scholarly journals Fluoroalkylsilane versus Alkylsilane as Hydrophobic Agents for Silica and Silicates

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Damian Ambrożewicz ◽  
Filip Ciesielczyk ◽  
Magdalena Nowacka ◽  
Joanna Karasiewicz ◽  
Adam Piasecki ◽  
...  
Keyword(s):  
Water System ◽  
Magnesium Silicate ◽  
Nitrogen Adsorption ◽  
Precipitation Method ◽  
Silicate Surface ◽  
Inorganic Supports ◽  
Silica Synthesis ◽  
Adsorption Desorption ◽  
Parameters Of Porous Structure ◽  
Bet Equation

Hydrophobic powders were obtained via surface modification of silica or magnesium silicate with selected silanes. A modified precipitation method, carried out in an emulsion system, was used for monodisperse silica synthesis, while magnesium silicate was precipitated in a traditional water system. Functionalization of the obtained inorganic supports was performed with selected alkylsilanes: one newly synthesized, 3-(2,2,3,3,4,4,5,5-octafluoropentyloxy)propyltriethoxysilane (OPF), and two commercial, octadecylsilane (ODS) and octyltriethoxysilane C14H32O3Si (OCS), in amounts of 3, 5, or 10 weight parts by mass of SiO2. It was determined how the chemical modification of the silica or magnesium silicate surface affected its physicochemical properties. The dispersive characteristics of both unmodified and functionalized silica-based systems were evaluated. The morphology and microstructure of the samples obtained were analyzed using scanning electron microscopy. The parameters of porous structure of the prepared systems were evaluated on the basis of BET equation as well as nitrogen adsorption/desorption isotherms. Wettability tests as well as elemental analysis of the obtained inorganic oxide hybrids were also performed. In order to verify the effectiveness of silica and magnesium silicate surface functionalization with selected silanes, FTIR spectra were investigated. The resulting experimental data allowed calculation of the degree of coverage of the silica-based systems with modifying agents.

Synthesis of Novel Core-Shell Structured Hydroxyapatite/Meso-Silica for Removal of Methylene Blue from Aqueous Solutions

2012 ◽  
Vol 463-464 ◽  
pp. 543-547 ◽  
Author(s):  
Cheng Feng Li ◽  
Xiao Lu Ge ◽  
Shu Guang Liu ◽  
Fei Yu Liu
Keyword(s):  
Methylene Blue ◽  
Aqueous Solutions ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Low Cost ◽  
Nitrogen Adsorption ◽  
Precipitation Method ◽  
Core Shell ◽  
Adsorption Desorption

Core-shell structured hydroxyapatite (HA)/meso-silica was prepared and used as absorbance of methylene blue (MB). HA/meso-silica was synthesized in three steps: preparation of nano-sized HA by wet precipitation method, coating of dense silica and deposition of meso-silica shell on HA. As-received samples were characterized by Fourier transformed infare spectra, small angle X-ray diffraction, nitrogen adsorption-desorption isotherm and transmission electron microscopy. A wormhole framework mesostructure was found for HA/meso-silica. The specific surface area and pore volume were 128 m2•g-1 and 0.36 cm3•g-1, respectively. From the adsorption isotherm, HA/meso-silica with the great specific surface area exhibited a prominent adsorption capacity of MB (134.0 mg/g) in comparison with bare HA (0 mg/g). This study might shed light on surface modification of conventional low-cost adsorbents for removal of organic pollutants from aqueous solutions.

The Different Morphology of Co3O4 Catalysts and Application in the Abatement of Carbon Monoxide

2021 ◽  
Vol 21 (12) ◽  
pp. 6082-6087
Author(s):  
Chih-Wei Tang ◽  
Hsiang-Yu Shih ◽  
Ruei-Ci Wu ◽  
Chih-Chia Wang ◽  
Chen-Bin Wang
Keyword(s):  
Carbon Monoxide ◽  
Catalytic Activity ◽  
Co Oxidation ◽  
Nitrogen Adsorption ◽  
Catalytic Performance ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Temperature Programmed ◽  
Adsorption Desorption

The increase of harmful carbon monoxide (CO) caused by incomplete combustion can affect human health even lead to suffocation. Therefore reducing the CO discharged by vehicles or factories is urgent to improve the air quality. The spinel cobalt (II, III) oxide (Co3O4) is an active catalyst for CO abatement. In this study, we tried to fabricate dispersing Co3O4 via the dispersion-precipitation method with acetic acid, formic acid, and oxalic acid as the chelating dispersants. Then, the asprepared samples were calcined at 300 ºC for 4 h to obtain active catalysts, and assigned as Co(A), Co(F) and Co(O) respectively, the amount of the dispersants used are labeled as I (0.12 mole), II (0.03 mole) and III (0.01 mole). For comparison, another CoAP sample was prepared via alkaliinduced precipitation and calcined at 300 ºC. All samples were characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), scanning electron microscope (SEM), and nitrogen adsorption/desorption system, and the catalytic activity focused on the CO oxidation. The influence of chelating dispersant on the performance of abatement of CO was pursued in this study. Apparently, the results showed that the chelating dispersant can influence the catalytic activity of CO abatement. An optimized ratio of dispersant can improve the performance, while excess dispersant lessens the surface area and catalytic performance. The series of Co(O) samples can easily donate the active oxygen since the labile Co–O bonding and indicated the preferential performance than both Co(A) and Co(F) samples. The nanorod Co(O)-II showed preferential for CO oxidation, T50 and T90 approached 96 and 127 ºC, respectively. Also, the favorable durability of Co(O)-II sample maintains 95% conversion still for 50 h at 130 ºC and does not emerge deactivation.

scholarly journals The Role of the Aluminum Source on the Physicochemical Properties of γ-AlOOH Nanoparticles

2020 ◽  
Vol 39 (1) ◽  
pp. 89
Author(s):  
Rafael Romero Toledo ◽  
Luis M. Anaya Esparza ◽  
J. Merced Martínez Rosales
Keyword(s):  
Electron Microscopy ◽  
Physicochemical Properties ◽  
Surface Area ◽  
Low Cost ◽  
Nitrogen Adsorption ◽  
Bet Surface Area ◽  
Precipitation Method ◽  
X Ray ◽  
Aluminum Salts ◽  
Adsorption Desorption

The effect on the physicochemical properties of aluminum salts on the synthesis of γ-AlOOH nanostructures has been investigated in detail using a hydrolysis-precipitation method. X-ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), were used to characterize the synthesized samples. The specific surface area, pore size distribution and pore diameter of the different γ-AlOOH structures were discussed by the N2 adsorption-desorption analysis. According to the results of the nanostructure, characterization revealed that for synthesized γ-AlOOH nanostructures from AlCl3 and Al(NO3)3, obvious XRD peaks corresponding to the bayerite phase are found indicating an impure γ-AlOOH phase. Furthermore, the nitrogen adsorption-desorption analysis indicated that the obtained γ-AlOOH nanoparticles from Al2(SO4)3 of technical grade (95.0 % of purity) and low cost, possess a high BET surface area of approximately 350 m2/g, compared to the obtained nanostructures from aluminum sources reactive grade, which was attributed to the presence of Mg (0.9 wt.%) in its nanostructure.

scholarly journals Carbonization of Lignin Extracted from Liquid Waste of Coconut Coir Delignification

2020 ◽  
Vol 20 (4) ◽  
pp. 842
Author(s):  
Widiyastuti Widiyastuti ◽  
Mahardika Fahrudin Rois ◽  
Heru Setyawan ◽  
Siti Machmudah ◽  
Diky Anggoro
Keyword(s):  
Pore Size ◽  
Surface Area ◽  
Liquid Waste ◽  
Nitrogen Adsorption ◽  
Nitrogen Atmosphere ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Coconut Coir ◽  
Xrd Patterns ◽  
Adsorption Desorption

Lignin as a by-product of the pulping process is less widely used for worth materials. In this study, the utilization of lignin by-product of the soda delignification process of coconut coir converted to the activated carbon by a simple precipitation method followed by the carbonization at various temperatures is presented. The by-product liquor of the soda delignification process having a pH of 13.4 was neutralized by dropping of hydrochloric acid solution to achieve the pH solution of 4 resulting in the lignin precipitation. The precipitated was washed, filtered, and dried. The dried lignin was then carbonized under a nitrogen atmosphere at various temperatures of 500, 700, and 900 °C. The dried lignin and carbonized samples were characterized using SEM, XRD, FTIR, and nitrogen adsorption-desorption analyzer, to examine their morphology, X-Ray diffraction pattern, chemical bonding interaction, and surface area-pore size distribution, respectively. The characterization results showed that the functional groups of lignin mostly disappeared gradually with the increase of temperature approached the graphite spectrum. The XRD patterns confirmed that the carbonized lignin particles were amorphous and assigned as graphitic. All samples had a pore size of 3–4 nm classified as mesoporous particles. This study has shown that the carbonization lignin at a temperature of 700 °C had the highest surface area (i.e. 642.5 m2/g) in which corresponds to the highest specific capacitance (i.e. 28.84 F/g).

Effect of Polyethylene Glycol Additive on Structure and Performance of Active Alumina by Reverse Precipitation Method

2012 ◽  
Vol 487 ◽  
pp. 649-652
Author(s):  
Fang Hu ◽  
Jiao Ma ◽  
Yu Sheng Wu ◽  
Di Zhang
Keyword(s):  
Polyethylene Glycol ◽  
Nitrogen Adsorption ◽  
Precipitation Method ◽  
Infrared Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Active Alumina ◽  
And Performance ◽  
Adsorption Desorption ◽  
Reverse Precipitation

Active alumina (γ-Al2O3) was prepared from NaAlO2 and HNO3 by a reverse precipitation method with addition of polyethylene glycol (PEG). The effect of PEG additived in the different stages during the preparing process was investigated by powder X-ray diffraction (XRD), fourier transform infrared analysis (FTIR) and nitrogen adsorption-desorption. It was found that the mesoporous alumina sample with the PEG additived into the initial HNO3 solution was the most effective at improving the surface area and the pore volume of γ-Al2O3.

scholarly journals Zinc Titanate Nanopowders. Synthesis and Characterization

2021 ◽  
Author(s):  
M Gabal ◽  
Y.M. Al Angari
Keyword(s):  
Nitrogen Adsorption ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Zinc Titanate ◽  
Low Dielectric ◽  
Transmission Electron ◽  
Different Temperatures ◽  
Precursor Decomposition ◽  
Co Precipitation ◽  
Adsorption Desorption

Abstract Zinc titanates nanopowders viz.; Zn2TiO4, ZnTi3O8 and ZnTiO3 were synthesized through the thermal decomposition course of ZnC2O4.2H2O-TiO2 precursor (1:1 mole ratio), prepared via a new co-precipitation method up to 900oC. Thermogravimetric measurement (TG) was utilized to characterize the precursor decomposition while X-ray diffraction (XRD), Fourier transform infra-red (FT-IR) were used to characterize the decomposition products as well as the phase transitions at different temperatures. XRD revealed the starting of titanates formation at 700oC via detecting Zn2TiO4 along with ZnO and TiO2 (anatase) diffraction peaks. By increasing the calcination temperature to 800oC, the ZnO content vanished with the appearing of Zn2Ti3O8 besides ZnTi2O4 and impurities of TiO2 (anatase). Finally at 900oC, the Zn2Ti3O8 content was decomposed into ZnTiO3. Nitrogen adsorption-desorption isotherm of the calcined precursor at 900oC indicated low specific surface area of 7.1 m2 g-1 in accordance with the agglomeration nature estimated via transmission electron microscopy (TEM) study. The conductivity measurements showed semiconducting behavior of the prepared titanates with ferroelectric transition in the range 200-308oC.The obtained low dielectric value suggests the uses of present titanates as a co-fired ceramic or resonator ceramics.

Characterization and Catalytic Performance Study of CuO-ZnO-ZrO2-TiO2 Catalyst for Methanol Synthesis from Carbon Dioxide Hydrogenation

2011 ◽  
Vol 233-235 ◽  
pp. 1552-1555
Author(s):  
Yun Peng Zhao ◽  
Li Hua Jia ◽  
Tao Jing ◽  
De Zhi Sun ◽  
Jong Shik Chung
Keyword(s):  
Methanol Synthesis ◽  
Nitrogen Adsorption ◽  
Space Velocity ◽  
Catalytic Performance ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Performance Study ◽  
Average Pore ◽  
Carbon Dioxide Hydrogenation ◽  
Adsorption Desorption

CuO-ZnO-ZrO2-TiO2 catalyst was prepared by parallel-slurry-mixing-precipitation method combined with addition of surfactant. The catalyst characterizations were investigated by Nitrogen adsorption-desorption, XRD, SEM and EDS. Results show that the average pore diameter of the mesoporous CuO-ZnO-ZrO2-TiO2 catalyst is 3.754 nm, and dispersion of CuOis better on CuO-ZnO-ZrO2-TiO2 catalyst. Under the conditions of reaction temperature of 503 K, reaction pressure of 2.0 MPa, space velocity of 2100 h-1 with a H2/CO2 molar ratio of 3:1, the catalyst exhibited favorable activity for methanol synthesis from CO2 hydrogenation. The selectivity to methanol and the yield of methanol were 27.42% and 4.50%, respectively.

Fabrication and Characterization of Hollow Zirconia Microspheres Using Calcium Carbonate as Template

2016 ◽  
Vol 230 (11) ◽  
Author(s):  
Shengsong Ge ◽  
Weixue Zhu ◽  
Qian Shao
Keyword(s):  
Calcium Carbonate ◽  
Nitrogen Adsorption ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Fabrication And Characterization ◽  
Adsorption Desorption ◽  
Spherical Hollow

AbstractStabilized spherical hollow zirconia was fabricated using calcium carbonate as template through a simple precipitation method. The as-prepared products were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM) and nitrogen adsorption–desorption isotherms (BET). Adsorption performance of the as-prepared products toward Congo red (CR) aqueous solutions was tested and discussed. Results show that the prepared hollow ZrO

Preparation of ZnO nanoflakes and assessment of their removal of HCN, NO2 and SO2 toxic gases

2021 ◽  
Vol 112 (1) ◽  
pp. 10-16
Author(s):  
Thi Hanh Nguyen ◽  
Xuan Manh Pham ◽  
Thanh Nhan Nguyen ◽  
Nhung Hac Thi ◽  
Tuyet Anh DangThi ◽  
...  
Keyword(s):  
Zinc Oxide ◽  
Nitrogen Adsorption ◽  
Zinc Nitrate ◽  
Precipitation Method ◽  
Potential Candidate ◽  
Lauryl Sulfate ◽  
X Ray Diffraction ◽  
Toxic Gases ◽  
Zno Nanoflakes ◽  
Adsorption Desorption

Abstract Zinc oxide nanoflakes were synthesized using the wet precipitation method from aqueous solutions of zinc nitrate and sodium hydroxide. The obtained materials were characterized by means of X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and nitrogen adsorption–desorption methods. The presence of sodium lauryl sulfate in the preparation of zinc oxide resulted in thinner, larger size, and higher specific surface area nanoflakes. The saturated adsorption capacities of zinc oxide nanoflakes for HCN, NO2, and SO2 were 216 mg g–1, 81 mg g–1, and 38 mg g–1, respectively. These results suggest that the material is a potential candidate for the removal of these toxic gases.

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.

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