Jing-Hua Li

Investigation of a eutectic mixture of sodium acetate trihydrate and urea as latent heat storage

Abstract In this paper, the pseudobinary system CH 3 COONa·3H 2 OCO(NH 2 ) 2 is studied by means of differential scanning calorimetry (DSC). Its eutectic mixture is found to melt congruently at 30°C, its heat of fusion is 200.5 J/g, considering the temperature of phase change and its heat storage capacity. This eutectic mixture is an excellent material for latent heat storage of solar energy.

Kinetic studies on the thermal dissociation of the inclusion complex of β-cyclodextrin with cinnamic aldehyde

The stability of the inclusion complex of β-CD with cinnamic aldehyde was investigated by means of TG and DSC. The mass loss takes place in three stages: dehydration occurs at 50–120°C; dissociation of β-CD·C9H8O proceeds in the range 200–260°C; and decomposition of β-CD begins at 280°C. The kinetics of the dissociation of β-CD·C9H8O was studied by means of thermogravimetry both at constant temperature and with linearly increasing temperature. The results demonstrate that the dissociation of β-CD·C9H8O is dominated by a one-dimensional diffusion process. The activation energyE is 160 kJ mol−1, and the pre-exponential factorA is 5.8×1014 min−1. Scanning electron microscope observations and the results of crystal structure analysis are in good agreement with those of thermogravimetry.

Kinetic studies on the thermal dissociation of β-cyclodextrin-anisaldehyde inclusion complex

The stability of β-cyclodextrin-anisaldehyde (β-CDA) inclusion complex was investigated by TG and DSC. The weight loss of β-CDA·9H2O takes place in three stages: the dehydration occurs at 50–120°C; the dissociation of β-CDA occurs at 210–260°C; and the decomposition of β-CD begins at 280°C. The kinetics of the dissociation of β-CDA in flowing dry nitrogen was studied by means of thermogravimetry both at constant temperature and with linearly increasing temperature. The results show that the dissociation of β-CDA is dominated by a two-dimensional diffusion process (D2). The activation energy E is 139.23 kJ mol−1, the pre-exponential factor A is 1.0394 × 1012 min−1.

The identification of the mechanism function and the kinetic investigation of the energy-storing reaction of ammonium hydrogen sulfate

Abstract The kinetics and the mechanism of the thermal decomposition of NH 4 HSO 4 were studied by means of thermogravimetry at constant temperature and with increasing temperature. The mechanism function of the reaction was found and identified by a three-stage identification method. Some kinetic parameters were determined. The results of the two methods showed that the thermal decomposition of NH 4 HSO 4 is dominated by an R 1 mechanism, i.e. a one-dimensional phase-boundary reaction. The activation energy E obtained by thermogravimetry at constant temperature is 141.25 kJ mol −1 . The frequency factor A is 1.563 × 10 10 min −1 . Its kinetic compensation effect is log A = 0.0899 E −2.5143.

Kinetic Studies on the Thermal Dissociation of β-Cyclodextrin·Ethyl Benzoate Inclusion Complexes

The stability of β-cyclodextrin·ethyl benzoate·6H2O(β-CD·C6H5COOC2H5·6H2O) was investigated by TG and DSC. The mass loss takes place in three stages: the dehydration occurs at 50-120°C; the dissociation of β-CD·C6H5COOC2H5occurs at 200-260°C; the decomposition of β-CD begins at 280°C. The kinetics of the dissociation of β-CD·C6H5COOC2H5in a dry nitrogen flow was studied by means of thermogravimetry both at constant temperature and linearly increasing temperature. The results show that the dissociation of β-CD·C6H5COOC2H5is dominated by a three-dimensional diffusion process (D3). The activation energy E is 116.19 kJ mol-1and the pre-exponential factor A 6.5358·109min-1.Cyclodextrin is able to form inclusion complexes with a great variety of guest molecules, and the studies focus on the energy of binding between cyclodextrin and the guest molecule. In this paper, the β-cyclodextrin·ethyl benzoate inclusion complex was studied by fluorescence spectrophotometry and infrared absorption spectroscopy, and the results show that the stable energy of inclusion complexes of β-CD with weakly polar guest molecules consists mainly of van der Waals interaction.

Mechanism and Kinetics of Thermal Dissociation of Inclusion Complex of Benzaldehyde with β-Cyclodextrin

The inclusion complex of benzaldehyde (BA) with β-cyclodextrin (β-CD) was prepared and was studied by thermal analysis and X-ray diffractometry. The composition of the complex was identified by TG and elemental analysis as β-CD·BA·9H2O. TG and DSC studies showed that the thermal dissociation of β-CD·BA·9H2O took place in three stages: dehydration in the range 70-120°C; dissociation of β-CD·BA in the range 235-270°C; and decomposition of β-CD above 280°C. The kinetics of dissociation of β-CD·BA in flowing dry nitrogen was studied by means of TG both at constant temperature and at linearly increasing temperature. The results showed that the dissociation of β-CD·BA was dominated by a one-dimensional random nucleation and subsequent growth process (A2). The activation energy E was 124. 8 kJ mol-1, and the pre-exponential factor A 5.04·1011 min-1.

Kinetic studies on the thermal dissociation of β-cyclodextrin-benzyl alcohol inclusion complex

Abstract The stability of β-CD · C7H8O · 5H2O was investigated using TG and DSC. The weight loss takes place in three stages: the dehydration occurs at 47–110°C; the dissociation of β-CD · C7H8O occurs at 200–250°C; and the decomposition of β-CD begins at 270°C. The kinetics of the dehydration of β-CD · C7H8O · 5H2O and the dissociation of β-CD · C7H8O in a dry nitrogen flow were studied by means of thermogravimetry, both at constant temperature and with linearly increasing temperatures. The dehydration of β-CD · C7H8O · 5H2O is dominated by a three-dimensional phase boundary reaction, R3. The activation energy E is 101.75 kJ mol−1. The pre-exponential factor A is 9.502 × 1010 min−1. The dissociation of β-CD · C7H8O is affected by a two-dimensional diffusion process, D2. The activation energy E is 158 kJ mol−1. The pre-exponential factor A is 3.3 × 1014 min−1. Scanning electron microscope observation and crystal structure analysis are in good agreement with the results obtained from thermogravimetry.

Thermal Stability and Decomposition Kinetics of the β-CD Cinnamic Aldehyde Inclusion Complex

The stability of the β-CD cinnamic aldehyde inclusion complex wasinvestigated by TG and DSC. The weight loss takes place in three stages:dehydration occurs at 50–120 °C; the dissociationof β-CD⋅C9H8O occurs at 200–260 °C;and the decomposition of β-CD begins at 280 °C. Thekinetics of the dissociation of cinnamic aldehyde from the β-CD cavitywere studied by means of thermogravimetry both at constant temperatureand linear increasing temperature. The results show that the dissociationof β-CD⋅C9H8O is dominated by a one-dimensional diffusionprocess. The activation energy, E, is 160 kJ⋅mol-1. Thepre-exponential factor A is 5.8 × 1014 min-1.

Kinetic studies on the thermal dissociation of β-cyclodextrin-cinnamyl alcohol inclusion complex

The stability of β-cyclodextrin-cinnamyl alcohol inclusion complex (β-CD·C9H10·8H2O) was investigated using TG and DSC. The mass loss took place in three stages: the dehydration occurred between 50–120°C; the dissociation of β-CD·C9H10O occurred in the range of 210–260°C; and the decomposition of β-CD began at 280°C. The dissociation of β-CD·C9H10O was studied by means of thermogravimetry, and the results showed: the dissociation of β-CD·C9H10O was dominated by a two-dimensional diffusion process (D2). The activation energyE was 161.2 kJ mol−1, the pre-exponential factorA was 4.5×1013 min−1.Cyclodextrin is able to form inclusion complexes with a great variety of guest molecules, and the interesting of studies focussed on the energy binding cyclodextrin and the guest molecule.In this paper, β-cyclodextrin-cinnamyl alcohol inclusion complex was studied by fluorescence spectrophotometry and infrared absorption spectroscopy, and the results show: the stable energy of inclusion complexes of β-CD with weakly polar guest molecules consists mainly of Van der Waals interaction.