Degradation kinetics of both pigment and color has
been found to follow first-order reaction kinetics as have
been seen in case of Ahmed, Kaur, and Shivhare
(2002a); Ahmed, Shivhare, et al. (2002b); Ahmed,
Shivhare, and Raghavan (2000a, 2000b); Gunawan
and Barringer (2000); Hutchings (1994); Steet and Tong
(1996); Weemaes et al. (1999). The first-order kinetic
model can be represented as,