Recovery of Pd(II) from Aqueous Solution by Polyethylenimine-Crosslinked Chitin Biosorbent

This study reports the recovery of Pd(II) from acid solution by a polyethylenimine (PEI) crosslinked chitin (PEI-chitin) biosorbent. FE-SEM analysis demonstrated that there are many slot-like pores on PEI-chitin. N2 adsorption-desorption experiment revealed that the average pore size was 47.12 nm. Elemental analysis verified the successful crosslinking of PEI with raw chitin. The Langmuir model better explained the isotherm experimental data and the theoretical maximum Pd(II) uptake was 59.6 mg/g. The adsorption kinetic data was better described by pseudo-second-order model and the adsorption equilibrium was achieved within 30 min for all initial Pd(II) concentrations of 50-200 mg/L. In the fixed-bed column, the adsorption of Pd(II) on PEI-chitin showed slow breakthrough and fast saturation performance. The desorption experiments achieved a concentration factor of 8.4 ± 0.4. In addition, adsorption-desorption cycles in the fixed-bed column were performed up to 3 times, consequently confirming the good reusability of PEI-chitin for Pd(II) recovery. Therefore, the PEI-chitin can be used as a promising biosorbent for the recovery of Pd(II) in practical applications.