Importance of the coating pH in fabrication of polyethylenimine-coated polysulfone-Escherichia coli composite fiber sorbent

•The pH is the crucial factor that affecting PEI-coating for PEI-PSBF.•The optimum pH for PEI-PSBF fabrication was around pH 9.•The speciations of E. coli and PEI could be obtained from titration and modeling.•Maximum electrostatic force between biomass and PEI was showed at around pH 9.2.

In present study, polyethylenimine-coated polysulfone-Escherichia coli biomass composite fibers (PEI-PSBFs) were prepared at different PEI-coating pHs. The PEI-coating pH was the critical factor affecting Pd(II) uptake and the optimum pH was around pH 9. The type and amount of functional groups in the biomass and PEI were estimated using potentiometric titration and proton-binding modeling, and these results used to simulate the pH-dependent speciations of their functional groups. As a result, electrostatic interaction between negatively charged biomass and positively charged PEI was estimated to be the largest at pH 9.2, and was closed to the experimentally obtained optimum PEI-coating pH.

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