Fig. 3 – Decolourization demonstration based on acid–base reaction. (a) t =
−5 s, pre-injection, acidic solution; (b) t = 0,
injection of base; (c) t = 2 s; (d) t = 10 s; (e) t = 120 s; (f) t = 1600 s (highlighted green areas: isolated mixing regions [IMRs];
transparent area: active mixing regions [AMRs]). (For interpretation of the references to colour in this figure legend, the
reader is referred to the web version of this article.)