Adsorption of Se species on crushed granite: a direct linkage with its internal iron-related minerals.
The adsorption of selenium species on crushed granite is investigated directly linking to its internal iron-related minerals. Experimental results demonstrated that granite has higher affinity toward Se(IV) adsorption than Se(VI) adsorption. Se(IV) adsorption on granite is insensitive to background electrolytes while the effect of ionic strength on Se(VI) adsorption is not observed, which is attributed to the overloading of Se(VI) ions. Results of chemical sequential extraction showed that the removal of crystalline iron oxides dramatically reduces Se(IV) adsorption, which corresponds to the disappearance of goethite signal within XRD pattern. Based on our results, it is proposed that goethite within granite dominates Se adsorption in crushed granite. Although these goethites probably stem from some sample preparation processes including drilling in situ, crushing, washing and drying granite samples in laboratory, the formation of goethite enhances the granite affinity toward Se species adsorption. Images of SEM/EDS furthermore revealed that goethite is embedded within the fractures. In addition, quantification by standard addition method by spiking goethite suspension indicates that only around 20% of goethite minerals are available during Se(IV) adsorption.
Jan
Yi-Lin
YL
Department of Civil Engineering, Ching Yun University, Jungli 320, Taiwan, ROC.
Wang
Tsing-Hai
TH
Li
Ming-Hsu
MH
Tsai
Shih-Chin
SC
Wei
Yuan-Yaw
YY
Teng
Shi-Ping
SP