Due to the existence of poly-hydroxyl structures,the temperature may have an effect on the thermal stability of oleuropein for its applications.In the current study,the thermal decomposition process and kinetics behav...Due to the existence of poly-hydroxyl structures,the temperature may have an effect on the thermal stability of oleuropein for its applications.In the current study,the thermal decomposition process and kinetics behavior of oleuropein from the olive resource were researched by thermogravimetric theoretical analysis methods and non-isothermal kinetics simulation.The results of thermogravimetry analysis showed the whole thermal decomposi-tion process of oleuropein involved two stages,with 21.22%of residue.It was also revealed that high heating rates of more than 20 K min^(-1) led to significant thermal hysteresis and inhibited the whole thermal decomposition behavior of oleuropein.Moreover,an investigation of the thermal decomposition kinetics indicated that the non-isothermal decomposition behavior followed a D3 model during thefirst stage(three-dimensional diffusion,Jander equation)and a D1 model in the second stage(one-dimensional diffusion).For thefirst and second ther-mal decomposition stages,the Kissinger,Friedman,Flynn-Wall-Ozawa,and Coats–Redfern four methods were applied to determine the activation energy(E=143.72 and 247.01 kJ mol^(-1))and Arrhenius preexponential factor(ln A=26.34 and 42.45 min^(-1)),respectively.Therefore,the study will provide good theoretical guidance for ther-mal stability and thermal transformation application of oleuropein.It will be suitable for low-temperature appli-cations in the cosmetic,food supplement and pharmaceutical industries.展开更多
Refractories have unique capabilities such as sustaining their shape and properties at extreme conditions such as the combination of high temperatures and thermal shock,contact with molten metals and slags and in some...Refractories have unique capabilities such as sustaining their shape and properties at extreme conditions such as the combination of high temperatures and thermal shock,contact with molten metals and slags and in some circumstances resistance to erosion from abrasive particles.Given the large processing output of the heavy industries such as the cement and steel ones which both require high temperature processes,the refractories structures span various meters and weight of several tons.As the water removal stage of hydraulic bonded castables in industrial sites takes hours(10-60 h)due to the risk of explosive spalling,efforts to mitigate it are commonly studied.This has provided theoretical understanding of the general aspects of drying and important tools,such as the thermogravimetry analysis(TGA),for the design of refractory compositions with higher explosive spalling resistance.However,the optimization of this process is still far from the industrial reality especially because the actual linings that require the drying are orders of magnitude larger than the samples considered in the laboratory tests.Therefore,this study proposed the analysis of the sample volume effect on the water removal dynamics through TGA of high alumina castables with calcium aluminate cement.Conventionalφ5 cm×5 cm cylindrical samples were assessed in a laboratory scale equipment whereas macro TGA were carried out considering 20 cm×20 cm×20 cm and 30 cm×30 cm×30 cm cubic samples.Additionally,the effect of polymeric fibers was also considered.It was found out that the different thermal gradients within the macro TGA samples resulted in an inflection on the sample’s heating rate and that the mass loss was affected by the volume considered,especially for the composition without additives.These findings highlight the requirement of carefully taking into consideration the different dimensional sizes and thermal gradients in the samples when analyzing and interpreting the laboratory studies,and especially when trying to extrapolate such results to the industrial reality.展开更多
以新疆克拉玛依油田采油污泥为对象,分别采用热重分析仪和小型流化床热解反应器研究了含油污泥的热解过程及其热解效果。结果表明,油泥热解主要经历了失水、轻质组分挥发、重组分快速热解失重和缓慢失重4个阶段,热解过程基本符合一级动...以新疆克拉玛依油田采油污泥为对象,分别采用热重分析仪和小型流化床热解反应器研究了含油污泥的热解过程及其热解效果。结果表明,油泥热解主要经历了失水、轻质组分挥发、重组分快速热解失重和缓慢失重4个阶段,热解过程基本符合一级动力学方程,提高热解的升温速率,可使油泥的最大失重速率Dm ax、失重速率峰值温度mθax、升温终点的最大失重率都随之增加,表现在动力学上,反映出表观活化能和碰撞频率因子的同时升高,即提高油泥热解转化率的同时也影响了热解效率。失水油泥用流化床热解,在热解温度600℃、反应时间3 m in时,油泥回收率可达到87%。展开更多
基金This work was funded by Guangdong Basic and Applied Basic Research Foundation(No.2019A1515111159)Characteristic Innovative Projects for Education Department of Guangdong Province 2021 Year(No.2021KTSCX302).
文摘Due to the existence of poly-hydroxyl structures,the temperature may have an effect on the thermal stability of oleuropein for its applications.In the current study,the thermal decomposition process and kinetics behavior of oleuropein from the olive resource were researched by thermogravimetric theoretical analysis methods and non-isothermal kinetics simulation.The results of thermogravimetry analysis showed the whole thermal decomposi-tion process of oleuropein involved two stages,with 21.22%of residue.It was also revealed that high heating rates of more than 20 K min^(-1) led to significant thermal hysteresis and inhibited the whole thermal decomposition behavior of oleuropein.Moreover,an investigation of the thermal decomposition kinetics indicated that the non-isothermal decomposition behavior followed a D3 model during thefirst stage(three-dimensional diffusion,Jander equation)and a D1 model in the second stage(one-dimensional diffusion).For thefirst and second ther-mal decomposition stages,the Kissinger,Friedman,Flynn-Wall-Ozawa,and Coats–Redfern four methods were applied to determine the activation energy(E=143.72 and 247.01 kJ mol^(-1))and Arrhenius preexponential factor(ln A=26.34 and 42.45 min^(-1)),respectively.Therefore,the study will provide good theoretical guidance for ther-mal stability and thermal transformation application of oleuropein.It will be suitable for low-temperature appli-cations in the cosmetic,food supplement and pharmaceutical industries.
基金the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior-Brasil(CAPES)-Finance Code 001.The authors would like to thank the Fundacao de Amparo a Pesquisa do Estado de Sao Paulo-FAPESP(grant number:2021/00251-0).Finally,the authors are also greatly thankful for FIRE support to carry out this work.
文摘Refractories have unique capabilities such as sustaining their shape and properties at extreme conditions such as the combination of high temperatures and thermal shock,contact with molten metals and slags and in some circumstances resistance to erosion from abrasive particles.Given the large processing output of the heavy industries such as the cement and steel ones which both require high temperature processes,the refractories structures span various meters and weight of several tons.As the water removal stage of hydraulic bonded castables in industrial sites takes hours(10-60 h)due to the risk of explosive spalling,efforts to mitigate it are commonly studied.This has provided theoretical understanding of the general aspects of drying and important tools,such as the thermogravimetry analysis(TGA),for the design of refractory compositions with higher explosive spalling resistance.However,the optimization of this process is still far from the industrial reality especially because the actual linings that require the drying are orders of magnitude larger than the samples considered in the laboratory tests.Therefore,this study proposed the analysis of the sample volume effect on the water removal dynamics through TGA of high alumina castables with calcium aluminate cement.Conventionalφ5 cm×5 cm cylindrical samples were assessed in a laboratory scale equipment whereas macro TGA were carried out considering 20 cm×20 cm×20 cm and 30 cm×30 cm×30 cm cubic samples.Additionally,the effect of polymeric fibers was also considered.It was found out that the different thermal gradients within the macro TGA samples resulted in an inflection on the sample’s heating rate and that the mass loss was affected by the volume considered,especially for the composition without additives.These findings highlight the requirement of carefully taking into consideration the different dimensional sizes and thermal gradients in the samples when analyzing and interpreting the laboratory studies,and especially when trying to extrapolate such results to the industrial reality.
文摘以新疆克拉玛依油田采油污泥为对象,分别采用热重分析仪和小型流化床热解反应器研究了含油污泥的热解过程及其热解效果。结果表明,油泥热解主要经历了失水、轻质组分挥发、重组分快速热解失重和缓慢失重4个阶段,热解过程基本符合一级动力学方程,提高热解的升温速率,可使油泥的最大失重速率Dm ax、失重速率峰值温度mθax、升温终点的最大失重率都随之增加,表现在动力学上,反映出表观活化能和碰撞频率因子的同时升高,即提高油泥热解转化率的同时也影响了热解效率。失水油泥用流化床热解,在热解温度600℃、反应时间3 m in时,油泥回收率可达到87%。
