Eutectic Temperature, Density, and Solubility of H3BO3–H2O, Na2B4O7–H2O, and NaBO2–H2O Binary Systems

This study aims to measure the solubility and binary eutectic point parameters (temperatures, densities, and compositions) of H 3 BO 3 –H 2 O, Na 2 B 4 O 7 –H 2 O, and NaBO 2 –H 2 O solid–liquid equilibrium systems. Eutectic temperatures were determined using multichannel thermometers equipped with high-precision Pt25 (±0.004 °C) sensors, whereas densities of the eutectic points were measured using a density meter equipped with an oscillating high-precision U-tube (±0.00005 g/cm 3 ) sensor. Chemical compositions of the binary eutectic point samples were analyzed using an ICP-OES instrument. Eutectic parameters, that is, temperature, density, and composition of the H 3 BO 3 –H 2 O binary system were determined to be −0.61 ± 0.01 °C, 1.0114 ± 0.0005 g/cm 3, and 2.37 ± 0.07 wt% respectively. Similarly, the same eutectic parameters were measured as −0.30 ± 0.01 °C, 1.0116 ± 0.0004 g/cm 3, and 1.05 ± 0.06 wt% for the binary system of Na 2 B 4 O 7 –H 2 O, whereas eutectic parameters of the NaBO 2 –H 2 O binary system were found to be −6.11 ± 0.01 °C, 1.1823 ± 0.0004 g/cm 3, and 13.40 ± 0.09 wt%.