The Determination of the Potassium Nitrate, Sodium Hydroxide and Boric Acid Molar Ratio in the Synthesis of Potassium Borates via Hydrothermal Method

Authors: M. Yildirim, A. S. Kipcak, F. T. Senberber, M. O. Asensio, E. M. Derun, S. Piskin

Abstract:

Potassium borates, which are widely used in welding and metal refining industry, as a lubricating oil additive, cement additive, fiberglass additive and insulation compound, are one of the important groups of borate minerals. In this study the production of a potassium borate mineral via hydrothermal method is aimed. The potassium source of potassium nitrate (KNO3) was used along with a sodium source of sodium hydroxide (NaOH) and boron source of boric acid (H3BO3). The constant parameters of reaction temperature and reaction time were determined as 80°C and 1 h, respectively. The molar ratios of 1:1:3 (as KNO3:NaOH:H3BO3), 1:1:4, 1:1:5, 1:1:6 and 1:1:7 were used. Following the synthesis the identifications of the produced products were conducted by X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR) and Raman Spectroscopy. The results of the experiments and analysis showed in the ratio of 1:1:6, the Santite mineral with powder diffraction file number (pdf no.) of 01-072-1688, which is known as potassium pentaborate (KB5O8·4H2O) was synthesized as best.

Keywords: Hydrothermal synthesis, potassium borate, potassium nitrate, santite.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1107049

References:

[1] U.S Geological survey minerals Yearbook (2008) section 13.1
[2] Z.G. Zhang, M.B. Boisen, Jr., L. W. Finger and G. V. Gibbs, “Molecular mimicry of the geometry and charge density distribution of polyanions in borate minerals”, American Mineralogist, Vol. 70 , pages 1238-1247 (1985).
[3] V. Joseph, V. Santhanam, S. Gunasekaran, P. Sagayaraj, S. Ponnusamy, “Vibrational spectra and analysis on the molecule of potassium pentaborate crystal”, Indian Journal of Pure & Applied Physics, Vol. 41, March 2003, pp. 161-166.
[4] F.Y. Zhu, C.H. Fang, Y. Fang, Y.Q. Zhou, H.W. Ge, H.Y. Liu, “Structure of aqueous potassium metaborate solution”, Journal of Molecular Structure 1070 (2014) 80-85.
[5] Gökhan Elmaci, Okan Icten, Ahmet Nedim Ay, Birgu