Fig. 1

Principal component analysis (PCA) on [EMIM][CH₃COO]-activated samples compared to untreated hybrid poplar. The principal component analysis (PCA) for [EMIM][CH₃COO]-activated samples at 3-, 24-, 48-, and 72-h activation times compared to an untreated control sample. The scores plot is shown on the top (a), and the loadings’ plot for PC1 on the bottom (b)