Thermodynamic and Dynamic Modeling of the Boron Species in Aqueous Potassium Borate Solution

Abstract

The concentration of B(OH) 3 , B(OH) 4 − , B 3 O 3 (OH) 4 − , and B 4 O 5 (OH) 4 2− in the solution and the solubilities in the system KCl−K 2 SO 4 −K 2 B 4 O 7 −H 2 O and its subsystems were calculated on the basis of the Pitzer model. The mole fraction of the four boron species is mainly affected by m(B) in the solution but less by m(Cl − ) and m(SO 4 2− ). m(Cl − ) and m(SO 4 2− ) mainly affect the solubility of K 2 B 4 O 5 (OH) 4 •2H 2 O. The calculated solubilities in the system KCl−K 2 B 4 O 7 −H 2 O agree well with the experimental data. The results show that the standard chemical potentials of K 2 B 4 O 5 (OH) 4 •2H 2 O at 298.15 K obtained in this work is reliable.The transformation between the boron species at 298.15 K was also conducted with the density functional theory (DFT) method. The results affirm that the boron species can transform other boron species as the boron concentration in the solution changes.

Density, pH, and Boron Species in the Ternary System NaBO2–Na2SO4–H2O at 298.15 K and 323.15 K

“…With the pH values in the solution and equilibrium constant between different boron species, the distribution of boron species was calculated [12][13][14][15]. e calculated results in these literatures [13,14] are in agreement with those with the Pitzer model in the systems NaBO 2 −H 2 O and K 2 B 4 O 7 −H 2 O [9,10]. e concentration of boron species was calculated in references [12][13][14][15], and it was considered that the activity coefficients of all boron ions were 1.0.…”

“…e distributions of boron species in the system NaCl−NaSO 4 −NaBO 2 −H 2 O were also calculated in our previous work [9]. e preponderant boron species is B(OH) 4 − , whose mole fraction is more than 0.95. e calculated results for distribution of boron species in the system KCl−K 2 SO 4 −K 2 B 4 O 7 −H 2 O at 298.15 K show that the mole fraction of the boron species is mainly affected by the concentration of boron but no other anions in the solution [10].…”

Insights into the borohydride electrooxidation reaction on metallic nickel from operando FTIRS, on-line DEMS and DFT

“…According to the literature data [41], the observed spectral features are indicative of the presence of tetrahedral B(OH)4ions with 1150 and 935 cm -1 peaks corresponding to the asymmetric stretching of the B-OH and to the B-O-H bending. The 1150 cm -1 peak is very broad, which may be attributed to the formation of polyborates due to the tendency of metaborate to polymerize in aqueous solutions at concentrations above 50 mM [42,43]. In NaOD + D2O, both peaks shift to lower frequencies (1030 and 835 cm -1 ).…”

Electrically programmable adhesive hydrogels for climbing robots

“…Besides, K 2 B 4 O 7 (as evidenced by the XPS result in fig. S3B) and tetrahydroxyborate anions may contribute to the hydrogel conductivity (48,49). Because most of these ions are introduced into TBVA hydrogels by the cross-linker TB, it is understandable that a higher content of cross-linker leads to an improved conductivity.…”