scholarly journals Efficient Synthesis of Biodiesel Catalyzed by Chitosan-Based Catalysts

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Anping Wang ◽  
Wenxuan Quan ◽  
Heng Zhang
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Efficiency ◽  
Homogeneous Catalyst ◽  
Process Technology ◽  
Active Centers ◽  
Covalent Bonds ◽  
Preparation Methods ◽  
Advantages And Disadvantages

Catalysts play an important role in the preparation of biodiesel. It is of great significance to study catalysts with high efficiency, low cost, and easy preparation. Compared with the homogeneous catalyst system, the heterogeneous catalyst is easy to separate and has a better catalytic effect. In heterogeneous catalysts, supports and preparation methods have important effects on the dispersion of active centers and the overall performance of catalysts. However, the supports of existing solid catalysts have defects in porosity, structural uniformity, stability, and specific surface area, and the preparation methods cannot stabilize covalent bonds or ionic bonds to bind catalytic sites. Considering the activity, preparation method, and cost of the catalyst, biomass-based catalyst is the best choice, but the specific surface area of the biomass-based catalyst is relatively low, the distribution of active centers is uneven, and it is easy to lose. Therefore, the hybrid carrier of biomass-based catalyst and other materials can not only improve the specific surface area but also make the distribution of active centers uniform and the catalytic activity better. Based on this, we summarized the application of chitosan hybrid material catalysts in biodiesel. The preparation, advantages and disadvantages, reaction conditions, and so on of chitosan-based catalysts were mainly concerned. At the same time, exploring the effects of different types of chitosan-based catalysts on the preparation of biodiesel and exploring the process technology with high efficiency and low consumption is the focus of this paper.

scholarly journals High MB Solution Degradation Efficiency of FeSiBZr Amorphous Ribbon with Surface Tunnels

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3694 ◽  
Author(s):  
Qi Chen ◽  
Zhicheng Yan ◽  
Hao Zhang ◽  
Lai-Chang Zhang ◽  
Haijian Ma ◽  
...  
Keyword(s):  
Specific Surface ◽  
Porous Structure ◽  
Surface Area ◽  
Free Volume ◽  
Specific Surface Area ◽  
Degradation Rate ◽  
High Efficiency ◽  
Amorphous Ribbon ◽  
Degradation Efficiency ◽  
Characteristic Distance

The as spun amorphous (Fe78Si9B13)99.5Zr0.5 (Zr0.5) and (Fe78Si9B13)99Zr1 (Zr1) ribbons having a Fenton-like reaction are proved to bear a good degradation performance in organic dye wastewater treatment for the first time by evaluating their degradation efficiency in methylene blue (MB) solution. Compared to the widely studied (Fe78Si9B13)100Zr0 (Zr0) amorphous ribbon for degradation, with increasing cZr (Zr atomic content), the as-spun Zr0, Zr0.5 and Zr1 amorphous ribbons have gradually increased degradation rate of MB solution. According to δc (characteristic distance) of as-spun Zr0, Zr0.5 and Zr1 ribbons, the free volume in Zr1 ribbon is higher Zr0 and Zr0.5 ribbons. In the reaction process, the Zr1 ribbon surface formed the 3D nano-porous structure with specific surface area higher than the cotton floc structure formed by Zr0 ribbon and coarse porous structure formed by Zr0.5 ribbon. The Zr1 ribbon’s high free volume and high specific surface area make its degradation rate of MB solution higher than that of Zr0 and Zr0.5 ribbons. This work not only provides a new method to remedying the organic dyes wastewater with high efficiency and low-cost, but also improves an application prospect of Fe-based glassy alloys.

scholarly journals Preparation and Application of 2D MXene-Based Gas Sensors: A Review

Chemosensors ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 225
Author(s):  
Qingting Li ◽  
Yanqiong Li ◽  
Wen Zeng
Keyword(s):  
Composite Materials ◽  
Specific Surface ◽  
Surface Area ◽  
Gas Sensor ◽  
Specific Surface Area ◽  
Gas Sensors ◽  
Room Temperature ◽  
Gas Sensing ◽  
Interlayer Spacing ◽  
Preparation Methods

Since MXene (a two-dimensional material) was discovered in 2011, it has been favored in all aspects due to its rich surface functional groups, large specific surface area, high conductivity, large porosity, rich organic bonds, and high hydrophilicity. In this paper, the preparation of MXene is introduced first. HF etching was the first etching method for MXene; however, HF is corrosive, resulting in the development of the in situ HF method (fluoride + HCl). Due to the harmful effects of fluorine terminal on the performance of MXene, a fluorine-free preparation method was developed. The increase in interlayer spacing brought about by adding an intercalator can affect MXene’s performance. The usual preparation methods render MXene inevitably agglomerate and the resulting yields are insufficient. Many new preparation methods were researched in order to solve the problems of agglomeration and yield. Secondly, the application of MXene-based materials in gas sensors was discussed. MXene is often regarded as a flexible gas sensor, and the detection of ppb-level acetone at room temperature was observed for the first time. After the formation of composite materials, the increasing interlayer spacing and the specific surface area increased the number of active sites of gas adsorption and the gas sensitivity performance improved. Moreover, this paper discusses the gas-sensing mechanism of MXene. The gas-sensing mechanism of metallic MXene is affected by the expansion of the lamellae and will be doped with H2O and oxygen during the etching process in order to become a p-type semiconductor. A p-n heterojunction and a Schottky barrier forms due to combinations with other semiconductors; thus, the gas sensitivities of composite materials are regulated and controlled by them. Although there are only several reports on the application of MXene materials to gas sensors, MXene and its composite materials are expected to become materials that can effectively detect gases at room temperature, especially for the detection of NH3 and VOC gas. Finally, the challenges and opportunities of MXene as a gas sensor are discussed.

A Novel Strategy to Obtain Hollow NaBiF4:Yb3+/Er3+ Upconversion Nanospheres by One Step Coprecipitation

2020 ◽  
Vol 20 (10) ◽  
pp. 6257-6265
Author(s):  
Jiaming Yu ◽  
Yumeng Wang ◽  
Yuxuan He ◽  
Huiling Li ◽  
Qian Cheng ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Diffusion Process ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Efficiency ◽  
Upconversion Luminescence ◽  
Hollow Structure ◽  
Emission Spectra ◽  
Upconversion Emission

Hollow upconversion luminescence nanomaterials have widespread applications in drug delivery, high efficiency catalysis, as well as energy storage owes to super-large specific surface area, cavity volume, and fluorescence properties. However, a series of complex processes and high temperature is required for the synthesis of these materials. Herein, a facile template-free coprecipitation route based on the Kirkendall diffusion process at room temperature had been developed to synthesize hollow NaBiF4:Yb3+/Er3+ nanospheres with upconversion luminescence. X-ray diffraction (XRD), nitrogen adsoption/desorption isotherms, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and upconversion emission spectra demonstrated the successful preparation of NaBiF4:Yb3+/Er3+ nanospheres with pervasive hollow morphology, relatively high specific surface area, and excellent upconversion luminescence properties. Moreover, the influence of some reaction parameters on the morphology and structure of the obtained samples were systematically explored. Additionally, the evolution mechanism of the hollow structure nanospheres was analyzed on account of the Kirkendall diffusion process related to the solid–liquid interfacial ion migration. It is expected that these hollow upconversion NaBiF4:Yb3+/Er3+ nanospheres with upconversion luminescence prepared by this type of synthetic strategy will have widespread medical, environmental, and energy applications.

scholarly journals Preparation and Properties of Graphene-based Inorganic Nanocomposites

2019 ◽  
Vol 2 (1) ◽  
Author(s):  
Qing Liao ◽  
Tingting Song
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Chemical Stability ◽  
High Performance ◽  
Inorganic Compounds ◽  
High Specific Surface Area ◽  
Two Dimensional ◽  
Preparation Methods ◽  
Inorganic Nanocomposites

Graphene is a two-dimensional hexagonal monoatomic layer crystal composed of carbon atoms, which exhibits the shape of a honeycomb and plays an important role in the fields of optics and mechanics. It also has the advantages of high specific surface area, strong chemical stability and special planar structure. It is an ideal carrier for carrying various inorganic compounds and is suitable for the development of high performance graphene-based inorganic nanocomposites.[1] Based on this, the paper introduces the characteristics of graphene, expounds the related content of graphene-based inorganic nanocomposites, and studies the preparation methods and properties of graphene-based inorganic nanocomposites.

scholarly journals Treatment of Cd2+ and Cu2+ Ions Using Modified Apatite Ore

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Phuong Thu Nguyen ◽  
Xuyen Thi Nguyen ◽  
Trang Van Nguyen ◽  
Thom Thi Nguyen ◽  
Thai Quoc Vu ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
High Efficiency ◽  
Adsorption Model ◽  
Phase Component ◽  
Area Element ◽  
Isotherm Adsorption ◽  
Lao Cai ◽  
Main Component

Apatite ore from Lao Cai (Vietnam) has large reserves and low prices. Its main component is fluorapatite. The purification and modification of apatite ore can produce a material that can be used as an absorbent for heavy metals with high efficiency. The molecular structure, phase component, specific surface area, element component, and morphology of modified apatite ore from Lao Cai province, Vietnam, were characterized by IR, XRD, BET, EDX, and SEM methods. The IR and XRD results show that the modified process transformed apatite ore from fluorapatite to nanohydroxyapatite. The specific surface area of modified apatite ore (100.79 m2/g) is much higher than the original ore (3.97 m2/g). The modified apatite ore was used to adsorb Cd2+ and Cu2+ ions in water. The effect of adsorbent mass, pH, contact time, and initial concentration of Cd2+ and Cu2+ on the adsorption efficiency and capacity was investigated. Besides, the isotherm adsorption model was determined using Freundlich and Langmuir theories.

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