Adsorption Behaviors of Palladium(II) in Simulated High-Level Liquid Waste Using 2,2’-[(2-ethylhexyl)imino]bis[N,N-bis(2-ethylhexyl)acetamide]-impregnated Adsorbent

A hybrid donor compound 2,2’-[(2-ethylhexyl)imino]bis[N,N-bis(2-ethylhexyl)acetamide] (DAMIA-EH) impregnated silicabased adsorbent [(DAMIA-EH+1-dodecanol)/SiO2-P] was prepared. Its adsorption performance toward Pd(II) in nitric acid solution was investigated by examining the effect of contact time, temperature etc. It was found that the adsorption rate of Pd(II) was fairly fast and can reach a constant state within only 10 min. (DAMIA-EH+1-dodecanol)/SiO2-P exhibited an excellent recognition ability toward Pd(II) than other 14 types of co-existing metal ions and could maintain this selectivity when the concentration of HNO3 varied from 0.5 to 5 M. On the other hand, the maximum adsorption amount of Pd(II) was calculated to be as high as 0.440 mmol/g when [HNO3] = 2 M. Moreover, with increasing the temperature in solution, the uptake ratio of Pd(II) slightly decreased, it still exhibited a dominant selectivity toward Pd(II) in a wide temperature range from 288 to 323 K. The fitted thermodynamic parameters revealed that the adsorption process of Pd(II) was exothermic in nature and happened spontaneously.