scholarly journals The Thermal Activation of Nsu Clay for Enhanced Alumina Leaching Response

2019 ◽  
Vol 16 ◽  
pp. 34-46
Author(s):  
Udochukwu Mark ◽  
Charles Nwachukwu Anyakwo ◽  
Okechukwu Onyemaobi ◽  
Chijioke Samson Nwobodo
Keyword(s):  
Activation Energy ◽  
Thermal Activation ◽  
Leach Solution ◽  
Kaolinite Clay ◽  
Alumina Production ◽  
Calcination Temperatures ◽  
Activation Conditions ◽  
Solid Liquid ◽  
Heating Up ◽  
Better Than

The thermal activation conditions for enhancing the leaching of alumina from Nsu clay from south-eastern Nigeria was investigated. The clay assayed 28.9% and 50.59% , comprising mainly kaolinite mineral (82.6%) and quartz (12.5%). Thermal activation rendered the alumina in the clay acid-soluble by transforming the clay from its crystalline nature to an amorphous phase or metakaolinite. The clay samples were heated at calcination temperatures of 500, 600, 700, 800, and 900 °C at holding times of 30, 60, and 90 minutes. Uncalcined clay samples and samples calcined at 1000 °C (holding for 60 minutes) were used in the control experiments. Leaching of alumina from the resulting clay calcines passing 300 μm sieve (-50 mesh) was done in 1M hydrochloric acid solution at room temperature using a solid/liquid ratio of 0.02g/ml and shaking speed of 100 rpm. The solubility data given by the fraction of Al ion taken into leach solution showed that the clay calcined at 700 °C (holding for 60 minutes) responded most to leaching. In general, it was observed that samples calcined for 60 minutes responded better than those held for 30 or 90 minutes. The activation energies for leaching the clay calcines were 29.50, 32.92, 26.71, 30.18, 29.18, and 33.24 kJ/mol for samples calcined for 60 minutes at 500, 600, 700, 800, 900, and 1000 °C, respectively. The activation energy of leaching for the uncalcined sample was 35.07 kJ/mol. Thus, calcines produced at 700 °C (holding for 60 minutes) had the highest leaching response for alumina and the lowest leaching activation energy of 26.71 kJ/mol. It is concluded therefore that Nsu kaolinite clay should be best calcined for alumina yield by heating up to 700 °C and holding for 60 minutes at that temperature. The clay deposit can be used as alternative resource for alumina production.

About the Electrical Activation of 1×1020 cm-3 Ion Implanted Al in 4H-SiC at Annealing Temperatures in the Range 1500 - 1950°C

2018 ◽  
Vol 924 ◽  
pp. 333-338 ◽  
Author(s):  
Roberta Nipoti ◽  
Alberto Carnera ◽  
Giovanni Alfieri ◽  
Lukas Kranz
Keyword(s):  
Activation Energy ◽  
Sheet Resistance ◽  
Annealing Time ◽  
Thermal Activation ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Thermal Activation Energy ◽  
Electrical Activation ◽  
Temperature Range ◽  
Annealing Temperatures

The electrical activation of 1×1020cm-3implanted Al in 4H-SiC has been studied in the temperature range 1500 - 1950 °C by the analysis of the sheet resistance of the Al implanted layers, as measured at room temperature. The minimum annealing time for reaching stationary electrical at fixed annealing temperature has been found. The samples with stationary electrical activation have been used to estimate the thermal activation energy for the electrical activation of the implanted Al.

Process optimization of chili flavor beef tallow and analysis of its volatile compounds by GC-IMS

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Hang Li ◽  
Jiamin Liu ◽  
Zhanzhong Wang ◽  
Xiaodong Liu ◽  
Xichun Yan ◽  
...  
Keyword(s):  
Volatile Compounds ◽  
Ion Mobility ◽  
Beef Tallow ◽  
High Performance ◽  
Raw Materials ◽  
Chromatic Aberration ◽  
Frying Temperature ◽  
Frying Time ◽  
Solid Liquid ◽  
Better Than

Abstract With chili and liquid beef tallow as the main raw materials, the processing conditions of chili flavor beef tallow were explored. Gas chromatograpy-ion mobility spectrometry (GC-IMS) was used to determine the volatile compounds in chili flavor beef tallow. The capsaicin and dihydrocapsaicin in chili flavor beef tallow were determined by high performance liquid chromatography (HPLC). The optimum technological conditions were determined, and the index of chromatic aberration, cholesterol was also determined. Based on GC-IMS analysis, 102 kinds of volatile compounds were detected, and the sample III (the ratio of solid–liquid was 1:5, the frying temperature was 120 °C, and the frying time was 15 min) performed better than other samples. The preparation of chili beef tallow improves its antioxidant activity and makes its aroma more intense and more in line with the taste of Chinese people, which provides a theoretical and practical basis for the development of spice beef tallow in the future.

Temperature/Doping-Dependency of the Electrical Properties of the Nickel Doped Copper Oxide Thin Films

2021 ◽  
Vol 16 (2) ◽  
pp. 163-169
Author(s):  
Alaa Y. Mahmoud ◽  
Wafa A. Alghameeti ◽  
Fatmah S. Bahabri
Keyword(s):  
Thin Films ◽  
Activation Energy ◽  
Electrical Properties ◽  
Thermal Activation ◽  
Doping Concentration ◽  
Energy Gap ◽  
Cupric Oxide ◽  
Electrical Energy ◽  
Thermal Activation Energy ◽  
Ni Doping

The electrical properties of the Nickel doped cupric oxide Ni-CuO thin films with various doping concentrations of Ni (0, 20, 30, 70, and 80%) are investigated at two different annealing temperatures; 200 and 400 °C. The electrical properties of the films; namely thermal activation energy and electrical energy gap are calculated and compared. We find that for the non-annealed Ni-CuO films, both thermal activation energy and electrical energy gap are decreased by increasing the doping concentration, while for the annealed films, the increase in the Ni doping results in the increase in thermal activation energy and electrical energy gap for most of the Ni-CuO films. We also observe that for a particular concentration, the annealing at 200 °C produces lower thermal activation energy and electrical energy gap than the annealing at 400 °C. We obtained two values of the activation energy varying from -5.52 to -0.51 eV and from 0.49 to 3.36 eV, respectively, for the annealing at 200 and 400 °C. We also obtained two values of the electrical bandgap varying from -11.05 to -1.03 eV and from 0.97 to 6.71 eV, respectively, for the annealing at 200 and 400 °C. It is also noticeable that the increase in the doping concentration reduces the activation energy, and hence the electrical bandgap energies.

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