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Conflict of Interest: In relation to this article, we declare that there is no conflict of interest.

Publication history: Received February 8, 2007
Accepted May 9, 2008

This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/bync/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Synthesis, crystal structure and dehydration kinetics of NaB(OH)4·2H2O

Aysel Kanturk Muge Sari Sabriye Piskin^†

Department of Chemical Engineering, Yildiz Technical University, 34210, Istanbul, Turkey

Korean Journal of Chemical Engineering, November 2008, 25(6), 1331-1337(7), 10.1007/s11814-008-0218-8

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Abstract

Sodium metaborate tetrahydrate (NaB(OH)4·2H2O) was synthesized by reaction of anhydrous borax (Na2O·2B2O3) with sodium hydroxide (NaOH) under conditions at 90 ℃ for 150 min. The structure was characterized by Xray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscope (SEM) and Thermogravimetric (TG) analyses. Moreover, dehydration kinetics of NaB(OH)4·2H2O was carried out under non-isothermal conditions and the Coats-Redfern method was applied to analyze the TG data for calculation of activation energies_x000D_ (Ea) and pre-exponential factors (ko) for different heating rates. It was determined that dehydration of sodium metaborate tetrahydrate occurred in five steps. According to the Coats-Redfern non-isothermal model, Ea and ko were calculated as 50.89 kJ/mol and 26×10^(4) min^(-1) for region I, 18.51 kJ/mol and 0.87×10^(3) min^(-1) for region II, 15.72 kJ/mol and 0.52×10^(3) min^(-1) for region III, 4.37 kJ/mol and 0.04×10^(3) min^(-1) for region IV and 37.42 kJ/mol and 8.56×10^(3) min^(-1) for region V, respectively.

Keywords

Sodium Metaborate Sodium Borohydride Synthesis Crystal Structure TG/DTG Coats-Redfern

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