热降解五水乳酸钙的热动力学和热力学研究

IF 0.9 Q4 ENGINEERING, CHEMICAL
S. Polat
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引用次数: 2

摘要

摘要本研究的目的是通过热重分析仪(TGA)在N2气氛中,在25°C至1000°C的四种不同加热速率下,研究乳酸钙五水合物(CLP)晶体的热降解动力学和热力学。首先,在pH 6和25°C的间歇式结晶器中沉淀CLP晶体,并通过X射线粉末衍射(XRD)和傅里叶变换红外光谱(FTIR)对所获得的晶体进行表征。XRD结果表明,l-乳酸钙五水合物(l-CLP)是唯一产生的结晶相。然后,基于Coats–Redfern、Flynn–Wall–Ozawa(FWO)、Kissinger–Akahira–Sunose(KAS)和Starink模型确定了热降解的活化能和指数前因子。通过Coats-Redfern模型确定降解反应级数为1.5。CLP的平均活化能分别为34.7、33.0和33.3 FWO、KAS和Starink模型分别为kJ/mol。根据转化度计算了焓、熵和吉布斯自由能变化的热力学参数。最后,TGA与FTIR和质谱仪(MS)相结合,用于检测CLP降解过程中释放的气体。H2O和CO2被确定为主要的进化产物。图形摘要
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Thermal degradation of calcium lactate pentahydrate using TGA/FTIR/MS: thermal kinetic and thermodynamics studies
ABSTRACT The objective of this study is to investigate the thermal degradation kinetics and thermodynamics of the calcium lactate pentahydrate (CLP) crystals by means of a thermogravimetric analyzer (TGA) at four different heating rates from 25°C to 1000°C in N2 atmosphere. First, the CLP crystals were precipitated at pH 6 and 25°C in a batch-type crystallizer and the obtained crystals were characterised by X-ray powder diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). The XRD result showed that the calcium l-lactate pentahydrate (L-CLP) was the only crystalline phase produced. Then, the activation energy and pre-exponential factor of thermal degradation were determined based on the Coats–Redfern, Flynn–Wall–Ozawa (FWO), Kissinger–Akahira–Sunose (KAS), and Starink models. The degradation reaction order was determined as 1.5 by Coats-Redfern model. The average activation energy of the CLP was 34.7, 33.0, and 33.3 kJ/mol for the FWO, KAS, and Starink models, respectively. Thermodynamic parameters as changes in enthalpy, entropy and Gibbs free energy were calculated depending on the conversion degree. Finally, TGA in combination with FTIR and mass spectrometer (MS) was utilised to detect the evolved gases during the degradation of CLP. H2O and CO2 were identified as the main evolved products. GRAPHICAL ABSTRACT
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来源期刊
Indian Chemical Engineer
Indian Chemical Engineer ENGINEERING, CHEMICAL-
CiteScore
3.00
自引率
6.70%
发文量
33
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