Simultaneous adsorption of Sr 2+ and ReO 4 − , which are surrogates of 90 Sr 2+ and 99m TcO 4 − , on hexadecyl pyridinium (HDPy + )-modified montmorillonite (HDPy/Mt) was investigated. When the amount of HDPy + corresponding to 0.92 times the cation exchange capacity (CEC) of Mt was added, the obtained composite (HDPy/Mt–0.92) showed considerable adsorption capacities for Sr 2+ and ReO 4 − . Some HDPy + desorbed from the Mt layer in the presence of ReO 4 − , providing negatively charged sites on the Mt surface for Sr 2+ adsorption. The desorbed HDPy + interacted with ReO 4 − and was trapped in the composite in the form of HDPy–ReO 4 , resulting in adsorption of ReO 4 − . At high initial concentrations of ReO 4 − , the HDPy configuration changed after adsorption because of the desorption–adsorption process, which was supported by X-ray diffraction. Based on the results of X-ray photoelectron spectroscopy, in the binary system (i.e., Sr 2+ and ReO 4 − ), Sr 2+ uptake occurred in the interlayer space, while adsorption of ReO 4 − occurred on the external surface and probably in the interlayer space. Desorption–adsorption and ion exchange account for Sr 2+ uptake, while adsorption of ReO 4 − was mainly attributed to desorption–adsorption. Compared with the one-adsorbate system, a synergistic effect of simultaneous adsorption of Sr 2+ and ReO 4 − was found in the two-adsorbate system.
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Physics and Astronomy(all)
- Surfaces and Interfaces
- Surfaces, Coatings and Films