scholarly journals Synthesis of ZIF-67- Effect of solvent on the structure

2021 ◽  
Vol 10 (1) ◽  
pp. 98-103
Author(s):  
Lien Tuong Kieu ◽  
Duc Hoang Van ◽  
Linh Nguyen Le My ◽  
Thu Nguyen Thi Anh
Keyword(s):  
Room Temperature ◽  
Nitrogen Adsorption ◽  
High Specific Surface Area ◽  
High Thermal Stability ◽  
Average Crystalline Size ◽  
Nitrate Hexahydrate ◽  
Effect Of Solvent ◽  
Methyl Imidazole ◽  
Adsorption Desorption ◽  
Nano Size

In the present paper, ZIF-67 material was synthesized from cobalt (II) nitrate hexahydrate and 2-methyl imidazole in three different solvents (methanol, ethanol and acetone) at room temperature. The obtained samples were characterized using XRD, SEM, FTIR, TGA and nitrogen adsorption/desorption measurements. The results show that the synthesized ZIF-67 materials had a high purity, nano-size, and uniformity with the sharp dodecahedrons structure of ZIF-67. Solvents had an influence on the size and nature of the ZIF-67 crystal. The average crystalline size of the nanoparticles calculated by Scherrer equation were 64 nm for sample in acetone solvent, 128 nm for sample in ethanol solvent and 132 nm for sample in methanol solvent. The obtained samples had high thermal stability ( 320 °C). The ZIF-67 material with ethanol solvent had a high specific surface area (SBET) of 1506 m2/g. The synthesized samples exhibited better adsorption capacity of methyl oranges than that of rhodamine B.

scholarly journals Synthesis of ZIF-11- effect of source of zinc salts on the structure

2021 ◽  
Vol 10 (1) ◽  
pp. 79-83
Author(s):  
Luy Nguyen Thi ◽  
Vu Dang Cong ◽  
Thu Nguyen Thi Anh ◽  
Lien Tuong Kieu ◽  
Duc Hoang Van
Keyword(s):  
Room Temperature ◽  
Zinc Nitrate ◽  
High Thermal Stability ◽  
Zinc Salt ◽  
Average Crystalline Size ◽  
Zinc Salts ◽  
Synthesized Materials ◽  
Nano Size ◽  
Very High ◽  
Zinc Sources

In this paper, ZIF-11 material was synthesized from benzimidazole and different zinc salt sources at room temperature. The obtained samples were characterized using XRD, SEM, FTIR and TGA measurements. The results showed that the synthesized materials had nano-size, and uniformity with the sharp dodecahedrons structure of ZIF-11. Zinc sources had an influence on the size and nature of the ZIF-11 crystal. The average crystalline size of the nanoparticles calculated by Scherrer equation were 85.5 nm for sample of zinc nitrate, 91.9 nm for sample of zinc chloride and 111.5 nm for sample of zinc acetate. The obtained samples had high thermal stability ( 460 °C). The adsorption capacity of the synthesized materials for iodine from aqueous solution was very high (236 mg/g).

scholarly journals Ultrasound-Assisted Rapid ZIF-8 Synthesis, Porous ZnO Preparation by Heating ZIF-8, and Their Photocatalytic Activity

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Pham Dinh Du ◽  
Nguyen Trung Hieu ◽  
Tran Vinh Thien
Keyword(s):  
Photocatalytic Activity ◽  
Room Temperature ◽  
Diffuse Reflectance ◽  
Nitrogen Adsorption ◽  
X Ray Diffraction ◽  
Zeolitic Imidazolate Framework ◽  
X Ray ◽  
Photocatalytic Activities ◽  
Ft Ir ◽  
Adsorption Desorption

Zeolitic imidazolate framework-8 (ZIF-8) is synthesized quickly at room temperature in methanol with the support of ultrasound. Porous ZnO is also prepared via the thermal treatment of ZIF-8. The photocatalytic activities of the obtained materials are demonstrated via methylene blue (MB) decomposition under UV radiation. The obtained materials are characterized by means of X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), nitrogen adsorption/desorption isotherms, UV-Vis diffuse reflectance spectra (DR-UV-Vis), and photoluminescence spectra. The results indicate that ZIF-8 and the materials obtained from ZIF-8 by heating in the air have photocatalytic activity under UV irradiation. The ZnO sample obtained by ZIF-8 calcination at 660°C for 5 h has the highest photocatalytic activity. However, the MB degradation photocatalytic efficiency of the ZnO samples is even lower than that of the ZIF-8 samples, indicating that ZIF-8 is an effective photocatalyst in the treatment of environmental pollution.

scholarly journals Spectral and Texture Properties of Hydrophobic Aerogel Powders Obtained from Room Temperature Drying

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1796
Author(s):  
Dimitar Shandurkov ◽  
Petar Ignatov ◽  
Ivanka Spassova ◽  
Stoyan Gutzov
Keyword(s):  
Room Temperature ◽  
Fractal Dimensions ◽  
Nitrogen Adsorption ◽  
Attenuated Total Reflectance ◽  
Ir Absorption ◽  
Solvent Exchange ◽  
Texture Properties ◽  
Surface Fractal ◽  
Desorption Isotherms ◽  
Adsorption Desorption

Attenuated Total Reflectance Infrared (ATR-IR) spectroscopy and texture measurements based on nitrogen adsorption-desorption isotherms are combined to characterize silica aerogel granules with different degrees of hydrophobicity. The aerogels were prepared from tetraethoxysilane via a room temperature hydrolysis-gelation process, solvent exchange, hydrophobization, and drying at subcritical conditions. The dependencies between the texture properties, pore architectures, surface fractal dimensions, and degree of hydrophobicity of the samples are extracted from the ATR-IR spectra and the adsorption-desorption isotherms. The IR absorption in the region of the Si-O-Si and Si-OH vibrations is used for a description of the structural and chemical changes in aerogel powders connected with their surface hydrophobization. The Frenkel–Halsey–Hill (FHH) theory is applied to determine the surface fractal dimension of the powder species.

Synthesis of Nanoporous SiO2 Based Ceramic Materials via Sol-Gel Technology

2018 ◽  
Vol 762 ◽  
pp. 317-321
Author(s):  
Margarita Karpe
Keyword(s):  
Room Temperature ◽  
Sol Gel ◽  
Nitrogen Adsorption ◽  
Ceramic Materials ◽  
X Rays ◽  
Xrd Diffraction ◽  
Ceramic Samples ◽  
Desorption Isotherms ◽  
Adsorption Desorption ◽  
Hydrolysis Of

The aim of research was developed area of nanoporous ceramic matrials of ternary - ZrO2-TiO2-SiO2 system. The ceramic materials of system ZrO2-TiO2-SiO2 was synthesized via sol-gel technology by hydrolysis of tetraethylorthosilicate (TEOS), zirconia propoxide and titanium isporopoxide solutions. The sols were polymerized at room temperature to obtain gels. Then gels were dried at 100 OC 72 hours. Xerogel was milled 1 or 6 hours and the powder was axial pressed for nanoporous ceramic samples. All the samples were sintered at 800 OC or 1000 OC in air. 1M HYPERLINK "res://\\\\ld1062.dll/type=1_word=hydrochloric%20acid" hydrochloric acid (HCl) and destilled water were used as a catalyst to promote the hydrolysis and condensation reactions. All samples were characterized by X-rays (XRD) diffraction, particle size distribution and compressive strength. Apparent density and specific surface area of ceramic samples were determined by a Brunauer, Emmett and Teller (BET) nitrogen adsorption-desorption isotherms.

Various Morphology of Hierarchical Pore-Structured Compound: MCM-41/Diatomite and its Adsorption Behavior for Methylene Blue

2013 ◽  
Vol 690-693 ◽  
pp. 3533-3540
Author(s):  
Fang Fei Li ◽  
Mao Sheng Xia ◽  
Yin Shan Jiang
Keyword(s):  
Hierarchical Structure ◽  
Catalyst Support ◽  
Nitrogen Adsorption ◽  
High Specific Surface Area ◽  
Sem Analysis ◽  
Structure And Morphology ◽  
Hierarchical Porous ◽  
Hierarchical Pore ◽  
Adsorption Desorption ◽  
Mcm 41

Hierarchical porous materials attract considerable attentions due to their interesting structures and superior adsorption capabilities. In this work, a novel macro- and meso-porous hierarchical material, MCM-41/diatomite, has successfully been synthesized from natural diatomite and tetraethoxysilane by basic hydrothermal method. Nitrogen adsorption/desorption isotherms, low angle XRD and SEM analysis were carried out to character the multiple porous structure and morphology of MCM-41/diatomite. The resultant compound displayed high specific surface area (862~1041 m2/g) and macro-meso-porous hierarchical structure. The morphology of MCM-41/diatomite could be various, such as worm-like, grape-like, flocky, and acaleph-like, due to different ratio between TEOS, PEG, and NaOH. Moreover, the results of adsorption experiments show that some of the resultant MCM-41/diatomite display stronger adsorption capabilities than simply mesoporous MCM-41, due to the macro-meso-porous hierarchical structure, which would further extend the application of MCM-41/diatomite as adsorbent and catalyst support.

scholarly journals Synthesis of mesoporous silica with ordered nanostructural morphology from natural quartz sand

2020 ◽  
Vol 64 (5) ◽  
pp. 544-550
Author(s):  
T. F. Kouznetsova ◽  
V. Е. Agabekov ◽  
A. I. Ivanets ◽  
E. V. Karpinchik ◽  
J. D. Sauka
Keyword(s):  
Quartz Sand ◽  
Molecular Sieves ◽  
Three Dimensional ◽  
Nitrogen Adsorption ◽  
Average Diameter ◽  
High Specific Surface Area ◽  
Mesoporous Molecular Sieves ◽  
X Ray Diffraction ◽  
Natural Quartz ◽  
Adsorption Desorption

Silica with ordered nanostructured morphology characteristic of mesoporous molecular sieves with cubic packing of cylindrical pores and a three-dimensional porous structure is obtained from natural quartz sand. It was shown by X-ray diffraction, scanning electron microscopy, and low-temperature nitrogen adsorption-desorption that the obtained silica material is thermally stable, amorphous, consists of submicron grains, has a high specific surface area of 1396 m2/g, a pore volume of 0.780 cm3/g and an average diameter of 2.2 nm with a narrow size distribution of mesopores.

scholarly journals Conductivity at Low Humidity of Materials Derived from Ferroxane Particles

2012 ◽  
Vol 2012 ◽  
pp. 1-7
Author(s):  
Alberto Lapina ◽  
Peter Holtappels ◽  
Mogens Mogensen
Keyword(s):  
Aqueous Solution ◽  
Acetic Acid ◽  
Carboxylic Acid ◽  
Room Temperature ◽  
Sintered Material ◽  
Nitrogen Adsorption ◽  
Proton Conductors ◽  
Low Humidity ◽  
Adsorption Desorption ◽  
Sintered Materials

Carboxylic-acid-stabilisedγ-FeOOH particles (ferroxanes) are synthesized using a precipitation from aqueous solution, and a following reaction with acetic acid. The materials produced with these powders are investigated by XRD, SEM, nitrogen adsorption-desorption, and impedance spectroscopy. Conductivity of both sintered and unsintered materials decreases strongly with a decrease in water partial pressure in the atmosphere during the test. The highest conductivity (7·10−3 S cm−1) is measured in air (pH2O = 0.037 atm) at room temperature on sintered material. The conductivity values are compared with other works in the literature and the dependence of conductivity on surface area and pore size is discussed. It is suggested that both unsintered and sintered materials act as proton conductors at room temperature under moderate humidity conditions.

scholarly journals Pore Modification and Phosphorus Doping Effect on Phosphoric Acid-Activated Fe-N-C for Alkaline Oxygen Reduction Reaction

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1519
Author(s):  
Jong Gyeong Kim ◽  
Sunghoon Han ◽  
Chanho Pak
Keyword(s):  
Phosphoric Acid ◽  
Photoelectron Spectroscopy ◽  
Structural Changes ◽  
Electronic States ◽  
Nitrogen Adsorption ◽  
Reduction Reaction ◽  
Phosphorus Doping ◽  
X Ray ◽  
Precious Metal Catalysts ◽  
Adsorption Desorption

The price and scarcity of platinum has driven up the demand for non-precious metal catalysts such as Fe-N-C. In this study, the effects of phosphoric acid (PA) activation and phosphorus doping were investigated using Fe-N-C catalysts prepared using SBA-15 as a sacrificial template. The physical and structural changes caused by the addition of PA were analyzed by nitrogen adsorption/desorption and X-ray diffraction. Analysis of the electronic states of Fe, N, and P were conducted by X-ray photoelectron spectroscopy. The amount and size of micropores varied depending on the PA content, with changes in pore structure observed using 0.066 g of PA. The electronic states of Fe and N did not change significantly after treatment with PA, and P was mainly found in states bonded to oxygen or carbon. When 0.135 g of PA was introduced per 1 g of silica, a catalytic activity which was increased slightly by 10 mV at −3 mA/cm2 was observed. A change in Fe-N-C stability was also observed through the introduction of PA.

scholarly journals Effects of Substitution of Y with Yb and Ce on the Microstructures and Mechanical Properties of Mg88.5Zn5Y6.5

Metals ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 31
Author(s):  
Hongxin Liao ◽  
Taekyung Lee ◽  
Jiangfeng Song ◽  
Jonghyun Kim ◽  
Fusheng Pan
Keyword(s):  
Mechanical Properties ◽  
Thermal Stability ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Yield Strength ◽  
Creep Resistance ◽  
Room Temperature ◽  
High Thermal Stability ◽  
Long Period ◽  
Microstructures And Mechanical Properties

The microstructures and mechanical properties of the Mg88.5Zn5Y6.5-XREX (RE = Yb and Ce, X = 0, 1.5, 3.0, and 4.5) (wt.%) alloys were investigated in the present study. Mg88.5Zn5Y6.5 is composed of three phases, namely, α-Mg, long-period stacking ordered (LPSO) phases, and intermetallic compounds. The content of the LPSO phases decreased with the addition of Ce and Yb, and no LPSO phases were detected in Mg88.5Zn5Y2.0Yb4.5. The alloys containing the LPSO phases possessed a stratified microstructure and exhibited excellent mechanical properties. Mg88.5Zn5Y5.0Ce1.5 exhibited the highest creep resistance and mechanical strength at both room temperature and 200 °C, owing to its suitable microstructure and high thermal stability. The yield strength of Mg88.5Zn5Y5.0Ce1.5 at room temperature was 358 MPa. The ultimate tensile strength of Mg88.5Zn5Y5.0Ce1.5 at room temperature and 200 °C was 453 MPa and 360 MPa, respectively.

Effect of Carbon Pre-Treatment on Pd Dispersion in Synthesis of Pd/C Catalyst

2014 ◽  
Vol 804 ◽  
pp. 149-152 ◽  
Author(s):  
Ji Sun Kim ◽  
Jae Ho Baek ◽  
Myung Hwan Kim ◽  
Seong Soo Hong ◽  
Man Sig Lee
Keyword(s):  
Surface Area ◽  
Nitrogen Adsorption ◽  
Area Ratio ◽  
High Dispersion ◽  
Co Chemisorption ◽  
Pd Dispersion ◽  
Before And After ◽  
Pre Treatment ◽  
Treated Carbon ◽  
Adsorption Desorption

In this study, we confirmed effect of carbon pre-treatment on Pd dispersion in synthesis of Pd/C catalyst. Physical characteristics on the surface of before and after pre-treated carbon were analyzed by nitrogen adsorption-desorption analysis. The dispersion and size of Pd particles were analyzed by XRD, FE-TEM and CO-chemisorption. After pre-treatment, surface area of carbon were decreased. And mesopore area ratio were increased with decreasing micropore area ratio. In the case of pre-treated carbon, we confirmed high dispersion of Pd particles.

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