Analytical Sciences

Adsorption Behaviors of Palladium Ion from Nitric Acid Solution by a Silica-based Hybrid Donor Adsorbent

Hao WU, Naoki OOSAWA, Masahiko KUBOTA, and Seong-Yun KIM

Department of Quantum Science and Energy Engineering, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan

The adsorption behaviors of a silica-based hybrid donor adsorbent (TAMIA-EH+1-dodecanol)/SiO₂–P towards Pd(II) were investigated under the effect of the contact time, temperature etc. in simulated high-level liquid waste. The adsorption rates of Pd(II) and Re(VII) were fairly fast and could reach the equilibrium state in only 1 h compared with other co-existing metal ions. The adsorption kinetics of Pd(II) was found to fit well with the pseudo-first order model. Even though with increasing the concentration of HNO₃ above 1 M, the adsorption performance of (TAMIA-EH+1-dodecanol)/SiO₂–P decreased gradually; it still exhibited a better selectivity towards Pd(II) when [HNO₃] > 0.5 M. The adsorption isotherms of Pd(II) and Re(VII) were well-described by the Langmuir isotherm model, while the Freundlich isotherm model was considered to be more suitable for the adsorption of Ru(III), Zr(IV) and Mo(VI). A high temperature of an aqueous solution was not good for the effective recovery of Pd(II). The calculated thermodynamic parameters revealed that the adsorption of Pd(II) was exothermic in nature.

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