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Effects of acid treatment duration and sulfuric acid molarity on purification of multi-walled carbon nanotubes

100%
Mortazavi S., Novinrooz A., Reyhani A., Mirershadi S.
Open Physics
|
2010
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vol. 8
|
issue 6
940-946
EN
Multi-walled carbon nanotubes were synthesized using a Fe-Ni bimetallic catalyst supported by MgO using thermal chemical vapor deposition. Purification processes to remove unwanted carbon structures and other metallic impurities were carried out by boiling in sulfuric acid solution. Various analytical techniques such as TGA/DSC, Raman spectroscopy, SEM, HRTEM and EDAX were employed to investigate the morphology, graphitization and quality of the carbon nanotubes. The obtained results reveal the molarity of sulfuric acid and immersed time of the carbon nanotubes in the acid solution is very effective at purifying multi-walled carbon nanotubes. It was also found that 5 M concentration of boiling sulfuric acid for a 3 h treatment duration led to the highest removal of the impurities with the least destructive effect. Moreover, it was observed that acid treatment results in decreasing of CNTs’ diameter.
2
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Utilization of used contact masses from the oxidation state of sulfur(IV) oxide to sulfur(VI) oxide

88%
Trypuć M., Mazurek K., Kiełkowska U., Drużyński S.
Polish Journal of Chemical Technology
|
2007
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vol. 9
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issue 3
26-28
EN
The research was conducted to determine the influence of the urea concentration in the leaching solutions on the efficiency of recovery of vanadium and iron compounds from the used vanadium catalyst from the node of oxidation of sulfur dioxide to sulfur trioxide.
3
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Optimization of rapeseed oil fatty acid esterification with methanol in the presence of sulfuric acid

88%
Brinks J., Malins K., Kampars V., Prilucka J., Apseniece L.
Polish Journal of Chemical Technology
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2013
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vol. 15
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issue 4
54-59
EN
The interest in biodiesel production from low cost feedstocks is still increasing. Such feedstocks usually contain large amounts of free fatty acids, which make the currently employed base catalysts inefficient, thereby promoting the use of acid catalysts. Due to the high activity and low cost, sulfuric acid could become the most widely used acid catalyst for biodiesel production. Research undertaken so far using sulfuric acid for esterifi cation of fatty acids has shown that the products obtained fail to meet the requirements of the standard EN 14214. This paper describes a systematic study of rapeseed oil fatty acids esterification in order to obtain a product complying with the standard EN 14214. The influence of sulfuric acid concentrations (0.1-3.0%), methanol molar ratios (1:1-20:1) and reaction time (0-360 min) was evaluated. Finally, a two-stage esterification process was developed, where in optimal conditions esterification yield of 97.8% and ester content of 99.6% were achieved.
4
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The influence of leaching solution pH and addition of peroxide hydrogen on the recovery of some components from the used vanadium catalyst with urea solutions

88%
Mazurek K., Trypuć M., Białowicz K., Drużyński S.
Polish Journal of Chemical Technology
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2008
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vol. 10
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issue 4
34-36
EN
The research was conducted to determine the influence of the pH of the leaching solutions and hydrogen peroxide addition on the efficiency of the recovery of vanadium, potassium and iron compounds from the used vanadium catalyst from the node of oxidation of sulfur dioxide to sulfur trioxide.
5
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Investigation of oxidation process of 3-aminotoluene with ozone in presence of manganese bromide catalyst

75%
Galstyan A., Galstyan G., Timoshyna L.
Teka Commission of Motorization and Power Industry in Agriculture
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2016
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vol. 16
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issue 2
6
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Extraction of vanadium compounds from the used vanadium catalyst with the potassium hydroxide solution

75%
Mazurek K., Białowicz K., Trypuć M.
Polish Journal of Chemical Technology
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2010
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vol. 12
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issue 1
23-28
EN
The paper presents the results of the research on the degree of the recovery of vanadium(V) from the used vanadium catalyst with the use of KOH solution. The extraction was performed at 293 - 323 K, for 0.5 to 4 h and the catalysts of the variable grain diameter. The concentration of the extracting solution was varied in the range 5 - 20%. The optimal ratio of solid to liquid phase S/L was determined. Additionally the degree of the recovery of total iron ions was presented.
7
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Extraction of vanadium and potassium compounds from the spent vanadium catalyst from the metallurgical plant

51%
Mazurek K.
Polish Journal of Chemical Technology
|
2012
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vol. 14
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issue 2
49-53
EN
A spent vanadium catalyst, from the plant of metallurgical type, was leached in a sulfuric acid solution to recover vanadium and potassium compounds. The effect of time, temperature, concentration of acid, catalyst particle size and phase ratio was studied. Additionally the concentration of iron, copper, zinc, arsenic and lead compounds was determined. The flow sheet for the proposed process of spent vanadium catalyst leaching is presented.
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