Home – Home – Jornals – Chemistry for Sustainable Development 2021 number 1

The spherical microstructures of bismuthyl (III) fumarate with the composition (BiO)₂С₄H₂O₄ were obtained using the standard method of precipitation from solutions at 23 and 60 ºС. The composition of the reaction product and its properties were studied using a complex of physicochemical methods. At 60 ^oC, the degree of bismuth precipitation in the product is not less than 99.8 % for the molar ratio of bismuth to fumarate ion equal to 1.5. According to IR and Raman spectroscopy data, both acidic residues of fumaric acid are deprotonated in the resulting compound, while the carboxylic groups have bidentate coordination to bismuthyl cation. The effect of temperature on the morphology of obtained compounds was studied by scanning electron microscopy and small-angle laser light scattering. According to scanning electron microscopy data, (BiO)₂С₄H₂O₄ obtained at 23 ºC is composed of spherical particles about 10-12 µm in size, consisting of thin nanoplates about 0.1 μm thick. The data of sedimentation analysis of the powder indicate a symmetric particle size distribution with the average particle size equal to 11.7 μm. With an increase in precipitation temperature to 60 ^oC, particle size decreases to 3-7 µm; an asymmetric function of particle size distribution is observed, and the average size of the aggregates is 30.9 µm. A possible mechanism for the formation of (BiO)₂С₄H₂O₄ spherical microstructures is described as a process combining Ostwald ripening and self-assembling. According to the data of thermal and XRD analyses, the product of thermal decomposition of bismuthyl fumarate at a temperature of 450 ºC is a monoclinic modification of Bi₂O₃.