Fig. 7. The spectra of 4-NP and 2-NA with the addition of NaBH₄ (a and b). Curves of the catalytic reduction of 4-NP (c) and 2-NA (d). Plots of ln(C_t/C₀) versus time for 4-NP (e) and 2-NA (f). Pictures (insets in (c) and (d)) represent the solutions before/after the catalytic reaction.