Effect of HNO3 concentration on a novel silica-based adsorbent for separating Pd(II) from simulated high level liquid waste

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 K d 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.