Solid–liquid equilibria in the ternary system NaBO2–NaOH–H2O thermal behavior of double salts

Polythermal diagrams of aqueous boundary ternary systems involving sodium borohydride hydrolysis for hydrogen generation

“…The proposed monovariant lines are based on experimental results from the literature. It shows the invariant points from isotherm at -10 °C determined by Churikov et al [12] and from isothermal at 10, 25 and 50 °C determined in previous work [11]. This polythermal diagram consists of eight invariant or monovariant lines fairly well defined (solid lines) and three hypothetical lines drawn in dot lines.…”

“…After the experimental work on isothermal of the ternary system NaBO2-NaOH-H2O published previously [11] an outline of polythermal diagram is proposed for this ternary system in Figure 7. The proposed monovariant lines are based on experimental results from the literature.…”

“…Structural analysis of the double compound leading to the formula Na3[(B(OH)4)2OH] was performed by the author in a previous publication [11].…”

“…In order to understand the behavior of the aqueous solution of sodium borohydride hydrolysis, the main challenge is to describe the solid-liquid equilibria involved in the quaternary system NaBH4-NaBO2-NaOH-H2O, which represents the evolution of the mixture during the hydrolysis reaction. In a previous work, the solubility limit of the hydrolysis's by-products, NaBO2.yH2O, has been investigated and the experimental results for the solubility limit in the ternary system NaBO2-NaOH-H2O under ambient pressure at 10, 25 and 50 °C have been presented [11]. In this present work, polythermal diagrams of the two aqueous boundary ternaries NaBH4-NaOH-H2O (corresponding to 0 % of hydrolysis reaction conversion) and NaBO2-NaOH-H2O (100 % of conversion) will be proposed from critical analysis of the description of several isotherm sections of each system [11][12][13][14] and will be completed by DSC analysis with the intent to give more precision about invariant transformations of the system.…”

“…In a previous work, the solubility limit of the hydrolysis's by-products, NaBO2.yH2O, has been investigated and the experimental results for the solubility limit in the ternary system NaBO2-NaOH-H2O under ambient pressure at 10, 25 and 50 °C have been presented [11]. In this present work, polythermal diagrams of the two aqueous boundary ternaries NaBH4-NaOH-H2O (corresponding to 0 % of hydrolysis reaction conversion) and NaBO2-NaOH-H2O (100 % of conversion) will be proposed from critical analysis of the description of several isotherm sections of each system [11][12][13][14] and will be completed by DSC analysis with the intent to give more precision about invariant transformations of the system. The third aqueous boundary ternary system NaBH4-NaBO2-H2O cannot be experimentally evaluated because of the spontaneous decomposition of NaBH4 in water, i.e.…”