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Differential Thermal Analysis of Mixed Organic Materials LOUIS HEMPHILL, Associate Professor Sanitary Engineering Department University of Missouri Columbia, Missouri The problems of waste disposal and water pollution control have stimulated interest in the revision of established analytical methods and fostered the development of new methods. Recent developments in analytical chemistry instrumental methods have shown that physical methods of analysis are sometimes able to measure selected constitutents below the sensitivity limit of wet chemistry methods. Instrumental analysis has demonstrated that often a chemical species can be determined qualitatively and/or quantitatively by measuring specific energy absorption or emission. A large portion of the analytical problems in sanitary engineering are centered about determining the nature and concentration of heterogeneous organic waste materials. Analysis of organic waste materials, qualitatively and quantitatively, by differential thermal analysis has shown that this analytical method may be useful for sanitary engineering application. It is the purpose of this paper to 1) describe the basic theory and features of differential thermal analysis and 2) present results of a laboratory study designed to evaluate differential thermal analysis for sanitary engineering application. BASIC THEORY AND FEATURES OF DIFFERENTIAL THERMAL ANALYSIS Differential thermal analysis (DTA) differs from conventional methods of thermal analysis in that temperature changes accompanying thermal energy reactions are measured rather than changes in dimensions or mass. Two major thermal reactions, exothermic and endothermic, may occur during heating or cooling of a material. Differential thermal analysis is the process of measuring and recording exothermic or endothermic reactions. In practice, a sample material and a thermally stable standard material are heated or exposed to the same temperature environment. During the heating period the sample material may undergo a series or sequence of thermal reactions such as melting, boiling, combusr tion or isothermal phase changes. In each of these reactions, energy is absorbed or emitted by the sample material. The thermal energy changes accompanying each reaction are reflected in the differential temperature generated by the sample and standard. An idealized DTA reaction peak is shown in Figure 1. The three basic or elemental components of the DTA system are a controlled heat source, sample holder and a differential temperature measuring-recording device. The type and construction of each of these units is often variable depending upon specific application. Several investigators have stated the general requirements of the heat source and have described this portion of the apparatus as being the most important (1). The heating rate available for conventional DTA furnaces is limited by the power supply and materials of construction. - 343 -
Object Description
Purdue Identification Number | ETRIWC196828 |
Title | Differential thermal analysis of mixed organic materials |
Author | Hemphill, L. |
Date of Original | 1968 |
Conference Title | Proceedings of the 23rd Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://earchives.lib.purdue.edu/u?/engext,15314 |
Extent of Original | p. 343-360 |
Series |
Engineering extension series no. 132 Engineering bulletin v. 53, no. 2 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital object copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Date Digitized | 2009-05-20 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 343 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital object copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Transcript | Differential Thermal Analysis of Mixed Organic Materials LOUIS HEMPHILL, Associate Professor Sanitary Engineering Department University of Missouri Columbia, Missouri The problems of waste disposal and water pollution control have stimulated interest in the revision of established analytical methods and fostered the development of new methods. Recent developments in analytical chemistry instrumental methods have shown that physical methods of analysis are sometimes able to measure selected constitutents below the sensitivity limit of wet chemistry methods. Instrumental analysis has demonstrated that often a chemical species can be determined qualitatively and/or quantitatively by measuring specific energy absorption or emission. A large portion of the analytical problems in sanitary engineering are centered about determining the nature and concentration of heterogeneous organic waste materials. Analysis of organic waste materials, qualitatively and quantitatively, by differential thermal analysis has shown that this analytical method may be useful for sanitary engineering application. It is the purpose of this paper to 1) describe the basic theory and features of differential thermal analysis and 2) present results of a laboratory study designed to evaluate differential thermal analysis for sanitary engineering application. BASIC THEORY AND FEATURES OF DIFFERENTIAL THERMAL ANALYSIS Differential thermal analysis (DTA) differs from conventional methods of thermal analysis in that temperature changes accompanying thermal energy reactions are measured rather than changes in dimensions or mass. Two major thermal reactions, exothermic and endothermic, may occur during heating or cooling of a material. Differential thermal analysis is the process of measuring and recording exothermic or endothermic reactions. In practice, a sample material and a thermally stable standard material are heated or exposed to the same temperature environment. During the heating period the sample material may undergo a series or sequence of thermal reactions such as melting, boiling, combusr tion or isothermal phase changes. In each of these reactions, energy is absorbed or emitted by the sample material. The thermal energy changes accompanying each reaction are reflected in the differential temperature generated by the sample and standard. An idealized DTA reaction peak is shown in Figure 1. The three basic or elemental components of the DTA system are a controlled heat source, sample holder and a differential temperature measuring-recording device. The type and construction of each of these units is often variable depending upon specific application. Several investigators have stated the general requirements of the heat source and have described this portion of the apparatus as being the most important (1). The heating rate available for conventional DTA furnaces is limited by the power supply and materials of construction. - 343 - |
Resolution | 300 ppi |
Color Depth | 8 bit |
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