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Research article2022Peer reviewedOpen access

Bismuth(III) Forms Exceptionally Strong Complexes with Natural Organic Matter

Kleja, Dan B.; Gustafsson, Jon Petter; Kessler, Vadim; Persson, Ingmar

Abstract

The use of bismuth in the society has steadily increased during the last decades, both as a substitute for lead in hunting ammunition and various metallurgical applications, as well as in a range of consumer products. At the same time, the environmental behavior of bismuth is largely unknown. Here, the binding of bismuth(III) to organic soil material was investigated using extended X-ray absorption spectroscopy (EXAFS) and batch experiments. Moreover, the capacity of suwannee river fulvic acid (SRFA) to enhance the solubility of metallic bismuth was studied in a long-term (2 years) equilibration experiment. Bismuth(III) formed exceptionally strong complexes with the organic soil material, where >99% of the added bismuth(III) was bound by the solid phase, even at pH 1.2. EXAFS data suggest that bismuth(III) was bound to soil organic matter as a dimeric Bi3+ complex where one carboxylate bridges two Bi3+ ions, resulting in a unique structural stability. The strong binding to natural organic matter was verified for SRFA, dissolving 16.5 mmol Bi per gram carbon, which largely exceeds the carboxylic acid group density of this compound. Our study shows that bismuth(III) will most likely be associated with natural organic matter in soils, sediments, and waters.

Keywords

bismuth(III); metallic bismuth; fulvic acid; mor layer; EXAFS spectroscopy; dimeric bismuth(III) complex; X-ray diffraction; electron microscopy

Published in

Environmental Science and Technology
2022, Volume: 56, number: 5, pages: 3076-3084
Publisher: AMER CHEMICAL SOC