Batch and Fixed-Bed Column Studies on Palladium Recovery from Acidic Solution by Modified MgSiO3.

Effective recovery of palladium ions from acidic waste solutions is important due to palladium's intensive usage as a catalyst for different industrial processes and to the high price paid for its production from natural resources. In this paper, we test the ability of a new adsorbent, MgSiO3 functionalized by impregnation with DL-cysteine (cys), for palladium ion recovery from waste solutions. The Brunauer-Emmett-Teller (BET) surface area analysis, Barrett-Joyner-Halenda (BJH) pore size and volume analysis, scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy and Fourier-Transformed Infrared (FTIR) spectroscopy have been performed to characterize this material. Firstly, the maximum adsorption capacity of the new obtained material, MgSiO3-cys, in batch, was studied. To establish the adsorption mechanism, the obtained experimental data were fitted using the Langmuir, Freundlich and Sips adsorption isotherms. Studies on the adsorption of palladium ions on the synthesized material were performed in a dynamic regime, in a fixed-bed column. The Pd(II) recovery mechanism in the dynamic column regime was established based on Bohart-Adams, Yoon-Nelson, Thomas, and Clark models. The obtained equilibrium adsorption capacity was 9.3 (mg g-1) in static regime (batch) and 3 (mg g-1) in dynamic regime (column). The models that best describe the Pd(II) recovery process for batch and column adsorption are Sips and Clark, respectively.