Font Size: a A A

A New Method For Measuring Specific Heat Of Powder And Its Application In Measurement Of Monosaccharide

Posted on:2018-04-04Degree:MasterType:Thesis
Country:ChinaCandidate:Y Y ZhangFull Text:PDF
GTID:2371330566489443Subject:Environmental Science and Engineering
Abstract/Summary:PDF Full Text Request
Specific heat is the most basic thermodynamic parameter.Accurate understanding of the basic meaning and appropriate measuring of experimental results of specific heat is of great significance.Differential scanning calorimetry(DSC)is a thermal analysis technology which is widely used in various fields.It can be used to measure a variety of thermodynamics and kinetic parameters,which need to be studied in detail in specific heat measurement.As a renewable biomass resource,monosaccharides have become a hotspot in chemistry,biology and environment in recent years.More and more areas have a certain demand for sugar thermodynamics data.In this paper,we use a heat-flux differential scanning calorimeter named Discovery DSC produced by TA Instruments to compare and improve the different measurement methods.A new method is proposed for the specific heat measurement of powder samples.The specific heat of D-ribose and D-mannose was accurately measured using this method.The results as follows:1.The advantages and disadvantages of different thermal measurement methods are compared and analyzed.The principle,classification and application of differential scanning calorimetry are studied in detail.2.The calibration process of DSC is discussed,and the principle and data processing of the specific heat measurement under the two methods which are direct measurement and three-step measurement are analyzed.In the experiment,different forms of alumina,copper and benzoic acid are used as experimental materials.The accuracy of the two methods is discussed,and the causes of the error are analyzed.The two methods are improved based on the actual measurement.The relative deviation between the experimental value and the standard value of the three standard samples is further reduced after the improvement.As an example,in three-step measurement,the relative deviation of the alumina column is less than 1.2%;the relative deviation of the alumina powder is less than 12.1%;the relative deviation of the copper column is less than 4.7% and the relative deviation of benzoic acid is less than 5%.3.The powder material is measured using a new sample preparation method.In this situation the relative deviation of the alumina powder is less than 9.7% and the relative deviation of benzoic acid is less than 1.8%.The best way to measure the specific heat of monosaccharides using DSC is obtained by comparing the experimental results.4.D-ribose and D-mannose are used as the research object.Their thermal stability is investigated by thermogravimetric analysis.The optimum method is used to determine the specific heat of D-ribose in the temperature range of(-85 to 165)℃ and the specific heat of D-mannose in the temperature range of(-85 to 175)℃.Simultaneously,specific heat of these two monosaccharides is measured using a Quantum Design Physical Property Measurement System(PPMS)over the temperature range from(-271.25 to 26.85)℃.Experimental results in the temperature coincidence area are compared and analyzed.The relative deviation of D-ribose after improvement is less than 3%.The relative deviation of D-mannose after improvement is less than 2.6%,and the results show an obviously cross point.This work deepened the understanding of differential scanning calorimetry in specific heat measurement,which provides accurate and efficient specific heat data of thermodynamics properties of the saccharide.
Keywords/Search Tags:Specific heat, DSC, D-ribose, D-mannose
PDF Full Text Request
Related items