Irreversible thermal transformation kinetics of halloysite to metahalloysite using XRD analysis

Önal M., Sarikaya Y.

JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY, cilt.148, sa.23, ss.13457-13462, 2023 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 148 Sayı: 23
  • Basım Tarihi: 2023
  • Doi Numarası: 10.1007/s10973-023-12640-0
  • Dergi Adı: JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, Chemical Abstracts Core, Chimica, Communication Abstracts, Compendex, Index Islamicus, INSPEC, Metadex, Civil Engineering Abstracts
  • Sayfa Sayıları: ss.13457-13462
  • Anahtar Kelimeler: Activation energy, Dehydration, Halloysite, Irreversible transformation, Metahalloysite, Rate constant
  • Ankara Üniversitesi Adresli: Evet

Özet

Dehydration of halloysite (Hly) to metahalloysite (m-Hly) was examined by X-ray diffraction (XRD). The Hly samples heated in temperature range of 80-400 degrees C. The heating time (t) at each temperature was changed up to 420 min. The peak intensities (I) for the basal spacing (d(001)) of Hly (1.0 nm) and m-Hly (0.7 nm) were determined. The variation of the intensities with the heating time was evaluated for each temperature. The full heating time (t(f)) for each completed crystal transformation was determined graphically and used as kinetic variable. The rate constant (k) was evaluated as k = 1/t(f) for the crystal transformation assumed from the zeroth order (n = 0). It has been observed that the drawn lnk-1/T graph conforms to the Arrhenius equation in the form of lnk = -3247.2/T + 3.4215. The activation energy was calculated as E-# = 27 kJ mol(-1) from the slope of this line equation, and the frequency factor from its intercept was calculated as A = 31 min(-1).