EPR Spectroscopy Investigation of Cu²⁺ Ions Adsorbed in Tannin-Formaldehyde Resins of Mimosa (Acacia mearnsii) Bark Extracts

Figure 2

Room temperature EPR spectra of the heated tannin-formaldehyde resins loaded with copper in an open tube (a) and under vacuum (b).

(a)

(b)