Reusable polyethylenimine-coated polysulfone/bacterial biomass composite fiber biosorbent for recovery of Pd(II) from acidic solutions

• As a biosorbent for Pd(II), the sorptive properties of PEI-PSBF were evaluated.
• Compared to PSBF, the maximum uptake of PEI-PSBF was enhanced up to 7.0 times.
• A mixture of HCl and thiourea was an effective eluent for the recovery of Pd(II).
• The developed biosorbent could be regenerated at least five times.

This study presents the applicability and reusability of polyethylenimine (PEI)-coated polysulfone/Escherichia coli biomass composite fiber (PEI-PSBF) as a biosorbent for recovery of Pd(II) from acidic solutions. To enhance accessible surface area for Pd(II), PEI-PSBF was fabricated by first extruding polysulfone/biomass blend into water, next coating with PEI onto the surface of the polysulfone/biomass composite fiber (PSBF), and finally cross-linking with glutaraldehyde. In batch sorption experiments, adsorption capacity of the PEI-PSBF for Pd(II) was compared with that of PSBF to investigate the enhancement by PEI coating on adsorption. In result, the sorption kinetics and isotherms showed that the sorption kinetics of Pd(II) was fast, and the maximum sorption capacity of PEI-PSBF was 7.0 times higher than that of PSBF. Additionally, it was observed that the sorption capacity of PEI-PSBF was significantly depended on the HCl concentration and the optimal range of HCl concentration to achieve high sorption capacity was found to be 0.1–1 M. After adsorption, Pd(II) loaded on the PEI-PSBF could be recovered using a mixture of 0.1 M HCl and 0.01 M thiourea solution. The desorption efficiency of the mixture was approximately 97.4%. Finally, in regeneration test of the biosorbent, it was confirmed that the PEI-PSBF can be regenerated at least five times.