A multitracer study on the adsorption of 32 elements on a natural hematite (α-Fe2O3): effects of pH and fulvic acid

The distribution coefficients (Kd) of 32 elements from Na to Bi on a natural hematite (α-Fe2O3) were determined at pH 4, 7, 9 and in the presence and absence of fulvic acid (FA) by using a multitracer technique and the batch method. The multitracer solution was prepared by irradiation of Th(NO3)4 with 40Ar ion beam. The effects of pH and FA on the Kd values of 32 elements on the natural hematite were studied. It was found that both the sequences of alkali elements and alkaline earth elements can be roughly explained in terms of chemical bond formation and ion hydration enthalpies. Though the various effects of pH and the positive and negative effects of FA on the Kd values of 32 elements were found, the prevailing tendencies were the increase in Kd value with increasing pH and the negative effect of FA on the adsorption of elements from Na to Bi at very low concentration and pH 7. The adsorption of lanthanides on the hematite against the atomic number exhibited approximately as a “W” figure, the peak was around the element Tb and the valley was around the elements Eu and Yb.