X-ray Micro-spectroscopic Investigations of Ni(II) Uptake by Argillaceous Rocks of the Boda Siltstone Formation in Hungary

Synchrotron-based μ-focused X-ray fluorescence, X-ray diffraction and X-ray absorption spectroscopy were applied to identify the potential minerals responsible for the uptake of Ni in microscopically heterogeneous clay-rich rock samples, originating from the Boda Siltstone Formation (BSF, Hungary). The X-ray fluorescence measurements indicate a correlation of Ni with Fe- and K-rich regions suggesting that Ni is predominantly taken up by these phases. X-ray diffraction identified the Fe- and K-rich regions as illite and iron oxides, respectively. X-ray absorption spectroscopy demonstrated that under the experimental conditions employed inner-sphere complexation of Ni(II) to clay minerals prevail, indicating that illite and iron oxides are an effective sink for Ni(II) in BSF. (authors)