硫脲及硫脲氧化物分解的热力学分析
Thermodynamic analysis of decomposition of thiourea and thiourea oxides.
作者信息
Wang Shun, Gao Qingyu, Wang Jichang
机构信息
College of Chemical Engineering, China University of Mining and Technology, Xuzhou, Jiangsu, China 221008.
出版信息
J Phys Chem B. 2005 Sep 15;109(36):17281-9. doi: 10.1021/jp051620v.
Thiourea has exhibited extremely rich dynamical behavior when being oxidized either through a chemical approach or via an electrochemical method. In this study, thermodynamic properties of thiourea and its oxides are investigated by measuring their thermogravimetry (TG), differential thermogravimetry (DTG), and differential scanning calorimetry (DSC) simultaneously. Online FT-IR measurements show that products of the thermal decomposition vary significantly with the reaction temperature. In addition to the determination of their apparent activation energy (E), preexponential factor (A), and entropy (DeltaS++), enthalpy (DeltaH++), and Gibbs energy (DeltaG++) of thermal decomposition, our investigation further illustrates that the decomposition kinetics of thiourea and thiourea oxides follows the Johnson-Mehl-Avrami Equation, f (alpha) = n(1 - alpha)-ln(1 - alpha) and G(alpha) = -ln(1 - alpha) with n equal to 2, 3.43, and 3, respectively.
硫脲在通过化学方法或电化学方法被氧化时表现出极其丰富的动力学行为。在本研究中，通过同时测量硫脲及其氧化物的热重分析（TG）、微商热重分析（DTG）和差示扫描量热法（DSC）来研究它们的热力学性质。在线傅里叶变换红外光谱（FT-IR）测量表明，热分解产物随反应温度有显著变化。除了测定它们的热分解表观活化能（E）、指前因子（A）以及熵（ΔS‡）、焓（ΔH‡）和吉布斯自由能（ΔG‡）外，我们的研究进一步表明，硫脲和硫脲氧化物的分解动力学遵循约翰逊-梅尔-阿弗拉米方程，f(α) = n(1 - α)[-ln(1 - α)]^(1 - 1/n) 和 G(α) = [-ln(1 - α)]^(1/n)，其中n分别等于2、3.43和3。
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