Recovery of high-purity metallic Pd from Pd(II)-sorbed biosorbents by incineration

• The combined method of biosorption and incineration was used for the recovery of Pd.
• Temperature and Pd amount modulated the recovery efficiency and purity of Pd.
• Higher temperature up to 800 °C showed higher recovery efficiency and purity of Pd.
• Pure metallic Pd was recovered at 900 °C and 136.9 mg/g of Pd uptake.

This work reports a direct way to recover metallic palladium with high purity from Pd(II)-sorbed polyethylenimine-modified Corynebacterium glutamicum biosorbent using a combined method of biosorption and incineration. This study is focused on the incineration part which affects the purity of recovered Pd. The incineration temperature and the amount of Pd loaded on the biosorbent were considered as major factors in the incineration process, and their effects were examined. The results showed that both factors significantly affected the enhancement of the recovery efficiency and purity of the recovered Pd. SEM-EDX and XRD analyses were used to confirm that Pd phase existed in the ash. As a result, the recovered Pd was changed from PdO to zero-valent Pd as the incineration temperature was increased from 600 to 900 °C. Almost 100% pure metallic Pd was recovered with recovery efficiency above 99.0% under the conditions of 900 °C and 136.9 mg/g.