Electrochemical Synthesis of Zirconia

1988 ◽  
Vol 121 ◽  
Author(s):  
Jay A. Switzer ◽  
Richard J. Phillips
Keyword(s):  
Aqueous Solution ◽  
Surface Area ◽  
Tetragonal Zirconia ◽  
Electrochemical Cells ◽  
Monoclinic Zirconia ◽  
Zirconia Powder ◽  
Zirconyl Nitrate ◽  
Hydroxide Ion ◽  
Divided Cell ◽  
Hydrated Zirconia

ABSTRACTZirconia powder was produced in aqueous solution from zirconyl nitrate using electrogenerated base. Both divided and undivided electrochemical cells were used. In the divided cell, hydroxide ion was discharged in the cathode compartment, and hydrated zirconia was produced. The as-produced material was weakly agglomerated, amorphous, and had a surface area of up to 316 m2/g. The surface area of the powder did not vary systematically with the electrosynthesis current density, but did depend on subsequent processing. Crystalline zirconia was produced by calcining in air at temperatures above 400°C. Tetragonal zirconia was the only phase observed until about 800°C. After calcining at 800°C the crystallite size increased to about 20nm and about 34% monoclinic zirconia was produced. When an undivided cell was used, the pH remained constant (1–1.5) throughout the electrosynthesis, and amorphous zirconia deposited on the cathode.

Preparation and characterisation of vanadium pentoxide supported rhodium catalyst

1988 ◽  
Vol 46 ◽  
pp. 946-947
Author(s):  
A. Legrouri
Keyword(s):  
Aqueous Solution ◽  
Thermal Decomposition ◽  
Physicochemical Properties ◽  
Surface Area ◽  
Vanadium Pentoxide ◽  
High Purity ◽  
Gas Adsorption ◽  
Rhodium Catalyst ◽  
Optical Methods ◽  
Reducible Oxides

The industrial importance of metal catalysts supported on reducible oxides has stimulated considerable interest during the last few years. This presentation reports on the study of the physicochemical properties of metallic rhodium supported on vanadium pentoxide (Rh/V2O5). Electron optical methods, in conjunction with other techniques, were used to characterise the catalyst before its use in the hydrogenolysis of butane; a reaction for which Rh metal is known to be among the most active catalysts.V2O5 powder was prepared by thermal decomposition of high purity ammonium metavanadate in air at 400 °C for 2 hours. Previous studies of the microstructure of this compound, by HREM, SEM and gas adsorption, showed it to be non— porous with a very low surface area of 6m2/g3. The metal loading of the catalyst used was lwt%Rh on V2Q5. It was prepared by wet impregnating the support with an aqueous solution of RhCI3.3H2O.

scholarly journals Microwave Synthesis, Characterization and Perspectives of Wood Pencil-Derived Carbon

2022 ◽  
Vol 12 (1) ◽  
pp. 410
Author(s):  
Nikolaos Chalmpes ◽  
Georgios Asimakopoulos ◽  
Maria Baikousi ◽  
Constantinos E. Salmas ◽  
Dimitrios Moschovas ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Surface Area ◽  
Microwave Synthesis ◽  
Chemical Activation ◽  
Added Value ◽  
Maximum Adsorption Capacity ◽  
Carbon Nanosheets ◽  
Process Stage ◽  
Domestic Microwave Oven ◽  
Original Length

More than 14 billion pencils are manufactured and used globally every year. On average, a pencil is discarded after 60% of its original length has been depleted. In the present work we propose a simple and affordable way of converting this non-neglectable amount of waste into added value carbon product. In particular, we demonstrate the microwave synthesis of carbon from the wood pencil with and without chemical activation. This could be a process stage before the final recycling of the expensive graphite core. In the latter case, irradiation of the wood pencil in a domestic microwave oven heats up the pencil’s graphite core, thus inducing carbonization of its wood casing. The carbonized product consists of amorphous carbon nanosheets having relatively low surface area. However, if the wood pencil is soaked in 50% KOH aqueous solution prior to microwave irradiation, a significantly higher surface area of carbon is obtained, consisting of irregular-shaped porous particles. Consequently, the obtained carbon can easily decolorize a methylene blue aqueous solution, can be used to make pocket warmers or gunpowder, and lastly, serves as an excellent adsorbent towards Cr(VI) removal from water, showing a maximum adsorption capacity of 70–75 mg/g within 24 h at 23 °C, pH = 3.

Raman spectra of tetragonal zirconia: powder to zircaloy oxide frequency shift

2001 ◽  
Vol 288 (2-3) ◽  
pp. 241-247 ◽  
Author(s):  
Pierre Barbéris ◽  
Gaëlle Corolleur-Thomas ◽  
René Guinebretière ◽  
Thérèse Merle-Mejean ◽  
Andrei Mirgorodsky ◽  
...  
Keyword(s):  
Frequency Shift ◽  
Raman Spectra ◽  
Tetragonal Zirconia ◽  
Zirconia Powder

scholarly journals Removal of Lead and Cadmium Ions from Aqueous Solution by Adsorption on a Low-Cost Phragmites Biomass

Processes ◽  
2019 ◽  
Vol 7 (7) ◽  
pp. 406 ◽  
Author(s):  
Abdulaziz N. Amro ◽  
Mohammad K. Abhary ◽  
Muhammad Mansoor Shaikh ◽  
Samah Ali
Keyword(s):  
Aqueous Solution ◽  
Metal Ions ◽  
Surface Area ◽  
Metal Ion ◽  
Low Cost ◽  
Waste Water Treatment ◽  
Study Data ◽  
Small Surface ◽  
Cadmium Ions ◽  
Lead And Cadmium

In recent years, the interest in waste water treatment increased to preserve the environment. The objective of this study is the removal of lead and cadmium ions from aqueous solution by treated Phragmites biomass (TPB). TPB was characterized by using Fourier transform infrared spectroscopy (FTIR) and energy dispersive X-ray analysis (EDS) which indicates the presence of functional groups that may be responsible of metal adsorption such as hydroxyl, carbonyl, sulfonate and carboxylate. Characterization by scanning electron microscopy (SEM) and surface area analysis using the Brunauer–Emmett–Teller method (BET) illustrated that TPB is nonporous with a small surface area. The influences of various experimental factors were investigated; the proposed method recommended the extraction of Pb+2 and Cd+2 metal ions by TPB at pH 5.0. A contact time of 60 and 45 min was required for the adsorption 50 mL (50 ppm) Pb+2 and Cd+2 respectively to reach equilibrium when 0.10 g TPB was used. The optimum TPB dosage was 0.20 g for adsorption both metal ions when adsorbate solution was 50 mL (50 ppm). Particle sizes of 0.125–0.212 mm showed the best metal ion removal of both metal ions. Thermodynamic study illustrated that both metal ions correlate more with Langmuir isotherm. Furthermore, chemisorption of Pb+2 and Cd+2 on TPB was more likely according to kinetic study data.

scholarly journals Adsorption of Ammonium Nitrogen from Aqueous Solution on Chemically Activated Biochar Prepared from Sorghum Distillers Grain

2019 ◽  
Vol 9 (23) ◽  
pp. 5249 ◽  
Author(s):  
Derlin Hsu ◽  
Changyi Lu ◽  
Tairan Pang ◽  
Yuanpeng Wang ◽  
Guanhua Wang
Keyword(s):  
Aqueous Solution ◽  
Specific Surface ◽  
Adsorption Capacity ◽  
Surface Area ◽  
Specific Surface Area ◽  
Adsorption Process ◽  
Ammonium Nitrogen ◽  
Activated Biochar ◽  
Distillers Grain ◽  
Kinetics And Isotherms

Chemically activated biochars prepared from sorghum distillers grain using two base activators (NaOH and KOH) were investigated for their adsorption properties with respect to ammonium nitrogen from aqueous solution. Detailed characterizations, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetry (TG), and specific surface area analyses, were carried out to offer a broad evaluation of the prepared biochars. The results showed that the NaOH- and KOH-activated biochars exhibited significantly enhanced adsorption capacity, by 2.93 and 4.74 times, respectively, in comparison with the pristine biochar. Although the NaOH-activated biochar possessed larger specific surface area (132.8 and 117.7 m2/g for the NaOH- and KOH-activated biochars, respectively), the KOH-activated biochar had higher adsorption capacity owing to its much higher content of functional groups. The adsorption kinetics and isotherms of the KOH-activated biochar at different temperatures were further studied. The biochar had a maximum adsorption capacity of 14.34 mg/g at 45 °C, which was satisfactory compared with other biochars prepared using different feedstocks. The adsorption process followed pseudo-second-order kinetics, and chemical adsorption was the rate-controlling step. The equilibrium data were consistent with the Freundlich isotherm, and the thermodynamic parameters suggested that the adsorption process was endothermic and spontaneous. Consequently, this work demonstrates that chemically activated biochar from sorghum distillers grain is effective for ammonium nitrogen removal.

scholarly journals Preparation of Zirconia Nanofibers by Electrospinning and Calcination with Zirconium Acetylacetonate as Precursor

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1067 ◽  
Author(s):  
Vyacheslav V. Rodaev ◽  
Svetlana S. Razlivalova ◽  
Andrey O. Zhigachev ◽  
Vladimir M. Vasyukov ◽  
Yuri I. Golovin
Keyword(s):  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Heterogeneous Catalysts ◽  
Tetragonal Zirconia ◽  
Nitrogen Adsorption ◽  
Average Diameter ◽  
High Specific Surface Area ◽  
X Ray ◽  
Adsorption Analysis

For the first time, zirconia nanofibers with an average diameter of about 75 nm have been fabricated by calcination of electrospun zirconium acetylacetonate/polyacrylonitrile fibers in the range of 500–1100 °C. Composite and ceramic filaments have been characterized by scanning electron microscopy, thermogravimetric analysis, nitrogen adsorption analysis, energy-dispersive X-ray spectroscopy, and X-ray diffractometry. The stages of the transition of zirconium acetylacetonate to zirconia have been revealed. It has been found out that a rise in calcination temperature from 500 to 1100 °C induces transformation of mesoporous tetragonal zirconia nanofibers with a high specific surface area (102.3 m2/g) to non-porous monoclinic zirconia nanofibers of almost the same diameter with a low value of specific surface area (8.3 m2/g). The tetragonal zirconia nanofibers with high specific surface area prepared at 500 °C can be considered, for instance, as promising supports for heterogeneous catalysts, enhancing their activity.

scholarly journals Changes in the Surface Area of Silica-supported 12-Molybdophosphoric Acid in Relation to the Degree of Loading and the Calcination Temperature

1994 ◽  
Vol 11 (2) ◽  
pp. 83-93 ◽  
Author(s):  
L.B. Khalil ◽  
W.E. Mourad ◽  
B.S. Girgis
Keyword(s):  
Aqueous Solution ◽  
Surface Area ◽  
Silica Gel ◽  
Heteropoly Acid ◽  
Surface Acidity ◽  
Molybdophosphoric Acid ◽  
Surface Species ◽  
Considerable Decrease ◽  
Acidic Aqueous Solution

A technical silica gel (Grace-113) was impregnated with 12-molybdophosphoric solution to attain loadings of 0.72–13.4 wt.%. The air-dried solids were then calcined for 3 h at 400, 600 and 800°C, respectively, followed by determination of their N2 adsorption isotherms. The silica gel was thermally stable and suffered about 15% loss in area at 800°C. The impregnated silicas showed considerable decrease in surface area as a function of their heteropoly acid content. Two processes are suggested as taking part in the modification of pore structure: (1) diffusion of the aqueous heteropoly acid solution and its subsequent deposition; and (2) dissolution of silica gel in the acidic aqueous solution followed by interaction with HPMo to form either molybdosilicate or P–Si exchange products. Correlation with the previously studied catalytic conversion of isopropanol indicated that the activity was independent of the surface area. Catalytic dehydration on the 600°C and 800°C products seems to be associated with silicate, molybdate or MoO3 surface species rather than being due to surface acidity or the extent of the surface area.

scholarly journals Investigation on adsorption capacity of TiO2-P25 nanoparticles in the removal of a mono-azo dye from aqueous solution: A comprehensive isotherm analysis

2014 ◽  
Vol 20 (1) ◽  
pp. 97-107 ◽  
Author(s):  
Mohammad Behnajady ◽  
Shahrzad Yavari ◽  
Nasser Modirshahla
Keyword(s):  
Aqueous Solution ◽  
Crystallite Size ◽  
Surface Area ◽  
High Surface ◽  
High Surface Area ◽  
Correlation Coefficients ◽  
Average Crystallite Size ◽  
Isotherm Models ◽  
Equilibrium Data ◽  
Pseudo Second Order

In this work TiO2-P25 nanoparticles with high surface area have been used as adsorbent for the removal of C.I Acid Red 27 (AR27), as an organic contaminant from aqueous solution. Characteristics of phases and crystallite size of TiO2-P25 nanoparticles were achieved from XRD and the surface area and pore size distribution were obtained from BET and BJH techniques. TiO2-P25 nanoparticles with almost 80% anatase and 20% rutile phases, the average crystallite size of 18 nm, have specific surface area of 56.82 m2 g-1. The effect of various parameters like initial AR27 concentration, pH, contact time and adsorbent dosage has been carried out in order to find desired adsorption conditions. The desired pH for adsorption of AR27 onto TiO2-P25 nanoparticles was 3. The equilibrium data were analyzed with various 2-, 3- and 4-parameter isotherm models. Equilibrium data fitted very well by the 4-parameter Fritz-Schluender model. Results of adsorption kinetics study indicated that the pseudo-second order kinetics provided the best fit with correlation coefficients close to unity.

Hierarchically porous carbons from an emulsion-templated, urea-based deep eutectic

2017 ◽  
Vol 5 (31) ◽  
pp. 16376-16385 ◽  
Author(s):  
Katya Kapilov-Buchman ◽  
Lotan Portal ◽  
Youjia Zhang ◽  
Nina Fechler ◽  
Markus Antonietti ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Specific Surface ◽  
Porous Structure ◽  
Surface Area ◽  
Porous Carbon ◽  
High Specific Surface Area ◽  
Hierarchically Porous ◽  
Carbon Monolith ◽  
A Chain ◽  
Micrometer Scale

A hierarchically porous carbon monolith (97% porosity) was generated through the carbonization of an emulsion-templated monolith formed from a chain extended, urea-based, deep-eutectic polymer. The highly interconnected micrometer-scale porous structure had a high specific surface area (812 m2 g−1, largely microporous) and exhibited promising results for aqueous solution sorption applications.

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