Thermal oxidation of graphite as the first step for graphene preparation: effect of heating temperature and time

2020 ◽  
Vol 56 (5) ◽  
pp. 3675-3691
Author(s):  
Sujith S. Nair ◽  
Tuhin Saha ◽  
Pranab Dey ◽  
Sambhu Bhadra
2008 ◽  
Vol 55-57 ◽  
pp. 293-296 ◽  
Author(s):  
E. Wongrat ◽  
P. Pimpang ◽  
N. Mangkorntong ◽  
Supab Choopun

ZnO nanostructures were synthesized by thermal oxidation reaction from zinc powder and then impregnated by gold colloid. The gold colloid was prepared by chemical reduction technique and had red color. The heating temperature and sintering time of thermal oxidation were 700 °C and 24 hours, respectively under oxygen atmosphere. The morphology of ZnO nanostructures and ZnO impregnated gold colloid were studied by field emission scanning electron microscope (FE-SEM). The diameter and length of pure ZnO and ZnO impregnated gold colloid were about the same value and were in the range of 100-500 nm and 2.0-7.0 µm, respectively. The ethanol sensing properties of ZnO impregnated by gold colloid were tested in ethanol atmosphere at ethanol concentrations of 1000 ppm and at an operating temperature of 260-360 °C. It was found that the sensitivity and response time were improved for gold impregnated sensor with an optimum operating temperature of 300°C due to the enhanced reaction between the ethanol and the adsorbed oxygen at an optimum temperature.


2012 ◽  
Vol 488-489 ◽  
pp. 437-441
Author(s):  
Raden Dadan Ramdan ◽  
Budi Prawara ◽  
Rochim Suratman

Thermal oxidation is believed as an important phenomenon that naturally occurs on material subjected to elevated temperature such as NiAl-Al2O3 coated material. In the present study, thermal oxidation on this coated layer was prepared by heating processes of NiAl-Al2O3 coated on mild carbon steel. Deposition of NiAl-Al2O3 was performed by high-velocity oxy fuel (HVOF) process, whereas subsequent heating processes were performed at 3 different temperatures 600oC, 800oC and 1000oC. After the process, the effects of this thermal oxidation process on the phases formation, microstructure and qualitative toughness of thermally sprayed NiAl-Al2O3 coating were investigated. The results showed that significant amount of NiAl-Al2O3 phase was transformed into NiO phase by heating process at temperature higher than 800°C. In addition, decreasing of thickness of the coating layer was also found as the service temperature increases from 800 to 1000oC. Increasing of hardness was also observed as the heating temperature increases, which is predicted due to the formation of excessive oxide on the coating layer that in turn might impart the toughness of this layer. These conditions suggested that a careful determination of service temperature have to be taken in order to avoid excessive oxidation of the coating layer.


Author(s):  
А.В. БОРИСЕВИЧ ◽  
Т.И. ЧАЛЫХ

Проведено исследование процесса термического окисления подсолнечного и кокосового масел при 175°С в условиях поточного обжаривания в них картофеля и куриных наггетсов с отбором проб растительного масла через каждый час работы. Для определения количества продуктов окисления был использован метод спектрофотометрии. Установлено, что после 10 ч проведения обжарки исследованные фритюрные масла были пригодны для дальнейшего использования (Е < 15). Показатель оптической плотности кокосового масла независимо от вида обжариваемого в нем продукта в течение всего эксперимента был ниже аналогичного показателя подсолнечного масла. Предложена оптимальная температура нагрева кокосового масла для обжаривания во фритюре – не более 0,9 от температуры точки дымления. Показано более активное накопление вторичных продуктов окисления во фритюрном масле при обжаривании продукта животного происхождения по сравнению с обжариванием продукта растительного происхождения, что можно объяснить наличием в составе картофеля ингибиторов окисления (пероксидаза, каталаза, витамин С). The study of the process of thermal oxidation of sunflower and coconut oils at 175°C under conditions of in-line frying of potatoes and chicken nuggets in them with the sampling of vegetable oil every hour of operation was carried out. To determine the amount of oxidation products the method of spectrophotometry was used. It was found that after 10 hours of roasting, the studied fryer oils were suitable for further use (E < 15). The optical density index of coconut oil, regardless of the type of product fried in it, was lower than that of sunflower oil throughout the experiment. The optimal heating temperature of coconut oil for deep frying is proposed-no more than 0,9 of the temperature of the smoking point. A more active accumulation of secondary oxidation products in deep-frying oil is shown when frying an animal product compared to frying a vegetable product, which can be explained by the presence of oxidation inhibitors (peroxidase, catalase, vitamin C) in the composition of potatoes.


2013 ◽  
Vol 538 ◽  
pp. 150-153
Author(s):  
Tian Hong Guo ◽  
Juan Li ◽  
Yong Cai Zhang ◽  
Zhan Jun Yang

An in situ thermal oxidation strategy was proposed for synthesizing different SnO2 nanostructures, using our homemade SnS2 nanoplates as a precursor. The characterization results from X-ray diffraction, energy dispersive X-ray spectroscopy, and field emission scanning electron microscope revealed that the heating temperature played an important role in the microstructure and composition of the resultant products. By heating the SnS2 nanoplates in air at 400, 600 and 800 °C for 5 h, nanoplates, a mixture of nanoplates and nanoparticles, and nanoparticles of SnO2 were synthesized, respectively. The residual S was about 2.2 mol % in the product synthesized at 400 °C, while no residual S was detected in the products synthesized at 600 and 800 °C.


2019 ◽  
Author(s):  
Chem Int

The study aims to use an adsorbent natural based of Moroccan oil shale of Timahdit area (Y layer) in a physical-chemical adsorption process for treating industrial discharges colorful. The used adsorbent is the insoluble party of the sub-critical extraction of decarbonized oil shale of Timahdit. The tests performed on the methylene blue (MB), showed a strong elimination in the first 10 minutes. The influences of various experimental parameters were studied: mass ratio of adsorbent, time and temperature of thermal treatment, contact time, pH of MB and heating temperature of solution on the parameters of material were studied. The experimental results have shown that the adsorption of methylene blue dye by the adsorbent is more than 90% at initial pH a range 6-7 at room temperature for 30 minutes. The process is simple and the adsorbent produced is a new material with interesting adsorption capacities of moderate cost which does not require an activating agent and can be used as industrial adsorbent for the decontamination of effluents containing organic pollutants.


2011 ◽  
Vol 53 (10) ◽  
pp. 634-638 ◽  
Author(s):  
Vesna Alar ◽  
Ivan Esih ◽  
Ivan Budic ◽  
Slavonski Brod

2020 ◽  
Vol 56 (4) ◽  
pp. 18-20
Author(s):  
A.D. Koval ◽  
◽  
A.N. Belov ◽  
A.V. Grishkova ◽  
A.V. Mironova ◽  
...  

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