| 盐卤硼酸盐化学 Ⅻ. MgO·3B2O3·7H2O的热行为和脱水动力学 |
| CHEMISTRY OF BORATE IN SALT LAKE BRINE ⅩⅠⅠ. THERMO-BEHAVIOUR OF MgO·3B2O3·7H2O AND KINETICS OF DEHYDRATION |
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| 摘要: 通过对合成MgO·3B2O3·7H2O的热分析研究确定热脱水反应的阶段、温度和产物,给出脱水过程的热化学反应方程式.利用甲醇、水与三氧化二硼之间的酯化反应进行相分离,确定该化合物高温结晶化产物的物相组成为晶态六硼酸镁(2MgO·3B2O3)和无定形B2O3.对该化合物的TG和DTG数据进行处理结果,给出了相应的非等温热脱水反应动力学方程. |
| 关键词: 盐卤硼酸盐 脱水动力学 |
| 基金项目: 国家自然科学基金委员会资助课题 |
Abstract: In this paper, the thermo-behaviour of MgO·3B2O3·7H2O and kinetics of dehydration during heating have been studied by DTA, TG, DTG, X-ray powder diffraction and IR-spectra. It is found that there appears only two phase transition process during dehydration as following 
The results of X-ray powder diffraction and IR-spectra show that the product of the first step dehydration at 122℃, MgO·3B2O3·5H2O,is different from that of the natural mineral.At 762℃, the amorphous product of dehydration,MgO·3B2O3, will be decomposed to form an amorphous B2O3 and crystal 2MgO·3B2O3 of which the composition is confirmed by chemical analysis after esterification with methyl-alcohol.The Freeman-Carroll method was used to calculate the parameter in kinetic equations of dehydration using the data of TG and DTG. It is obtained that the kinetic equations of step of dehydration are as following:the kinetic equation of the first step of dehydration is dα/dt=8.34*1017*exp(124662/RT)*(1-α)0.96 the kinetic equation of the second step of dehydration is dα/dt=6.74*1019*(171605/RT)*(1-α)2.15 |
| Keywords: borate in salt lake kinetics of dehydration |
| 投稿时间：1988-08-24 |
| 摘要点击次数: 1986 |
| 全文下载次数: 1674 |
| 高世扬,肖高懿,顾宁申,夏树屏.盐卤硼酸盐化学 Ⅻ. MgO·3B2O3·7H2O的热行为和脱水动力学[J].无机化学学报,1991,7(1):30-36. |
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