Dissolved organic matter (DOM) has been widely existed in the soil, which has great influence on the adsorption of heavy metals by minerals. In this paper, the effects of DOM on Cd (II) adsorption by calcite were studied. In the presence of DOM (5 mg/L, 10 mg/L, and 20 mg/L), the maximum sorption of Cd (II) by calcite reduced from 48.94 mg/g to 44.14 mg/g, 28.11 mg/g, and 22.30 mg/g, respectively. The characterizations (XRD, SEM, XPS, FTIR, 3D-EEM, and UHPLC-Q-Orbitrap) were used to further study the mechanism about the effects of DOM on the adsorption of Cd (II) by calcite. These results showed calcite exhibited a significant adsorption capacity for Cd (II) at pH = 6.0, and CdCO3 was formed on the surface of calcite after calcite reaction with Cd (II). Meanwhile, the fractionation of DOM by calcite could change the binding characteristics of DOM to calcite, which would increase the migration of Cd (II) in the solution. After the reaction of DOM with Cd (II) and calcite, Cd (II)-DOM complex was formed, and part of calcite was dissolved in the solution which would further increase the migration of Cd (II) and decrease the adsorption of Cd (II) by calcite. This paper might help further understand the effect of calcite and DOM on the environmental behavior of Cd (II) in the soil environment.
Keywords: Bivalent cadmium; Calcite; Dissolved organic matter; Interface reaction.
© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.