Spectrometry recognition of polyethyleneimine towards heavy metal ions

- The UV-vis spectrum of PEI and complexes with metal ions were investigated.
- The UV-vis detection method of Cu2+, Co2+ and Cr3+ with PEI was established.
- Stoichiometric ratios of amino groups and Cu2+, Co2+, Cr3+ are 4:1, 4:1, and 3:1.
- Adsorption process of PEI fitted Freundlich equation better than Langmuir.
- Coordination of PEI with metal ions is exothermic, entropy increasing reaction.