Clarification For Hg (II) Removal Mechanism in Ferrihydrite Co-Precipitaion Process by XAFS Analysis
Inorganic mercury is known as one of the toxic elements and strictly regulated by Japanese effluent standard that need to be under 0.005 mg/dm3 for discharged water. This value is the lowest among other inorganic toxic elements regulated in Japan. As a result, high quality method has been required for Hg(II) wastewater treatment. Objective of this study is to clearify Hg(II) removal mechanism using ferrihydrite in co-precipitation process. Isotherm drawing, X-ray diffraction (XRD) and X-ray Adsorption Fine Structure (XAFS) analysis were conducted for both co-precipitation and adsorption processes to investigate the immobilization mechanism at pH 4. These experimental results suggested that the sorption mechanism of Hg(II) with ferrihydrite was almost the same between co-precipitation and adsorption processes, but it involved not only surface complexation but also three dimensional uptakes such as surface precipitation.
Index terms- XAFS, Co-precipitation, Hg(II) removal, Ferrihydrite, Isotherm