Box–Behnken experimental design for zinc borate Zn2B6O11•7H2O

Abstract

The present study investigated the effect of the operating conditions on the crystallization of zinc borate. For zinc borate crystallization, sodium tetraborate decahydrate and zinc sulfate heptahydrate were used as reactants. In the first part of the study, the crystals were characterized by X-ray diffraction spectroscopy (XRD), Fourier-transform infrared spectroscopy (FTIR), light microscopy, and particle size and thermogravimetric analysis. The results show that the obtained crystals were in the form of Zn2B6O11•7H2O, and the operating conditions had a significant effect on the size, morphology, and filtration characteristics of the zinc borate crystals. In the second part of the study, Box–Behnken design (BBD) with response surface methodology (RSM) was employed to determine the optimal operating conditions for zinc borate crystallization. The effects of stirring rate, temperature, and reactant feed rate on the average particle size were investigated. The results show that the data sufficiently fit the second-order polynomial model. The crystallization conditions, including stirring rate, temperature, and reactant feed rate, were studied at 400–500 rpm, 45–85ºC, and 300–900 mL/h, respectively. The minimum particle size (3.3 µm) was obtained at a stirring rate of 450 rpm, a temperature of 85ºC, and a reactant feed rate of 300 mL/h.

Keywords

• Zinc borate
• Box–Behnken design
• crystallization
• morphology

References

1. [1] Gostu, S., Mishra, D., Sahu, K.K., Agrawal, A., Precipitation and characterization of zinc borates from hydrometallurgical processing of zinc ash. Mater. Lett. 134 (1), 198-201, 2014.
2. [2] Bardakçı M., Acaralı, N.B., Tuğrul, N., Derun, E.M., Pişkin, M.B., Production of Zinc Borate for Pilot Scale Equipment and Effects of Reaction Conditions on Yield. Mater. Sci. 19 (2), 159-163, 2013.
3. [3] Li, S., Long, B., Wang, Z., Tian, Y., Zheng, Y., Zhang, Q. Synthesis of hydrophobic zinc borate nanoflakes and its effect on flame retardant properties of polyethylene J. Solid State Chem. 183, 957–962, 2010.
4. [4] Çakal, G.Ö., Baltacı, B., Bayram, G., Özkar, S., Eroğlu, I., Synthesis of zinc borate using water soluble additives: Kinetics and product characterization. J. Cryst. Growth. 533, 125461, 2020.
5. [5] Liang, P., Li, S.Y., Synthesis, characterization and standard molar enthalpies of formation of two zinc borates: 2ZnO•2B2O 3•3H2O and ZnB4O7. J. Chem. Thermodyn. 139, 105868, 2019.
6. [6] Gürhan, D., Çakal, G.Ö., Eroğlu, İ., Özkar, S., Improved synthesis of fine zinc borate particles using seed crystals. J. Cryst. Growth. 311(6), 1545-1552, 2009.
7. [7] Eltepe, H.E., Balköse, D., Ülkü, S., Effect of Temperature and Time on Zinc Borate Species Formed from Zinc Oxide and Boric Acid in Aqueous Medium. Ind. Eng. Chem. Res. 46 (8), 2367- 2371, 2007.
8. [8] Shete, A.V., Sawant, S.B., Pangarkar, V.G., Kinetics of fluid–solid reaction with an insoluble product: zinc borate by the reaction of boric acid and zinc oxide. J. Chem. Technol. Biotechnol. 79 (5), 526-532, 2004.

9. [9] Gillani, Q.F., Ahmad, F., Mutalib, M.I.A., Megat-Yusoff, P.S.M., Ullah, S., Messet, P.J., Zia-ulMustafa, M., Thermal degradation and pyrolysis analysis of zinc borate reinforced intumescent fire retardant coatings. Prog. Org. Coat. 123, 82-98, 2018.
10. [10] Savas, L.A., Dogan, M., Flame retardant effect of zinc borate in polyamide 6 containing aluminum hypophosphite. Polym. Degrad. Stabil. 165, 101-109, 2019.
11. [11] Tian, Y., Guo, Y., Jiang, M., Sheng, Y., Hari, B., Zhang, G., Jiang, Y., Zhou, B., Zhu, Y., Wang, Z., Synthesis of hydrophobic zinc borate nanodiscs for lubrication. Mater. Lett. 60 (20), 2511- 2515, 2006.
12. [12] Zheng, Y., Qu, Y., Tian, Y., Wang, C.R.Z., Li, S., Chen, X., Ma, Y., Effect of Eu3+-doped on the luminescence properties of zinc borate nanoparticles. Colloid Surface A. 349 (1-3), 19-22, 2009.
13. [13] Gao, Y.H., Liu, Z.H., Synthesis and thermochemistry of two zinc borates, Zn2B6O11•7H2O and Zn3B10O18•14H2O. Thermochim. Acta. 484, 27–31, 2009.
14. [14] Guo, Y.W., Mao, L., Rong, F., Li, Z.H. Preparation of Zn3B10O18•14H2O nanomaterials and their thermochemical properties. Thermochim. Acta 539, 56– 61, 2012.
15. [15] Design-Expert software, Version 10 User's Guide, Stat-Ease.