Thermal degradation of calcium lactate pentahydrate using TGA/FTIR/MS: thermal kinetic and thermodynamics studies


Polat S.

INDIAN CHEMICAL ENGINEER, cilt.1, sa.1, 2021 (ESCI) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 1 Sayı: 1
  • Basım Tarihi: 2021
  • Doi Numarası: 10.1080/00194506.2021.2017359
  • Dergi Adı: INDIAN CHEMICAL ENGINEER
  • Derginin Tarandığı İndeksler: Emerging Sources Citation Index (ESCI), Scopus, Academic Search Premier, Aerospace Database, Communication Abstracts, INSPEC, Metadex, Civil Engineering Abstracts
  • Anahtar Kelimeler: Calcium lactate pentahydrate, kinetics, TGA/FTIR/MS, thermodynamics, evolved gas, DEHYDRATION, PARAMETERS, SOLUBILITY, COMPLEX, WATER
  • Marmara Üniversitesi Adresli: Evet

Özet

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 degrees C to 1000 degrees C in N-2 atmosphere. First, the CLP crystals were precipitated at pH 6 and 25 degrees 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.