Search for: colloidal-dispersion
Nanoscale graphene oxide sheets as highly efficient carbocatalysts in green oxidation of benzylic alcohols and aromatic aldehydes, Article Cuihua Xuebao/Chinese Journal of Catalysis ; Volume 38, Issue 4 , 2017 , Pages 745-757 ; 02539837 (ISSN) ; Heidari, M ; Akhavan, O ; Sharif University of Technology
Science Press 2017
Nanoscale graphene oxide (NGO) sheets were synthesized and used as carbocatalysts for effective oxidation of benzylic alcohols and aromatic aldehydes. For oxidation of alcohols in the presence of H2O2 at 80 °C, the NGOs (20% mass fraction) as carbocatalysts showed selectivity toward aldehyde. The rate and yield of this reaction strongly depended on the nature of substituents on the alcohol. For 4-nitrobenzyl alcohol, <10% of it was converted into the corresponding carboxylic acid after 24 h. By contrast, 4-methoxybenzyl alcohol and diphenylmethanol were completely converted into the corresponding carboxylic acid and ketone after only 9 and 3 h, respectively. The conversion rates for...
Quantitative analysis of ultrasonic wave radiation on reversibility and kinetics of asphaltene flocculation, Article 4th International Conference and Exhibition: New Discoveries through Integration of Geosciences, Saint Petersburg, 5 April 2010 through 8 April 2010 ; 2010 ; Najafi, I ; Ghazanfari, M. H ; Kharrat, R ; Ghotbi, C ; Sharif University of Technology
European Association of Geoscientists and Engineers, EAGE 2010
Recently, it was found that ultrasonic wave technology can be used as a method for asphaltene deposits removal from the near wellbore region. However, ultrasounds can affect asphaltene resolution.In this work, asphaltene resolution in several crude oil samples exposed to ultrasonic waves for different time intervals is studied by confocal microscopy. The colloidal structure of flocks is described by analysis of asphaltene particle size distribution to investigate ultrasonic application in solving asphaltene deposition problems.. The results show that for the first 90 minutes of flocculation time, the size of aggregates increases rapidly, and reaction limited aggregation model matches well...
Quantifying the role of ultrasonic wave radiation on kinetics of asphaltene aggregation in a toluene-pentane mixture, Article Petroleum Science and Technology ; Volume 29, Issue 9 , 2011 , Pages 966-974 ; 10916466 (ISSN) ; Mousavi, S. M. R ; Ghazanfari, M.H ; Ghotbi, C ; Ramazani, A ; Kharrat, R ; Amani, M ; Sharif University of Technology
Recently, ultrasonic wave technology has received much attention as a method for removal of asphaltene deposits from the near wellbore region. However, very little is known about another feature of this technology on the kinetics of asphaltene molecules aggregation. In this work, the kinetics of asphaltene flocculation in several crude oil samples exposed to ultrasonic waves for different time intervals is studied by confocal microscopy. The colloidal structural evolutions of flocks are described by analysis of size distribution of flocculated asphaltene particles. The results show that for the first 90 min of flocculation time, the size of aggregates increases rapidly, and a...
Voltammetric studies of sumatriptan on the surface of pyrolytic graphite electrode modified with multi-walled carbon nanotubes decorated with silver nanoparticles, Article Talanta ; Volume 80, Issue 1 , 2009 , Pages 31-38 ; 00399140 (ISSN) ; Shahrokhian, S ; Ghorbani Bidkorbeh, F ; Sharif University of Technology
Multi-walled carbon nanotube decorated with silver nanoparticles (AgNPs-MWCNT) is used as an effective strategy for modification of the surface of pyrolytic graphite electrode (PGE). This modification procedure improved colloidal dispersion of the decorated MWCNTs in water, affording uniform and stable thin films for altering the surface properties of the working electrode. Robust electrode for sensing applications is obtained in a simple solvent evaporation process. The electrochemical behavior of sumatriptan (Sum) at the bare PGE and AgNPs-MWCNT modified PGE is investigated. The results indicate that the AgNPs-MWCNT modified PGE significantly enhanced the oxidation peak current of Sum. A...
Multi-walled carbon nanotubes with immobilised cobalt nanoparticle for modification of glassy carbon electrode: Application to sensitive voltammetric determination of thioridazine, Article Biosensors and Bioelectronics ; Volume 24, Issue 11 , 2009 , Pages 3235-3241 ; 09565663 (ISSN) ; Ghalkhani, M ; Adeli, M ; Amini, M. K ; Sharif University of Technology
Multi-walled carbon nanotubes (MWCNTs) were immobilised with cobalt nanoparticles and analyzed by transmission electron microscopy. This modification procedure substantially improved colloidal dispersion of the immobilised MWCNTs in water and organic solvents, yielding uniform and stable thin films for modification of the glassy carbon electrode surface. The modified electrode showed an efficient catalytic role for the electrochemical oxidation of thioridazine (TR), leading to remarkable decrease in its oxidation overpotential of approximately 100 mV and enhancement of the kinetics of the electrode reaction, which can be confirmed by increasing in the peak current and sharpness of the peak....