Abstract
A new kind of silica-based (Crea + TODGA)/SiO2-P adsorbent with high selectivity adsorption for palladium (Pd) was synthesized to examined the applicability for partitioning process of high level liquid waste (HLLW). Adsorption behavior of Pd(II) towards (Crea + TODGA)/SiO2-P adsorbent and stability of adsorbent against HNO3 solution were investigated by batch method. The degradation parts of (Crea + TODGA)/SiO2-P dissolved in liquid phase were estimated by total organic carbon (TOC) analyzer. (Crea + TODGA)/SiO2-P adsorbent showed good selectivity adsorption for Pd(II) and reached equilibrium within 24 hr. The adsorption ability of (Crea + TODGA)/SiO2-P for Pd(II) and the content of TOC leaked decreased with the increasing of HNO3 concentration. In 3 M HNO3, the average of Kd values were 85.03 cm3/g and 26.10 cm3/g after contact time one to 28 days at 298 K and 323 K, respectively. While the content of TOC leaked from the adsorbent after 28 days were 1095 ppm (298 K) and 2989 ppm (323 K), respectively. Therefore, the adsorbent showed good stability at 298 K after contact with nitric acid for a long time. All results indicated (Crea + TODGA)/SiO2-P can be proposed as an applicable and efficient absorbent for separation of Pd(II) in 3 M HNO3 at 298 K.
Highlights
While the content of total organic carbon (TOC) leaked from the adsorbent after 28 days were 1095 ppm (298 K) and 2989 ppm (323 K), respectively
For separation Pd(II) from high level liquid waste (HLLW), a new kind of silica-based (Crea + TODGA)/SiO2-P absorbent was prepared by impregnation of Crea and TODGA two extractants into SiO2-P support with a mean diameter of 50 μm
The nitric acid resistances of (Crea + TODGA)/SiO2-Pabsorbent and the degradation of the absorbent were investigated by batch methods
Summary
Considering of the service life of adsorbent, effect of contact time on the adsorption of Pd(II) towards (Crea + TODGA)/SiO2-P adsorbent in 0.1 M and 3 M HNO3 was observed at temperature 298 K and 323 K to further understand the resistant behavior of (Crea + TODGA)/SiO2-P adsorbent against nitric acid. In 0.1 M HNO3 solution, adsorption of Pd(II) on (Crea + TODGA)/SiO2-P adsorbent increased with contact time increase from 1 day to 28 days which showed similar adsorption behavior at 298 K and 323 K. The adsorption ability of (Crea + TODGA)/SiO2-P adsorbent for Pd(II) was obviously reduced under the effect of the high temperature and high HNO3 concentration. The influence of low temperature on the stability of (Crea + TODGA)/ SiO2-P in low HNO3 concentration was basically permissible under experimental conditions
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