scholarly journals EFFECT OF PHYSICOCHEMICAL PROPERTIES OF d-METAL OXIDES ON SUNFLOWER OIL TRANSESTERIFICATION

2021 ◽  
pp. 113-120
Author(s):  
Yurii Melnyk ◽  
Stepan Melnyk ◽  
Halyna Mahorivska ◽  
Viktor Reutskyy
Keyword(s):  
Specific Surface ◽  
Metal Oxides ◽  
Surface Area ◽  
Specific Surface Area ◽  
Sunflower Oil ◽  
Aqueous Suspension ◽  
Surface Acidity ◽  
Weak Acid ◽  
Transesterification Reaction ◽  
Acidity And Basicity

The physicochemical indicators of d-metal oxides (NiO, CuO, MnO, FeO, PbO, ZnO) which are heterogeneous catalysts for the transesterification process of sunflower oil triglycerides by ethanol and butan-1-ol have been determined. The available specific surface area, surface acidity and basicity, as well as the hydrogen potential change of the catalyst suspension in water were determined for the oxides. The available specific surface area of the oxides was determined by titration of their aqueous suspension with a solution of methylene blue with a predetermined concentration. The surface acidity and basicity of the catalysts were determined by back titration of samples treated with an aqueous solution of ammonia and acetic acid, respectively. It was found that all investigated d-metal oxides have a low specific surface area. The value of specific surface area is in the range of 0.6-1.5 m2/g. The surface acidity and basicity of the catalysts is 0.13-0.27 mmol/g and 0.019-0.066 mmol/g, respectively. It is shown that the change in the aqueous suspension hydrogen potential of the investigated catalysts relative to the distilled water pH is maximum for NiO and ZnO and it is 0.6-0.65, while for CuO this change is the smallest and it is only 0.3. The character of the pH change curves and the pH values of the oxides suspension in equilibrium condition indicate the presence of weak acid sites in the studied catalysts. The indicated catalysts characteristics are compared with the results obtained in the transesterification process of sunflower oil triglycerides by ethanol and butan-1-ol. It was found that there is a correlation between the surface acidity of catalyst and the reaction initial rate of triglycerides transesterification by ethanol and butan-1-ol. At the same time, such a correlation is absent for the surface basicity of the catalysts. This is consistent with the data on the catalysis of the triglyceride transesterification reaction only by strong major active sites. It is concluded that the transesterification reaction of sunflower oil triglycerides by ethanol and butan-1-ol occurs predominantly on the weak acid centers of the d-metal oxides.

scholarly journals Design and Photocatalytic Activity of Mesoporous TiO2/ZrO2 Thin Films

2005 ◽  
Vol 23 (6) ◽  
pp. 497-508 ◽  
Author(s):  
Yu. Gnatyuk ◽  
N. Smirnova ◽  
A. Eremenko ◽  
V. Ilyin
Keyword(s):  
Thin Films ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Surface Acidity ◽  
Sol Gel ◽  
Pluronic P123 ◽  
Vis Spectroscopy ◽  
Gel Technique ◽  
Doped Titania

Optically transparent, crack-free mesoporous titania and zirconia-doped titania thin films were fabricated by the sol—gel technique using the non-ionic amphiphilic triblock copolymer Pluronic P123 as the template. The structure and optical properties of these films were characterized using TEM, low-angle XRD, DTA/TG measurements, UV—vis spectroscopy and hexane adsorption investigations. It was found that addition of ZrO2 into the TiO2 matrix retarded sintering of the films, thereby increasing the specific surface area after treatment up to 500°C. The catalytic activity of the mesoporous TiO2 and TiO2/(5–30%) ZrO2 films in ethanol photo-oxidation increased with increasing specific surface area and surface acidity of the samples.

New Silica Supported Titanium Dioxide Catalysts: Characteristics and Photocatalytic Efficiency in Waste Water Depollution

2006 ◽  
Vol 61 (10) ◽  
pp. 1311-1318 ◽  
Author(s):  
Noureddine Kamil ◽  
Mohamed Khalid El Amrani ◽  
Najiba Benjelloun
Keyword(s):  
Titanium Dioxide ◽  
Photocatalytic Activity ◽  
Specific Surface ◽  
Surface Area ◽  
Calcination Temperature ◽  
Specific Surface Area ◽  
Inductively Coupled Plasma ◽  
Aqueous Suspension ◽  
Textile Dye ◽  
Photocatalytic Efficiency

Silica gel supported titanium dioxide photocatalysts were prepared by sintering TiO2/SiO2 mixtures under variations of TiO2 content, calcination temperature and calcination time. The method allowed to obtain catalyst samples, which can be used in aqueous suspension and which were found to be easily separated by decantation after the photocatalytic treatment. The photocatalytic efficiency of the catalysts was tested by carrying out the photooxidation of the textile dye Acid Red 88 (AR88) in aqueous solution, used as “model” water pollutant. The obtained photoefficiency results were correlated to catalyst physicochemical characteristics, as determined by Inductively Coupled Plasma (ICP) analysis, X-ray diffraction, specific surface area (BET) and scanning electron microscopy (SEM). No positive correlation has been observed between titanium dioxide content and photocatalytic efficiency. The decrease of photocatalytic activity at high calcination temperature (1000 °C) is attributed to the phase transition anatase/rutile as well as to the decreasing specific surface area. According to SEM analysis, no significant fixation of TiO2 on silica is observed for catalysts prepared at low temperature (400 °C). The observed photocatalytic activity is consequently due to free TiO2 particles. The best efficiency is observed for photocatalyst prepared at 800 °C and containing around fifty percent titanium dioxide.

scholarly journals Hydrothermal Synthesis of Three-Dimensional Perovskite NiMnO3 Oxide and Application in Supercapacitor Electrode

Energies ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 36 ◽  
Author(s):  
Hyo-Young Kim ◽  
Jeeyoung Shin ◽  
Il-Chan Jang ◽  
Young-Wan Ju
Keyword(s):  
Hydrothermal Synthesis ◽  
Transition Metal ◽  
Specific Surface ◽  
Metal Oxides ◽  
Surface Area ◽  
Specific Surface Area ◽  
Transition Metal Oxides ◽  
Coulombic Efficiency ◽  
Three Dimensional ◽  
Perovskite Oxide

Supercapacitors are attractive as a major energy storage device due to their high coulombic efficiency and semi-permanent life cycle. Transition metal oxides are used as electrode material in supercapacitors due to their high conductivity, capacitance, and multiple oxidation states. Nanopowder transition metal oxides exhibit low specific surface area, ion diffusion, electrical conductivity, and structural stability compared with the three-dimensional (3D) structure. Furthermore, unstable performance during long-term testing can occur via structural transition. Therefore, it is necessary to synthesize a transition metal oxide with a high specific surface area and a stable structure for supercapacitor application. Transition metal oxides with a perovskite structure control structural transition and improve conductivity. In this study, a NiMnO3 perovskite oxide with a high specific surface area and electrochemical properties was obtained via hydrothermal synthesis at low temperature. Hydrothermal synthesis was used to fabricate materials with an aqueous solution under high temperature and pressure. The shape and composition were regulated by controlling the hydrothermal synthesis reaction temperature and time. The synthesis of NiMnO3 was controlled by the reaction time to alter the specific surface area and morphology. The prepared perovskite NiMnO3 oxide with a three-dimensional structure can be used as an active electrode material for supercapacitors and electrochemical catalysts. The prepared NiMnO3 perovskite oxide showed a high specific capacitance of 99.03 F·g−1 and excellent cycle stability with a coulombic efficiency of 77% even after 7000 cycles.

scholarly journals The Simplest Way to Iodine-Doped Anatase for Photocatalysts Activated by Visible Light

2011 ◽  
Vol 2011 ◽  
pp. 1-13 ◽  
Author(s):  
Václav Štengl ◽  
Tomáš Matys Grygar
Keyword(s):  
Photocatalytic Activity ◽  
Visible Light ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Aqueous Suspension ◽  
Organometallic Compounds ◽  
Orange Ii ◽  
Iodine Doping ◽  
Doped Titania

Iodine-doped TiO2was prepared by thermal hydrolysis of aqueous solutions of the titanium peroxo-complex, which includes no organic solvents or organometallic compounds. The synthesized samples were characterized by X-ray diffraction (XRD), Raman spectroscopy (RS), infrared spectroscopy (IR), specific surface area (BET), and porosity determination (BJH). The morphology and particle size was determined by high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED). All prepared samples have a red-shifted band-gap transition, well crystalline anatase structure, and porous particles with a 100–200 m2 g−1specific surface area. The photocatalytic activity of iodine-doped titania samples was determined by decomposition of Orange II dye during irradiation at 365 nm and 400 nm. Iodine doping promotes the titania photocatalytic activity very efficiently under visible light irradiation. The titania sample with 0.32 wt.% I has the highest catalytic activity during the photocatalyzed degradation of Orange II dye in an aqueous suspension in the UV and visible regions.

Vapor-assisted preparation of Mn/Fe/Co/Zn–Cu bimetallic metal–organic frameworks based on octahedron micron crystals (PCN-6′)

2019 ◽  
Vol 43 (17) ◽  
pp. 6452-6456 ◽  
Author(s):  
Jiangfeng Yang ◽  
Bingjie Du ◽  
Ning Yuan ◽  
Xiaoxia Jia ◽  
Jinping Li
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Pore Volume ◽  
Crystal Morphology ◽  
Metal Organic Framework ◽  
Metal Organic Frameworks ◽  
Strong Acid ◽  
Weak Acid ◽  
Metal Organic

A Cu-based metal–organic framework (PCN-6′) with octahedral crystal morphology was synthesized using a strong acid (HCl) and characterized by SEM, TGA and BET, which showed a larger specific surface area and pore volume than the corresponding counterpart that was prepared using a weak acid (oxalate).

scholarly journals Pengaruh Kalsinasi Hidrotalsit Terhadap Aktivitas Katalitik Pada Reaksi Transesterifikasi Etil Asetat Menjadi Metil Asetat

2018 ◽  
Vol 1 (1) ◽  
pp. 26-37
Author(s):  
Imam Januar
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Methanol Concentration ◽  
Transesterification Reaction

This research is aim to study the optimum of time and calcination ffict on hydrotalcite in transesterification reaction in obtaining metyl ester. The reagen has been used in this reaclion were etyl acetat, methanol and hydrotalcite as catalyst. In the reaction was used various of times; 0,5, 1, 2, 3 hours and various catalysts; calcinated catalyst and non-calcinated catalyst. The caracterization of hydrotalcite has used XRD, BET and FTIR instrument.The result of GC intrepetation showed the decreasing of methanol concentration. The result caracterization hydrotalcite using XRD showed difractogram d= 7,60882; 3,79933 and 8,42876Å. These peaks have similiarity to the d of Mg/Al standar of hydrocalcite. BET intrepetation showed the specific surface area is 12,337 m2/g, averages of pores are 15,352 Å, volume of pores is 3,9 x 10-2 cm3/g. The result of FTIR showed the appearance of hydroxil group with the wavelength; 3450,40 cm-1 and 1635,38 cm-1, CO32- was 1366,66 cm-1  and 660,20 cm-1, MgO was 553,23 cm-1, Zn-O is 447,04 cm-1, these wavelengths showed the characteristic of hydrocalcite. Infrared intrepretation showed that the compound Mg-Zn-AlCO3.4H2O was hydrocalcite

scholarly journals The Structure and Properties of Sepiolite with Partial Lattice Ions Substituted by Aluminum Ions

2021 ◽  
Vol 9 ◽  
Author(s):  
Huiwen Chen ◽  
Junming Geng ◽  
Zepeng Zhang ◽  
Rui Jiang ◽  
Jingya Zhai ◽  
...  
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Bonding Strength ◽  
Surface Acidity ◽  
Functional Materials ◽  
Structure And Properties ◽  
Obvious Change ◽  
Aluminum Ions ◽  
Weather Resistance

Sepiolite was modified with Al3+ via hydrothermal reaction. The substitution amount of Al3+ for Mg2+ and Si4+ located at sepiolite lattice and the influence of substitution amount on the structure, specific surface area, and surface acidity of Al-modified sepiolite were investigated. On this basis, indigo–sepiolite composite pigments were prepared by Al-modified sepiolite and indigo via grinding method to evaluate the influence of Al-modified sepiolite on the structure, bonding strength, and weather resistance of composite pigment. The crystal structure of Al-modified sepiolite had no obvious change after modification. Al3+ mainly substituted Mg2+ located at the octahedron of the sepiolite lattice, and the substitution amount was positively related to the dosage of Al3+. The specific surface area of Al-modified sepiolite decreased and the distribution of channel size became wider after Al modification. In addition, the absolute value of zeta potential decreased as well as the solid acid sites increased with the increase of Al substitution in Al-modified sepiolite. For indigo–sepiolite composite pigments, the structure of Al-modified sepiolite had no obvious change as well. The adsorption amount of indigo in composite pigment after treating by DMSO and Al content as well as weak acid amount in Al-modified sepiolite presented linear correlation, indicating that Al modification could enhance the bonding strength between indigo and Al-modified sepiolite by increasing the amount of coordinated water with Al. For indigo, Al-modified sepiolite could brighten the color and reduce the weather resistance of the prepared composite pigment. The results of this study provide a new idea and basis for regulating the structure and properties of clay and for studying the preparation of composite pigment and clay functional materials.

scholarly journals Hydrothermal and mechanochemical synthesis of crystalline CaCO3

2017 ◽  
Vol 35 (7-8) ◽  
pp. 668-676 ◽  
Author(s):  
J Skubiszewska-Zięba ◽  
B Charmas ◽  
H Waniak-Nowicka
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Aqueous Suspension ◽  
Microwave Treatment ◽  
Porous Structures ◽  
X Ray Diffraction ◽  
X Ray ◽  
Saturated Water ◽  
Crystallite Sizes

Mechanochemical and microwave-assisted hydrothermal (MicroWave Treatment [MWT]) procedures were applied to prepare crystalline CaCO3. Mechanochemical process was carried out at different speeds of rotation (500 or 850 rpm/min), different duration times (30 or 60 min) and in the aqueous suspensions or in dry state. MWT synthesis was conducted in a saturated water vapour or under the layer of water. The crystalline and porous structures of the prepared samples as well as their morphology were investigated using N2 adsorption, X-ray diffraction and scanning electron microscopy methods. As a result, the calcium carbonate samples in the form of calcite were obtained. The materials prepared by the mechanochemical route performed in the aqueous suspension are characterized by smaller crystallite sizes as compared to those obtained without the addition of water. The samples obtained hydrothermally have the largest size of crystallites. Powders prepared by energetical milling possess higher values of specific surface area in relation to the parameter for those synthesized hydrothermally. In the process of hydrothermal treatment, macroporous structure of the prepared materials is created. With the increasing specific surface area of the sample, the size of the crystallites decreased.

Sign in / Sign up

Export Citation Format

Share Document