Solubility products of sparingly soluble barium perborates in aqueous solution that contains B(OH)3 and H2O2 at 25 °C

Reclaiming Boron as Calcium Perborate Pellets from Synthetic Wastewater by Integrating Chemical Oxo-Precipitation within a Fluidized-Bed Crystallizer

“…No obvious characteristic peaks are found to indicate the crystallinity of the proposed precipitated compounds, such as CaB­(OH) 3 OOB­(OH) 3 and Ca­(B­(OH 3 )­OOH) 2 . Restated, the calcium perborate shall be amorphous, unlike BaB­(OH) 2 (OO) 2 B­(OH) 2 which formed from slow phase transformation of Ba­(B­(OH 3 )­OOH) 2 using barium salt as a precipitant . The formation of CaCO 3 was attributed to the precipitation of Ca with the absorbed CO 2 in alkaline solution, consuming calcium salts and thereby reducing BR in the aforementioned discussion.…”

“…Our previous research revealed that pH significantly affected the solubility of barium perborates due to the speciation of peroxoborate anions (B­(OH) 3 OOH – , B­(OH) 2 (OO) 2 B­(OH) 2 2– , and B­(OH) 2 (OOH) 2 – ) . Starting with synthetic wastewater containing 1000 ppm-B, COP was conducted with a molar ratio of [Ca]/[B] of 1, [H 2 O 2 ]/[B] of 2, and varied reaction pH from 7 to 11.…”

“…In alkaline solution (pH > 11), the hydroxyl ion competes the Lewis acid sites of boron with hydrogen peroxide and thus borate anion (B­(OH) 4 – ) dominates the species of boron. Therefore, the dissolution of metal perborate improves at pH higher than 11 . On the other hand, the solution was exposed to open air.…”

“…As displayed in Figure c, BR and CR are around 50% when a surface loading is lower than 2 kg m –2 h –1 ; CR declines to below 10% as L increases beyond 3 kg m –2 h –1 . Since varying the surface loading by controlling the flow rate directly changed the HRT, shortening the HRT (from 1 h to 18 min for an L of 3.3 to 0.8 kg m –2 h –1 ) and reducing the frequency of collision of the initially formed small nuclei . Meanwhile, a high up flow rate also caused the easy draining out of small particles from the fluidized-bed reactor before they could agglomerate to form larger ones.…”

“…). 26 Starting with synthetic wastewater containing 1000 ppm-B, COP was conducted with a molar ratio of…”