Spectrometry recognition of polyethyleneimine towards heavy metal ions

Branched Polyethyleneimine (PEI) is biocompatible material and has strong adsorption towards heavy metal ions for abundant amount of primary, secondary and tertiary amine. Spectral response of PEI towards different heavy metal ions was investigated in aqueous solution by UV–vis spectrophotometry. It was found that Cu2+, Co2+ and Cr3+ could be selectively recognized by PEI in terms of blue shift of characteristic absorption peak and changes of absorbance. Static coordination process and coordination dynamics between PEI and Cu2+, Co2+, Cr3+ were systematically investigated. Parameters including stoichiometric ratio, coordination equilibrium constant, isothermal adsorption equation, reaction kinetic equation, activation energy, reaction entropy and reaction enthalpy were calculated and discussed. The maximum adsorption capacity of Cu2+, Co2+ and Cr3+ at room temperature (298 K) was 234.25 mg/g, 184.98 mg/g and 52.08 mg/g, respectively, indicating that PEI has strong application in spectrometry recognition and adsorption of Cu2+, Co2+ and Cr3+ heavy metal ions.