Characterization and Thermal Dehydration Kinetics of Highly Crystalline Mcallisterite, Synthesized at Low Temperatures

Abstract EN

The hydrothermal synthesis of a mcallisterite (Mg2(B6O7(OH)6)2 · 9(H2O)) mineral at low temperatures was characterized.

For this purpose, several reaction temperatures (0–70°C) and reaction times (30–240 min) were studied.

Synthesized minerals were subjected to X-ray diffraction (XRD), fourier transform infrared (FT-IR), and Raman spectroscopies and scanning electron microscopy (SEM).

Additionally, experimental analyses of boron trioxide (B2O3) content and reaction yields were performed.

Furthermore, thermal gravimetry and differential thermal analysis (TG/DTA) were used for the determination of thermal dehydration kinetics.

According to the XRD results, mcallisterite, which has a powder diffraction file (pdf) number of “01-070-1902,” was formed under certain reaction parameters.

Pure crystalline mcallisterite had diagnostic FT-IR and Raman vibration peaks and according to the SEM analysis, for the minerals which were synthesized at 60°C and 30 min of reaction time, particle size was between 398.30 and 700.06 nm.

Its B2O3 content and reaction yield were 50.80 ± 1.12 % and 85.80 ± 0.61 %, respectively.

Finally, average activation energies (conversion values ( α ) that were selected between 0.1 and 0.6) were calculated as 100.40 kJ/mol and 98.31 kJ/mol according to Ozawa and Kissinger-Akahira-Sunose (KAS) methods, respectively.