Recycling of sodium metaborate to borax

Abstract

This study investigated an electrochemical method for recycling sodium metaborate (NaBO2) to sodium borohydride (NaBH4). Palladium (Pd), boron-doped diamond (BDD), gold (Au) and platinum (Pt) were used as electrodes. Cyclic voltammetry and chronoamperometry were used to recycle the NaBO2 either to NaBH4 or to an intermediate material for making NaBH4. The electrochemical products were characterized by X-ray diffraction (XRD) as well as B-11 nuclear magnetic resonance ((11) Be NMR) and Fourier transform infrared (FT-IR) spectroscopy. Borax was generated preferentially on the Pd and BDD electrodes compared with Pt only at a constant potential of + 1.54 V vs. Hg/HaO. An analysis of the XRD and FT-IR data clearly showed the formation of borax hydrate with a higher reactivity than NaBO2. (c) 2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.