Thermal analysis of physical and chemical changes occuring during regeneration of activated carbon

High-temperature thermal process is a commercial way of regeneration of spent granular activated carbon. The paper presents results of thermal analysis conducted in order to examine high-temperature regeneration of spent activated carbon, produced from coconut shells, previously used in drinking water treatment. Results of performed thermogravimetric analysis, derivative thermogravimetric analysis, and differential thermal analysis, enabled a number of hypotheses to be made about different phases of activated carbon regeneration, values of characteristic parameters during particular process phases, as well as catalytic impact of inorganic materials on development of regeneration process. Samples of activated carbon were heated up to 1000?C in thermogravimetric analyser while maintaining adequate oxidizing or reducing conditions. Based on diagrams of thermal analysis for samples of spent activated carbon, temperature intervals of the first intense mass change phase (180-215?C), maximum of exothermic processes (400-450?C), beginning of the second intense mass change phase (635-700?C), and maximum endothermic processes (800-815?C) were deter-mined. Analysing and comparing the diagrams of thermal analysis for new, previously regenerated and spent activated carbon, hypothesis about physical and chemical transformations of organic and inorganic adsorbate in spent activated carbon are given. Transformation of an organic adsorbate in the pores of activated carbon, results in loss of mass and an exothermic reaction with oxygen in the vapour phase. The reactions of inorganic adsorbate also result the loss of mass of activated carbon during its heating and endothermic reactions of their degradation at high temperatures.

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A DTA Study on HVOF Thermally Sprayed WC–M Coatings

Materials Science Forum ◽

10.4028/www.scientific.net/msf.566.155 ◽

2007 ◽

Vol 566 ◽

pp. 155-160

Author(s):

M. Heydarzadeh Sohi ◽

Shahin Khameneh Asl ◽

Kazuyuki Hokamoto ◽

M. Rezvani

Keyword(s):

Heat Treatment ◽

Thermal Analysis ◽

Differential Thermal Analysis ◽

High Temperature ◽

Amorphous Phase ◽

Exothermic Reaction ◽

Intermetallic Phase ◽

Chemical Compositions ◽

Crystalline Phases ◽

Sprayed Coatings

Five types of tungsten carbide based powders with different chemical compositions (WC-12Co, WC-17Co, WC-10Ni, WC-10Co-4Cr and WC- 20Cr-7Ni) were deposited onto ST37 mild steel substrate using high velocity oxy fuel (HVOF) spray technique. The feedstock powders and sprayed coatings were studied by using X-ray diffraction (XRD), and differential thermal analyzing (DTA). The results were shown during HVOF thermal spraying, WC-M powders become partially melted before being sprayed on the surface of the substrate with supersonic speed. In these types of coatings, the crystallographic structures are normally non equilibrium, because the cooling rates of the deposited splats are very high due to the cold substrate acting as a thermal sink. These partially melted powders are then rapidly solidified to an amorphous phase. XRD analysis showed that the amorphous phase was existed in all of the as sprayed coatings. The amorphous phase in WC-12Co, WC-17Co and WC-10Ni coatings was transformed to crystalline phases by heat treatment at high temperature. Heat treatment of these coatings at high temperature also resulted in partially dissolution of WC particles and formation of new crystalline phases. In cobalt base coatings, the new phases were eta carbide phases like Co6W6C and Co3W3C but in WC-10Ni coating a NiW intermetallic phase was formed. Heat treatment of WC-10Co-4Cr and WC-20Cr-7Ni coatings did not change the amorphous phases in these coatings. Differential thermal analysis of cobalt containing coatings revealed an exothermic reaction at approximately 880°C. This exothermic reaction may be related to the transformation of the amorphous phase to eta phases. On the contrary, DTA analysis of feedstock powders of these coatings showed an endothermic reaction at approximately 1000°C. DTA analyses of nickel containing cermets also showed similar results. Differential thermal analysis of chromium containing cermets did not show any noticeable exothermic or endothermic reactions.

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Dehydroxylation of Minerals of Gadisunkapur Area with Special Reference to FTIR and Thermal Study

International Journal of Economic and Environmental Geology ◽

10.46660/ojs.v11i1.415 ◽

2020 ◽

Vol 11 (1) ◽

pp. 72-76

Author(s):

Marularadhya C. Hiremath ◽

A. Sreenivasa

Keyword(s):

Thermal Analysis ◽

Differential Thermal Analysis ◽

High Temperature ◽

Thermogravimetric Analysis ◽

Special Reference ◽

Thermal Studies ◽

Thermal Study ◽

Granitic Rocks ◽

Schist Belt ◽

Chlorite Schist

This paper attempts to explain the presence of OH group for micas along with some sulfate, chlorite, quartz and feldspar minerals. These minerals are found to be associated with barite vein, metasediments (quartz-chlorite schist), metarhyolite and varieties of granitic rocks of Gadisunkapur area of Hungund-Kushtagi Schist belt. The samples were collected in and around Gadisunkapur village of Bagalkote district, Karnataka and further processed to determine OH group anion in different minerals present based on FTIR and Thermal studies such as Thermogravimetric analysis (TGA) and Differential Thermal analysis (DTA). The high temperature dehydroxylation is investigated using this analysis. Furthermore, present study indicates the presence of different extra species (CO2, CO32- and OH-). The results show the incorporation of CO2 into the structures due to heating or enhanced by the dehydroxylation process.

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Structural and thermal analysis of BaFe11.9Ga0.1O19 and BaFe11.7Ga0.3O19

International Journal of Modern Physics B ◽

10.1142/s0217979218503034 ◽

2018 ◽

Vol 32 (27) ◽

pp. 1850303 ◽

Cited By ~ 9

Author(s):

Sakin H. Jabarov

Keyword(s):

Crystal Structure ◽

Thermal Analysis ◽

High Temperature ◽

Active Surface ◽

Central Peak ◽

X Ray Diffraction ◽

X Ray ◽

Difference Formula ◽

Loss Of Mass ◽

Tg And Dtg

Crystal structure and thermophysical properties of BaFe[Formula: see text]Ga[Formula: see text]O[Formula: see text] solid solutions have been studied by X-ray diffraction, thermogravimetry and differential scanning calarimetry methods. It is determined that these compounds have characteristic transitions at 72[Formula: see text]C and 85[Formula: see text]C temperatures. From the spectra of the TG and DTG loss of mass and energy are determined in the temperature range of 30–950[Formula: see text]C. At the temperature of T [Formula: see text] 120[Formula: see text]C, the endoeffects are chemically absorbed water on the active surface of the compound and are a decomposition of the hydroxide group. The endoeffect, at which its central peak reaches T [Formula: see text] 80[Formula: see text]C, is associated with an OH group that has been chemically absorbed, observed revised effects with a difference [Formula: see text]T [Formula: see text] 35[Formula: see text]C for relative decomposition at high-temperature.

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Dehydroxylation of Minerals of Gadisunkapur Area with Special Reference to FTIR and Thermal Study

International Journal of Economic and Environmental Geology ◽

10.46660/ijeeg.vol11.iss1.2020.415 ◽

2020 ◽

Vol 11 (1) ◽

pp. 72-76

Author(s):

Marularadhya C. Hiremath ◽

A. Sreenivasa

Keyword(s):

Thermal Analysis ◽

Differential Thermal Analysis ◽

High Temperature ◽

Thermogravimetric Analysis ◽

Special Reference ◽

Thermal Studies ◽

Thermal Study ◽

Granitic Rocks ◽

Schist Belt ◽

Chlorite Schist

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Use of activated carbon to remove undesirable residual amylase from refinery streams

Sugar Industry ◽

10.36961/si18170 ◽

2017 ◽

pp. 96-103 ◽

Cited By ~ 1

Author(s):

Gillian Eggleston ◽

Isabel Lima ◽

Emmanuel Sarir ◽

Jack Thompson ◽

John Zatlokovicz ◽

...

Keyword(s):

Activated Carbon ◽

High Temperature ◽

High Performance ◽

Activated Carbons ◽

Amylase Activity ◽

Sugar Industry ◽

End User ◽

Customer Complaints ◽

Carry Over ◽

Very High

In recent years, there has been increased world-wide concern over residual (carry-over) activity of mostly high temperature (HT) and very high temperature (VHT) stable amylases in white, refined sugars from refineries to various food and end-user industries. HT and VHT stable amylases were developed for much larger markets than the sugar industry with harsher processing conditions. There is an urgent need in the sugar industry to be able to remove or inactivate residual, active amylases either in factory or refinery streams or both. A survey of refineries that used amylase and had activated carbon systems for decolorizing, revealed they did not have any customer complaints for residual amylase. The use of high performance activated carbons to remove residual amylase activity was investigated using a Phadebas® method created for the sugar industry to measure residual amylase in syrups. Ability to remove residual amylase protein was dependent on the surface area of the powdered activated carbons as well as mixing (retention) time. The activated carbon also had the additional benefit of removing color and insoluble starch.

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