Role of pH in the Aqueous Phase Reactivity of Zerovalent Iron Nanoparticles with Acid Orange 7, a Model Molecule of Azo Dyes

Figure 3

Section (a): removal efficiency of AO7 (%) obtained with sample Fe_fresh at different initial pH values after 15 min (grey columns) and 60 min (light grey columns); numbers in parenthesis refer to pH values measured after 60 min. Section (b): UV-Vis spectra of 0.67 mM AO7 solution and of the supernatant solutions after 15 min and 60 min at both pH = 8.00 (grey curves) and pH = 2.00 (black curves).

(a)

(b)