 mg/L to 99.47 mg/L, the adsorption capacity increased and Cr(VI) removal rate decreased. Cr(VI) adsorption on β-FeOOH was a single-molecule layer chemical adsorption, conforming to the Langmuir adsorption model. The maximum saturation adsorption was 16.35 mg/g. [ABSTRACT FROM AUTHOR]

316L stainless steel spherical powder for 3D printing and metal injection molding was prepared by supersonic laminar flow atomization. Then the as-prepared samples were characterized by XRF, XRD, SEM, and an oxygen/nitrogen analyzer. Characterization results indicated that the prepared 316L spherical powder had the high sphericity, high tap density, low oxygen content, small particle size and narrow size distribution and were applicable to 3D printing and MIM. [ABSTRACT FROM AUTHOR]

Nanosized magnesium hydroxide (Mg(OH)2) with sheet and flower structure were prepared via precipitation reaction between magnesium chloride and alkaline precipitant, such as ammonium hydroxide, sodium hydroxide and urea. The structure and morphology of as-prepared samples were characterized through X-ray diffraction and scanning electron microscopy. Effect of precipitants and surface modifier on morphology and size of nano-Mg(OH)2were investigated. Heat-resistance of Mg(OH)2in polymer was discussed by thermogravimetry-differential thermal analysis. Mg(OH)2nanostructure present superior morphology and heat-resistance with NH4OH-NaOH as precipitant and 3mol% acrylic acid as surface modifier. [ABSTRACT FROM PUBLISHER]

High mineralization activity is a crucial requirement in bone tissue engineering. In this study, a novel calcium citrate compounded amorphous calcium phosphate (CAP)/polyurethanes (PUs) composite porous 3D scaffold was developed by in situ polymerization via gas foaming method. The physical and chemical properties were characterized and discussed. The results showed that the HDI can react mildly with hydroxyl (–OH) groups of PEG, while gas foaming action was caused by the release of CO2 occurred in the reactive process, resulting in a uniform porous structure of PUs scaffold. The porosities of the synthetic PEGCAP porous scaffolds are all above 70% with high interconnectivity, while the porosity decreased 27% with increasing CAP to 40%. Furthermore, the mechanical properties of porous scaffolds enhanced about 16 times after addition of CAP. After immersing in simulated body fluid (SBF), the surface structure of the porous scaffold kept stable, and surface deposits formed, indicating that the porous scaffold has good mineralization activity. In addition, the in vitro cells proliferation assay confirms the excellent bioactivity of PEGCAP porous scaffolds. [ABSTRACT FROM AUTHOR]

As an important industrial catalytic material, ZSM-5 zeolites are still facing durability issues. The long-time exposure among high temperature steam during the catalytic reaction becomes the main drawback for ZSM-5 zeolite application in industry. In this study, we investigate the effects of rare-earth-ions (La, Ce, Nd, Sm, Gd, and Dy) doping on the catalytic activity and hydrothermal stability of ZSM-5 zeolites based on density functional theory. The results demonstrate that the introduced rare-earth-ions prefer to adsorb on the top of Al atom (T12 site). The Milliken charge transfer and electron density difference confirm the strong electrostatic interactions between the ZSM-5 zeolites and rare-earth-ions. The activation reaction of butene is investigated to estimate the catalytic activity of rare-earth-ion doped ZSM-5. The results demonstrate that La and Sm doped ZSM-5 zeolites exhibit superior performance on butene activation. In addition, rare-earth-ions decoration show enhanced sodium tolerance performance with decreased affinity toward Na during the catalytic process. This study demonstrated that the modification of rare-earth-ions can effectively improve the hydrothermal stability and catalytic activity of ZSM-5 zeolites. [ABSTRACT FROM AUTHOR]

As a new zero-optic luminescent material, carbon quantum points are widely focused and sustained, and many researchers are trying to use simple and fast methods and stable, good carbon sources to be prepared with a good fluorescent properties of carbon quantum dots. In this paper, carbon quantum dots were synthesized by solvothermal method with vanillin as carbon source, and the effects of solvothermal temperature and time on the luminescence properties of carbon quantum dots were explored. Then, carbon quantum dots were characterized by X-ray diffraction analysis, transmission electron microscopy analysis, infrared spectrum analysis, fluorescence spectrum analysis. Research results showed that ethanol solvent with vanillin as a carbon source by solvothermal method could synthesize good water soluble carbon quantum dots with weak crystallization, and its size was about 10 nm. This carbon quantum dots had obvious excitation wavelength dependence and produce blue light, which had potential application value in ion fluorescence probe or cell labeling. [ABSTRACT FROM AUTHOR]

Via wet chemical method with organic assistant, ZnS:Cu/ZnS core/shell structure was prepared. X-ray diffraction measurements showed that ZnS:Cu was formed with zinc blende structure, and ZnS shell growth on the surface was indicated through a red-shift in the UV-Vis absorption spectra with increasing particle size. The emission peak at about 510 nm was observed, which should be assigned to recombination of an electron from the shallow delocalized donor levels at thet2level of Cu2+centers. As passivation layer, effect of ZnS shell on luminescence intensity and lifetime of ZnS:Cu were investigated. Comparing with uncoated ZnS:Cu, ZnS shell really enhanced the luminescence intensity and lifetime significantly, which resulted from the reduction of nonradiative recombination sites. [ABSTRACT FROM AUTHOR]

In this study, porous composite materials were prepared from calcium citrate (CC) and polylactic acid (PLA). Scanning electron microscopy (SEM) showed that the prepared composite materials had the uniformly pore distribution and suitable pore size for bone tissue engineering and displayed proper mechanical properties. As confirmed in X-ray diffraction (XRD), SEM and thermal analysis, the lipophilic property of CC had the improved compatibility and uniform dispersion in the PLA matrix. In addition, the prepared materials showed the high mineralization activity and the ability to guide the formation of apatite since the hydrophilicity of CC improved the wettability of the composite materials. In vivo animal experiments showed that the material was nontoxic and had good biocompatibility. Furthermore, the synergic degradation of CC and PLA effectively neutralized the acidic environment, thus preventing partial inflammation caused by acidic products. CC/PLA composite materials provide a promising new bone repair material for bone tissue engineering. [ABSTRACT FROM AUTHOR]

A novel material Bi1-xGdx-BTC was obtained in situ via the solvothermal method. The effects of Gd3+ substitution on the Bi-BTC structure and photocatalytic properties of Bi1-xGdx-BTC were investigated. A standard Bi-BTC structure was observed in the X-ray diffraction spectra of the Bi1-xGdx-BTC(x ≤ 0.07). However, some diffraction peaks were changed when the x is more than 0.07 due to the different ion radius. The developed Bi1-xGdx-BTC samples exhibited higher photocatalytic activity than the pure Bi-BTC material. In RhB degradation experiments, the Bi1-xGdx-BTC(x = 0.03 and x = 0.05) materials show degradation efficiency conversion of 71% within 60 min under visible light. The high photodegradation efficiency of Bi1-xGdx-BTC could be ascribed to efficient charge transfer between Bi(III) ions and Gd(III) ions. Moreover, an active species trapping experiment confirmed that photo-generated ·O2- and ·OH is the major species involved in RhB degradation. [ABSTRACT FROM AUTHOR]

With sugarcane bagasse as the carrier and iron chloride hexahydrate (FeCl3·6H2O) as the iron source, Fe3O4@C materials were prepared in this study. Then the adsorption properties of the prepared adsorbents were characterized by XRD, SEM and VSM analysis. The effects of adsorption time, initial pH value and initial methylene blue concentration on methylene blue adsorption performance were studied and the adsorption mechanism was discussed. The Fe3O4@C materials synergistically exerted the good adsorption capacity and magnetic properties. The adsorption process of methylene blue on Fe3O4@C adsorbent was in accordance with Freundlich isothermal equation and quasi-second-order kinetic model. The saturated adsorption capacity in the experiment of Fe3O4@C material was 270.51 mg/g. The adsorption capacity was high in both acidic and alkaline environments, especially the alkaline environment. [ABSTRACT FROM AUTHOR]

As a new type of fluorescent carbon nanomaterials, carbon quantum dots have been widely concerned in recent years because of their good biocompatibility, low cytotoxicity and easy surface functionalization. In this paper, nitrogen-doped carbon quantum dots (N-CQDs) were prepared by one-step hydrothermal method with citric acid as the carbon source and urea as a nitrogen source. The fluorescence spectrophotometer, Fourier infrared spectrometer, X-ray diffractometer, and transmission electron microscope were utilized to discover the luminescence properties, structural characteristics, morphology and size of the synthesized N-CQDs. The results showed that the best reaction conditions for preparing N-CQDs were as follows: the hydrothermal process parameters were 240 °C for 10 h, and the concentration of nitrogen doping was 0.6 wt%. Under these conditions, the prepared N-CQDs with bright blue fluorescence solution was uniform and stable. And the results showed the structural characteristics were weak crystalline graphite carbon, and the shape characteristics were nearly spherical quantum dot with about 5–10 nm diameters. [ABSTRACT FROM AUTHOR]

In this study, a novel hydroxyapatite (HA)/polyurethane (PU) composite porous 3D scaffold was developed by in situ polymerization. Aliphatic hexamethylene diisocyanate (HDI) as a nontoxic and safe agent was adopted to produce the rigid segment in PU polymerization. HA powder was compounded in a PU polymer matrix during the polymeric process. The macrostructure and morphology as well as mechanical strength of the scaffolds were characterized by FTIR, XRD and SEM. The results show that the HDI can react mildly with hydroxyl (–OH) groups of polytetramethylene ether glycol and a mild foaming action caused by the release of CO2 gas occurred simultaneously in the reactive process, thus producing a uniform porous structure of HA/PU scaffold. The HA/PU composite scaffold with a high HA content of about 30 wt% has a porosity of more than 60% and a pore size from 100 to 800 μm. After immersed in simulated body fluid, the scaffolds were investigated by weight loss experiments and FTIR. The results show that polymerized component of HA/PU scaffolds degraded gradually in vitro, while HA component presented a classic trend of dissolution then deposition procedure. Three hydrolysis processes may happen in the PU degradation. The HA/PU scaffolds should be a promising material for bone tissue regeneration in clinic. [ABSTRACT FROM AUTHOR]

Luminescent perovskite photocatalysts activated by Pr3+ were prepared by combustion. The structural phase, morphology, and chemical composition of the as-prepared photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) analysis, and ultraviolet–visible (UV–vis) diffuse reflectance spectroscopy. The photocatalytic activities of the synthesized samples were investigated on the basis of the degradation of methylene blue (MB) under UV light irradiation. CaTiO3:Pr3+ was obtained in high purity and good crystallinity with a perovskite structure. The degradation of the photocatalyst was fitted with pseudo-first-order kinetics according to the Langmuir–Hinshelwood model. Compared to CaTiO3:Pr3+, Ca1–xTiO3:Pr3+ (x = 0–0.3) multifunctional materials exhibit higher luminescence intensity and photocatalytic activity toward the degradation of MB. Ca0.8TiO3:0.1%Pr3+ exhibited the best performance. [ABSTRACT FROM AUTHOR]