Home – Home – Jornals – Chemistry for Sustainable Development 2017 number 4

The paper studied an opportunity of obtaining bismuth formates from solid basic bismuth nitrate by its interaction with formic acid solutions of different concentrations at process temperatures of (22±1) and (55±2) °С. Interaction products of bismuth oxohydroxonitrate having the composition Bi₆О₄(ОН)₄(NO₃)₆ • H₂O with formic acid solutions were studied by X-ray phase analysis (XPA), thermogravimetry (TG), electron microscopy, IR spectroscopy, and chemical analysis. It was found that solubility isotherms had two branches driven by the formation of bismuth formates with the composition BiOCOOH and Bi(COOH)₃ and proceeded via a maximum at bismuth concentrations in solutions of 31 and 23 g/L at 22 and 55 °C, respectively. An opportunity to obtain bismuth oxide formate was demonstrated through treatment of bismuth (III) formate with water at the mass ratio of water to bismuth formate of 10. Bismuth oxide formate is spherical particles with a size of about 6 µm comprising of smaller crystals, and middle-sized bismuth is needles crystallised as druses with a size of about 100 µm. It was demonstrated that thermal decomposition of basic bismuth formate in air allowed obtaining tetragonal (β) bismuth oxide. It was found that thermal decomposition of a mixture of bismuth oxide formate and oxohydroxynitrate (~50 %) proceeded in several steps, began at 200 °С and completed at 560 °С with the formation of monoclinic (β) bismuth oxide. It was demonstrated that thermal decomposition of a mixture of bismuth oxonitrate/oxoformiate was a promising synthesis method of basic bismuth oxonitrate with the composition Bi₅O₆(NO₃)₂OH or Bi₅O₇NO₃.